08:00:51 Okay. 08:05:03 Okay, It's now five past the hour. 08:05:07 So I welcome back to the workshop, they do. 08:05:12 And we have our first keynote talk today. 08:05:16 Before I introduce the speaker, I just want to mention the format. We've asked Hsiao-Wen Chen to talk for about 45 minutes, give or take. And what we're going to do is after that's done, we're going to have like a five minute break, where you can start putting 08:05:32 into the chat. 08:05:33 Okay, so you're going to put questions into the chat window, and then we'll go through the chat questions and see for kind of as long as it takes to kind of get a good discussion of what the talk was about what questions people might have. 08:05:49 And I don't know exactly how long that's going to go. 08:05:53 So now I want to introduce our speaker Hsiao-Wen Chen. 08:05:58 Hsiao-Wen has been working on the CGM since before we know it was called the CGM and. 08:06:07 And when we thought about how to, how to gases Halo is kind of Halo mass, she's working everything from the CGM around dwarfs to the CGM around a massive logical galaxies. 08:06:19 So I thought that would be good way to kick off our consideration of this question. So I'm going to stop sharing and share when to start sharing and get going on our talk. 08:06:36 Hey, they see. 08:07:06 I'm seeing it. Here we go. 08:07:11 So, good morning. For those who are in the US, and even for those who are outside of the US. Glad to be here today as Mark said, I'll be working on gaseous halo properties for a while now. 08:07:28 It has been a exciting time. And I'm glad to be here to share some of my perspectives and, and those as Mark mentioned this week's motivating question is on how gaseous Halo depend on, gaseous halo properties depend on Halo mass, and specifically 08:07:45 my assignment is about how the cool face in the gaseous Halo depend on Halo mass, up from low mass scale up to about 10 to 13 solar mass. Understand that Megan will be focusing more on the X ray properties of more massive halos on Thursday. 08:08:07 So before I start, I want to acknowledge some of my longtime collaborators listed down here, in particular, I want to highlight my former students who whose work I will be highlighting in the next 45 minutes. 08:08:23 Fun-Hsin Huang, a finishing grad student at University of Arizona. Shawn Johnson, starting assistant professor at the University of Michigan and Arbor, and Fakhri Zahedy, Carnegie Fellow at Santa Barbara Street. 08:08:40 So just a quick outline. 08:08:54 First I will outline what we have learned, based on the ensemble statistics. Average properties around different Halo populations, and then we'll move into more detailed discussion about different physical properties of individual Halo content. 08:09:14 But before we get into the detail, I like to cover some brief background overview, just to be on the same page. 08:09:24 So I'd like to start with this galaxy mass function. 08:09:29 Basically this is a theoretical view of the summarizes the success, and also some issues you may need in our understanding of galaxy formation and evolution. 08:09:41 What you see here, this is the expectation, assuming path make me have baryon fracture in dark my halos and different curves show different expectations from different simulation work. 08:09:57 If you can, squint your eyes you can see data points. These are observations 08:10:03 on the X scale up x axis, you know you can see the still MS ranges from anywhere below 10 to the nine to be on ten to their 12 solar masses. 08:10:16 And it's well known that the mass fraction is suppressed at both low and high mass and and conventionally This is understood is due to feedback at low mass in specific specifically is be attributed to star supernova feedback in the low mass doors. 08:10:39 While at a time as an AGM feedback is frequently in volt. And you can see that, while it provides a general success in suppressing there's still a mass fraction. 08:10:51 There's still a lot of scattered in different theoretical models. In fact, if you look at observations. There's also sufficient negligible discrepancy between different measurements. 08:11:05 So I think it's good to keep that in mind. 08:11:25 But what's relevant to the discussion today is nationally, we talked about feedback inside galaxies, one would also expect that they will also influence the surrounding gaseous halos. 08:11:23 And this is a nice opportunity I borrowed from Andre Kravtsov from his talk edison around two years ago, they shows the complex interplay between gas and stoppers feedback, you can see a pristine get gas coming from the IGN feeding star formation is 08:11:45 the star formation, kick, the material out into the Halo, we would expect that the properties of the gaseous Halo to be modified accordingly. So, understanding the properties have been a good picture of how the CGM properties change with time, across 08:12:07 different mass range, really provide a critical and independent constraint on the overall galaxy formation as a model. 08:12:16 And so this is a comprehensive plot, again if I wrote from this nice review article by Jason Tumlison, Peeples, and Jess Werk from, from 2017 will show the shows here is from the in the background you can see the great skill 08:12:39 part two of distribution that shows the temperature and density face diagram of the fuse gas content. It goes from high density, low temperature up to low density and high temperature region. 08:12:54 And on top of that you can see a you know for many decades now, tracer absorption spectroscopy has provided very sensitive tool to prove this spacious content, because they are so many different line transitions. 08:13:10 that served as really sensitive tracer of these different faces of the depths of gas, and for the, for the context of this talk, in particular when we talk about cool gas content. 08:13:25 I have very liberally extend the temperature range up to beyond almost 10 million degree Calvin. So this is the range that I want you to focus on today for today's talk. 08:13:39 Beyond about a million degree Calvin expected that will be covered. On Thursday, and within this sort of cool guest face. You can see this is more than just the alphabet soup. 08:13:52 But the many sensitive strong absorption lines, they will come in a different wavelength, they've shown you the upper right panel here is a function of redshift. 08:14:04 You can see most of them really occurred in the UV range, they require the Hubble Space Telescope, UV spectrograph. And that's why we were here today because you're having tremendous progress coming out of many different survey projects using the 08:14:17 particular the cosmic cosmic or region spectrograph in the past decade. 08:14:25 A couple of exceptions. Here are the main medium to doublet that's down here, that really provides a very sensitive tracer if we're dense and co guess that they arise both in the eyes in, and also in dense, specifically dense quantum in the gaseous 08:14:44 Halo. So magnesium two and iron two a number of iron two lines can serve as a sensitive tracer of diffuse gas at relatively low ratio and easily accessible on the ground. 08:15:01 So, in case you're not familiar why if you have questions about why people care about magnesium two. This is the reason you're going to hear more about magnesium two later in a moment. 08:15:13 And in terms of mass dependence and like this figure from well fans. Recent papers from ego zoom. that shows the expected. 08:15:26 Extent of low ions is shown in the top row traced by silicon two from low mass attention to each other, solar masses to high mass beyond the normal mass is in contrast, you can see what we see, or what does simulation. 08:15:55 Show in terms of the high ions again so chased by oh six from low to high mass in I mean without showing any numbers. The visual difference is quite clear that it clearly depends strongly. 08:16:03 on The mass scale that we are looking at. 08:16:07 So, this is just to give you a general motivation, why we should care about gaseous properties as a function of mass. 08:16:20 But before I move on. I want to highlight a time before we get into the detailed discussion. While theoretically we want to understand halo gas property as a function of mass empirically is actually not so straightforward. 08:16:37 And the main reason is math is not observable. 08:16:40 And I think this is a good venue to remind ourselves that the way astronomers came to our experiments, is we we detect light. And we actually have to do a number, a number of maneuvers, the whole day to convert a light to mass, and the caveat counting immediately. 08:17:03 Based on this nicely summarized by the two panels here. This is also extracted from a reviewable article that was put together by Charlie Conroy in 2013. 08:17:16 It shows on the left, the cumulative still a mass for difference in usual mass function. 08:17:22 And it shows that most of any given any unusual stellar mass function. Most of the mass lighting in low mass stars, less than solar mass, whereas most of the light come out of massive stars and that's where our observation of signal is. 08:17:44 So when we talk about mass, the first order of businesses, really, we have to specify and justify the use of initial mass function for analysis. 08:17:54 And just as a tracer. I use 16 COS halos red galaxies. As an example, plotting the storm as estimated using Salpeter function, versus storm as estimated using their Chabrier in usual mass function, there's a clear system and offset systematic 08:18:18 offset by about one two decks. 08:18:22 Just between the two functions, along. 08:18:26 And on top of that Charlie also did a very extensive overview. If you haven't read that article I encourage you to do so. 08:18:35 depend on the total you use, and also different stellar libraries, there will be additional systematic differences in the, in the result. So that's the first step to go from observed light to Halo mass. 08:18:53 So now, it just assuming we can reach agreement using based on the stellar mass estimate. The next step is to go from stellar mass to Halo mass. 08:19:06 And here you can see in the middle. This is the current best estimated, I want to say best estimated but this is the latest resolve of how stellar mess is related to Halo mass from the recent paper by Peter Behroozi in 2019. 08:19:26 You can see more or less a tonic relation from. 08:19:40 Maybe you're more familiar with this on the Stairmaster halo mass relation, using the ratio in the y axis. 08:19:51 What I want to emphasize here is on top of the main relation. There's also a large amount of scatter from different work. So this is all summarized in Peter Behroozi's latest paper. 08:20:05 So you can also check it out. This is, in particular as your point one, which is relevant to most of the discussion today. 08:20:14 I want to highlight that. 08:20:16 Why it shows maybe, on average, point three Dec dispersion in the main relation. When we put a relation on top of the middle panel, a straightforward stellar mass to Halo mass ratio is clear. 08:20:32 I hope it's clear that. 08:20:35 Whoops. 08:20:39 halo mass depends on which relation you use. 08:20:45 It's gonna. It could result in more than an order of magnitude difference in the inferred halo mass. 08:20:52 So this is just a cautionary note, and usually I remember Mark mentioned that one of the topics for tomorrow is about bureau temperature estimate. So, here's one of the fundamental parameters. 08:21:07 Before we go into any derived for the right parameters, the starting point of the adopted Halo mass really is relevant. So I want to put that out there before we move on. 08:21:21 So nowadays the background just to highlight. 08:21:26 While the main caveat is that has been very much on my mind. So moving into the discussion on the halo gas property. I want to start with this summer. 08:21:39 Summary graph, just to highlight that how exciting The time has been for the CGM community. And this is just to highlight the mass distribution for different survey samples. 08:21:55 And I, I know that many of you can help me to to advocate for the fact that there are actually more sample that I can accommodate here. 08:22:06 In addition to the low mass. 08:22:11 For example, there was put together by Shawn Johnson back in 2017 now updated with new data from the news cube survey led by Yuo Shin, plus the luminous re galaxy sample. 08:22:29 that my group has been focusing on for the past few years, there's many other surveys, in addition to gas halos post doors. 08:22:34 I want to say what comes to mind include prospers, and cause gas plus individual efforts. But the main point is. 08:22:47 We had a lot of data, enormous amount of data, and low ratio range for a very detailed study of the CGM property. Right now we have sample that covers anywhere from 10 to the seven. 08:23:07 So the methods in stellar mass up to 10 to the 12. 08:23:07 So the masses. In comparison, I want to borrow this to show that I'm not sure if there's going to be a talk on the high ratio of universities. When I prepared with putting together to talk. 08:23:27 I feel like there should be, you know, there's another axis that goes point in time, going back to your high ratio. 08:23:28 In terms of the halo gas property, but given time limit I'm not gonna talk much about it, but just want to point out that this last panel here the green histogram shows the effort of coming out of the survey from Caltech that shows how at two 08:24:00 ish is really difficult to prove the low mass range that there's a normal set of data that focuses on ten to the ten solar mass range. And what you're going to hear a lot about is this new survey that focused on magnesium two search, you know the the tracer 08:24:09 we use I mentioned earlier, that's sensitive to dense and cool clumps, both in the ice and and in the circle galactic space was shown here is mass distribution of the latest sample that we put together from the M3 survey, which I will describe in a 08:24:28 moment, plus a large set of luminous red galaxy coming out of the slow Digital Sky Survey, that reaching help studied about five years ago now. 08:24:41 So it is mainly using this combined sample that we are able to learn quite a bit about the main properties of cool clumps in a wide range of Halo mass. 08:24:58 So just a few words on the M3 survey, this is the Magellan MgII Halo project that that's been going on for almost a decade now in collaboration with Steve checkmate. 08:25:12 Carnegie. This is a large sample of galaxies blindly selected from slaw that occurred in closed projected enclosed projected distance from a background Quasar all together. 08:25:25 We collected 380 galaxies, every show for less than point five. And I want to mention before I go on that. Incidentally in parallel, there's an independent effort coming out of the Durhing group led by Mughelli who also published a 08:25:45 paper, just last year. 08:25:48 The Magnesium two Halo gas property average of one, and the surprising thing is their finding is very much consistent with what we see at low ratio. 08:26:00 So, just to continue just summarizing the sample property. So of all the 380 galaxies. You can see the ratio of distribution, and also impact parameter distribution, Virginia Quasar satellite and location of the galaxy. 08:26:20 It goes all the way out to about 500 k PC, and it covers a wide range in luminosity that's something we can robustly measure it goes from less than a 10th L star to Super L star. 08:26:34 And because of the slow, you know, really exquisite slow data multi band for the metric data we're able to do comprehensive still a population synthesis analysis to country and both Stellar mass, and also using the spectra to infer the specific star formation 08:26:54 rate based on the observed a Java line flux. 08:26:58 Using there we can separate sub divide our sample into star forming Blue sequence with a active star formation in the recent past, and also more quiet and sample sample that has not shown really prominent star formation. 08:27:19 So, in the last couple years. 08:27:22 And just to convince you given the caveat aligned earlier that in terms of estimating the stellar mass, using the multi band pass data. We are pretty confident about the overall scaling the linear relationship between luminosity intrinsic luminosity and 08:27:42 stillness, coupled with the intrinsic difference in the star formation history. 08:27:48 They can be roughly captured by their resting optical color between the optical red band and dice also clearly shown here. 08:27:58 The main thing is, despite the uncertainty in the zero point in in the exact stellar mass scale. We are very confident about the overall scaling between within the sample itself. 08:28:15 So moving further into the, the magnesium two Halo property, out of this M3 sample, we are able to quantify the magnesium to show constraints as a function of distance. 08:28:30 At the top you can see this is the inferred copy of fracking incidents of the magnesium two transition. There's a general decline in terms of the incidence of the clumps. 08:28:45 And the points here are further divided into the blue and red galaxies that I mentioned earlier. 08:28:52 And, like, before we have tried to improve the inverse correlation we see here, the overall decline as we move to larger distances in the magnesium two strength. 08:29:07 When we actually include the mass scaling normalize the projected distance by mass to account for the size scaling relation it's clear that the inverse correlation is further tightened. 08:29:22 and at the top you can see that the incidence of these magnesium two features. Really declined rapidly. 08:29:32 Beyond the hundred k PC for a typical Milky Way type galaxy. 08:29:39 We can further move into using Halo radius, as inferred from Halo mass mentioned earlier that tells us. 08:29:52 While confirming the continuing declining trend to our larger radii that also shows that the incidence of this cool clumps these cool clumps reveal by magnesium two really drop. 08:30:09 Really quickly, beyond roughly half of their bluer radii. 08:30:13 In these halos. 08:30:15 So putting everything together. In terms of the mass dependence that's the main theme of this talk. This week, the workshop of this week. 08:30:28 This is showing the mean gas covering fraction, being cool gas covering fraction as proved by the magnesium two feature. 08:30:40 Average within the traditional gaseous radii I mentioned earlier roughly half of their bluer Radii versus the first stella mass. 08:30:50 This is combining RM three magnesium two sample with the slow luminous red galaxy sample into the 10 to the 13 stellar mass regime. So at the bottom you show, are your first stellar mass, at the top is the inferred Halo mass, using a relation that was published by 08:31:13 Andre Kartskov 1998. 08:31:15 And you can see have a very clear decline. 08:31:19 In addition to there's the mass dependence, as you go to a higher mass. 08:31:28 The incidence of these cool clumps appear to drop very fast. There's also a difference between different galaxies of different star formation history. 08:31:35 And that's captured by this next plot that shows the mean gas covering fraction as a function of specific star formation Ray. 08:31:48 And that means he raises question about whether the original these magnesium two absorbers, are they coming out of Starburst Reba outflows or is due to accretion. 08:32:00 They come to you from outside of the Halo. 08:32:06 So, to, to really address this question is non trivial, of course. 08:32:12 Correlation doesn't mean causality, but there are a few hints that we can, we can get from just looking at the data, the observations themselves. 08:32:25 The first one I would note is. 08:32:28 There's a reason why we're very interested in studying these luminous ray galaxies, given the fact that they haven't been forming stars for a couple of billion years will continue to see abundant presence of these cool clumps in these massive halos. 08:32:46 And you. In addition, when we actually look into the gas kinematics, we see that this is again ensemble average over a sample of 1000 galaxy absorber payers, we see that the lossy dispersion of the absorber around these luminous Ray galaxies appear to 08:33:12 be sub-virial. is less than what we would expect, just based on the simple inference, based on virial motion. 08:33:22 And this is nicely illustrated by this recent paper from Afruni and 08:33:32 in the, in the Netherlands, was what they show is, this is can be explained by the clumps, moving through a halo experiencing the drag have the energy being dissipated through the rem pressure drag in the interaction with a hot halo. 08:33:57 And that has a lot of implication for basically the massive creation rate, and also the survival time scale. 08:34:07 In the interest of time, I will leave the detail to later discussion. 08:34:12 But, so, you will do for the rem pressure drag to be effective, that you pose a strong limit on the mass of the clump individual clumps that presumably are falling through the hot Halo, using a simple assumption. 08:34:31 The limit will work out is, is actually quite stringent opt to ten to the four solar mass level. 08:34:36 And if we just assume a typical hot halo low profile. The expectation is the clouds will either evaporate and. 08:34:46 But when we look into the m3 galaxy sample that's more typical of L star galaxies. To our surprise, we don't see such suppression, in terms of the velocity dispersion in more typical mass halos, we see that either is less than 10 to the two times 08:35:06 10 to the 10 solar masses, or just beyond that, the observed velocity dispersion is very comparable to what we would expect, based on bureau motion, and using the same calculation, we would infer, either. 08:35:22 The clump is more massive in these lower mass halos will have to be more than 100,000 solar masses, or this is a strong implication on the properties of the hot halo around these galaxies. 08:35:40 I expect this is an area, we will learn a lot more in the CNBS 4 era. Where are the seniors although the observation will be more sensitive down to this kind of low mass scale, or perhaps in the links era maybe they will be able to prob down to te 08:35:58 to the ten solar mass Halo, the, you know, put some constraint on the, on the heart plasma around these relatively low mass galaxies. 08:36:09 So I want to mention that this is while we observed at low ratio of the Washington spiritual in between the core clumps and the galaxies appear to be either comparable to what we expect from real motion in the halo or suppressed in more massive luminous 08:36:26 galaxy halos. This is very different from what people will see a heavier ship universe. And this is a part of our ongoing Rudie's paper from 1990. They shows that many of the galaxies show absorption systems that exceed the velocity expected for these 08:36:46 galaxies. So while they are. So again, when coupled with star formation history. We do see very different behaviors, between galaxies from different app box. 08:36:59 So before I move on to lower mass doors. I want to also mention that in addition to magnesium two. We are now also able to put constraints. 08:37:12 The oh six Halo, in terms of mean, oh six gas covering fraction. What you see here at the top panel is the mean covering fraction for oh six from 10 to the ten solar mass Halo instill a mass out to, again, lrG level, at the top, just to for contrast and 08:37:32 comparison. This is the first Halo mass. 08:37:49 With these different galaxy sample. Down here we show them mean 06 top density. And this is really, because of the large amount of HST data that allows us to put constraints on stellar mass gas calm density. 08:37:54 And in comparison to simulation expectations again from one of Ben's paper back in 2018. 08:38:01 While the oh six in magnesium two you can see that they come from very different analyzation state, but we see general overall decline in terms of the incidence and presence of these ions, as we move into the high mass region. 08:38:22 And so now moving in to the low mass halos. 08:38:28 In this particular talk, I want to focus on really low mass content below 10 to the nine solar masses. This is really, if you recall back to the first part I show this is where theoretical work expects supernova feedback dominates the, 08:38:53 the feedback. Basically, drive the suppression of star formation in these low mass Halo. And this was made possible by, you know, continuous effort being finding these little mass galaxies from deep galaxy surveys, this is part of Sean Johnson's thesis, 08:39:12 he started out with, with a very complete data set, we can identify these dwarves, then that are relatively isolated with no nearby massive galaxies, meaning they are not civilized, but more likely to be central galaxies. 08:39:29 And right now we have increased the sample to do much more statistically representative study, but just to show you what we are talking about here. This is a field. 08:39:42 A very fortunate field where we see two of the such examples. I want to highlight this. The so called D1 here at 16 k PC from the background Quasar from available HST spectra. 08:40:01 We see a series of the social features including hydrogen, oh six and other ions. 08:40:13 So for those who are not familiar with this. 08:40:15 This kind of clump. 08:40:17 Just know that the zero velocity here corresponds to the systemic ratio of the galaxy. So we put the absorption feature centered on the system a velocity, the line of sight dispersion, be the some measure of the gaps kinematics projected along the wild 08:40:37 side. 08:40:38 What I want to point out is for this kind of high resolution data. 08:40:44 You can see many of these metal lines are resolved into. In this case, minimum of two components. In addition, when you compare that with hydrogen absorption. 08:40:57 You can see clearly that between the two components. They are differential ionization state, the weaker each one components and out you have stronger metal ion absorption. 08:41:09 This is the first indication of the presence of multi-phase gas that are coming out they're very different ionization state. And we can do that now with exquisite data from the hybrid solution spectrograph, and they really enable us to do a detailed to derive 08:41:30 constraints, the ionization state of the gas that I will come back to that in a moment, but to continue on the topic on the lower mass of regime. This is based on the unusual sample Sean put together, we can do the usual experiment just to look at 08:41:50 the absorption strength is a function of distance. In this case, it's been normalized by the halo radius to to see that how the absorption strength would evolve with will change between with a distance, and those are different. 08:42:10 halo mass if I just blink between the low mass, for example with high mass sample coming out of our own collection including Hawk halos data point. You can see that the dual halos average produce weaker metal absorption lines. 08:42:31 In contrast to hydrogen, there's no visual difference observable difference in the hydrogen content, but for metal eyes. You see that, on average, not dwarf halos do not produce a strong metal absorbance, this is also including O6 is shown in 08:42:50 the mean covering faction earlier. 08:42:55 And on top of that, so so worth emphasizing that beyond your radius. We don't detect any metal lines. 08:43:05 So, what this is significant because, going back to the expectation of how supernova feedback, maybe responsible in reducing the star formation these mass dwarfs. 08:43:19 As a result of potentially removal of material out to outside of the dwraf Halo. 08:43:28 In this case, either the guest is fully all nice beyond the state of oxygen six, or the energetics is not as strong as previously expected. 08:43:40 Certainly, we hope, going forward with more data coming out of past, we will be able to put strong constraint on the, on the state of the gas, they will help to address different possibilities, I mentioned here, the only case based on the current resolve 08:43:58 we can already infer. 08:44:01 You know the total amount, metal budget in the dwarf mass halos. 08:44:07 So that's, that's the ensemble statistics I wanted to cover and understand that I'm already up to have maybe 10 minutes left. 08:44:20 But quickly I think this is really the most interesting part, going forward, especially given the opportunities that are presented to us. Now, our ability to really constrain 08:44:32 density and temperature enrichment, in these in different gaseous Halo using available socialite data really is right, have any right now. 08:44:48 And just to illustrate again borrowing another figure from Ben's previous papers. This is just by coincidence that I tend to quote Ben's papers, but what you see here is for different elements from covering the top oxygen in the middle, silicon at the 08:45:06 bottom in different ionization state between different ionization mechanism. 08:45:13 We theory can predict very precisely the relative abundance ratio between different ions, coupled with observations, we are able to constrain the temperature and density of the gas very well. 08:45:29 But the key is to really fully utilize what the data has to offer. In this case, on the left I use a example coming out of the cuts sample that shows a single Lemme lemme system with resolved hydrogen and metal line profile is quite clear that the central 08:45:49 component here shows 06 absorption, but the satellite component with lower each one actually shows the strong strongest o six absorber is really each using this specially resolved component analysis, who we actually put strong constraint on 08:46:03 the multi face gas, individual Halo. 08:46:15 And we did, we did this using the initial survey, which we call cause lrG, this is a small sample of luminous rare galaxies. This work was done by Fahri Zahedy as part of his thesis PhD thesis, where he should fully utilize the resolved absorption component 08:46:36 as a illustration here. I'll just show that this single absorber at 140 k PC here is resolved to each a minimum of three components, which we can put strong constraints on in terms of the density and the whole city. 08:46:53 I would just highlight that while the central component dominates the gas density. 08:47:00 We were able to based on the relative line ratio, we're able to put derive a very strong constraint upper limit on the density of the additional clumps. 08:47:13 And we did that or I should say Farhi did that for everyone of the 16 systems in our costal lRG sample. 08:47:23 And the end result is we see a strong large density variation individual halos. 08:47:29 Similarly, as you can imagine that it also has strong implication on the inferred metal content. 08:47:38 We also see a large scatter individual halos in terms of the same point we mentioned. 08:47:46 When we come here to be elemental abundance, we, we can certainly also look into the relative abundance between alpha elements which is driven by core collapse supernovae, as opposed to iron, with a predominant fraction supernova a or evolved stars 08:48:14 These are all the different possibilities that these high resolution data have offered us. 08:48:21 So, but looking to the dynamics obese Halo using the inferred density clumps. 08:48:27 What was shown here is repeated from the previous density panel. 08:48:34 And in addition, we have added the density profile inferred from the combined X ray and tSZ analysis by Singh et al back in 2018. This is for the hot corresponding hot Halo. 08:48:49 So given the expectation that this mass range the halo temperatures are over. 08:48:55 million degree. And the cool clumps. 08:49:00 Has the expected temperature of ten to the four for Calvin. If we are up upward correct the density, the measured density profile for the halo by a factor of 100 to account for the temperature differential. 08:49:14 We see that this hot. 08:49:16 The first Halo density profile for the cool clumps nicely envelope, the densest clump that we inferred from the. 08:49:31 The socialized study. 08:49:31 It really shows that very likely these cool clumps. Once you take into account the component by component analysis resolving the density structure, are likely to be in pressure equilibrium with the hot Halo in these massive halos. 08:49:47 You might ask, what happened to these low density clumps. We can imagine due to projection effect. These don't low density clumps may actually arise from larger distances. 08:49:59 In terms of the 3d radius, and a further look into the correlation between density inferred density and the column density, we see that there's a overall theory model large scale here there's a rough correlation, as you go to high higher density, the higher 08:50:21 density clumps are revealed by heart higher calm density absorbers, that gives you a characteristic last scale size feel of these clumps on the order of 100 cars x. 08:50:33 So, this is also quite consistent with what people see using this Quasar sidelines. How reassured by Michael's earlier work, and also Grant's recent study. 08:50:45 So, we can continue on the analysis to infer for the total mass, which is also very relevant in terms of the understanding of the gaseous Halo. 08:50:57 So, by simply adding up all the cool clumps, all the competencies, we can infer out 260 k PC, which is what the sample allows we infer there's a total of more than, ten to the ten solar mass cool. 08:51:15 gas mass in the cool face. That's very much comparable to what people will see in store for m halos. And in terms of the mass fraction protein cooler than half phase is over 10%. 08:51:26 So we certainly the idea of the two phase model is naturally, possibly, likely simplified. We certainly expect that there's more than just 2 faces, and that's already evidence from a couple systems from a few systems that we have seen so far. 08:51:48 When we look into the comparison for O6 and magnesium two the very different to the magic profiles that we see, and also the large language in the o six absorber. 08:52:02 So you also highlight that there's additional face, and not. Not only that, but not thermal broadening maybe driving the line with of these features. 08:52:15 So, I see that on my computer. The clock is running up almost 45 minutes. So, I can either stop here, or going on to talking about the Cubs survey. So Mark where do you think, 08:52:34 I think. Let's hear a few words about the survey, enough, so people get acquainted enough to ask questions about it and discussion. 08:52:46 Okay. 08:52:47 So I want to quickly mention this new survey, that's coming out of HST cycle 25 large GO program is cosmic ultra violet Baryon survey. 08:53:02 They are designed to study the CGM over the record range from local all the way out to beyond one, trying to bridge the gap between cosmic noon, and the nearby universe, and the idea really is to try to understand better using all the techniques I just 08:53:25 summarize to to probe the gas and Galaxy cool evolution and also enrichment history. I want to acknowledge wonderful team that we have this is every team player. 08:53:36 Some of them are on this call here. So, So I just want to acknowledge acknowledge the contribution. 08:53:44 But quickly over the last three years, we have been very busy collecting a large number of comprehensive and delivery data, including ground based supplemental optical QSOs spectral absorption to cover the magnesium 2 and iron I mentioned earleier 08:54:17 earlier. And also, massive galaxy surveys on Magellan, and those OVOTUC Muse to two complementary enable a joined absorber and Galaxy study. This is just to give you a sense of the survey, the scope the survey, we have secured more than 800 spectroscopy 08:54:37 pressure per field that's designed and sort of going deep really deep in the inner satellite to really complete the census. And this is just to show you the, the impact prompt your distribution for one field is a function of pressure, with a sort of 08:54:46 wedding cake structure going really deep at the center. 32nd radius to progressively shower out you know that document that radius. 08:54:56 So in the first couple papers are on the archive. I encourage you to check it out. Like I said earlier, we take full advantage of this spectral resolution, that's available from past, and those who ground Basie shell data to resolve complex multi face 08:55:13 gas, and from the company in galaxy survey we see we can, we have uncovered a diverse range in terms of galaxy environment, from where you can see that for all five strong lemon in the system really actually thick get, we see a wide range in terms of 08:55:34 the halo mass improved from low mass dwarfs you know this is coming, ten to the eight solar mass range for this ultimately the system of each one competency of 17.6 to massive groups, they evolved a lot of galaxies of different star formation history, 08:55:54 showing that issue and policy is by no means a good tracer of the halo mass, but also just to look at the result. 08:56:07 Density structure and the velocity to compare simply just from looking at magnesium to to each one ratio. We can already see a wide range in in the data, when we do a full blown analysis that accounts for other ions, we see again. 08:56:26 we knew of these halos range in terms of density structure and Kymco enrichment. 08:56:33 So, again, in terms of going to multi phase structure, we see a very clear correlation, in terms of language, we uncovered for ions, with increasing ionization potential. 08:56:47 So this is one. 08:56:50 One of the focus is being analyzed by Tom Cooper, at the moment. 08:56:58 So I think, so I also wanted to highlight, you know, for any survey there are surprises. And this is one of the surprises that Aaron Boettcher published last year. 08:57:10 The discovery of circumgalactic molecule a hydrogen at 40 k PC from a massive elliptical. so going to read the recurring theme of multi face gas in in Halo two different mass scale. 08:57:24 So I'm just gonna leave up the plot here for discussion sake, going forward. 08:57:34 Some I was joking about how we're moving into the next generation of CGM analysis with abundance data really high quality data available. 08:57:44 We are really at the cusp of getting a lot of results out, and I'm sure we're going to hear more about it from Patrick next week. 08:57:53 Thank you. 08:57:56 Well, thank you very much. I'll clap audibly since I'm unmuted. 08:58:01 Okay, at this point, I want to take a five minute break but while that's happening please start populating the chat window with questions because that'll be my primary resource for proposing them. 08:58:16 And what I'm also going to do. I opened up a thread on Slack channel and slack which is Halo 20 on week one Halo mass. And so any big discussion about this talk, beyond what we can do live can happen there, and I can actually copy, after we're done copy 08:58:36 whole chat in there, so that if there are questions that go unanswered Hsiao-Wen can still address them on slack. So, we'll come back at three minutes after the hour whatever your hour happens to be. 09:03:04 Okay well according my computer, we've reached three past the hour Hsiao-Wen's had a chance to preview some of the questions, and some of them are compliments I'm not going to read out the compliments she can you can read the compliments and just smile 09:03:19 inwardly while you do that. 09:03:21 There's also Mateusz Ruszkowski has a point about the clump velocities being slower than expected. I'm not going to read all that because it's more of pointing out of paper by Hsiao-Wen rather than a question. 09:03:33 I'm going to go down to the question that says, Is there a trend with mass for thermal to non thermal broadening of the lines, especially oh six. 09:03:45 Right, okay. Should I share my slide again. I think that'd be helpful, 09:03:54 maybe find it relevant plot. 09:04:31 So, to answer the question, I, I went over this very quickly. 09:04:39 The quick answer is bluer appears to be. 09:04:43 What you see here is the grayed out point in the background was dark radar points are from star forming galaxies that include also cause Halo sample, I believe, whereas the colors solid color points are for luminous red galaxies. 09:05:01 So just based on you know the visual comparison here, there, there seems to seem to be a higher fraction of oh six with broadened line width from the massive halos. 09:05:17 So, this is something we noted in the paper, but certainly we tend, we hope to look at this in more detail with a larger sample coming out of the Cubs. 09:05:43 We at the moment we do see such trend. 09:05:35 Okay, next question is from Mary Putman, a great talk, I noticed that most of the low mass galaxy metal observed points for non detections are the detections bias towards the higher mass galaxies by any chance. 09:05:50 Right, so I think this is related to well bias in a way that the Sochi strength coming out of the drop halos appear to be weaker. So I think that means we need higher quality of socialized data to to push stronger constraints. 09:06:11 So I don't know about in terms of selection bias, I don't think so. I think it's all likely. 09:06:19 But I was asking for the detection, their show and are you like there's not many points are the points that were detection so are they already the higher mass galaxies. 09:06:37 No. So, for example, this one is the one I highlighted here. 09:06:35 Oh, 09:06:38 yeah. So this is a detection. 09:06:41 You can see sort of three here. 09:06:57 Yes. 09:06:59 Right. Next question. 09:06:59 Alankar did it extremely insightful talk from acid halos as you pointed out, it can be cold clumps moving in a hot background when simulations out there indicate their survival requires low t cool to free free fall. 09:07:12 Do these observations have some estimates of such quantities 09:07:18 quantities in terms of free fall time or, um, well I guess if Alankar can clarify. Yeah, I was just asking the issue of equal to equal equal in time to free fall time. 09:07:33 So, that would tell me whether these gas this cool gas comes will survive or not right. As far as the simulations are concerned, so do these observations also put some estimates on these quantities and maybe some different ways, which one can 09:07:51 compare with these observations then. 09:07:57 So, in the paper we did a very simple tagging back of the envelope calculation is not about freefall time because if we are expectation is, is the fact that grand pressure direct may be effective, we, we worked out. 09:08:15 The, the rem pressure direct involved time to basically the sparring downtime. 09:08:22 And so the conclusion was. And if the clumps were formed at 100 k PC, they will never reach this center given the mass, given the fact that they, they are slowing down, they cannot be too massive. 09:08:35 So the survival time due to rem pressure drag force is is much shorter than the you know the modified fall time. 09:08:49 And what we find is, but we do see these quote quotes as small radii. So, the expectation is there for me in situ or close to easy true as small radii. 09:09:01 Now, that's the only way we can see them as a small distances. 09:09:07 And I just go ahead, you have another follow up. 09:09:11 No, no, I just wanted to acknowledge, go ahead. I just received the very helpful suggestion that to have people ask the questions themselves so we can see them and hear their voices. 09:09:28 The next question on the list is from Michael Stein. So Michael, if you're on. Yes, ask a question. So yeah, thanks for coming to talk. I was just wondering about this. 09:09:38 Yeah, the apparent did you find the equilibrium between the cold clouds and the hot Halo. pressure equilibrium So where would that come from and discern like what type of posts, it was it would it motivates that this equilibrium comes up. 09:09:57 So I think maybe we will have more discussion on this part later part, maybe next week. 09:10:04 I mean there are different possibility I think Mark has thought about this a lot, coming from observers perspective, the simple interpretation will be just due to thermal instability, you know the density fluctuation the clumps contains out of the Halo. 09:10:23 But certainly, if you think about feedback. My moderated dynamic state of the gas. 09:10:33 That's one possibility as well you can do the precipitation that Mark has been advocating. 09:10:39 Yeah, actually I'm gonna put an ad in here, not not sure what I've been advocating but for Drummond Fielding's talk next week, because I yeah I expect him to talk about this issue of when things may be in or out of pressure equilibrium as they change phases. 09:10:57 Yeah. Great. 09:10:58 Thanks. Okay. 09:11:01 Next person up Todd Tripp has a few questions right well so this is the question that always dogs us in this business which is that oftentimes there are multiple galaxies that are close to the sideline. 09:11:15 And this is particularly problematic with the dwarf galaxies because they're often satellites, as you know, in the halos have more massive galaxies and so in job merchants dwarf galaxy study from a few years ago there's some plots that show. 09:11:31 You know all the galaxies within some velocity range and it's really quite gnarly sometimes So, how is your team, trying to establish whether that absorption can be uniquely assigned to the dwarf galaxy, or whether it might just be stuff in the halo of 09:11:50 the more massive thing. 09:11:53 And, you know, it's, it's very interesting that the metals are much are clearly weak or, but then there's the h1 and the h1. I wonder is that the dwarf CGM, or is that maybe the just stuff in the halo of the bigger galaxy. 09:12:10 And the other question was related which is. 09:12:13 How have you, I think you were kind of favoring that the difference between the dwarf CGM and the more massive CGM is that the feedback or something has changed the physical conditions and the halo of the dwarf but it could also be medalists it. 09:12:31 So I was wondering if you could comment on whether it's just lower medalist cities in the in the halos of these little galaxies which are of course known to have lower medalists at ease in general. 09:12:42 Thanks. 09:12:44 Thank you, Tom, that those are many questions I will try to remember them all, but starting off from the beginning. So Mark will help me start on the beginning 09:12:56 my screen I can really see normal healthy. 09:12:59 Okay, thank you. 09:13:02 So the first was about the environment, right. 09:13:09 So, this is what part of the main reason actually is the main reason why this thing is been taking us a while for to do the Cubs survey. We're very careful about knowing all the caveats you all aligned in terms of trying to identify central galaxies as 09:13:24 to several white dwarfs. That's folded into the dissolve galaxy survey starting from the first generation, oh six survey day job I started. 09:13:32 Our goal is to really go deep. And in the inner, you know, inner volume from the quasar sideline by deep I mean we try to reach hundred percent completeness, for all star galaxies and the ratio of interest. 09:13:49 In the case of the doors in Shawn Johnson's sample he went Still deeper in identify some star galaxies by combining the new, you know, integral field unit data. 09:14:01 So while the, the survey the ideal goal is to have hundred percent complete to say, with high confidence that there's no, they'll start or brighter galaxies need with the, you know, 300 500 TPC of the door, that we are looking at. 09:14:22 Oftentimes, are we reach about 90% completeness, just to be, you know, really open about the survey status. So, with that kind of data galaxy data said the mind, we can say that these are the isolated doors that we don't see our data can can rule out 09:14:43 the presence of luminous galaxies within the surrounding 300 500 k PC volume. 09:14:50 And that's the sample that you're looking at. in front of you. 09:14:55 So, so I agree with you, there's definitely ambiguity, but we are doing this, we're trying to make it up from really pounding on the Galaxy survey company knows and depth. 09:15:07 Cool. So, Can I just follow up. You can turn that around. 09:15:11 What if you look at the CGM of satellite dwarf galaxies. Yeah. 09:15:17 So, thanks is complete, separate subject I think during the break I saw somebody else asking about CG and properties in group environment. So maybe I will come back to that, when we reach that question. 09:15:36 Okay. 09:15:33 In fact, that's Arif's question. Next, so Arif. 09:15:55 No but I thought had more questions. Oh, well, he was also asking about metal so it could be due to metal scene. 09:15:46 So, so yeah, that's definitely one thing we want to address but I should also reiterate that either you have a halos, we see a little by little metal in clumps. 09:15:56 So it's not unique to, you know, loving holistic as it's not unique to low mass or halos, but while the challenge in getting the most out for these are the current dwarf sample is, as you can see, this is the h1 coverage we have both are saturated, to make 09:16:19 the following series to constrain the h1 competency is crucial. So that's definitely in progress. We hope that's one of the goals we hope to to accomplish, using the additional sample. 09:16:31 The End The moment I cannot address the only to emphasize that low metals in the columns are present in either high mass halos. 09:16:42 I guess now we will move on to Arif. 09:16:46 Thank you, actually Todd set me up quite, quite well. So, the question is about massive galaxies, particularly, extending into group environments. And have you looked at the CGM structure around such systems, and what are some of the highlights. 09:17:04 So, I would refer. So first of all, I should say that Joe Burchett that's part of his work. So maybe he will try me in a moment, but I will refer you to this paper, all by Huang, that's on the archive, given the limited of time, I didn't show the 09:17:23 pub, we do have a plot that shows how the magnesium two incidents and strength, changes in the group environment. So since I don't have that in my slides, I will just basically I will basically hand draw. 09:17:38 So what we see here is in the group environment we don't see your trend. either we use a lightweight it. So, in the group environment. There's some ambiguity in the x axis, the distance measure, do you use the closest galaxy, or use some sort of massive 09:17:56 galaxy or something else in the paper, we up to us, lower weight center, and this is what we see in terms of the overall incidence of the fraction is lower. 09:18:11 And in terms of the distance dependence in the absorption strength is flat. 09:18:19 And the flight trend does not depend on how the distance is measured, either we use the way we did distance or using the closest galaxy because 09:18:31 the galaxies all tend to be more luminous. So, it turns out that they are all L star, very comparable so lightweight it or not. The, the trend is insane is flat and how far in killer process, have you managed to go out. 09:18:50 We have limited our effort to 500 k PC. Okay. 09:18:55 That's a pretty good distance. 09:18:58 Good, thanks to slow is really we benefited a lot from this long survey. Hey, Joe, Joe has a question coming up I'll ask them to save comments on this topic because this question is related. 09:19:04 The next one is from Frank van den Bosch. 09:19:16 Right. 09:19:16 So, you showed that the observed velocity dispersion of the cold clumps was in massive galaxies was significantly lower than the expectation. 09:19:26 And then there was a idea that this could have something to do with REM pressure stripping which and then during results to mass limit on the clouds. 09:19:35 But in order to meaningfully interpret such a loss of explosion you need to know something about a radial distribution of the clumps. 09:19:42 Right, so if they for example their specialty buys, they're very much more centrally concentrated in the dark matter than they would have naturally low velocities version. 09:19:50 You don't need to invoke any rem pressure or any of that. So my question is if you take the incidences function of radius and you try to translate that into an radio number in the profile of clouds. 09:20:01 What does it look like does it look like an Fw like in other words they're like, close to an unbiased racer of the halo or is it more concentrated less concentrated a not sure or if we bet. 09:20:21 from the observation going back How can we infer, but halo does not license right so so we know that if you, if your cloud suppose, would be much more centrally concentrated. 09:20:33 Okay, they never make it out to more than half a very radius, then the velocities version of the clouds should be significantly lower than the velocity dispersion sigma v the inverse on the halo mass. 09:20:45 Right. Um, well I think it really depends on the skill then I'm not sure if we can put all the clumps within the inner radius, the, I mean, exceeds the projected distance already told you, the minimum distance, they can be projection right so i want i 09:21:07 want to translate Yeah, great. So you make a model for the clouds give them cross section for cloud, and then you can translate to a number. 09:21:15 Yeah. 09:21:18 So even though you say, Is this true I understand that. I'm not sure about baryon on the Halo. In earlier paper I had of mine. We I use the ISO thermo profile to describe the, the observed, magnesium two profile, and it actually was quite it quite well. 09:21:42 So that's, that's a different sort of for modeling. 09:21:47 I didn't fit I didn't infer backwards, of the density probe I just assumed this is isothermal and see if there's any fit. So I don't know if that's good enough answer, but I just want to emphasize that we, the clumps come out. 09:22:03 A lot of them come out of, you know, 40 k Pc 50 k PC hundred k BC and beyond. So that says the minimum radios that the clumps can come along, right. So, when you say the clumps can come from the because you're projecting that could come from inner radius. 09:22:24 There's a minimum there, it cannot all come from the inner radius, understanding, I think, I think, simply summarize the question is basically has anyone tried to translate the incidents assumption of radius into a number NC profile of clouds, and that's 09:22:32 what I'm interested in. 09:22:35 To some extent is, as I said I use an iso thermalprofile, it fits their observed projected profile. So I don't know if that's good enough. 09:22:47 Okay. Okay. OK, The next question is from Prateek Sharma. 09:22:55 Yeah, thanks. Nice talk. 09:22:58 So I had a question about how you infer this clump mass, and the clump size and the column density. 09:23:06 If you can briefly tell us about that. 09:23:09 So those are two different methods. So the quantum mass here really is very simply using the fact that the cloud, you know, in this case, we just assumed that the observed velocity is the terminal velocity and aimed for the mass minute that way. 09:23:28 But in terms of the size that you saw that's really from full blown ionization analysis, given. 09:23:41 Given the inferred clump density that's the space density. 09:23:47 We also know the ionization fraction, and modify that we can infer the corresponding h1 space density, with observed calm density. That's how we for, you know, the clump size here. 09:24:04 So two different sets of analyses. 09:24:09 And they are right. 09:24:14 The agrees with the, the, yes, but you know the size has a wide range, but roughly speaking order of manager Yes. 09:24:22 So I had to actually a related question about this assumption of terminal velocity, and you know so there are these simulations cloud crashing simulations and also rem pressure stripping simulations would show that sometimes cold gas can actually grow, 09:24:41 grow, rather than getting mixed in details, if the cooling can be short enough, right, the cooling down with the mixed gas is short enough. 09:24:53 So what do you think about that connection of that two observations. 09:25:01 Oh, to be honest I haven't considered that possibility, but I look forward to the continuing discussion next week to, to learn the latest in terms of the theoretical modeling effort, but that will be interesting but it will present a challenge to the 09:25:18 observation we have here I imagine. 09:25:24 In terms of the growth of cool clumps. 09:25:28 How about we Yeah Okay, how about we return to that question next week. Yeah. No. 09:25:35 Ben Oppenheimer is next it's not phrased exactly like a question but I'll have him speak anyway. 09:25:41 Okay. 09:25:48 Well, a great talk, I liked it quite, quite a bit, um, I was wondering about this exact slide here, the inference of the hot phase. And this is kind of a broader question for for for everyone here. 09:25:59 If we assume a halo massive 10 to the 13 and I'm assuming you're, you're driving this from the inferred Halo temperature or the bureau temperature expected for 10 to the 13 solid mass Halo, and then you drive the density for that, you know, the hot phase, whether 09:26:17 there are you know there's there's some you know us from stacks from seeing it all for X ray and Ts thermal scenario of Zelda batch. But I wonder if there's like individual galaxies that have been observed in the last few years, with x mmm that can provide 09:26:36 a constraint because I would think that you know that you know density in that temperature of gas should should create some, some x rays signal. 09:26:48 Yeah, Yeah. I wonder if there's something. 09:26:51 Yeah, go ahead. 09:26:53 Smita is here. Um, I think my, my impression is, and she's one of the teams that has reported detection directly touching nearby john spirals I believe, but I thought my impressions Smita please correct me, this x ray signal doesn't go out to 100 09:27:12 k PC does it, but but anyway Smita could you comment, 09:27:16 or is she here. 09:27:18 She was maybe she's stepped away. I think that, yeah, I'll, I'll. Yeah, I will just say, real question as you say is dependent out to what radius. 09:27:37 There are plenty of LR G's that have been measured out to. 09:27:36 There's actually observations out to 10 or 20 or maybe even 40 kilo parsecs but as you start getting beyond that, it gets harder and harder. 09:27:42 It's what we have is consistent to a factor of 10. 09:27:46 But there's also a wide range in the X ray luminosity these are very surface brightness is out, in tens to kilo parsecs, so it's hard to then say, if there's such a wide range of gas densities out there. 09:28:05 Is it consistent or not with this range of inferred pressures, but we would sure love to get deeper X ray observations of all that listing we have now is the stacks. 09:28:17 Yeah, yeah. The, there's just a zoo of like elliptical halos out there and they're very different, and you know the ones that are LRGs versus the ones that are more massive groups, I mean, you know and somewhere someone else has 09:28:31 observed a number of these and I'm always confused about what exactly these things are the LRGs and sometimes, you know, some of them are pretty bright but often then they're in a group environment. 09:28:44 Okay, so I see two more. 09:28:49 Probably, common sense. 09:28:54 This question so in fact our group I was doing some deep observations of massive galaxies. Well there are, it's very complicated here, I think, is largely affected by the background. 09:29:09 I mean, it's bandwidth limited, so it's not really going deeper as you can get too large already are, but based on stacking analyzes we can now goes to, at least one or 200 or 100 or 200 kilobytes and from the galaxy for both of them as and galaxies. 09:29:25 So that's why, so probably one of the key problem is what you are talking about if you talk about CGM, so you have to separate the contribution from the intro class the medium, and from the CGM. 09:29:40 So in this case you'd have to choose the cleanest of cases. And before there's such massive galaxies, most of them are just located in the center of clusters and on very few of them are isolated. 09:29:53 So, the case is very complicated. I mean, I think you still have two more questions, one from Joe Burchett than one from Kartick Sarkar So Joe you're up. 09:30:06 Yeah. 09:30:07 If I could just comment on a couple of things. Earlier, it actually leads up to my question if that's okay. 09:30:15 Go ahead. Yeah. Okay, so, so about the the issue of dwarf galaxies around. 09:30:22 Analyzing the CGM of dwarf galaxies due to the proximity more massive galaxies in the 2016 paper I lead we actually did try to separate galaxies dwarfs that were not within the virial radius of another more massive galaxy and and consistently, we find 09:30:40 much lower covering fractions of carbon for in the in the lower mass galaxies relative to desert L stars, galaxies. 09:30:51 And regarding the CGM in group and cluster environments. 09:30:55 We also found much lower covering fraction of H one in groups and clusters. 09:31:04 Then around isolated L stars, galaxies, less massive galaxies. I'm in a suppression of carbon for in the more massive groups. 09:31:17 And I also point out that Nikki Nielsen, and Stephanie point and have looked at the kinematics of magnesium two and oh six in group environments in. It's complicated. 09:31:30 The oh six seems to be the profile seem to be on average narrower and group environments which is kind of interesting, whereas the magnesium two a potentially broader. 09:31:41 But getting back to the cup the issue of covering fraction, and h one contents. 09:31:48 Because we find so much less h1 in the CGM of group, and cluster galaxies. 09:31:55 And there's a seemingly a plethora in the lrG halos. 09:32:00 There is a little bit of a redshift difference here between my X ray bright sample at about pressure point two, and Hsai-Wen your LRG sample average redshift of what about point four. 09:32:13 So, I'm just curious if you had some comments on this potential discrepancy. 09:32:19 So just to clarify the discrepancy in terms of the h1 content. That's right. 09:32:25 So, so here he, I want to, you reminded me of one thing I should have mentioned. 09:32:35 So what you see here is in terms of equivalent width in terms of that. And that's really driven by necessity, and we don't have the full, because this is a strong line. 09:32:46 The single line is saturated, we can't constrain the each one. 09:32:49 But like all the saturated life that you want to work really is measure measuring the underlying kinematics. My expectation is, a lot of these may be contributing from the correlating structure where the galaxies to reside. 09:33:09 So, so it's not really unique in, or really entirely inside to have galaxy Halo. 09:33:19 But in terms of the luminous right galaxy. So you're saying we see a larger fraction of halos with high competency absorber. When you don't see that in low ratio. 09:33:33 So, I think, for cause a larger the sample is quite small, as I say this 16 within 160 I forgot how big your sample size is. 09:33:44 I'm not sure how much of this is, this part of the noise given the limited sample size, it will definitely, I think, are used for continuing effort between large The, the sample size. 09:33:56 So could you remind me the, how many galaxies were there your sample 09:34:02 sort of the X ray right clusters I mean it was, it was maybe, you know, 10 or 11 galaxies. 09:34:09 And those were spread across, you know, five clusters or so. 09:34:24 Right. And also, going out too much further distance away right is not within `60 will be about a third of the bluer radio for these massive halos. If I remember correctly, you go out to beyond the bluer radii with these clusters, well this, the sightlines 09:34:31 are actually sightlines are within a variable radius largely of the cluster but I'm talking about galaxies that we went back and surveyed and found galaxies, near the sideline so so those are definitely well within a variable rate, you know what would 09:34:44 be the nominal variable radius of a sub Halo, for those galaxies. So, we're talking about impact parameters of like 100 kilo parsecs from the galaxies themselves, where you would certainly expect to see, you know, plenty of H1. 09:34:57 Right, right. So, I guess. It will be good to look at in more detail about the, you know the galaxy environment is is possible because we do see that for galaxies that are in group environment. 09:35:12 The incidence of even just magnesium two is in the lower. So, I'm not sure how much of that could be explained by the environmental effect. 09:35:26 Does that make sense. 09:35:29 Yeah, yeah, thank you. Um, I think, I think Mark was was interjecting. I was gonna say, um, how about that, that discussion can continue on slack. 09:35:40 We're gonna have one more question. Yet another question has appeared, since I said there were two more questions. It's from Crystal Martin and what I'm going to do is I'm going to copy and paste this whole chat into the Slack channel Hello 21 week one 09:35:56 halo mass, and I'll ask Hsaio-Wen to address crystal's question there. 09:36:01 So the discussion can segue. And people who need to be elsewhere, can, can do that after this last question is answered from Kartick Sarkar. 09:36:12 Hi, thanks for the talk, as wondering like, what would be the effect, assuming a different radiation field in the ionization calculation when, when someone estimates the density of this clumps, cold or warm clumps. 09:36:33 So if we let's say if we can't increase the density of radiation field by a factor of two, would that change the estimation of the density. 09:36:42 So the second question is that, is there any estimation, that if we, destination of this density. If we don't assume that the clumps are in ionization equilibrium. 09:36:57 Instead, assume some kind of non equilibrium formation scenario. 09:37:02 What would be the density estimation. 09:37:05 Hmm, okay. So, going back to your first question, great question. um, this is one of the challenges in doing this kind of analysis. 09:37:16 It's not just the intensity radiation, but those are the slope of the spectrum. 09:37:21 So, if. So to answer your question, I imagine you're talking about a dilemma edge. If the intensity changes by a factor of two, the density will change accordingly because what we have here under a symbol for line ionization model is really the annotation 09:37:37 parameter which is the ionizing photon, or actually a hydrogen ionizing photon per hydrogen particle that that we have constraints for. So if the number of ionizing photons at 13.6 ev changes the info density will change accordingly. 09:37:53 So, but going below, up to the Stig regime, either into the optimally thing regime will be more worrying about the effect on the slope change or difference in the ionizing spectrum, but within the optimistic regime hydrogen does help us filtering out 09:38:22 all these. 09:38:24 The effect of the high energy photons. So, our results will be is actually quite robust, you know, in that context. 09:38:42 The estimations for the, you know, many lines that are many lines like silicon three carbon four they have high energy potential so they're probably all slope of the background or any spectrum that you're assuming will matter Yeah, a lot. 09:38:51 Yeah, so, so what I'm trying to say is the spectrum, if they are within the hydrogen cloud, much of the photon is filtered out. 09:39:00 So they give us a little bit that reduces the fact that you are. 09:39:05 We expect quite a bit. 09:39:07 Okay, but I agree with you once you include a higher ions, you, we do need to be careful. 09:39:19 I forgot your second question. 09:39:29 So, how much will the density estimations change, like for example in one of the slides you showed a block from now Oppenheimer's Benjamin Oppenheimer's paper shows that the effect of non equilibrium effect ionization, which is the changing the column density 09:39:46 so I nation fractions by a lot. So, is there any such estimation, that how much it can change the estimation of the density. 09:40:00 We are looking into that right now, the density. 09:40:06 Yeah, once you get into the equilibrium region it gets really much more complicated. 09:40:13 I don't have a number for you. 09:40:15 Okay, and there is some activity. 09:40:20 I'm going to ask for the discussion now to transition as smoothly as possible.