09:12:02 Okay, um, let's reconvene, and we have our panel today.
09:12:12 In no particular order.
09:12:15 Dylan Nelson, Mary Pittman staging Shannon and, and Cameron Hummels.
09:12:22 So I'm going to look for hands. To start off with, but we had a very nice talk, and definitely a lot of questions.
09:12:37 Well, then in that case i'm gonna i'm gonna i'm going to take the prerogative and ask about the nature of jets to to blow, you know, for the AGM feedback to scheme like in that mode of, you know, tend to the 1310 to 14 solar mass halos groups and clusters,
09:12:57 clusters, where you have to blow bubbles and have spherical bubbles.
09:13:03 And you said that the jet feedback needs to be placed closer to make it more spherical and I wanted to hear more about that because I think about like, you know, radio jets and fr to objects and how that correlates with observations.
09:13:26 Yeah, so I go into great question.
09:13:32 So in particular what the, the observational connection.
09:13:37 Yeah. So
09:13:44 keeping. Keep in mind that the, what the radio is showing you is, is largely the you know the jet fluid itself so the relativistic particles the synchrotron emission from relativistic particles, and not necessarily the cocoon, the shock to gas, which.
09:14:05 So there's some, some, there's a few nice observations which show that connection, clearly show a jet coming out and then where you can actually in the X ray see the bow shock.
09:14:15 But there's.
09:14:20 But I think your point is is a good one in some cases the, the jet seems to propagate for a long, long period of time. In fact, I was looking
09:14:32 to see if I can, I can dig it up in an amazing image of a four way cluster was some max object, Mark I'm sure knows that the number of a four week class.
09:14:47 The interpretation was the former cluster
09:14:51 collision, and there was a whole series of jets, including one which was just straight as an as an arrow.
09:15:00 And so whether that was, I was surprised to see that because I normally jets are, are there, their momentum flux is not that high so they take a while to drill through the CGM.
09:15:15 Yeah.
09:15:17 Yeah, I wonder if this is you know, for those that do drill through that the CGM or the CRM into group media or ICM. I wonder if that goes if that radio mode goes on, if that if you call that radio mode if that goes on at high redshift as well I mean
09:15:32 people invoke it, but ignore redshift when you have a hot Halo, but as a way to like eject baryons from groups and and clusters.
09:15:42 I wonder if that could be effective at high redshift and if that can be observed.
09:15:48 But I'm not sure if we'll get an answer to that here.
09:15:56 But.
09:15:58 Does anybody else have any comments on that I saw you Yeah, you wouldn't. I don't know what can be observed, but uh oh. One thing to keep in mind is that I've hired redshift Black holes are also smaller, and the, the, the absolute attrition rate just
09:16:19 the unit of solar mass tends to be higher. So it's less likely for a massive black hole to be doing the radio moat feedback. So it's, it's more likely that the more massive black holes you're doing the quiz hormone feedback.
09:16:30 Of course or radio without quasars but it's not what you're thinking about, really. So there's probably there might be some but probably not that many, and I have no idea what we
09:16:44 should.
09:16:47 All right, and I'm going to try to get the, the, the panel involved here. I think there's I'm going by voting here. So I'm going to read one from from Jes what controls the CGM galaxy can connection.
09:17:05 And she is interested in what observations can constrain these three different scenarios that you talked about, rather than bulk condenses gas kinematics of different phases may be able to discriminate a little bit more.
09:17:23 So, um, and I actually do not recall the three phases so maybe just if you want to speak up and clarify that a little bit better. Yeah sure there was the like precipitation, you know pressure profiles in the supernova dominated regime there was the mass
09:17:42 loading, you know the the kind of what's driving the pressures and then otherwise it's cosmic ray pressure supported right and so I was one of the things I've been really interested in from simulation, I haven't seen so much of yet is, what are the predictions
09:18:00 for, you know, the kinematics of the different you know gas phases, because that is something we can constrain observational II and something that hasn't really been probed as much as the kind of bulk column densities and and in these cases it's not clear
09:18:16 that kind of column density ratios are the kind of stuff that you get from column densities like a loose estimate of the pressure could actually discriminate between the scenarios.
09:18:29 So I don't know if any other observers are here and want to weigh in on that or if any simulators who think that, like for example I guess Mark admitted that the kinematic predictions from the precipitation models are actually not super well constrained
09:18:47 in a reply to me. I know Rena boots ski is working on kinematic predictions from like cosmic rays and low and high on kinematic correspondence and simulations, maybe somebody wants to talk about the mass loading scenario but it'd be really nice to me
09:19:03 to hear about what people think our ways forward for answering these questions.
09:19:12 I guess I can comment on yeah so so there's so many threads of conversation going on just can ask me questions over here and people are speaking them over there and you know we're taxing everybody's neurons.
09:19:24 But, in principle, there should be ways to link the phenomenon precipitation to kinematics because precipitation does require and does produce some motion and and the the kind of practical issue is that the amount of precipitation you get might be exponentially
09:19:46 sensitive to the amount of disturbance.
09:19:48 So you can make a kind of an undisturbed model and say well if you don't have much disturbance or precipitation This is the kind of kinematics you would get.
09:19:57 But then as you start to disturb the medium and get stuff condensing out.
09:20:03 There's a threshold or what you should expect to the start to happen.
09:20:09 In, as in the 2019 paper on the Milky Way, that I wrote it actually compares to your 2016 data and tries to show that there is a correlation between the breadth of the oh six, and the, in the, the excess column of those broad lines that that actually
09:20:31 qualitative.
09:20:33 I know and that has always bothered me that trend and maybe other observers want to weigh in too because you won't detect the broad week stuff so the fact that that trend exists could easily be an observational bias, it so I guess what I'm saying is,
09:20:47 there's still there's simulation work yet to come. When how to put that in a more quantitative footing.
09:20:52 Good, good. I will respond to that. Since then, at least in the initial paper on this subject we actually showed that what you're saying, couldn't actually be true so we could construct synthetic specter of broad shallow features and show where in this
09:21:09 diagram you becoming a complete. So it is true that there's a regime. In this diagram where you won't be able to measure lies but it's well below where the locus of points are
09:21:21 good.
09:21:26 Okay well Cameron has his hand up.
09:21:29 He's a member of the panel.
09:21:31 Um, one thing that ties into this question from chess and one thing that I worry a little bit about is, you know, obviously the work done by Mark and critique and and a variety of different people on the subject of precipitation.
09:21:51 Makes sense.
09:21:51 But we, it still seems like we don't have clear indications at least in the cosmological simulations of seeing precipitation actually occurring.
09:22:02 And, and, and the observational implications for this that it doesn't seem like there's strong confirmation of this which is why Jess is asking presumably part of the reason Jess is asking the question that she is like what are the, what's the observational
09:22:15 signature of this so we can make sure that this is actually happening because, yeah, it makes sense it's a really good explanation for this quenching and the cycling of gas through the Halo and star formation cycles and that sort of thing but I think
09:22:29 it's not a foregone conclusion that it actually is happening because we don't see it in all of our simulations and because we don't have necessarily observational follow up on it so I don't know, maybe that's just a part of it but I'm interested in getting
09:22:42 the tape from other people on the panel
09:22:54 and panel members can speak up.
09:22:57 They don't have to raise their hands.
09:23:00 Okay, we have season.
09:23:04 Good thing to.
09:23:06 Yeah, go ahead season, you're on mute Susan is yes. Okay. So, regarding this question about the kinematics and not what Jess is just talking about the, the correlation between the condensed and the kinematics absorbers in simulation we seem to be able
09:23:25 be able to reproduce it, no problem.
09:23:27 Of course I mean we haven't really investigated what is the origin of those, oxygen, no six absorbers because it seems to me that it really depends on actually the simulation.
09:23:41 It depends on how fast the CGM is able to call and how fast is feedback which we only investigate supernova feedback is able to inject energy.
09:23:53 So, I don't know.
09:24:13 I mean I have to say, I haven't really investigated precipitation model but it seems like it's not, no big trouble to reproduce that kind of kinematics.
09:24:09 But I also read them, no dealings and recent paper, which talks about the tea quality pre four, and dealing probably you probably want to comment on that.
09:24:20 Because you investigate it and we were reading at your paper and you seem to say that it is not always said it's quite, not always the case.
09:24:32 Actually I wanted to bring up a point where data points about the kinematics because I agree with Jessica sentiment that motion of the different phases is very interesting, and one context I think that's definitely true is for the magnesium to absorption
09:24:45 in the elliptical so around the other Geez, right and we always not we I've often read in an observational papers this buzzword of sub variable motion and what this could mean and the fact that the absorbing energy to clouds seem to be moving slower and
09:25:01 would be expected for rotation or dispersion and a given Halo mass that this is often interpreted as 100 and amicable drag effect. So it is very cool ideas and I think we should push more on this also from the simulation sites, but I met in the paper
09:25:18 we did about the magnesium to clouds we didn't yet get to kinematics at all, but this is for the future.
09:25:33 Evan go ahead
09:25:39 and turn my video on to some talking, um, so I actually wanted to kind of echo Cameron's question, and maybe pose it to the simulators, because we had a lot of conversation, you know, early on in this workshop about the sort of parameter regimes where
09:25:52 precipitation works versus condensation etc.
09:25:55 Most of the models of precipitation that I've seen numerically have been quite idealized but it's not obvious to me why there should be a numerical resolution requirement to see precipitation so have any of the folks who have done these precipitation
09:26:13 models demonstrated that that you know if you just go to to low resolution you can't you can't see it, because it seems like that that's the question that you would need to answer to connect those to the, to the CGM simulations.
09:26:30 So, the partially in response to this Evan.
09:26:36 I in the tempest paper from two years ago.
09:26:42 suggested. So, okay, we don't see precipitation occurring in the tempest paper which is, you know, consistent with foggy consistent with the surge stuff that Frank has been doing the enhanced Halo resolution in the CGM so we have very good resolution,
09:26:57 you know, 500 parts co moving par sec spatial resolution in the Halo, we don't really see like full on precipitation, where you've just got spontaneous cooling that's occurring in the Halo.
09:27:09 And so that's why I kind of brought this up like we're all talking about precipitation like it's a done deal but we don't really see it. We see it in idealize simulations, you know, drama, has demonstrated this in some idealized simulations and then on
09:27:21 the larger Halo masses like cluster, yes we see it there but for like Milky Way mass halos and lower we don't see precipitation happening in the cosmological scales, the cosmos cosmological simulations.
09:27:35 And one thing that I proposed is simply in a cosmological zoom simulation like fire like Tempest like foggy like whatever your domain is moving relative to the background of it because your your your domain sits there and a galaxy might move through that
09:27:54 zone and so you get some numerical diffusion from gas that's moving across those cell.
09:28:01 The cell structures very quickly. So you might get some loss there that doesn't allow you to allow the gas to be resolved at high enough resolution where the cooling would take over but that's the only argument that I can see that's tied to the resolution.
09:28:18 Sorry I mean I think I posed my question wrong, I wasn't asking the people who do the CGM simulations who don't see it. I was asking you know like right like Drummond in his CGM simulations where he sees precipitation, is it the case that if he degrades
09:28:33 the resolution. Go away, doesn't see it anymore yeah exactly that seems like a simple question to to answer, right.
09:28:47 Go ahead, Mark. Go ahead. My.
09:28:51 I have a bit of a philosophical point to make.
09:28:55 So, is I said a bunch of weeks ago right there to kind of different complimentary aspects of this idea of precipitation. One is, how dense Can I make, or how high pressure can I make the ambient medium until it starts to disintegrate into rain.
09:29:15 Okay.
09:29:16 and I think from an observational point of view, it's been established that that does place a pretty good upper limit on what the density of the ambient CGM can be.
09:29:27 So that part of kind of precipitation, I think, is, is, is kind of observation Lee well supported.
09:29:34 Then there's the question of, to what extent can precipitation produce cold gas that you're seeing.
09:29:41 And I think the semantic problem we have there is an idealized simulation everything's so idealize you can kind of make a disturbance and then something comes out and you call it precipitation in a cosmological simulation.
09:29:53 There are many sorts of disturbance, that you can then say, Oh, well that's actually stripping oh that's actually outflow. And so you don't call it precipitation because you, you have a more specific explanation for the source, I think, originally people
09:30:06 thought maybe you could have a very small perturbations grow.
09:30:14 And since then we've got a better understanding of the conditions under which you have precipitation we understand you need some disturbance. And so in cosmological simulations, you simply call it the disturbance.
09:30:25 And I think that that that's kind of a semantic issue we're grappling with. And so to sum up, precipitation as a limit on what the ambient meeting can be doing.
09:30:37 I think is is becoming kind of better understood and supported, how much the gas supply is something that can be called precipitation is a hard conversation to have.
09:30:48 For the semantic issues. But what if the disturbances overwhelm the thermal instability and the gas because they're slammed by, you know, outgassing from a neighboring galaxy or stripping or whatever that that in a cosmological simulation that's treated
09:31:03 correct well, more correctly than in an idealized simulation and that could overwhelm that the like Ambien level of precipitation that would occur in its absence, and maybe that means that precipitation isn't actually occurring in reality, or at the level
09:31:16 that, that is predicted.
09:31:19 I think we're still have to sort out our semantic issues here.
09:31:43 Yeah, we have some hands up and
09:31:34 she has her hand up again. So, all right and Greg, you don't have to raise your hand.
09:31:39 You can I just I mean if critique or someone was going to try to answer my question I'd love to know their budget hands up and no one has answered it.
09:31:48 Yes, I can answer this question so.
09:31:51 So in the idealize.
09:31:57 You might have lost critique for a moment right at the critical moment.
09:32:06 Sir, if it's okay for me to jump in. Yes sir to Evans question is yes.
09:32:13 So if you have very low resolution and the idea of assimilation, you will not resolve precipitation just because when you have the motivation and you have some
09:32:25 high density low entropy material, you don't have the resolution to resolve that and it's not going to precipitate just like that, which is great because then you can put a specific resolution limit that you need in cosmetics simulations to see it.
09:32:58 of moving around, that will give you very large part of Asians.
09:33:04 moving around, that will give you very large part of Asians. So you probably don't need the kind of resolution you will need in a class for example, an idealized classrooms in relation to resolve person, or just calling you on Can you convert this into
09:33:16 into a number for us so and I'm still
09:33:28 here is that if you if we quote this number and kill a parsecs for the Milky Way Halo and if cosmological simulations already satisfy this number, but we still don't see precipitation maybe this is where Heaven is headed.
09:33:41 And also, the number is important.
09:33:43 Okay do well work on it.
09:33:47 Sorry, I haven't worked out very much on this but I just have a question can we separate what is not the conversation from other kind of shaking of the gas from outflows or from ram pressure or what is the actual pure precipitation from no instability,
09:34:04 can we separate this kind of processes and simulations, or is it. One is going to be completely dominate over the other, or is this also depends on the halo environment, maybe more quiescent quenched halos, we see more precipitation which is what people
09:34:20 demonstrate its but in Milky Way size kind of galaxies, can we split the two Is it possible,
09:34:28 can we tell the difference.
09:34:30 By looking at energy injections.
09:34:36 And
09:34:36 I personally think there's an important distinction between cool gas seated only by hot gas and a disturbance in the Halo, so like an Ag and jet, that creates cool gas and a halo that I would call precipitation and cool gas that seated by other sources
09:34:50 like a satellite falling in or winds that are cool, that are moving out right that's, that's sort of we tried to distinguish between precipitation and condensation while acknowledging precipitation will create condensation.
09:35:02 And so that was the source of my question was for these precipitation only models. Is there a resolution criterion that you need to hit and maybe, maybe is already being hit in cosmological simulations.
09:35:15 Yeah, I think, I think that's an excellent question. sorry I just want to say one thing which is.
09:35:22 I think it is really important to go and determine, you know what is the exact exact source of the condensing gas you know if you have some cool cloud where did it come from the precipitate out was a condensed by inflows was it strip.
09:35:40 But I also want to stress something that, that I was trying to get across in my talk, which is that if what you're interested in, is the is the overall principle which is setting the halo right so so the halo property, then maybe that's less important,
09:36:00 because
09:36:03 the point is that is the is the regulation aspect that if the Halo, or the halo adjust itself cell, such that, whatever source of of cold gas is sufficient to condense out and to whatever the source of the coal gaseous whether it's you know, precipitate
09:36:30 classic precipitation from purely from the hot phase or whether it's some, it comes from, you know, low density filaments which come in and have slightly lower entropy and so then are easier to condense out, or whether it comes from actual condensation
09:36:50 of cold clumps which are throwing up and then create more mass and then come down. The point is that once your healing properties are at a certain point, this becomes possible, all of these mechanisms start to operate.
09:37:04 And then that's, that's when you establish this feedback procedure, so I think it's both important to understand the individual contributions to the coal, gas, but I also think it's it's useful to just think about this in a very broad brush picture.
09:37:20 What are the hot halal properties, or the Halo, what whatever property this which is setting the structure of the halo external pressure.
09:37:30 For example, how does that, what what state of that is required in order to allow cool gas to form by whatever.
09:37:55 Go ahead. Okay, so this is perhaps an educated guess I'm curious what people think with regard to Evans question about the resolution limit, um, something that I found in a series of cosmological simulations that I ran enhancing the resolution systematically
09:38:02 in the intergalactic medium and finding a phenomenon that is somewhat perhaps reminiscent of precipitation although in a very different context formation of condensation of cold clouds in the intra pancake medium, if you will, is that I only saw them
09:38:19 beginning to form.
09:38:21 If and when I resolve the cooling length so CST cool but not of the cold face out of the 10 before killing guests but of the hot phase.
09:38:32 Is that not a reasonable resolution requirement that might answer Evans question to cosmological simulations resolve CST cool of the hot component. Very well.
09:38:46 I mean, this is something that we looked at in Tempest and. And yes, we, we are able to resolve the cooling length of the hot gas reasonably well for, I think most high resolution cosmological simulations, certainly the ones that are enhancing the resolution
09:39:02 in the CGM, but certainly we're not getting close to being able to resolve the cooling length of the, of the cold gas, and I, and I thought, according to Mike McCourt's paper, you know, kind of seminal paper from a few years ago, the suggestion was that
09:39:16 you really need to be able to resolve the cooling length of the, of, of what the gas would cool to be the size scale of as opposed to the hot gas, no I certainly agree if you want the results to converge in terms of you know covering fractions or cloud
09:39:33 sizes or number of clouds. Yeah, I agree, but if you just want to see something that you could call precipitation, you see the formation of cold condensates that may not be converged or at their final size.
09:39:46 It's enough to have the cooling length of the initial cooling medium be well resolved so that you can get initial separation, even, you know.
09:39:56 into into cold clouds, again may not be converged but.
09:40:00 So you say that in the tempest you do resolve that scale well and yet you don't see any precipitation, well, so this brings up something that we talked about earlier in the meeting, and Greg mentioned just now and that is like.
09:40:13 So what do you define is as true precipitation versus condensation, you know, Evan. Evan was touching on this point and, and, and one thing that we do see in the temperate simulations, is when you have a cold film entry info coming in, that's kind of
09:40:26 seeding additional cooling on it, we do see that, and I have a really nice movie that demonstrates this that I showed a couple of times earlier in the meeting, but I don't see it.
09:40:38 Okay, maybe I it just is about me needing to reprogram myself about what precipitation actually means because when I think of precipitation I think of like this beautiful static hot medium that's metal and rich or whatever to cause it's cooling.
09:40:53 Time to be much shorter and then spontaneously it just like turns into cold gas and starts flowing into the galaxy, and I have seen this in idealize simulations that this this picture can be you know manifested.
09:41:06 But that's not the kind of picture that I see happening in an actual cosmological simulation where you know your galactic Halo was moving through the GM and it's getting slammed by this and that and their outflows coming out.
09:41:17 It's never that nice quiescent picture of just like this Stark creation of cold gas on the outskirts that flows in. But, again, that might be an oversimplification of of what happens in reality but actually Kevin I also wanted to you mentioned earlier
09:41:31 the fact about the halos moving through the AGM and the kind of numerical effects that that might induce there was a really nice genetic modification paper, I forget who the authors were but I just remember it was using genetic modification where the
09:41:47 the from six months ago or so called doesn't change. Perhaps the change that they made it was about dwarf galaxies and they were the only change it they made was what is the velocity of the of the galaxy they were focusing on with respect to its surroundings.
09:42:02 And when they made the change to basically make the galaxy at rest with respect to the box if you if you will.
09:42:12 They found much sharper features much more cold gas, everything was a lot less flow. So that is an important effect, which is very often, I think especially for for satellite galaxies or streams or stuff like that is just ignored, even in our numerical
09:42:26 conversations.
09:42:28 Yeah, that was from the trunk.
09:42:31 Gasoline group.
09:42:33 I forget the first author.
09:42:34 He's in the UK.
09:42:36 But, yes. Yeah, that's how Andrew Johnson.
09:42:40 Yes, thank you.
09:42:48 Let's have a meal. He has her hand up. Let's hear from her. Yes, so I was looking at the chat window and I think he wrote their post the very, you know, very, very helpful helpful point that is to the suffered model feedback model that you know in those
09:43:03 cosmological simulations. I mean thinking I'll precipitation.
09:43:06 You know, it's not, you know, it happens build up the feedback the outflow. And also the pre existing gas in the Halo. And I think the separate model matters with both point.
09:43:18 I mean for outflow part. What I'm talking about is the hot outflow that, you know, you do we need a certain condition, you know for precipitation to happen if say the hot outweighs too energetic, then you can imagine that you know before it kind of Kool
09:43:34 Aid just break out of the halo sort of in a spherical way so it has no chance to cool. Therefore, you may not observe this precipitation. On the other hand, if the hot out of ways to week, then it doesn't really proper get into the Halo.
09:43:48 So you also don't see you know it's not even emerged from that does not far that you may also, you know, not able to, you know, observe this precipitation in cosmological simulations.
09:43:59 So this is when the outflow part. The other part is the pre existing guess it's sort of the the accumulation effect of, you know, outflows over, you know, cosmological time.
09:44:13 So, in that sense, you know, the, the halo may not have the right amount of pre existing gas with this new old Floyd emerging. So that may up maybe another, you know, factor that, you know, goes into that not observing this precipitation cosmological
09:44:32 simulations.
09:44:37 Okay. Um, I think, you know, we are talking a lot about precipitation here and I kind of want to shift gears and crystal has a really nice question and I want to see if she would like to ask it about dwarf galaxies and CT collapse supernova propagating
09:44:54 feedback through them.
09:44:59 I really liked the stained glass window picture that Greg presented.
09:45:05 And, you know, at the end of his talk, you got to the lower mass galaxies. But then we kind of jumped all the way down to tend to the six solar mass halos, and I thought the region of that plot and kind of tend to the ninth to the 11th solar mass halos
09:45:22 looked very interesting because like the dividing line for the supernova feedback was very steep so that it tend to the 11 solar masses. A lot of the halo was affected by the supernovae but by tend to the nine.
09:45:38 You know your Rrv are there for the supernova feedback, it was, it was like 10% or something, it was a small amount.
09:45:46 And I was a bit confused then you showed the Pangea simulations and we're saying that I guess that was 10 to the 10 solar masses or something to the supernova we're going through the whole CGM, but is there something that happens at these lower kind of
09:46:03 tend to the nine solar masses, where the supernovae don't get there because there's just not enough stars or something or what's, is there some big transition that we should expect in the CGM between 10 to the nine and 10 the 11 that as observers we could
09:46:23 go look for. Yeah, I think that's a that's a really great question just one point of clarification. The, so I quoted a number for the first star stuff is tend to the six solar mass halos, but I just want to say that the the connection that we what's important
09:46:37 is the variable, temperature, and the connection between math and temperature has a redshift.
09:46:45 So, so, so really since those are high redshift those correspond to effectively a low redshift, there would be much more massive systems, but the, the interesting transition there of course is where the temperature the temperature gets down to about 10
09:47:00 to the four degrees.
09:47:02 And at that point, then the cooling property state changed quite a bit. So, the you know the stability of the gas depends on the, the, The kit the dependent the steepness or the dependence of the cooling function on temperature.
09:47:22 So, when it's rising like that that's stable the thermal the stable gas.
09:47:27 So those very low mass halos have potentially. Thirdly, if they're low enough, their, their thermal is stable and so that then moves towards a picture which might be more like more like a classic cooling flow that, for example, Jonathan stern was talking
09:47:43 about, in which the.
09:47:49 There is no condensation of precipitation, and you just get cooling at the very center of the Halo.
09:48:05 In fact, I think you saw something like that happening in some of the fires. We've seen similar for the lowest mass halos. So in terms of observational predictions, I would really I have just started to think about that.
09:48:11 I would, I, The gas densities of those halos are typically quite low.
09:48:20 Because of the, the, what I talked about beginning the supernova feedback can can easily remove gas from those halos. And so, So they're hard to observe.
09:48:33 But on the other hand, they're temperatures which are quite observable down to the floor. So, I haven't made any concrete predictions.
09:48:43 I would be.
09:48:46 I would be really interested in hearing from people who have fun.
09:48:52 That sounds like I know Mary's Mary patents on there on the panel and she is, she observes sightlines around dwarf galaxies but I see she's see June's hand up.
09:49:06 So I just wanted to add a little bit just so I completely agree with the picture that if you goes down below tend to know a few times tend to the ninth and the Veera temperatures pretty much to close the ITM temperature.
09:49:20 But for this little system actually know from my very limited no sample of little dwarf galaxies, this very very stochastic. So this is kind of echoed the point that analyst I made yesterday which is no more massive system how environment can affect the
09:49:37 satellites, and this exactly the same thing happens to the dwarf galaxies even for the cases which we will call as fuel dwarf galaxies. So in one of our recent studies of just few dwarf galaxies, so there's no Milky Way kind of no big massive things around.
09:49:55 If you have a few No, just tend to the 10 of just above 10 to the 10 Halo mass of dwarf galaxy around.
09:50:04 And then the CGM created by those supernova explosions within this 10 to the 10.
09:50:20 No halos can affect the nearby tend to the nine.
09:50:16 The formation of the nearby 10 tonight so it is to effect to it which we observe is one is that if you, if you have gravitational interactions that can actually promote the gas secretion coming into the little dwarf galaxies, so the 10 to nine galaxy
09:50:33 which promotes. So the Ignite star formation, it doesn't last very long. You have a pecan scum. Know that happens. And on the other hand if you have really CGM created from the massive galaxies, then you will quench the formation, it will quench and stuff
09:50:51 will completely from the little ones.
09:50:54 And this is actually really sensitive, to my surprise into the separate models, so we have tested two separate models. One is you know the delay coding projects.
09:51:04 So we have ballistic, so the winds come out and you delay pulling a little bit, and then you let the wind go and do it the other approach is the so called the Superbowl approach where in the main point is that the, the wind or the CGM have a high entropy.
09:51:20 So in the first picture you will see that you have the metals spreading everywhere know all the way to mega pass even okay and you have to have the velocity to reject those master get this know, Stella Stella masturbation.
09:51:33 No, Stella mass healing masturbation. So, no it's, it's kind of spread around kind of picture, and the second picture was a super bubble you have the high entropy so the gas is sort of just around it was high entropy without being dispersed very much.
09:51:46 And then when you little growth gallons come in, the interesting happen is that gas accretion into this little dwarf galaxies is suppressed. So some of sort of starvation going on for this little dwarf galaxy, and it doesn't form at all.
09:52:00 So, in the low man system I will say this is really complicated, depends on what kind of environment they're in, and this is also the same case for. Hi.
09:52:14 But observational Lee, I don't know I would really be excited to hear some opinions from service what. Now what kinds of things we can prob with look at the column densities and stuff but that seems to be okay, it's more, no more diagnostic way to tell
09:52:31 the difference will be nice.
09:52:35 Curl has his hand up.
09:52:44 I guess. On a related note,
09:52:50 One moment, may sound weird.
09:53:02 We we've we've lost you yeah we hear you. Yeah.
09:53:09 Headphones doing great things.
09:53:19 To what extent.
09:53:16 Sorry, right so we can talk about predictions for a general tendency. Right. And I think that is kind of what a lot of the predictions for more massive galaxies have been right you know you predict a typical amount of oxygen six or a typical relation
09:53:31 between.
09:53:34 I don't know right like the line with the something in the comments, or something, etc. Right, or you know, amount of hydrogen versus persistence, matter of X rays vs distance right but basically central tendencies.
09:53:55 And so, if it's true that there is a scale at which you switch over to being extremely stochastic, what would it makes sense to look for that scale right and basically to make predictions for a scale at which, You know, the variance of properties should
09:54:06 be caught should blow up right because if it's true that work galaxies are extremely stochastic systems.
09:54:31 Then the stochastic it should be observable somehow right and it's observable perhaps in star from in star formation rates.
09:54:21 But it cannot be observed in the CGM as well, and can people make predictions for the scale let's say at which you go from, you know, just knowing that something is it worth galaxy isn't going to tell you much about exactly what you expect to see, to
09:54:37 knowing that something, you know, is a bit more massive does tell you something about what you expect to see.
09:54:57 Okay, it's a very that that cat is paying attention.
09:55:01 Joe, go, go ahead.
09:55:07 Wait Mary Mary was about to marry for great guy I'm sorry Mary, our panel members will raise their hand they're kind of an unsure and, yeah. Either way, you have prerogative though, go.
09:55:17 Oh well, no, I actually mainly have questions to be honest I don't think that I actually think observers like Jess was asking or looking to you a little bit into what we what you would expect to observe I mean we do have some observer both but we're not
09:55:31 not sure what it fits so we're just trying to sort that out.
09:55:35 But Cedric, I'm wondering if one prediction from what you're talking about it sounds like most of us would be happy at higher redshift and also that Greg This is related they want to ask you about the model where you have the expanding the gas station
09:55:48 and going out into the AGM as well, which sounds along the lines of what CJ was saying, is whether you would expect them to have four dwarf galaxies to have little gas flow stores around them, and is that a clear observational prediction.
09:56:04 And in terms of what we've detected. We're somewhat limited Of course because then you're talking about gases little blobs like we have around our Milky Way.
09:56:12 With with not many stars but you know the measurement clouds now we think there's a bunch of those small little blurbs that possibly came in with that.
09:56:21 And then, I think we are starting to get to those kind of dubs going out to the nearest gas storage course and so far there's not a lot out there we definitely see gas, gas stores, but.
09:56:32 So I'm wondering Would you say that to clear prediction of your model that you would expect that that you would find quenched little dwarfs around doors.
09:56:41 No, no.
09:56:44 In our simulations, I mean, these are still start from indoors in the world.
09:56:49 In the end of the day, I mean, not.
09:56:52 I think you were talking about the one that is actually formed stars right now the one that has been not formed at all. So there's.
09:57:09 Oh, this is so high redshift it hasn't funded at all. No. So, this situation is that for 10 to 10, we still have a lot of supernova ejections and we get a lot of gas and all the metals, but the dwarf galaxy itself is still gas rich, because the ratio
09:57:17 between the gas and stars are still very high, it's it's it's quite high in the case at least is one to one or even the fact of few more times gas compared to the compared to the, to the stars, so the Keck know can be characterized as gas rich Dorf galaxy
09:57:34 rather than guests pool, but the ones that God's quenched completely we're talking about the main one yeah the main one.
09:57:43 Okay.
09:57:45 But it's already a little quench things that's what I'm asking.
09:57:50 The main one you're talking about right now the main one yeah I understand the main one would be a slightly larger dwarf galaxy probably guests and star for me, but that it would based on your description have little quench smaller dwarf galaxies noon.
09:58:23 Cosmic ratio. Exactly. Okay, so I think they are relatively gas poor because gas has trouble to come in but they are not completely gas free, unless they are going to also another environment effect which is the ram pressure stripping so if they fall
09:58:37 into the massive galaxy then it's just a little bit more massive the stupid still kicks in. So the gas production goes well. But other than that, they have gas fraction, normally not not very privacy.
09:58:51 That's, but they haven't really looked at in detail. Okay. And Greg related to that I'm curious, how long does this heating that you seem to indicate that the temperature, it stays at the temperature so there's basically a continual heating going on and
09:59:08 going on and a continual heating out to quite large radio, which kind of puzzled me.
09:59:14 Yeah, me too.
09:59:18 So I don't have a good answer for what what in in the simulations. I mean, clearly you know you can see from them from, from all from both of these that, you know, this for these low mass guys these there are regular shocks which goes through.
09:59:55 Part of the heating maybe if it's a true cooling flow it may just be compression, as these things flow in.
09:59:47 Okay, well I do think that, like, like you said, I think the problem is the densities are so low observable those are going to be tricky but it definitely sounds like it produces some clear predictions.
10:00:01 Yeah, I think we don't have I mean at least I don't have those predictions, yet I think you would need to do some simulations, but I think it would be.
10:00:09 I think would be really interesting to try and do that to look at, you know, various as you suggest correlations between start forming properties of galaxies of different masters at the low end.
10:00:21 And I think in because it's so stochastic we actually a lot of those simulation to actually get progress.
10:00:31 We're Joe virgin has a point that there is data at low Halo adore around dwarf galaxies in the CGM.
10:00:41 And I'm going to have that conversation, continue on Slack, where you can hit him up. I want to, I know it's 10 o'clock but I see critiques hand up and let's give him the last word he's got the answer.
10:00:56 The answer.
10:01:08 So, the restaurant.
10:01:25 in my mind. There are two very broad classes of.
10:01:21 One is the existing big cloud, you know, and you grow multi-phase gas and its tail. So you know, Ram pressure tales of galaxies, or is them chunks lifted in hot galactic outflows and IBM filaments penetrating the heart CGM are in this class.
10:01:41 The other classes when multi phase gas condenses out of the hot diffuse CGM the Delta rover rose small or you know order unity or largish, but no, No dense gas present.
10:02:00 So, no. So, once connectors in precipitation to, it forms a dance club which falls through the CGM so you know the the precipitation model gets quickly converted into growth question right so that, you know, you cannot really separate all these very cleanly
10:02:21 into one another but precipitation, or thermal instability model is useful because it gives like a very nice upper limit on the state of the hot gas.
10:02:32 Right. So, that is what I think Mark is saying about the global value of this precipitation, but of course. Reality is so complex that this cannot be the answer for almost everything you know.
10:02:49 You know that there has to be a lot of knobs and other things which are which are more dominant and other in different situations so that's my take on it.
10:03:00 Okay, thank you, particular I that was there, that was worth it.
10:03:05 All right. Yeah.
10:03:08 That was an active active session today like that we got to talk about both.
10:03:14 Hi mass halos mo mass halos and again thank you to Greg for covering all of our galactic halos that we study and to the panel.