09:20:25 So I think, Jason Why don't you start your presentation. 09:20:31 All right, you can see it correct. 09:20:35 I can, yes. Okay, good. 09:20:38 Let's do it. I'm. 09:20:41 Good morning, folks, wherever you are. 09:20:44 I'm Xavier I also known as Jason to some. I'm here in Santa Cruz California with the sun shining lovely. 09:20:52 And I'll give you a, a fast radio burst tutorial in the context of Halo guess next 40 minutes or so. 09:21:00 I've targeted the slides and presumably the discussion at folks that will have heard of fast radio bursts before like read a paper to watch the talk, not complete newbies and not experts either if you are an expert you're welcome to jump in and correct 09:21:19 But that's the target audience kind of folks that have some basic knowledge of FRB's but not much working. 09:21:28 And I'm going to have the discussion as we go. So I'm not going to present for 20 minutes and then open the forum I'm going to pause every slide or two, and we'll discuss. 09:21:42 We can do it. 09:21:43 I turning on your audio or we can do it by typing in the slack. 09:21:47 I'll be monitoring the selection. 09:21:50 And last, I want to introduce Bryan Gaensler who's, I believe in the audience. 09:21:56 And his co conspirator on FRBs in this workshop, 09:22:00 and will speak especially the last few slides but you also hopefully correct all the mistakes I make about radio astronomy, given that stuff by background at all and it's for Surely it's okay. 09:22:14 I put this a link of the five on the channel, and the Travel Channel and FRB channel. 09:22:19 And I've tried to make a fair number of the links are clickable. 09:22:24 So that you can jump around. 09:22:26 If you come back to them. That includes this GitHub repository or actually it's an organization with multiple repositories for FRBs. 09:22:37 You're new to the field. It's a place where you can get some analysis tools that may be helpful to you and data. 09:22:55 So let's just keep going. Alright so let's see, I should give credit due credit to a team that I'm a part of called the F four, fast and fortunate for FRB follow up. 09:22:59 So are the majority of the team members, I'm the goofy guy on the far right. 09:23:01 Our main objectives are to follow up fast radio bursts, we do not detect them ourselves. 09:23:08 We rely on radio telescopes and their collaboration to do so. 09:23:12 But we spend a fair bit of time with ground based telescopes and space. 09:23:17 Most wavelengths these days following up. 09:23:21 If that interests you, we're Welcome to have others join in the crowd. 09:23:28 FRBs In my opinion, begin with Lorimer Burst. 09:23:32 The This is I've put photos in those of you don't know the field will try to make this a bit homey. 09:23:39 And put some photos of some people involved in this business. That's Duncan Lorimer, West Virginia University he detected. 09:23:48 I'd say by accident, the first fast radio burst. 09:23:51 given that name there are 10724 2001. 09:23:56 July 24 by the parts telescope. 09:23:59 The figure is a plot of the arrival time that's x axis of the pulse, as a function of frequency the y axis, often called a waterfall plot. 09:24:15 And that delay in the arrival of the lower frequency radiation is due to the fact that the pulse had to traverse through a plasma of electrons that retarded the speed for a little time of the shorter frequencies more so than the higher frequencies, this 09:24:32 This is 101, electromagnetism. 09:24:47 It leads to will be referred to as the dispersion measure I won't go through all the equations here they're not that exciting, But the group velocity. 09:24:48 Sorry, the velocity of the lower frequency radiation is slower, lower than the higher frequency. And that's what we see on the previous figure. 09:24:58 And it's characterized the degree to which light is retarded is characterized by this dispersion measure dm, which is the bottom equation down there. 09:25:07 Which, if you're in the Milky Way. 09:25:09 And the rest of frame, and it's the simple integral of the electron density along the path. 09:25:15 There are more nuances to it than that. 09:25:18 There's a nice write up by Shu Kulkarni from last year you can go check out see all the ins and outs of that dispersion measure, but in the context of Halo gas, those nuances are small enough to be particularly interesting, 09:25:36 pause there 09:25:41 questions feel free to type them into the world, chat window or whatever channel. 09:25:49 Go. 09:25:50 Okay, so dispersion measure. I like to call it a blessing and a curse. It's a blessing because you were sensitive to all the electrons along the path line. 09:26:00 That's something that technique that many of us have employed absorption line safe with quasars. 09:26:06 It's not true for with quasar spectroscopy we usually typically we're typically sensitive to one phases we tend to call it of density in temperature with dispersion measure you're sensitive to all the electrons formally when you go to expanding universe, 09:26:22 you have to introduce scale factor. See here, but it's also a curse in that you are sensitive to all the electrons and your scientific interests are in an isolated portion of the universe as the opener. 09:26:44 the observed dispersion measure includes all the other components too. And so I'm cartooning the major ones here including the length skills of the universe that go with them. 09:26:51 I'll walk through handful these in the next few slides but the green area is gas associated with our Milky Way. The warm ionized medium predominantly. 09:27:01 Most, I suspect of the people listening believe there's a payload of the Milky Way of baryons. 09:27:09 And many of us are interested in characterizing that better than we have thus far. 09:27:13 Those will contribute to the DM. 09:27:15 The Milky Way's local group may contribute as well. 09:27:20 And then there's the cut what I will feature the cosmic web that's both the intergalactic medium so diffuse gas between galaxies and Halo gas, the gas around galaxies CGM cosmic web includes them both. 09:27:34 And then there will be electrons in the local environment of whatever it is that generates FRBs, and I'm not going to speculate or discuss at all today what the origin of FRBs are. 09:27:47 But they undoubtedly will we know that we now know for sure they occur within galaxies. 09:28:00 And there will be local contributions as well, which will call the host country. 09:28:04 question so far. 09:28:09 So, the green from the previous is the green here it's the dispersion measure from the ISM formula we call it the warm ionized medium predominantly. 09:28:19 We have a well, one now. Um, Well, constrained data driven model of that distribution. 09:28:28 Bryan amongst others has retired on measuring the dispersion measure to pulsars and measuring the distances absolute distances to those pulsars to map out the electrons in our galaxy. 09:28:42 Jay Lazio has a picture here as well. 09:28:44 Part of that effort. 09:28:45 And we have now this, but I tend to use this any 2001 model for the distribution of electrons in in the Milky Way. 09:28:55 And as projected on the sky. This is the dispersion measure from those electrons. 09:29:00 If you go through the plane of the disc of the galaxy. 09:29:04 You can incur a very large dispersion measure even any hundreds even thousands. 09:29:10 But as soon as you get off the plane, say it's 30 degrees or so you can see you're down to the 10s of dm units. It's parsecs per cubic centimeter, which is not negligible, but small compared to best radio burst dispersion issues. 09:29:28 So we take that as a given. There are, I'd say the uncertainties off the plane we're in the 10s is a 10% or 20%. 09:29:39 A few dm units maybe five maybe 10 even. 09:29:44 But this tends to be a small contribution to the air budget, pure interest in dm scientifically, 09:29:54 Bryan, you can enhance that kindly kindly enhanced what I just said about DMS them if you wish. 09:30:01 About the and what sorry about the estimates of the dispersion measure from the warm ionized medium. If I didn't speak it well enough. 09:30:13 I think that the situation is not great. 09:30:15 I think the important thing about models like any 2001 is the fair 09:30:24 statement about what is known about the warm ionized medium in front of the full size that you have. So although by taking the equations that have arrived and making a map like this, it seems to have predictive power, the predictions of these models have 09:30:39 never worked out that well in that, as the name suggests, this, this used all pulsars known through 2001, but many pulsars that have been discovered subsequently did not fit very well into this model. 09:30:50 So it's a great way of characterizing or visualizing the data you have the predictive power is is limited, particularly off the plane because also surveys have spent very little time looking for pulsars off the plane just because it's hard work and 09:31:03 you don't find many pulsars and the ones you do find the quite boring. So, the information of all life is gives off the plane which is perhaps the interest for this workshop is pretty limited and has not done well and making forward predictions. 09:31:20 So the situation is not great. 09:31:22 And what error bar would you put on there, five units 10 units 20 units for off the plane. 09:31:28 Oh my goodness, sometimes it can be a factor of two out by factor of two depending on the sideline. 09:31:35 Thank you 09:31:43 There have been lots of discussions about the workshop, a whole channel devoted to check it out. 09:31:50 We, myself and Maio-Wong, published a model based on some fair bit of the data, known for the Milky Way and models of how Halo gas may be distributed in dark matter halos. 09:32:03 That's what this blue diagram is. And it also includes contributions estimated guests contributions from M 31. And the Magellanic Clouds. 09:32:15 But presumed to be basically a nice a tropic distribution of Halo gas, and we estimated the dispersion measure to be about 50 to 80 units. 09:32:24 This is not well constrained. 09:32:28 Subsequent paper by Keating and Pen argues based on effectively the same data that the dispersion measures and local halo may be less than 10% 09:32:43 plots at all. 09:32:44 As part of have used existing FRB dispersion measures and assumptions about the PDF of the external contribution to set a lower limit. But the big error bar on that contribution 63 plus or minus 25. 09:33:02 And then there's a recent publication by Dosetal kind of also using the iOS seven, which again gives a range somewhat similar to what our model had a couple years back, anyways this is a big unknown. 09:33:15 I think this is an area where FRB's will greatly improve the situation with analyses like what was in plots at all but more sophisticated ones as well. 09:33:25 And one can look for variations across the sky and I know. 09:33:28 Bryan and his colleagues are hard at work, and using the time to do that. 09:33:35 Questions on the Milky Way. 09:33:55 I had a question, surely dispersion measure towards the FRB bubbles be higher. I mean, we'd expect that they have an excess of electron density. 09:34:04 Well, we can't get that wrong London was it was a couple units. Yeah, that was very far away, I mean especially towards the galactic center should it have higher contribution. 09:34:14 I'm not including at all. 09:34:17 The underscore medium. 09:34:19 Gotcha. 09:34:23 x doesn't tend to be Halo beyond with gas beyond 10 cool part of the desk. Yes, please. 09:34:30 Yes. So recently. Halo set the satellite kind of image. The electron density and they found that it follows more like two model, I think, when is circular and the other one is sort of dislike that yours and many other models, except Yamasaki 09:34:57 all of them, assume a spherical density, kind of distribution. So, I'd say the data allowed. 09:35:01 Lots of different distributions. 09:35:03 So continue to make models that you like, but going forward. I think that will be well constrained by large survey FRB surveys like chime. 09:35:17 And second thing is specially on these of all the models yours and you also know that they kind of assume NFW profile. So what about, like, the model that really proposed me as in two pac maximal eyes and tropic distribution, where certain radius, instead 09:35:35 of isotonic distribution here's your maximum entropy. How can we constrain that model. 09:35:43 I don't feel expert enough to speak about Whaley's model. 09:35:47 But maybe someone else in the channel. 09:35:51 Sorry, but I don't think you. 09:35:53 All right. 09:35:56 I had a good trivial question, perhaps, please. 09:36:01 In the previous slide, what is this excess at 270 degrees, and get different time. I'm pretty confident one's a supernova remnant. 09:36:12 And the other might be an age two region but Bryan help me out, 09:36:17 which is very large, extremely nearby old shell probably a supernova, and then a smaller one inside it is the villa supernova arena, which is is still quite large to take degrees across that's somewhat more distant for two unrelated shells that 09:36:37 a large area on the sky. And why, why is the DM so high, you know, this is an indicative of any DL. 09:36:43 It's a supernova remnant there are so many of them, and it's an integrated quantity what why is dm so high. 09:36:51 So it's high for all explorations of supernova remnants and that's. 09:36:55 It's just that those two a large enough that you that despite the pulsars that we have can detect it. but if you're asking what what basically any supernova remnant is high just . 09:37:23 taking a 3d volume and converting it to a 2d shell. And so that greatly increases the DM associated with that volume. 09:37:22 Okay, so these are at the, you know, they are at a higher latitudes perhaps they are. That's why the problem with our close, that's another key point here. 09:37:31 There's an age to age and throughout this figure, but most of them are far away and hence, small as observed, but they'll have large value. 09:37:39 Okay, got it. Thanks. 09:37:43 You give us like the order of magnitude number of how many pulsar observations go into that into 2001 I'm gonna guess 200, Bryan knows better than me. 09:37:56 You have to have a pulsar, and you have to have an independent distance for and getting the independent distance to full size is very difficult there's only a few ways you can do it, and as the pulsars get more distant most of those methods don't work. 09:38:07 So, yeah, I think off the top of my head. 09:38:10 At the 200 would be a pretty hard limit and might be less than that it's not many, many, many more pulsars only have dispersion measures and positions that we don't know their distances. 09:38:22 By the way, just as an aside that includes the one so called in a large measure like clouds. Those distance are not known factually, or I should say absolutely. 09:38:30 They're expected, given their location to be associated the cloud. 09:38:37 Of course they're not truly measured. 09:38:40 I have two questions. 09:38:43 One is Joe Hennawi. 09:38:47 One is a by looking at h alpha map of the galaxy it looks quite a bit different than the, than the last slide that you showed, part of that is that the alpha map is technically density squared, integrated don't say, whereas map is density integrated 09:39:04 one website but I guess I just wondering if you thought about why it looks so different. I posted it and I say Bryan spent three pages of his paper on that topic. 09:39:13 So, I'll defer to him. 09:39:15 Yeah, so there's a few reasons why is one is pumping emission metrics is n squared. Yeah, the other is is of course as the mission measure for myself is sufficient that's the extinction. 09:39:28 So you're, you're losing, most of the DC offset. And so the fluctuations, but much more not to just think a little metal structure where with the pulsars is not extinction. 09:39:40 And as x alluded the N and N squared actually have different scale Hots. 09:39:47 So they they look, they look different for that reason, as well. 09:39:53 Yeah, but the main the main reason is that, that is that the mission measures clumpy and stuff so extinction. 09:39:59 But it's the same gas. Well, some people argue that they're using different phases and the DM and the A but that the mainstream view is is that is that the, that is the same gas, it's just that because it goes in squared, em is totally dominated by 09:40:13 density regions that contribute very little to the exposure because the depth is not that large. And my second question was, can you actually detect or measure DMs, from pulsars and Andromeda that would allow one to test the next slide. 09:40:32 We all want them. 09:40:38 I bought five 09:40:39 times working hard on it and so the fast telescope in China. 09:40:46 And what about in the LMC, I guess, or the SMC I mean, they're pulsars are known right so. Well, as I was saying they're, they're pulsars known to lie in that direction with DMs that suggest they're not in the Milky Way. 09:41:00 But the distances aren't 09:41:14 like a strongest statement, but there are some of the pulsars are known to be associated with EMC and SMC some other inside Magellanic supernova efforts. I think the problem there is that the SMC and EMC both have a significant internal range of of disposure. 09:41:20 measure, so all you can really do from those is take the collection of pulsars that are in each of those galaxies, and take the lowest the end and say that that's an upper limit on the foreground contribution. 09:41:30 But there's, if you look at the range of of the DMs and those galaxies it's quite large. The other really useful private globular clusters, there are many globular clusters that have pulsars in them. 09:41:41 In all cases that especially measure every pulsar in a given cluster is basically the same. And if that cluster is far enough about the plane, then you have a very clean line of sight of the dispersion measure through the halo at least out to the 09:41:53 distance of that cluster. 09:42:07 Are there targeted ,educate me Bryan are there targeted surveys of global clusters still ongoing proposals. Um, I, That's, that's not really my, my area. 09:42:11 My understanding is is that there's not a lot of work going on. It's tough work you have to spend huge numbers of hours counting away at these things, and the pulsars are very fake. 09:42:19 So I think all the low hanging fruit has been done. 09:42:23 But there are some other classes that probably haven't had time invested on them and surveys like chime well hopefully start to pick these up as we see the whole sky every day and just integrate deeper and deeper and. 09:42:36 Thank you. 09:42:39 And the cosmic web contributes as well. This is what I'd say it sucked me into this field. 09:42:45 And the integral here it gives the average contribution. 09:42:51 Based on the average density universe, and cosmic LG. 09:42:55 It does include one factor the Hubble's parameter. 09:42:59 Each not. 09:43:03 And otherwise, it's just Baryon density which we've known and loved and measured well for a couple decades now. 09:43:11 And the fraction of gas that's in Baryons that are in a diffuse ionized state, which is the majority but not. 09:43:25 Not all 09:43:25 on that topic. Um, I guess last year now. 09:43:30 We published the first set of data. 09:43:37 Comparing the an estimate of the cosmic dispersion measure. Previously, against the redshift of the FRB based on its association to a galaxy. 09:43:48 And the redshift comes from the galaxy now. 09:43:51 This is the data set the color then we'll go into great detail the color are kind of the gold standard, the ones that met all of our criteria for analysis. 09:44:01 And this is now referred to as the Macquart relation, JP Macquart the gentleman in the middle. On the left is this some kind of card that some of you may know about a week after the publication JP passed away unexpectedly. 09:44:15 very sad. 09:44:16 We miss him. 09:44:18 But he did see through what was. 09:44:21 I'd say one of the main driving factors of his interest in FRV is probably the main to this publication. 09:44:28 The data lie. 09:44:31 I think you agree quite closely to that black line that black line is that in a row. 09:44:37 So the average dm cosmic based on what we know from, say, the plonk cosmological parameters and good estimations for the amount of gas in the diffuse state, and the correspondence between the two allows us to assert that we've detected all the so called 09:44:55 missing baryons that many of us have been concerned about where the past few decades. 09:45:03 Was there. 09:45:13 Can you on for Halo gas. 09:45:18 There's still plenty of work to be done. 09:45:21 The left two panels show some model predictions for the dispersion measure. 09:45:28 If you penetrate a halo at some impact parameter. 09:45:32 Our purpose. 09:45:34 And there's just two different halos depicted there's three different masses. 09:45:38 The wax is the log scale the linear. 9:45:42 You can see you get orders of magnitude variation depending on the mass of the halo you intersect the distance from the center of the Halo, not shown in this cartoon or the variations you will have four different soon density profiles, which we don't 09:45:57 know. 09:45:58 Also not cartoons here's the variation you'll get from the amount of gas you predict have been expelled from the Halo. 09:46:06 This these curves assume none has been expelled but that's some over or 20% or in its stars and neutral. So, 80% in the hot. 09:46:13 Did you see the lower panel. Maybe it won't go into too much depth is describing the differences you get if you, if you vary the size of a halo. I mean, we've arbitrarily one one is one has to arbitrarily effectively choose size of dark matter Halo radius 09:46:38 is it twice the radius, three times. 09:46:42 That's what's being cartoon. 09:46:47 That's what's being card tuned on the right is a conversion of estimates of the surface density column density of ionized gas through L star halos from the gas Halo survey, taken from Jess Werk's paper. 09:47:02 The blue is the cool component, as we call it, the red is a lower limit to the hot component based on oh six lower limit, and the green is another model soon for an all star galaxy. 09:47:15 With a student density profile and give you the details. 09:47:21 But the point is, or galaxies every teen significant fraction of their gas else are galaxies that have retained the same fraction the baryons you expect the ends of order, many 10s to even hundred. 09:47:32 As you go through, even out to about a radius. 09:47:39 This is pseudo theory, the blue histograms data and the blue line is an estimate the data to green theory questions on that. 09:48:03 Want to expect from intersecting a single Dark Matter Hill. 09:48:05 X, i have a naive question here. So, do we expect the density to follow. Same isotope models kind of profile, after second turn around radius means after at radius greater than two times the video radius. 09:48:21 That's a great question that I don't have an answer to but a bit someone on the channel does are on the call does. 09:48:27 What's plotted here is just an NFW, what is it here is the modified NFW profile that we've adopted at those large radios it's basically NFw so one over R cubed. 09:48:40 But the question is Is that a fair profile out at two and three radii. 09:48:47 Yeah, thank you. Anybody know anybody have an opinion, I should say. 09:48:55 I have an opinion I have a question. 09:48:58 Is this Frank van den Bosch. 09:49:01 We have a data like this with a shown with the blue histogram, how do you link it to a halo and this doesn't think like from, from the rest of the line of sight. 09:49:11 Yeah, so you should be visualize, or to. 09:49:16 Well, what's been done heres. Take the analysis of the cos Halo sample which is worth 30 sightlines pin them up. 09:49:26 What we 12 bins they're not sure of order that says maybe a couple sightlines contributed each. Then, and then generate a PDF of the column density, based on the uncertainties which are large. 09:49:42 So on plot and those are large uncertainties. 09:49:43 To make the 2d histogram 09:49:52 other questions. 09:49:57 Cool. 09:49:59 I'm convinced will have a very nice description of M 31 Halo, and the next couple years by we looking towards Bryan and the team. 09:50:11 That's the signal that m 31, the model based on our estimates of M31 Halo mass assumption that it's retained most of its baryons and assume density profile that's the signal for M 31, so many 10s even will be on 100 vm units. 09:50:32 And with enough FRBs covering both it and random sky You don't even need to know the redshift the FRBs, the differential experiment. 09:50:42 Here we had estimated several thousand would be sufficient to several thousand across the sky, not crossing the sky. 09:50:51 Not just several thousand and 31 would be sufficient to get a signal. 09:50:55 So I'm optimistic Chime will have first results and M 31 in the next couple years. 09:51:02 And I'm now more optimistic that the offseason play. So, Andy Fak, if he's on the line, and his colleagues published a new result on the nebula, the nebula of LMC, and between when I made this figure and now I guess the LMCs mass is increased by 09:51:28 a factor of 10 or factor of something big. So the signals only gotten stronger in fact I think it's stronger than the M 31. If that mass estimates correct, but it's in the southern hemisphere, and not covered by Chime, which is the only big survey by number, the moment. So probably that's going to wait till the SKA. 09:51:43 But I predict the LMC will also be well mapped. 09:51:49 Comments on that 09:52:01 How about the cosmic web. So, and asserting the baryons have been detected. 09:52:09 Not asserting they've been found. 09:52:11 And so we've pivoted if you will to that question Where are the baryons To what extent are they really the questions coming out to what extent have halos retained the baryons they're either. 09:52:24 There's a fraction of gas around galaxies and CGM, and the rest of it, I think we all believe is in the, in the intergalactic medium. 09:52:31 And so what's the balance between the two. This paper by Simha adopted this slime mold technique of check to make a model of the gas and the cosmic web on that sideline, using Sloan galaxies and our own data and make some comparisons if you're interested, 09:52:54 check that out. 09:52:55 There's work underway by KG Lee and his team that IBM you to do a similar analysis for sure better. 09:53:06 These are predictions, if you will, of what a survey of or 30 fFBRs survey will be called Flim Flam ongoing using the at to do wide spectroscopy, which is required for the cosmic web reconstruction, as well as narrow deeper data to identify Halos 09:53:30 close to the sideline. 09:53:34 And this is a three parameter model that would show the constraints, you would have on the host dm. 09:53:42 The extent of the Halo, R max there. And what fraction the baryons are in the hot Halo. What fraction the Baryons and the halos versus intergalactic medium 09:53:54 that topic interests you, I encourage you to reach out to kg. 09:53:58 Maybe on the line despite it being almost 3am in Japan. 09:54:02 Let me pause there cosmic web analysis. 09:54:08 The last two slides. 09:54:18 Can you provide more details about how you combine the cosmic web observations with the FRBs to get these constraints. 09:54:27 Yeah. 09:54:29 This cartoon helps me better at least like speak this one better it's I know better. 09:54:33 So, for this field, as I said, the FRB from ASCAP happen to go up and as part of the slim footprint section the edge but still had fair number of galaxies, their distribution on the sky plus redshift. 09:54:50 enables a reconstruction of the cosmic web. We use slime mold ag phone plans can use Metin's approach, you're probably familiar with. 09:55:05 To make an estimate of the cosmic web contribution parameter rise by the things you saw in the next bigger. Next slide. 09:55:16 And then it's also valuable. 09:55:20 Maybe not required but valuable to include whatever knowledge we can generate or derive about galaxies close to the sideline. 09:55:28 Because while there's only a handful predicted expected. 09:55:33 They can contribute substantially so that's part of the models, is how many halos around the galaxy closest sideline. 09:55:42 And based on their based on the observed magnitudes convert that to a stellar mass convert that to a stellar Halo, sorry. 09:55:58 Halo mass substantial uncertainties along the way there to be included in the modeling 09:56:01 that helped you say yeah I guess I was more just, is there actually given the contribution from the FRB host, yet our galaxy, like, I guess how sensitive actually is it that's just trying to understand. 09:56:16 I know they're marginalizing over that. But here there's, it's part of the model. I'm actually here Sorry, go, go, kg. That's, that's a time over all FRBss have the same host you and what breaks the degeneracy is that you have a host the DM that 09:56:32 That's, that's divided that the in the contribution of dm has like a one plus Z FRB in it. So if you have samples of spreading or wide range of redshift dm contribution will change. 09:56:49 Functional redshift if you are. 09:56:51 If you are. 09:56:54 If, If the host dm is the same. 09:56:58 So that's what breaks the degeneracy. 09:57:11 Of course, if you assume that the host dm is embedded in the is from the host galaxy itself then of course the problem just falls out the modeling the halo contribution on the host galaxy. 09:57:15 Okay thanks guys. 09:57:17 And then we also need first at one point which is an optimism whatever the, the blessing of that FRBs the fact that there are the curse that we're sensitive all components. 09:57:29 The good news is we can actually attack them somewhat independently so the technique I didn't go into depth on it, or the Milky Way dispersion measure that can be assessed independently of some large extent, anything that's described in this slide. 09:57:44 And so, the community is going to be refining and look you estimate, it will find ways to refine the host estimate. 09:57:51 It will find ways to hopefully improve cosmic web estimates, somewhat independently, whether that cannot be thrown in at the end of the day into some huge mC mC I don't know, but probably probably instead of just use them as priors. 09:58:08 They'll just improve over time. 09:58:10 Well the answer is yes because each FRBa independent likelihood, so you can literally just one of them one by one and combine the likelihoods at the end. 09:58:21 But I'm saying KG is that if people are in they should be concerned about the Milky Way contribution to this analysis. 09:58:28 I'm asserting that China which is not can be, because there's no redshift information, most of times FBS. Nevertheless, that surveys going to place constraints on the Milky Way dispersion measure that can be used as a prior into this model. 09:58:42 Yeah, but by doing the crucial thing is that issue for FRBs independent sideline so you can you know you can tweak the assumptions in every single FRB that you analyze. 09:58:58 Other questions on this.