08:05:03 Okay, welcome back.
08:05:08 Before I introduce the speaker, I want to talk about how we've shifted our format for that the keynote talks.
08:05:18 Instead of having the keynote speaker, have to bear the brunt of sustaining the entire discussion.
08:05:26 What we're going to do is after the talk. We're going to have you enter questions and potential discussion topics into slack on the Slack channel for this week.
08:05:37 The speaker can then answer the questions, you know, it asynchronously.
08:05:43 Get to all the questions you might have about the talk itself but you may also answer at potential discussion topics in that channel.
08:05:52 So, about an hour from now, we will convene to have a panel discussion where we have other people you might want to bounce questions off of, and they'll be leading the discussion.
08:06:03 So that's how we're going to run it, so that we have a little more diversity of ideas involved in the panel.
08:06:15 The next speaker. I have been following her scientific career for over 35 years very closely.
08:06:23 It's making Donahue, and she'll be giving us this the part two of how to gaseous halos depend on Halo mass and stop my screen share and asked her to start hers for the top.
08:06:58 All right, now.
08:07:02 Looks like it's working.
08:07:03 So, the slack idea is interesting, I'm gonna have to turn on my slack after I stopped speaking because I turned it off, because it was ringing off the hook.
08:07:18 because I'm in another meeting at the Ws right now this week is the Ws I'm the past president and the current president was stuck in the power outage at in Seattle yesterday.
08:07:35 And so, things got kind of hectic and I'm still not sure if she's back online yet so.
08:07:42 But other people are handling that now and so when I'm going to be here.
08:07:48 Um, so I've been asked today to talk about gaseous Hales and how they depend on Halo mass and in specifically. Um, I've been asked to talk about how highest math halos dependent for the guests in the highest mass halos depend on their mass, and by high
08:08:08 mass.
08:08:09 I think this group would consider a few times tend to the 13 solar masses to be fairly high mass.
08:08:16 Would I would consider a pretty high mass would be another order of magnitude higher than that.
08:08:21 Because when you get down to tend to the 13 solar masses, those gaseous halos get hard to see.
08:08:29 And when I'm talking about seeing it I'm talking about seeing the gaseous halos in the x rays.
08:08:35 So here is a picture of a single cluster of galaxies it's a bell 383 it's.
08:08:43 It has a fairly spectacular lensing system which you see here
08:08:50 in the Hubble Space Telescope picture on the left, there's a lens and images of background galaxies. You can see those in the blue. And also, these orange extended loops, the distortions of that image, allow us to measure the distribution of matter in
08:09:10 the center of clusters of galaxies and the statistical distortion of background galaxies, can be leveraged to measure the distribution of matter even at a much larger API technique known as we cleansing.
08:09:30 And on the right hand side is that same cluster of galaxies as seen with the Chandra X ray telescope and there you're what you're seeing is the gaseous Halo in this cluster.
08:09:41 And it's a smoother. There's some lumpiness to it because of possible feedback effects but, you know, when it comes to approximating the distribution of stuff in that Halo, that first.
08:09:59 You know spherical approximation turns out to be not too terrible.
08:10:04 I'm so I'd like to make a segue from shell wins.
08:10:12 Nice talk.
08:10:15 And in that segue includes the role of feedback and making these halos look the way they do show in mentioned how supernova and AGN feedback, they suppress the baryonic mass function from what you'd expect if baryons simply follow the dark matter.
08:10:35 And she mentioned that AGN feedback may be, what, what suppresses the, the mass function at the high math end. And the one comment I'd add is there's another factor that suppresses that and that's simply that cosmological in fall of matters.
08:10:55 shocks the guests sufficiently high temperatures that it doesn't easily. Cool.
08:11:02 And so cosmological appreciation can also set that becomes quite important that setting that scale at high masses and that the warm cooling times prevents the gas from condensing into two every morning massive galaxies.
08:11:17 The idea is that galaxy galaxy velocities gets sufficiently high that you don't simply take a cluster, you know, a cluster of galaxies.
08:11:27 If it was completely dominated by a single galaxy would be
08:11:33 kind of what you'd expect if you just expect galaxies to get bigger with their Halo masses.
08:11:39 That can't happen in a cluster of galaxies because the galaxy galaxy velocities are too high so you don't merge all the satellite galaxies into a single Halo.
08:11:48 So, so feedback is important in in in setting the conditions in the gaps Hello, and feedback is is critical in understanding why a gas halos are harder to see them, what you'd expect from simple install ideas, but it's not the only thing going on so I
08:12:11 just wanted to make that point.
08:12:22 So, measuring cluster Halo masses is a map is a huge industry. And there are many techniques for measuring the mass of a cluster Hello, I'm good contrast that to how how tricky it is to exactly measuring the halo mass of a galaxy.
08:12:34 Because we have these multiple techniques so I had mentioned gravitational lensing.
08:12:39 This is considered the gold standard mass, it's considered on bias considered fairly reliable. It's difficult, but the techniques have been proved that the access to Whitefield.
08:12:54 Large Telescope Imaging such as Subaru, and the dark energy cam on in the south, have enabled some extraordinary efforts from the ground.
08:13:07 Space Telescope is pretty good. For more distant clusters of galaxies because it can it can measure the sheer distortions of of a higher density of background galaxies, as you saw from that first image I showed, but it's it's limited to usually the course
08:13:39 clusters of galaxies and getting these big week lensing data sets has required large format cameras on the ground. Coming up though we're going to be looking at Space based Wednesday, that would is going to really transform this field from Euclid and
08:13:47 from the Nancy Roman telescope, I'll mentioned that at the end of the talk again.
08:13:55 Traditionally, a cluster masses have been measured with Galaxy by tracking galaxy orbits measuring the dispersion there caustic their face base.
08:14:06 And it check out works by Viviano capacitive for updates on that other mass surrogates.
08:14:15 It turns out the extra gas mask is a pretty good surrogate for the total mass.
08:14:22 Outside of if you measure the gas mask to enclosed radio outside of about half a mega power set the gas mass is about one eighth of the Lindsay mass at about our 500.
08:14:32 I did that with a study, I'm using a clash clusters of clash with a sample of 25 clusters that were was studied with the Hubble Space Telescope and then it had an attractive a lot of ancillary data.
08:14:48 And this this has been measured for other cluster samples.
08:15:06 And another traditional way of measuring cluster hail a mass is using the assumption of near hydrostatic equilibrium, and you use the pressure profile, as measured in the gas density to infer the gravitational potential gradient and calculate the enclosed
08:15:14 mass, and this method does not explicitly
08:15:28 account for possible non thermal pressure that is pressure support from both promotions or turbulence.
08:15:30 But it's been calibrated, and the variations in sort of total masses that you get from this, this analysis prepared to say we cleansing masses is typically about, you know, the gas masses.
08:15:49 I mean I'm sorry the hydrostatic mass and fruit from classes about 80%, that of the, the week Lindsey mass.
08:15:59 And so that's something that could be calibrated out in principle.
08:16:04 And so this is this is a tough business, I was in it for a while, I have to admit I, I had to step away and do other things for for a few years.
08:16:15 But the challenges.
08:16:20 One is is because the mass is distributed, you have to be very specific about radius out to what at which you're measuring and this can make the literature, going back and figuring out what other people do rather challenging sometimes and refer you to
08:16:44 The directly the mass is hard to measure, so you need to define a contrast and usually this is you know in terms of like 500 times the ambient critical density although some workers use the contrast with the mean density as opposed to the critical density,
08:17:00 and it's important to keep track of the distinctions.
08:17:06 There are systematics in these measurements backgrounds in four grams of both for week lensing x rays. These are all things that are technical and you know you have to get your hands dirty in if you have if you want to do a good job and this business.
08:17:22 Um, and then there's an observational biases, so I'll bring up, mon Chris bias, which is a, the bias you get from selecting a sample by its flux and so, you tend to include
08:17:39 the brightest examples of the underlying say volume limited set. And that can skew your answer and another one on which is particularly important, I think, you know, for clusters and mass measurements, is a bias that's called Eddington bias and Eddington
08:17:58 biases is a shorthand jargon term for that bias that you get when the underlying population is deeply dependent on the parameter you're trying to measure so.
08:18:12 So, the number density of clusters drops like a rock exponential with mass so the higher the master, the more rare, a cluster is. And if your mass measurement has an uncertainty which it always does.
08:18:30 Then, on your lower mass object scout scatter into your height of her mass bins. And so you have to take into account of all these biases, when you're fitting a mass scaling relation.
08:18:41 And that's why sometimes you see a mass scaling relation where you see the data, and then the fit doesn't seem to go through the data. So if you see a masculine relation, like of mass versus luminosity in the line doesn't data that's the reason they're
08:18:58 accounting for the bias that you're only seeing the brightest examples, and this is.
08:19:05 So you have to simultaneously fit for the underlying distribution and the end the masculine relation which is usually what the thing is, planet. So, um, so this has cosmological implications because cluster cluster mass is one of the things that you can
08:19:22 predict from cosmological principles. And so it's it's gotten a lot of attention forget for example there is a there is still I, as far as I understand, a continuing controversy and intention between the for example the plonk cosmological parameters that
08:19:44 allow you to predict the number density of clusters as a function of mass, and the number and masses of the clusters that clunk auction actually sees.
08:19:55 And so the gray line on this, this plot, where when mine is be is just the ratio of the mass of divided by the, the week Lindsey mass, the gray bar at the bottom this plot is the bar that that the measurements would be neat would have to be biased to
08:20:17 60% that the Sydney is a mass would have to be 60% of the week Lindsay massive pretty severe bias.
08:20:28 In order to bring the cosmological parameter based prediction of the number density of clusters into agreement with the number of density number density of clusters and masses that were estimated for the block survey.
08:20:45 And the plank analysis assumed something more like a point eight so that there's 20% shortfall in the estimate estimate from this thing is though the defect which is based on the inner Girl of the gas pressure integrated through a cluster that, that gives
08:21:10 you a signal that you would see against the cosmic microwave background. And so you see plotted here from a 2020 review from Keech you met Sue, a number of different estimates for what this bias actually is based on weekends the measurements of clusters
08:21:23 you see the clash point at a mass, a typical master that sample is six times 10 to the 14 solar masses.
08:21:33 There's some other weighing the Giants is the one of the first studies CCC CP clusters for the masses, is the purple points and some other recent
08:21:49 analyses are also plotted there so you see that there is steps, there is some disagreement about what the bias is everything most boast would say it's somewhere between, you know, 25%, or, you know, 20%, or so, but there's some uncertainty and some debate.
08:22:09 None of the management's really reached the point of of resolving the conflict and that's why it's still kind of a conflict. However, the complaint is actually these massive measurements turned out to be better than expected.
08:22:27 And, from my point of view, from the cosmologist point of view it's like, oh my goodness we have this you know this this difference but from my point of view and I want to understand clusters and how gas behaves in gravitational potentials.
08:22:44 This is pretty good. And so, why is this better than expected it, yes, it's better than 10 to 20% mass estimates is better than expected because just, just go back to the literature from the 90s, I mean there's, you know sometimes factors of three and
08:23:03 four discrepancies with the earlier measurements and they just turned out that a lot of people. They weren't measuring it far enough, and the measurements weren't
08:23:16 quite accurate yet.
08:23:18 So, one reason cluster mass measurement that's pretty good, pretty good shape is because they're, they're decent fair samples of the universe and they're not quite as biased as some may have hoped back in the 90s.
08:23:31 When a mega matter was supposed to be one and they were trying to explain why clusters weren't giving them that.
08:23:38 But it turned out clusters were pretty first samples of the universe, make them matter It was not one hydrostatic equilibrium. While it's it's clearly not the case for clusters that are emerging and so forth.
08:23:51 It's not a bad zero order basis on which to start, you know, analyzing clusters and estimating their masses,
08:24:01 because gravity is such an important process in, in, in setting the scales and the energy scales in the cluster.
08:24:11 The bias is never It was never expected to be zero percent it's going to be larger where non thermal processes, provide pressure support over gas pressure, and it's going to be smaller where those processes are negligible and I'll show you some examples
08:24:27 of that in a couple slides. So, let's go way back, and and talk a little bit about self similar expectations. Some of these slides will have a line showing what these expectations are and I just wanted to walk you through what stuff simulator is and why
08:24:49 we bothered to talk about it, even though it's obviously not correctly representing what happens. And, and one of the reasons I think we do this is because us sometimes our models really aren't expected to determine what happens but it, it provides the
08:25:08 baseline.
08:25:11 So we can have a conversation about when are the observations deviate from self similar.
08:25:21 You know, the question is why and often, the answer is because feedback and other processes are important. So so similar just starts out with a gravitationally gravitational collapse in an expanding universe that's described by a horrible constant that
08:25:39 varies with redshift based on the contents of the universe. So, it generates you know scale for you there's no, there's no scale.
08:25:49 In that, that's where the term self similar comes from parallel scaling relations.
08:25:55 And you can write down on the back of an envelope, what you'd expect for the mass inside a contrast radius based on on some number, like 200 or 500, times the critical density of delta replace that delta with the 200 or 500 to give.
08:26:17 Typical math skills that we use.
08:26:21 And you can calculate the expected circular velocity proportional to em over are so Vq is proportional to the mass times the Hubble constant, which ports to T square and you get that the X ray temperature you'd expect is proportional to mass times this
08:26:44 Hubble parameter to the two thirds power.
08:26:48 This self similar expectation also allows us to scale observed properties of clusters at different redshift to kind of put them on the same footing with respect to each other so you'll see self similar scaling even though self similar might not apply
08:27:08 on Danny, we just take that a little further, you know, as, as Kaiser did in 1986 and you know estimate what the expectations are for the hot gas, and the hot gas in a cluster is going to be proportional to the gas density squared because it's a conditional
08:27:23 process.
08:27:25 Thermal brimstone, and an emission line production is occasional process proportional to r cubed, and then lambda, which here is a term we use for the cooling function which is a
08:27:47 function of temperature medalist city of medalists at the ass, which I'm throw here is a capital Z I'm not going to talk about medalist city anymore.
08:27:59 And depending on the band passed on, this is lambda, the X ray band past you're looking at the gas in this land, maybe have a strong dependence on temperature or fairly weak ones so if you're just looking at the lowest energy or soft x rays.
08:28:18 For example from Rosset.
08:28:22 This.
08:28:23 This cooling function is.
08:28:26 It's insensitive to temperature.
08:28:28 And if you're, you're making a bola metric estimate make based on a broader band pass on the lambda is proportional to the one half.
08:28:42 So, um, you can write down in expressions for the relationship between X ray luminosity masks, depending on whether your X ray luminosity is being measured in say the Rosset van pass or bull metric and pass, and similar expressions can be done for a sec.
08:29:03 What the white parameter and SP or the gap, which is going to be proportional to the gas mass times the temperature. So, You have different expectations from self similarity for different parameters scaling with math.
08:29:25 And here's an example of a paper. A very nice paper written by Sarah Melroy for the locus analysis. It's based on 41 clusters between a redshift of point one five and point three on this work is not a ball because there's a very well defined X ray selection
08:29:44 function that they take into account. and they drive scaling, very rich ancillary dataset. So they were, they have fit scaling functions to X ray Cindy is they'll do a bit and optical mass estimators arm, they also have week Lindsey Madison's for all
08:30:09 of these clusters.
08:30:11 So, these estimators don't depend on the assumption of hydrostatic equilibrium.
08:30:17 They find a one to two sigma discrepancies with self similar expectations, if you look at their table five it's just it's a massive list of comparisons to between their fits and self similarity.
08:30:36 I note that their, their analysis assumes that this week lensing mass is unbiased tracer of mass. And I've shown a couple of their plots, one is a temperature.
08:30:50 We cleansing mass plot on the left and the plot on the right is it gas mask versus we cleansing.
08:30:59 You see this EZ that's just the, the dependence of redshift on the Hubble parameter where you would write the Hubble Crowder agency is equal to H naught times EMC, so that that takes out any scaling that simply going to the different values of the critical
08:31:23 density at the redshift of the cluster, and the blue and red codes are coded for clusters with low and high gas entropy.
08:31:36 And I'll get into this a little bit later but the blue eyed so called cool core clusters, with low gas and central entities and the red or the non cool core clusters, and what you should notice is that least for these two indicators, whether it's a cool
08:31:53 core or a non cool core doesn't seem to to matter. And one of the reasons for that is that the CE, so it's the 10, the extra temperature, and then subsea that's core exercise so it's taking out the so called cool core and just showing the, the temperature
08:32:14 plotted here is the temperature outside of the core.
08:32:18 You can see similar analyses by advance from 2016 and
08:32:27 some people have attempted to extend these these things to lower masses I appoint you to Petula at all from 2015, who included group scales clusters from the CCP and Cosmos survey.
08:32:46 And there's some work by the Mets you from the XMMXSL survey.
08:32:51 These on these projects have weak losing masses that probe that tend to the 13 to the tenant 14 solar mass gals bet it's noisy.
08:33:04 And so, a lot of those works are often fitting, just the normalization they're assuming the same slope.
08:33:12 And it's it's it's still very very tough, tough work.
08:33:18 Okay, so I'm gonna show you a couple of pretty pictures. This is the center of the Perseus cluster this.
08:33:24 This. The red is coating where the radio is the pink it's a little harder to see that's h alpha filaments in in that central galaxy, and the purple is where the X rays are.
08:33:43 And then my next picture is going to show you and an edge enhanced an X ray image of the same region where the smooth arm X ray mission, that's peaked on the central galaxy has been divided out, and you see an amazing amount of contrast.
08:34:05 That's in these in the X ray gas so you know, might wonder well how can we possibly call this you know hydrostatic Lee hydrostatic equilibrium.
08:34:19 Um, and so, so there is evidence for fluctuations there is evidence for time dependent impulses from the AGN coming from the center galaxies, but every piece of evidence, even for this cluster shows that these fluctuations are sub dominant in terms of
08:34:39 providing pressure support to the gas.
08:34:43 If I'll point you to work by arena, surely, surely ba who studied these fluctuations.
08:34:51 And, and was able to make estimates of, you know, what the level of turbulence and so on, so forth and the guests and concluded that it was sub dominant.
08:35:04 And that was confirmed by on the Hitomi observation on in 2016 it was able to make an observation of the center of the Perseus cluster and resolve the X ray mission lines, primarily of iron here, and showed that there was very low turbulence levels in
08:35:32 the core, the nature paper argues that this was you know surprising and amazing. But, I mean, you know, people like arena, were were predicting this that the turbulence levels were consistent with the, the levels of fluctuations in the surface brightness
08:35:47 mass.
08:35:49 And so the conclusion is, is that the pressure profiles are consistent with being nearly hydrostatic in these in these cluster course. Okay, so this is one example it's a nearby example, you'd love to have more of these.
08:36:04 The, the prism mission which is the follow on to the Hitomi mission is is under construction and underway.
08:36:16 It will be able to look at a few more examples, and possibly map.
08:36:26 Even the person is cluster a little bit better.
08:36:28 And I'm the but Athena, and later and hopefully those links mission will be able to do a much more comprehensive job of mapping out these cluster course so so Christian will have fairly low, angular resolution compared to say.
08:36:47 Athena, and definitely lower spatial resolution, then the links mission well so stay tuned, but this is, this is the kind of data that that Chandra and xmm, you know, cannot provide, especially with CCD spec dress so this is for an X rays astronomer who
08:37:10 So, this is for an X rays astronomer who has studied specs, trust me since I was an undergrad. This.
08:37:16 This is very very exciting stuff.
08:37:19 So we got a glimpse of our feature, X ray astronomy, through the autonomy observations.
08:37:28 Okay, so, um, we have some pretty good ideas of how much baryonic mass in the universe I was claiming that clusters are pretty good.
08:37:41 Fear samples on. So from the plank mission, I make, there's good constraints on a mega berry on and make a matter.
08:37:51 We heard about that about the constraints on where these baryons are from fast radio burrs from export 2020, I had no idea he had passed away, I was what exciting work and what exciting science, this young man was doing and I have to say it was just a
08:38:16 book.
08:38:13 I did not now so I was taken aback.
08:38:19 All right.
08:38:22 So, with the X rays we can measure the baryons a closers they light up in clusters and on on the right I'm showing a compilation plot from a Larry David.
08:38:35 the slides, but uh he he compiled these measurements for to compare his observations which are in the red there, but the blue observations are for the groups that F Gasper groups.
08:39:10 inside of our 2500 which is below the field circles, which is the gas fractions inside of our 500, or 500 is really difficult to measure out to four groups so there's fewer of those points, but they're clearly higher than the gas fractions inside our
08:39:28 2500.
08:39:29 In the same sort of color code scheming field versus open is plotted for the clusters, the dark points are from the Clinton and the green points are like, I'm forgetting.
08:39:47 Um, but, but the point being is that the
08:39:51 the measurements that are 2500 are screwed systematically lower than the measurements that are 500 and as you as you include more and more of the clusters be realized.
08:40:04 volume on the gas fraction also increases, and the distinction is bigger for groups than it is for four clusters. And if you include in that Barry on senses, the stars on the cluster sided this, the mass scale you pretty much account for the baryons in
08:40:24 clusters if you add up the gas and you add up the stars that some is very very close to the baryonic fraction you'd expect.
08:40:35 cosmological.
08:40:58 Okay, so I been spending a lot of my career thinking about the central galaxies in halos, and the central galaxies are good.
08:40:54 They're not okay. Not every cluster has a clearly identifiable central galaxy but when they do, they're either this giant quiescent galaxy old stars not made much cool gas, or they are an active central galaxies.
08:41:15 And what I mean by active central galaxy is concerned, a little evidence for cold molecular gas hundreds and millions of solar masses.
08:41:26 I recent star formation. This star formation is not assembling that galaxy but it's big and an absolute sense sometimes up to 100 or more solar masses per year so the galaxies that are forming the stars most rapidly in our, in our local universe, are,
08:41:44 are some of the central galaxies in terms of their absolute star formation rates. And when you look at their, their normalized star formation rates that is their star formation rate divided by the total stellar mass, they, they almost don't register as
08:42:00 as a star for me and Galaxy they're fairly consistent by that definition, but they look like this.
08:42:07 That's because you're dividing, you know that hundred by a trillion solar masses so
08:42:14 anyway.
08:42:16 So why are some of them on and some of them off.
08:42:20 Seems to be directly associated with the thermodynamic state of the halo that they're embedded in.
08:42:30 And we've known this in a way for many many years so here's a couple of example plots. On the left, this is a x ray surface brightness profile of two galaxies galaxy clusters, with very very similar outer temperatures.
08:42:50 There's a called Cooper cluster a bell 2390, and then just comparing it to a well studied non cool core cluster April 2219, the cool cloud clusters tend to host these active brightest cluster galaxies, the non core core cluster.
08:43:11 Never host an active right brightest cluster galaxy so there's a real Stark dichotomy in in the on the cluster scales. And it seems to be related to what their extra gas is doing so the cool cores, have a higher central density, higher central surface
08:43:31 brightness, um, they also tend to be more prominent in X ray selected sample so if you're going out there and you're trying to find clusters of galaxies by by their X ray profiles that the cool course standout
08:43:46 was prominently, sometimes they're a little too prominent, I'll give you the example of the Phoenix cluster which is the most luminous X ray cluster in the universe that we know about.
08:43:56 And it was not discovered in the x rays because in the x rays, it was, it was so bright and so peaky that it was classified as a point source and the Rosset old Sky Survey.
08:44:07 And it took us in the eyes of dovish survey the, the South Pole Telescope, to find it and I did you know cross identify with a cluster of galaxies, so it's a little mud on our faces X ray astronomy is that the that the radios from responded first.
08:44:25 Anyway So these things are called cool cores or non cool cores based based in park. They're typically in a cool car cluster the central temperature declines.
08:44:38 So this is what I'm showing over on the right is the cool core cluster temperature profile shows a decline the temperature, into the center. This is not due to clean this is just due to the structure of the X ray gas Halo in its gravitational potential.
08:44:56 So I want to eliminate that misconception right away.
08:45:01 And you have the non dual core cluster on with, with a fairly constant temperature is a functionary radius.
08:45:10 And so when we compare these there clusters for the characteristic temperature.
08:45:16 Their clusters for the characteristic temperature. It's been a typical to how much time I have.
08:45:29 Okay. Um, I think I have five minutes.
08:45:33 Anyway, so I'm all wrong. So, we can plot a luminosity temperature relation, and and, again, If you exercise that central template that that central core which is brighter and often a different temperature from the rest of the cluster.
08:45:54 If you sighs those cores, you get an lt relation that's a lot better behaved. So I've been spending too much time on clusters so I want to extend that lt relation down to lower masses.
08:46:04 And this is a plot showing a number of measurements of luminosity in temperature from a clusters at the high bass high temperature end of the scale two groups from being set at all that's those are the green plots, and I wanted to call your attention
08:46:20 to an effort to it to stack X ray data around luminous red galaxies. This is the Anderson at war, work, and those are the purple. And that takes this lt relation down to very low temperatures and low masses in, and it seems to show that the LT relation
08:46:43 that applies to clusters extends over many orders of magnitude of luminosity down to low masses. Also on this plot, I'm showing the self similar expectation, which is a much higher luminosity.
08:46:56 But feedback works to reduce the density of that gas Halo and suppress the luminosity, and it, it may looks like a similar sort of it. lt relation may apply over many decades of temperature and mass.
08:47:17 I'm here are a plot of Halo gas densities.
08:47:23 Here are a plot of Halo gas densities. This was submitted in a white paper to the Astor 2020 survey galaxy clusters is on the left that's from the except sampled the blue are the core clusters, the red or the non core core clusters, the brown line shows
08:47:38 shows you the cosmological expectation, and the purple line, the purple magenta dashed line shows the upper limit the density that set by the participant precipitation limit, which causes the gas to condense if it gets any more dense than that it's going
08:47:58 to condense and feedback will regulate it up to that, that purple line. So that's a, an envelope that limits how dense these clusters can be, and the combination of the cosmological limit, and the precipitation.
08:48:21 Limit gives you a, you know, like, a rule up against which the observed profile seem to bump up against. So clusters are regulated, at least at large radio at our 500 grade integrated in a 10th of our 500 or so, by cosmological parameters, which is why
08:49:04 they're more regular out there. Okay. And, and why exciting their course shows more regular relationships with mass and temperature, were inside that that you have
08:49:01 their upper mass density is regulated more by precipitation which is a feedback, balance, and as you move to lower mass systems. The cosmology limit is less relevant and feedback is more and more important in determining on the, the density profiles.
08:49:26 And therefore, the luminosity how how easy it would be able to see these things in mission, um, as you go to lower and lower scales, all the way down to the Milky Way.
08:49:36 And my last plot. I'll show you here is a all these things combined clusters, upper left groups, which wasn't shown in the previous slide.
08:49:50 In the upper right or left galaxy density profiles from x ray observations from the Chandra archive from Babbitt get all 2018 and an ensemble of constraints on the Milky Way Halo compiled by voice at all.
08:50:12 The purple lines that is on the bottom of each plot is a fit to the Anderson data. I'm from seeing at in in a paper that would be published in 2021.
08:50:16 2019.
08:50:25 And you notice that it's lower than the density profiles for groups in galaxies, and it kind of runs through the middle of the clusters. So, so maybe the clusters are relatively representative, whereas in the galaxies we're still probably seeing some
08:50:43 of that MapQuest and Eddie Tim bias that I had mentioned at the beginning of this talk, and I'll just close with this last closing flat side it's not really a summary slide on, and that is thoughts, you take forward to this workshop in this meeting.
08:51:01 One is that we cleansing acids are considered to be relatively unbiased so if we can get we cleansing masses of galaxies, this is gonna be great but we need simulations of observations that connect on the weekends during expectations with what you'd expect
08:51:19 from x ray emission and UV absorption, a Subaru and Dec cam measurements are are pushing these week cleansing techniques to nearby local volumes on on evolved in a new project that just got a lot of debt cam time these data sets are extraordinary like
08:51:40 two terabytes per cluster, and that we're going to manage that. Anyway, but it's pushing these measurements to lower math skills and looking to the future Euclid and Nancy Roman telescope is going to are going to make extraordinary sheer measurements
08:51:57 and constraints at higher case smaller mass structure.
08:52:03 The gas Hill is where most of the countryside, it's where the fuel for new stars and black hole growth, ultimately originates. And if you look into past history CGM is often relegated to a tiny little slice of the berry on budget but I think we should
08:52:17 be remaking those those pie charts so that the CGM is properly represented because I think it's important, and sometimes missions and observation of follow up is dictated by how relevant the sciences.
08:52:34 I think this workshop is going to show that the CGM science is super important.
08:52:39 And it's where most of the variants are so I think we need to rework some pie charts as maybe one of the outcomes of this workshop.
08:52:50 And lastly, on the physics of gaseous halos combined by a dark matter.
08:52:56 Potential spans of q3 range of mass scales from galaxies through clusters, and we can learn a lot if you can somehow pay attention across all these observations and all these simulations and all these different ways of coming at
08:53:12 measuring these things and studying these things. It's really hard because the volume of work is amazing.
08:53:21 But I think we have to take the effort to pay attention to cross disciplinary progress. So, that's my closing slide, and I think it was 45 minutes.
08:53:36 Thank you. I'll give you actually live applause.
08:53:43 And if you.
08:53:45 Yeah, we will, I will be sending people back five after the hour for the panel discussion will give people a 12 minute break. I see questions are already going into the.
08:54:00 The Slack channel. So there are always some questions there to think about to dress. Please keep putting your questions there and Megan will answer them throughout the day if necessary.
08:54:12 And, and will be reconvening live for discussion, a little over 10 minutes from now five after the hour.
08:54:23 And I will thank the speaker again.