08:05:10 Good morning, everyone. Welcome to our third week of the KGP program on gashes halos fundamentals of gashes halos I'm Cameron Hummels, one of the organizers, and I will be the moderator slash organizer for this week's theme, which is, which is what role
08:05:33 do non thermal components, play in defining the circle galactic medium.
08:05:37 I'm really excited about. I mean all of us are really excited I think about how things have gone so far. We're, we're 25% of the way through this eight week long program.
08:05:49 Of course, everyone has their own personal time constraints and will wax and wane in terms of the attention that they can give to this program, but so far I think we've had an overwhelming response from all of you in terms of your participation and enthusiasm
08:06:05 and, and it's been it's been pretty awesome.
08:06:09 I hope everyone had a restful weekend. This, this weekend to kind of recover. I was a little bit saturated by the end of the week, and all that was going on, but saturated in a good way, because there's so I feel like there's so many avenues and opportunities
08:06:25 and ideas that that have come up in the past two weeks about projects and collaborations, I hope you guys feel the same.
08:06:34 So, just to remind everyone each week has a different topical theme. The first week we dealt with Halo mass and its relation to galactic halos the second week last week was on multi-phase.
08:06:49 This week, as I mentioned, is non thermal components, but we have various different themes that we will address over the course of these eight weeks.
08:06:58 I just want to take a moment to thank my co organizers Jess work, Mark Voight and Ben Oppenheimer, I think you guys have all done super well and. And as I mentioned, each, each week will have a different theme, but we'll also have a different kind of
08:07:14 organizers for that week. Next week is the Milky Way, and then Oppenheimer will be a moderator so if you have ideas, specific to an individual week, you can always reach out to all of us or specifically the person who's who's associated with that week.
08:07:33 Okay, a few announcements before we get to the fun stuff. the science of the day.
08:07:40 This Friday, we will have a virtual trivia night.
08:07:44 It's at 4pm Pacific, so I know that may not work for every time zone but that's one of the, the challenges of this program and being a global event.
08:07:55 But at 4pm on Friday I encourage everyone who's interested to to connect to a zoom that's linked in the halo 21 socializing channel already. It is hosted by a professional trivia host who does this sort of thing, all family members or partners are household
08:08:14 members are welcome to join you don't need to do anything in advance. We will organize into teams, when we, when we arrive by the host of this, you're encouraged to bring your own beverage of choice, and it should be super fun so check it out.
08:08:31 I know all the organizers are planning to be there. So at least there will be four of us, and hopefully many many more.
08:08:38 Okay, there's a quick survey that I encourage everyone to check out. It was sent to the halo 21 General Slack channel and it should only take about five minutes of your time, but it gives us a lot of feedback, particularly, We're trying to do this.
08:08:55 Each week to get feedback and and and improve upon this experiment, since this is our, our first time doing this in such a virtual manner and and I can't TP program of this, of this type.
08:09:09 And, yeah, maybe it's I think it's going pretty well but I'm bias so if you have suggestions we're definitely trying to implement as many suggestions as we get.
08:09:19 So go ahead and check that out hopefully sometime. By midday today, you know, in the next few hours Monday Pacific, I guess.
08:09:27 Okay, um, there is a Google document that you've probably seen but in case you haven't, you can easily access it at the at the short URL URL, bit Lisa KRTPCGM, it has all the information about the program, including the detailed schedule of events for
08:09:46 each day, including links to past recorded lectures and slides and all sorts of stuff there's. We're working on getting transcripts from the videos linked as well that was a suggestion that was brought up recently and links to the various outlets for
08:10:04 getting on zoom, of course, you've been able to manage that because you're hearing my voice today, get on to slack, our YouTube page and so on and so forth.
08:10:14 Speaking of YouTube page, there's been a lot of activity in our new results YouTube page. I think we have 16 videos now Eight. Eight submitted last week.
08:10:26 These are new results that have been either published or put on the archive. In the last year, so we're making the cut off like has to have been submitted in the last since 2020 AND and OR or hasn't yet been submitted.
08:10:45 We encourage audience members, you know you, to if you have such a result or if you have a graduate student who has such a result or a postdoc to write it, or not to write it up you've already written it up to, to make a video like a four minute long
08:10:59 video kind of summarizing the relevant points for the community of the circle galactic medium and gashes halos. And there's even a video on how to make such a video So, so check that out if you're not as familiar with video, creating tools, it's pretty
08:11:15 easy. You can use like keynote or PowerPoint or zoom to do this sort of thing. And then you just submit the video in the halo 21 new results channel on slack.
08:11:25 We will grab it we will upload it, and we will advertise it to the audience so we had eight new submissions last week.
08:11:34 And they're, they're great. You know, I really enjoyed them learn to lunch, a lot, you know there's there's so much you can learn when someone's like, just addressing you and showing like this is a really cool relevant plot or here's the main theme, instead
08:11:49 of sitting down with what could be a rather large paper rather large and rather dense paper so yeah there's a good presentation on turbulence in the ICM by rush the car, mama, papa.
08:12:05 There are two papers on cloud crushing a results, one from digit country law, and along card data. And then one from G boy Lee, just he just submitted that last night, as the last one.
08:12:20 Mark Voight.
08:12:21 One of our organizers submitted a trifecta of various different results related to precipitation and gravity waves in, in, in the Halo.
08:12:34 Then there's a very popular one on the saturation point of cosmic rays in the Halo, you know, it has like 200 hits already, and it was only posted in the last day or so, so I don't know, this is, it's really cool.
08:12:49 cool result and and taking YouTube by storm.
08:12:52 And then finally, Shmuel lb Ali posted a really interesting paper about the interstellar radiation field.
08:13:01 In, in discs, so I encourage people to check them out. Like I said they're short, and you can just sit down, as it's been suggested, sit down over dinner and turn that start the playlist and watch a few different videos on on relevant papers to our field.
08:13:17 Okay.
08:13:18 Another thing that I wanted to announce is, we have featured conversations that conversation groups are essentially just different slack channels that are focused on different topics.
08:13:30 So, these are really run by you guys, if you feel there's, there's a, an absence of a particular discussion that's going on and you really want to initiate this, we encourage usually two people to start such a conversation group on a particular theme,
08:13:47 and you feel free to reach out to us organizers to, to, to make sure that that's that's cool but it should. I mean, really this is about you guys and starting new discussions.
08:13:58 So the two that we wanted to feature this week that are relevant to the topics that we're discussing and have a lot of activity recently are medalists at in the circle galactic medium and a project that's kind of spontaneously started led IN PART BY ZACH
08:14:25 Haven and Jane Charlton. And then one on turbulence a discussion of turbulence and its effect in the CGM led by going Rudy and Drummond fielding. So, we will hear about that in a few minutes, but also check out there's a magnetic fields channel, and a
08:14:33 cosmic rays channel that you should check out since those are relevant to non thermal effects.
08:14:38 Okay so, um, just to announce really quickly. The theme for today, or not the theme the activities for today, we will have, as I mentioned these featured conversations will have like 10 to 15 minute introductions to these, these groups these conversation
08:14:53 groups, and then we'll take a brief break and then we'll start up for speed collaboration so speed collaboration has gotten a lot of a lot of positive feedback from the community I think for most of the people who've participated.
08:15:08 We weren't able to do it last week because of the holiday on Monday, but we did it the first week, and that's a random pairing between you and another member of the community who's on zoom today.
08:15:21 You have five minutes, where one minute each of you kind of introduces who you are and the research that you work on and then the remainder of that five minute period you're, you're looking for ways to collaborate, it.
08:15:32 This doesn't obligate you to collaborate with with with with this other person, but it's just an idea of kind of breaking ice about what you work on and.
08:15:44 And sometimes, you know, sometimes the collaborative ideas that you guys have with shared themes between your, your various research components, won't necessarily work out, but sometimes it will in dramatic fashion so I encourage you to brainstorm new
08:15:57 ideas that that will relate with the science that both of you are interested in.
08:16:02 We have a couple of constraints, you have to be able to enable your video and your audio and be able to speak freely you can't be like, I can't talk right now, because that's not very good for collaboration.
08:16:13 And right now we're limiting the participants to people who will have their PhD sometime this year.
08:16:21 We are working on potentially having a junior version of this where other graduate students or even senior undergrads can participate with each other but right now we've made the constraint that in order to participate, you, you need to you need to be
08:16:35 a little bit more advanced in in your, in your preparation.
08:16:40 And we'll do five rounds of that, and then kind of come back to the main group and and debrief on what particular topics may have come up.
08:16:48 Before we get started with that.
08:16:51 I'll just take you really quickly through the rest of the events this week. We have a keynote, that's being given by paying Oh from UC Santa Barbara.
08:17:01 Tomorrow, and it'll be followed with a panel discussion with experts in the field of non thermal processes Blakeslee Burkhardt Chad bustard arena blocky and Evan Skinner Pico will be speaking, I'm really excited about that this paying always gives like
08:17:15 super stellar talk so I encourage everybody to check that out tomorrow.
08:17:21 On Wednesday, we will have tutorials, three tutorials given last week we had four tutorials and it seemed a little bit crushed. So this week we'll have three searching G is going to talk about cosmic rays and its impact on the on the on the CGM material
08:17:48 shrews kowroski will talk about AGN effects, non thermal effects on the circuit galactic medium, and then you want Lee is also going to talk about observational measures of Halo turbulence. So, really good. I'm excited for that.
08:17:51 Thursday we will also have a keynote talk this time by Ellen's Bible.
08:17:57 Probably the most prominent astrophysicist plasma physicist who works on cosmic rays in the world, so I'm super super psyched for that, and we will follow her present her keynote presentation with a panel of Dr Aaron better Professor feel Hopkins john
08:18:13 Hey john and Christophe Fromer, which should be great.
08:18:18 jaan and Christophe Fromer, which should be great. Finally, Friday's events. We will feature the feature conversations that we're going to hear from momentarily.
08:18:25 As updates of what's occurred in the group since there, and then have a structured discussion where these are topics that you guys can suggest and vote on through our mentee mentor, calm, I think it's worked pretty well in the past, we've gotten some
08:18:38 positive feedback about it, but these are small scale discussions with five or six members in breakout rooms that then come back to the larger group to talk about the questions that you all will explicitly raise and vote on to say whether or not that's
08:18:57 a good question to to discuss.
08:19:02 Just put together these awesome slides she talked about in last week, it's just to make sure everybody is up to date on being able to use slack effectively.
08:19:11 If you're in Slack, we encourage you to to update your your your profile to have an appropriate pictures so people know how to recognize you.
08:19:25 and name pronunciation if that's relevant for you.
08:19:29 You can join interesting channels, simply by going to the channel button the three dots here, and then browse channels, all the channels that start with Halo 21 are relevant for our program there are like 30 of them now on various sub topics.
08:19:48 So feel free to join whichever ones are relevant
08:19:53 in each channel, there's a little pin up in the upper left corner that you can click and that will have pinned messages that might be like highlighted.
08:20:02 Long term messages about the, the discussion or slides that are posted or something like that.
08:20:09 And finally, threads are super important, so you can thread different discussions and rather than responding in line in the bulk of the text from the, from the, from the channel discussion, if you respond specifically in a thread to to someone's someone's
08:20:26 statement or comment, it can really help to self organize these into relevant self contained sort of discussions and conversations.
08:20:37 Okay. So getting back. Well first of all, do you guys have questions, I've been yapping here for like 15 minutes.
08:20:44 Are there other questions from the audience. Feel free to raise your hand if, if you have a question for myself or the other, organizers.
08:20:59 I'm not. I don't even know if I can see if people have questions, let's see, participants. Okay.
08:21:06 Okay, no questions. All right, then we'll get to get to the science.
08:21:12 Okay, so let's move on to the featured conversations. We're going to have, as I said 10 to 15 minute presentations by these two groups, we'll start off with the medalists at group led by Zach Haven and Jane Charlton.
08:21:27 Do you guys want to, to unmute.
08:21:31 Yep, can do, can you hear me all right. Yes, I can hear you Zach. Great.
08:21:37 And I can share my screen as soon as you're finished. Oh yeah, sure, stop. Okay. it's all yours.
08:21:44 Okay, so we have a few brief slides to help.
08:21:50 Accompany ours conversation discussion.
08:21:52 So this is a challenge, or really kind of a experiment of sorts that came out spontaneously, close to the beginning of the workshop, and the overall stated goals of this challenge, are in two parts, plus a bunch of minor additional bonuses.
08:22:12 And these are to determine what the new generation of observational modeling tools, many which use this nice Bayesian technique for determining what the melody is or other general features of absorption sightlines what these tools can constrain about
08:22:28 Mel listy when analyzing mock observations from simulations.
08:22:34 And so therefore we understand that the input.
08:22:37 The second part is to also understand the extent to which the results basically agree with one another, and how consistent they are across community.
08:22:48 Now this is not necessarily trivial. Because melody, and generally the ionization stage absorption absorption line systems is notoriously difficult to model, do to large ionization corrections.
08:23:02 Due to large ionization corrections. But people have been doing a lot of good work, so I'm optimistic.
08:23:06 So this procedure has four parts. First, we choose a model certain black comedian.
08:23:13 Then from that certain light, medium, we generate these blinded synthetic observations that will pass to the observational modelers who modelers do their excellent work, and we compare the results.
08:23:26 All together pretty straightforward.
08:23:27 Let me go through each of these steps to kind of try and explain the idea in a bit more detail.
08:23:33 So first we choose a model CGM, and there are a ton of excellent options to choose from.
08:23:39 So here I've shown a bunch of different simulated CGM or parts of simulated CGM.
08:23:47 That could be potential input. So on the left hand side we have IDs idealized simulations that focus on a pretty small area of the circle back to media.
08:24:00 So expandable those by Drummond and arena.
08:24:03 And then we get to simulate isolated galaxies.
08:24:08 And then after that cosmological simulations, some of which, like these, some of which have forced resolution in their Halo. And then finally, from cosmological zoom simulations and from force resolution halos we also have the larger scale overall cosmological
08:24:26 simulations.
08:24:27 So, these are kind of the typical options you might expect, and I've actually included that about a simulation from most of the theorists who have said that they want to at least participate in the conversation.
08:24:39 So I'm not just reflecting some sort of arbitrary span. This is the actual span of potential data that we could access.
08:24:49 Now, the next step is to produce a blinded synthetic observations and I'm going to just basically steal a pot or two from Cameron's Trident paper which really explains this quite well.
08:24:58 So, this is where it gets a little more detail. I'm going to go into a bit more detail for the beginning grassroots as you're well aware. The CGM is often best observed through absorption sightlines that pass through the Halo, and you can see just some
08:25:17 cartoon version of that here. So beforehand, you have the quasar spectrum the background passes through and then you get absorption features afterwards.
08:25:25 Now the actual process of figuring out what happens, can be thought of as follows. Here we have the sightlines.
08:25:33 That's passing through a simulated field, you've got the velocity the field on here and you have the density, and each one for each of the cells.
08:25:43 And as you pass through.
08:25:45 You get different column densities, along the line of sight.
08:25:50 And each piece of this also has a line of sight velocity.
08:25:58 Now, once you take these lines size velocities and put them in redshift space or sorry, once you take these columnist e absorbers and then put them Russia space and then shift them appropriately for dollars shifting.
08:26:13 You then get something like this blue distribution here, and this is where the absorption will actually be deposited along line of sight and temperature space, but look something like this potentially.
08:26:28 The next step after that is to apply Doppler broadly to the servers themselves terminators. Right. You certainly brought in them.
08:26:33 And then you deposit each of their individual spectral features to make the final absorption in line system.
08:26:41 So this is how we do it computationally, and it also describes a number of the physical processes that happen along the way that you need to be thinking of in this process.
08:26:51 So this can be done for any of the simulations.
08:26:56 And the result can be hopefully realistic.
08:27:01 But also, one way or another interesting to think about because still does provide a background data set to analyze.
08:27:09 The next step is to perform observational modeling, and I'm going to let Jane chime in here to talk a bit about why she chose these particular enlightening plots.
08:27:20 Yeah. So, until recently, the general procedure was to measure a single h one column density, perform some kind of an ionization correction and specify a metal acidity of usually the strongest little ionization component, it was sort of an average medalist
08:27:42 at over a whole system. Either that, or to perform. Careful, cloudy component by component modeling, as our group has for about 20 years but we have had always done it completely by hand and it would take six months or a year to look at a single system
08:28:01 carefully.
08:28:03 And there were no error bars on the measurements.
08:28:09 Recently, several groups have been doing a considerable considerably better job at constraining multi phase parameters cloud by cloud.
08:28:22 And I'm sure that there are there are some other folks besides these three but these are the three papers that come to mind the Hades paper, which showed that in fact in the same system listed like vertically here, you see the same systems and you see
08:28:40 the inferred medalists from the models with their errors. And you see that within the same system. The Mentalist the various considerably along the line of sight, from one velocity to another.
08:28:56 And there's phase structure involved as well.
08:29:00 Here's a recent paper by Hazel Meyer at all working with Todd trip, and you know cats.
08:29:08 And this is not something I'm going to explain in detail but the point is that it is possible to in a rigorous way compare mock column densities, to the model, or to the actual observations and to put in as many different parameters as necessary.
08:29:34 This is a corner plot sort of showing the range of parameters that might be possible based upon the data, and then in that way, inferring properties. And here is my own students Amir's summary plot, sort of showing by looking at absorption profiles and
08:29:58 doing a Basie and approach to match models to the actual observed profiles to infer what the metal is these are of the different phases. An average medalist is shown here on each of these plots, and then the metal is cities have different phases of gas
08:30:26 our show and showing that the average is really just that and that there are a lot of processes to be involved. And so I think that we really are ready now to do a reasonable job in a relatively efficient way.
08:30:38 You know to in for phase structure and more importantly, if we can't infer the middle of the city accurately. This procedure will give us the error on the medalist and we will know that okay, we can do the component on the left, and we can constrain the
08:30:56 component on the right very well but the one in the middle. Since we don't hit either edge of the hydrogen maybe we can't constrain that one very well, but we would have error bars on that.
08:31:10 And so, maybe it's time to have a look at simulations, and see how well we can do with those understanding of course that they are generated under pretty different circumstances, because the universe doesn't have little boxes in it of gas, and then suddenly
08:31:38 there's another box right beside it with a different property of gas. Nonetheless, it should be an interesting exercise.
08:31:39 Great. Thank you for that summary.
08:31:42 All right, and then this is the final step and this is the one where there's the most interesting discussion. The rest provides a lot of valuable work in order to actually provide the basis for discussion, but following that we get to talk about some
08:31:56 interesting questions. So, you know, the most obvious one is candles additional monitors get Middle East is all out of the provide mock data.
08:32:05 And then do them observation momentous use match the simulated ones, of course, keeping in mind some caveats.
08:32:13 If there are certain methods that were more successful or more efficient than others, which ones were these and why.
08:32:23 And of course we care about efficiency both computational, and probably most of us especially human efficiency. So let's make sure that we're not spending too much time trying to do this.
08:32:37 And then we get to the more philosophical questions to some extent.
08:32:42 So how much does group analysis is an issue.
08:32:46 Do they agree within the certainties that calculated. Can we calibrate the errors in terms of theoretically relevant quantities for example, different medalists to use or produce different cooling rates, which could have implications for different mass
08:33:00 influence rates and therefore separation star formation rates and galaxies.
08:33:06 So, hopefully we'll get to some interesting conversation within the next few weeks.
08:33:11 So where are we now. Well, right now we're doing a first pass to get down the structure.
08:33:27 We're doing this with a single model CGM, and a small set of the delivers.
08:33:24 And then the second pass, is when will be doing the experiment, much more intentionally and broadly.
08:33:33 Now you might ask why misty well misty is very commonly used First of all, it's also physically meaningful, in the sense that it is a decent tracer of the origin of the gas, at least to the extent of differentiating between fresh accretion from the IGN
08:33:50 and wins from galaxies.
08:33:54 There are many many many different variations that would be informative for this, so we could look at different derived quantities besides my listings, for example, on ratios, we could look the levels of noise applied this synthetic data, change the observer
08:34:08 instruments, how much data, we give it might be possible that with enough data we could find out an area where the mall observations converge, the different types of synthetic data, instead of just giving calling gets us which is all we're going to be
08:34:22 doing for the very first pass will be given full spectrum.
08:34:26 And of course, different models eg EMS.
08:34:31 So, there's also now a call for anybody who would like to join us. So we particularly would welcome more observational modelers.
08:34:43 But we also have room for more synthetic generators.
08:34:48 And if you would like to provide input on either side of things. For example, if you're a theorist that would like to talk more about the observational modeling, you're welcome to chime in there as well, or if your observer, that would like to provide
08:35:02 more insight on how we can make some tech generations, more reliable, please join that side as well.
08:35:10 So, with that, we'll end the presentation.
08:35:14 Thanks. Excellent, thank you guys very much.
08:35:18 I'm excited to see where everything goes over the course of the course of this week.
08:35:25 Right.
08:35:26 Okay.
08:35:28 So for our second featured conversation. I'd like to invite when Rudy and Drummond fielding to talk a bit about turbulence and its impact on the CGM.
08:35:41 Oh, perfect.
08:35:43 I'll let you guys take it away.
08:35:49 Sorry, I had to.
08:35:52 I had to stop sharing in order to unmute myself.
08:35:58 Okay.
08:35:59 Are you guys seeing the slides. Yes, perfect, and Drummond Are you here.
08:36:05 I'm here. Perfect. Alright, so we started this channel over a week ago now to discuss the combination of observational tracers of potentially turbulence within a certain galactic medium, as well as some different theoretical ideas about, about that topic.
08:36:25 And in particular, I'm very excited about the cross talk that can happen between simulators and observers because I think there's a lot of space for progress there.
08:36:35 So we just broke this up pretty simply into some sort of observational constraints that might exist for for turbulence and this is far from complete and the drum is going to motivate some of the sort of angle of turbulence from theory and then we have
08:36:49 a set of questions that we are posing, which are already in the Slack channel pins so if you guys are interested in commenting on those please go ahead and do so.
08:36:58 And you can just thread it in with the pin, pin two questions. Alright. So to get started.
08:37:07 How can we probe turbulence observation Lee and I'm going to mostly focus on line with an absorber kinematics, which are to two methods that I'm familiar with.
08:37:16 And so, we know that by looking at absorption lines from different species that have very different masses but relatively similar ization potentials that we can actually disentangle different types of broadening within the circle epic medium.
08:37:31 So these are examples from my own data from the periodic structure survey at high redshift, but the idea is the same, regardless of redshift as long as you have enough spectral resolution to resolve these lines.
08:37:41 You can look for places where heavier ions are narrower than lighter ions, like this carbon line here.
08:37:49 Those are examples of thermal broadening because you expect the width of the line to be inversely proportional to the squared of the mass of the ion in the case of an ISO thermal gas.
08:37:59 Non thermal broadening shows the opposite situation where basically the width of lines are relatively similar independent of the mass of the ion. Okay, so these are cases that I pulled out from the data where I think you can see this by I.
08:38:13 But the question is this non thermal broadening What is this actually telling us this is telling us about turbulence or is it telling us about other things like will be discussing this week during non thermal week.
08:38:23 All right, um, what kind of constraints, do we have on the properties of absorbers as a function of redshift so show and show this slide, during the first keynote and so I thought I'd bring it back in here she's showing examples from far as a heady is
08:38:36 is really nice papers. Last year, over the last two years, showing that in the case of oxygen six we actually see, they see relatively large line with as a function of column and evidence that non thermal broadening really dominates at the sort of lower
08:38:55 redshift massive halos.
08:38:59 If we go to high redshift we see sort of the opposite case we see a large amount of thermal broadening of lines and a little bit lower overall scale of non thermal broadening here I'm calling a terminal velocity is but again this is part of the discussion
08:39:12 for the week.
08:39:14 We can see basically by rearranging these, that in fact, the internal cloud motion so here when we're talking about absorber line which we're talking about the bulk motions of gas within an individual gashes structure, as opposed to maybe the turbulence
08:39:28 of the halo which we'll get to potentially in a minute.
08:39:32 But here the idea is that these internal motions we know actually from these observations are largely dominated by by sub Sonic internal motions within these clouds and so turbulent.
08:39:43 If there is turbulence and these clouds, it has a relatively small, small overall scale.
08:39:49 Now we can contrast this perhaps with the kinematics of the gas moving through the halo perhaps, and that I think can give us some constraint, sort of like an upper limit on the turbulence at least have that phase, and within this halo.
08:40:07 And so again, pulling from Sharon's show and slides, we can see that overall the velocity profile of absorbers within the halo are either sub Ariel or typically virile at low redshift.
08:40:21 So, have an overall velocity scale that's either in proportion to the halo or perhaps significantly smaller.
08:40:28 While I think this contrast to high redshift observations that show thousand kilometer per second, range of of metal and rich outflows and unbound gas, gas moving at very high velocities.
08:40:41 Now I wouldn't necessarily say this represents the turbulence of the halo but I think it again gives us sort of upper limit and also might represent some driving force for turbulence within the Halo.
08:40:53 Lastly, we also might be able to look at optically Finn admission from the circle lactic medium and that could tell us something about turbulence. And so, this is from a really nice paper from Aaron Fletcher who hopefully will tell us more about this
08:41:06 When she's on the panel, I think it was Thursday.
08:41:09 But anyway, this is showing that non thermal broadening is very critical and interpreting optical emission lines and x extra planner gas, and I think this is sort of, I'm hopeful that we'll be seeing these kinds of observations, a little bit more frequently
08:41:29 from Muse and Casey wi results that will come out, hopefully in the future. So that's sort of a really fast observational perspective on this. And then this is a simulation from Drummond and he's gonna, I'm gonna turn it over to him.
08:41:39 Cool. So, Glenn that was great, you kind of just covered everything so I'll just add a few tiny things while we look at this swirling swirling multi-phase medium here to highlight some points that I think would be interesting to discuss theoretically,
08:41:56 we've already started a lot of this discussion but I'm, I'm particularly interested in how turbulence works in a multi phase medium, you know, could be why I showed this last week.
08:42:08 But in, in particular, you know, in this touches really well with what Glenn was just talking on there sort of the the turbulence of the hot phase which you could think of as sort of ambient or extrinsic turbulence.
08:42:20 And then there's also the turbulence, you know, there's sort of two other types of turbulence that I think are really important both theoretically and observation Lee one is the turbulence at the interface between the hot and Nicole, this is, this is
08:42:34 sort of the mixing layer turbulence that I was talking about. And then, and this is of course intimately related they're all intimately related the turbulence within the cold clouds themselves, okay good this finally stopped so we can now like.
08:42:46 Hold it here for one sec going yeah so we have the big swirling motions, then also the small sort of motions on the interface and then the motions within the clouds themselves so I think these how these manifests observation is a really interesting question
08:43:02 and then also how these play into the overall survival and evolution of the different phases in the CGM is really important and then from sticking with the theoretical perspective for another minute I think there's a bunch of other really rich veins for
08:43:19 us to discuss.
08:43:22 There's been great conversations already on turbulence in stratified media.
08:43:27 There's also a good Mark just ask the question Drummond is your turbulent box gravitational a stratified No, this is not gravitational a stratified.
08:43:38 I, we, there's been some other examples posted already that are I think there was a new results video as well that was about stratified target and so I think that's something we should discuss and then also how turbulence plays a role, feeding on, you
08:43:51 know, building on what Mark just said in precipitation models and how turbulence might affect those so I think there's a lot for us to to dig into both this week and and and coming week so I think we can move on now Glenn and we can ask the, the questions.
08:44:13 Here we go.
08:44:15 Alright, so we have three questions that we're seeing the chat with if you will but I think, you know, what Drummond just said is likely to prompt additional additional comments we heard from Mark already.
08:44:30 So, basically the set of questions that we have here that are already in the slack.
08:44:35 We mentioned this observational non thermal broadening that we we capture in a few different ways.
08:44:40 So is this actually dominated by turbulence or are other processes ongoing that we're going to talk more about this week like cosmic rays and magnetic fields.
08:44:49 More important, and does that change as a function of the type of galaxy we're looking at or the redshift of the galaxy that we're studying.
08:45:09 I'm drumming you want to introduce to.
08:44:59 Sure, so we spend a lot of time analyzing, you know the kinematics of these absorption line systems and I think would be good to really discuss exactly what those connect to physically you know line centroid.
08:45:15 The the spread of velocities the width of the lines themselves.
08:45:20 And you know what is that what is that telling us.
08:45:24 And in particular, you know, are the code clouds. A good tracer of the background turbulence in the sense that they're perfectly in train so their velocities perfectly follow the hot phase velocities or are they not perfectly in trained.
08:45:39 And so then we need to account for that when trying to interpret the to make some statements about the hot phase turbulence using the code phase observations.
08:45:51 I think, three we pretty much already talked about when the when the video was up.
08:45:56 So there it's again how turbulence operates in a multi phase medium and talking a little bit about in training gas reading it, etc.
08:46:05 So, anyway, these are some questions that we thought would be interesting to discuss this week but if you're interested in in turbulence observations and or theoretical discussions of this please come join us on the Slack channel and we'll look forward
08:46:18 to hearing what you guys have set.
08:46:23 Excellent. Thank you guys. In particular I like that, that very last suggestion, what's the role of turbulence in in precipitation models, I think that's really intriguing so yeah great thank thank you both.
08:46:52 Gwen and Drummond, and I am eager to see what discussions and conversations take place over the course of this week and we'll hear back again Friday morning on what progress has occurred. Okay, so our. Well, let's see. Let's give everybody like a five
08:46:58 minute break.
08:47:00 Before we get started with the speed collaboration.
08:47:04 I'm just gonna put my slides again here,
08:47:11 my slides, Oh hey there.
08:47:15 Oops.
08:47:18 Yeah, so it is 847, let's say, at 855. People come back and we'll get started with the speed collaboration again for speed collaboration.
08:47:30 You need to be able to participate by having your video on and your, your audio on So, and be able to talk freely wherever you are. And, and we want to limit it to people who have PhDs that they're obtaining this year, or who have already obtained their
08:47:47 PhDs and.
08:47:50 Yeah, well, I'll see you guys in like seven minutes, so get a coffee or glass of water, and we'll be back.
08:48:09 Yeah, well, I'll see you guys in like seven minutes, so get a coffee or glass of water, and we'll be back.