08:07:40 So, today's keynote speaker is Dusan Keres.
08:07:45 and following his talk. We're going to have a panel discussion, including, of a shy Dekel Glenn Rudy, Craig event award and Filippo finale. So I'm very interested to hear what the panel has to say about these questions.
08:08:13 So I'm going to now see the screen to do Shawn.
08:08:19 And he can get started on his talk.
08:08:38 Well, I would just like to thank just been Cameron and mark for organizing this great meeting it's been really inspirational and discussions are great, I'd be mostly lurking while making breakfast and things like that but those were excellent and all
08:08:54 the discussions for like super interesting.
08:08:57 And as Mark mentioned, I will just continue with Cassie and falling into San Diego and following talk by Kate.
08:09:08 Nice observational results I build mostly.
08:09:12 I would say 90% of our simulation results and mentioned some related theoretical work and occasionally some observations.
08:09:20 And I just kind of evolved light before I go into detail so I just going to shortly into go directly motivate gassy and fall, and then talk about cold and hot mode accretion.
08:09:38 Those were the simple times before we started worrying about feedback, then I'll talk about, but feedback does this inflammation gas, and how involved in now for my interact.
08:09:57 It's actually kind of weird to talk about the info and not go into both kinds of flows, and is going to lead a little bit into galactically cycling, and then towards the end I will try to discuss how guys actually joined the galaxy of the sense of quotation.
08:10:10 Be start seeing in the unfolding guys, holding theory and observation.
08:10:15 And I'll touch at the end on these issues of vertical and particular condition and flow of gas through the galaxy, those will be kind of more detail stuff at the various.
08:10:26 Alright, so one thing that kind of puzzles me and probably most of us here is why and how is universe forming stars actively overall cosmic times we can observe from earlier that I have seven eight to present time, star formation activity of universe
08:10:46 is pretty high I mean he dropped by maybe order of magnitude things that he will do galaxies are still connecting cast into stars and kind of related question is what brings, and what is the fuel for this cosmic star formation and related topic is how
08:11:05 how is the galaxy connected to the broader network of gas is distributed throughout the universe.
08:11:12 And one thing to note here is that even though star formation activity big about ready to have per unit volume of the universe most of the stellar mass in the universe form after that, about 70 80% of magic shoot for.
08:11:27 After that you have to just universe kind of slowly started cranking down gas into stars, the lower right but there's a lot of times is then.
08:11:38 So, first thing you might wonder if the gas available in galaxies can form all of the stars.
08:11:45 And we know that stars form in molecular gas molecular gas has predicted consumption timescales definitely much harder than the age of the universe typically want to do Giga years, depending on the output.
08:11:59 So molecular Guess how.
08:12:02 Doesn't matter how much there is it's a transition phase, which is going to quickly spend it. and form stars or do something.
08:12:09 Well, the other bigger reservoir that sits in the comic series is atomic Gas and Electric zero v like to observe these atomic guys see my mission. But the time that shift, most of the time, because the BC in the universe actually sits in them by myself
08:12:20 absorbers, and the blood here on the right shows the density of linemen alpha absorbers in these critical density units as a function of redshift.
08:12:37 And you see that this density is brought to the flood between zero and maybe two and then it increases maybe by 50% effective two doors hired a chief.
08:12:48 By then you compare it to the stellar mass density in the universe.
08:12:51 At present time, which is shown here as this star going out of the blocks, and that's roughly it's not fully to scale to see that there was never enough gas seeping in the galaxies to produce this many stars, and most of the stars furthermore for optimistically
08:13:06 do so that as you have to.
08:13:09 There is only a tiny fraction of what they are both fuel to form this many stars by present time.
08:13:14 So from the simple considerations, we know that globally, some sort of gas info from the island ice intergalactic medium needs to supply galaxies, the form stars overall costs with that.
08:13:28 And they've been studying this issue mostly through simulations in the past few decades and we found a couple of basic things about this gassy involved.
08:13:51 and in lower mass halos versus late I galaxies. So in general, when galaxy Haley smaller than few times 10 to 11 solar masses.
08:13:57 From simulations, we found that gas in falls into the galaxies or very close to the galaxies by a cold filaments that are not strongly heated to the video temperature of the Halo and pilot edge of this cosmological info tends to be of order of 10,000
08:14:14 degrees scaled involved typically with video temperatures of halos and pitches two or three of L stories a little lower galaxies, is a million degrees Kaldi so there are these phases or Bell distinguish so Sharky the gas it's roughly million collagen
08:14:30 softly 10,000.
08:14:32 And this type of occasion where you just don't really care so much about the video temperature of the Halo and we go straight to the galaxy v term called another condition.
08:14:44 In 10 years ago.
08:14:46 And it's called more aggression is efficient because you can directly fall onto the center part of the halo so the rates are an athlete determined by to grow the structure of the universe of Halo growth rate.
08:15:03 rate as well. And this was also recognized very early but wasn't really explained how it works so in very early semi on the models.
08:15:14 Recognize that something will happen, and cooling time at the video interviews is shorter than for the full time.
08:15:23 The, something will happen with the stability of potentially podcasting Halo, and in semi big models, this would be the gas that's can just go straight to the Galaxy by they didn't quite explain what will happen, such gets clarification came with Boeing
08:15:39 and Becca Ellsberg in the early 2000s and then they come under Burgoyne that look into these issues in much more detail.
08:15:47 And they found that cooling time needs to be longer than compression time after the shock if you want to have a stable shock in the Halo, and they calculate the conditions for this to help all happen for the halos and found that only halos there are a
08:16:00 couple of times until 11 solar masses can have stable shock. If you are lower than your show will be unstable and crazy things might happen in a situation might be a little bit more complicated in reality because of these filaments so you might have stable
08:16:18 shock in between there there's these super low, and you can still streams with the center but we'll get to this in a second.
08:16:25 Here I just want to say that this is typical for higher nature galaxies, those verses seven through 11 solar mass Halo. Three. This is three to four times that 11 solar mass Halo.
08:16:37 Three also from auger it's a beautiful illustration shelving called the unfolding gas, very close to the galaxy metal and that each guest, mostly from the satellite and perhaps a little bit of Athlone around the galaxy, and some of the hard media starting
08:16:52 to develop in low density regions around.
08:16:56 When you go to lower end of things are a little bit more complicated because filaments get a little bit warmer, the density of IGN is lower so you tend to be heated to slightly higher temperature.
08:17:13 The typical at the given Halem us your lower seat my peak so you tend to sit in thicker more isolated filament, and the video temperature of the halo ever given mass goes down.
08:17:20 So, called modes exists and you can find the shock stability criteria in low mass halos even at a later time. But it's not as well defined. And when you go to really low mass Halo then you jump to the other side of the cooling curve and you might switch
08:17:35 to have more than two lovers my sales. I just want to illustrate this by this selection, one image here.
08:17:42 I just want to illustrate this by this selection, one image here. That still shows some sort of info but it's not as cleanly Philip military and hardcore guys are not as distinct anymore in temperatures. So kind of looking for the clean distinction between
08:17:54 call them had more the lower mass halos present time.
08:18:00 So when you go to higher mass halos, things change.
08:18:04 So, info is mostly cold in halos below few times that 11 solar masses but when you go to hire my tables. Oftentimes, Halo starts being dominated by the hot gas.
08:18:19 So this is illustrated here in this older word by our sphere that lots of fraction of the halo material that it's in falling in blue as cold, and that is hot, and the lower panel shows distraction at going to reality here, and the upper part of the show
08:18:40 distraction integrated between 42 in one video idea. So in the very center. After three to four times that the 11 you start having more hot gas but in the outskirts filaments can still survive and bring this cold my video deep into the Halo, even to several
08:18:58 thousand to 12, perhaps even attempted 30 solar masses, the higher energy to go more likely to have this cold 11 surviving.
08:19:08 So, so what happens then in these halos. Well, after, let's say five times that 11 details depending on mentality and the body and fraction of the halo, halo is contained mostly video lies Shockey the gas and regions that are falling through the cold
08:19:28 and filaments are much lower cooling time than the rest of the Halo. So they have much smaller chance to have a stable shock that would kind of support in that region supplements can still go in and bring the supply of gas very close to the galaxy PR
08:19:51 even connect to the galaxy, depending on the details of it all again discussing the second. So, we have this mix scenario where some of the hot gas will clearly cool in the central region, if it has high enough density and shorter cooling ties, but you're
08:20:02 also pumping the coal guests very close to the center of the table.
08:20:07 Finally, but the late even later times judges will find the below the tend to disrupt fully the filament very involved in the very center, and in, he was like the Milky Way or slightly higher minus, we tend to be dominated by the cooling of the hard material
08:20:24 in central regions, again in the outskirts, you might still bring some of the lower entropy and lower temperature.
08:20:35 Gas deeper in by the very center, typically it's going to be the cooling of the hard stuff that will give us supply of gas.
08:20:39 The issue here is not fully closed.
08:20:44 There are all kinds of tests to the scenario being done from all sides which is great.
08:20:51 And the results are still not fully conclusive which way things go when you put in the feedback whether you destroy the info or and has the involved when you increase resolution.
08:21:03 There were some suggestions that you might be strapped certain elementary regions but recent work, I think for us it is illusion show that you might actually enhance the lemons, is an example from better than she actually the recent paper from last year
08:21:27 they increase their base simulation of a massive several times that fell solar mass Halo, which of six. Then the gas is a high density so filaments can survive very deeply into the halo even, they're surrounded by have guessed, it can be increasing resolution
08:21:35 They can be increasing resolution by factor of 500 fell, especially focusing around the shocks.
08:21:40 And they found very crazy results when you go, bonds, you go to this extremely high resolution their Halo changes the fraction of the hot gas drops dramatically, the number of elementary folding rages increases the turbulence of the halo increases providing
08:22:04 extra support for the gas and so on and the governing factor of this whole guests also decreases. So we are working on this but we are still not at the not resolving older levels that I live on skills, such as this droplet scale.
08:22:17 For example from the courts work so there is still some work to do. But we are learning more and more over time and resolution definitely matters for the results.
08:22:26 Some of the other issues that we've been worrying about in the community. Community over time is that you have this call gas streaming through the heart Halo can be can be may be destroyed at the end by a shot but can it be destroyed also by hydrological
08:22:44 instabilities that occur during these motion. And, again, there were different results depending on what physics you included this is a recent results for from near Mandelker he actually gave a nice tutorial yesterday about this.
08:23:00 And the punch line is that venue include cooling is moving filament through the hot surrounding medium, not only survive for much longer time during this motion but you can actually increase the mass of the cold moving component, through the next thing
08:23:16 layers of the moving Street.
08:23:20 So, the picture of athlete holds, but there are details that needs to be studied and are being studied at all times.
08:23:28 However, however, most of the stuff I discussed so far was ignoring all flows from galaxies that occur at all times.
08:23:38 And if we had only info in the universe. Without regulating it to be able to produce galaxies that are made to have massive.
08:23:48 So this is a illustration actually from my own old work where these Blake herb is the observed minus function of galaxies.
08:23:56 The big black curve is just the line I drew by hand and that represents what would be the mass function of all the variables school in all the halos, and the red line is results from simulations that don't have outflows but only have you read background
08:24:12 as a only source of eating.
08:24:15 Outside of gravitational field.
08:24:17 So you see the info forms galaxies, there are a two massive order the high mass and, and then the llamas and at the high margin. The problem is about factor of two or three to match, same number that's the the low margin.
08:24:31 Problem is, orders of magnitude.
08:24:33 If you want to match the same number of density, you need to decrease the mass of galaxies by a factor of hundreds or even more. So we know that gas needs to be expelled from the galaxies or somehow location needs to be prevented.
08:24:47 And in the law Muslim is most likely done by some sort of stellar feedback. And then the high minds and the most commonly vote candidate is the age gap.
08:24:59 So I will focus mostly at the lower mass galaxies from milk eBay and below and we did discuss potential gas info through Halo condensation in a big one or two.
08:25:14 So we did discuss this high margin in much more detail so we will focus now in the lower NASA.
08:25:21 And just the general
08:25:24 conclusion about the info and outflows so info fuels boat, because you need for your first the forum stars and then to eject the material from galaxies.
08:25:36 So you really need to model. Both of these processes doesn't matter if you're studying guys going out there in you have to take into account, or both.
08:25:44 And you need to figure out what is their interaction with the Halo.
08:25:47 And there is more and more work done on this, both from the large scale cosmological simulations that have relatively crude realization of outflow where you describe what your outflow will be doing close to the galaxy and then you let it do its damage
08:26:02 further out.
08:26:04 But they have really good statistics so you can see all kinds of scenarios that can happen there. And it's been also look at from the zooming type of simulations like fire that's, in many cases, how actually very detail accounting for sale consistent
08:26:21 generation of verse the outflow from galaxies so your subdued scale it's kind of around, few parts in the star from usual and then you try to put our understanding of stellar population and see if you can generate the alpha from galaxy.
08:26:36 And these can provide more details, but statistics are very limited so they kind of have to play both.
08:26:45 Alright so here are some examples of what might be going on, then info and outflow interact.
08:26:53 This is the results from the relatively old now fire simulations.
08:26:58 From Sasha Morocco.
08:27:02 And first of all, we find it star formation in the low mass galaxies a pilot you so this would be really low mass Halo that achieve do it's pretty bursted black line here shows star formation.
08:27:13 The consequence of this versus star formation our strong outflow from the galaxies, shown by these headlines. This is the author of an inner Halo Videsh, an outer Halo built it.
08:27:24 And they're so strong and so much loaded, they can actually damage the involving gas in the inner Halo, you see that even the info becomes more episodic, it's still more continuous than the star formation outflows but strong alpha episodes tend to disrupt
08:27:42 people temporarily. But when you go close to the video they do is the info the semi continue So, even this highly mass loaded galactic beings don't do too much damage to the info, very far from the galaxy but close to the galaxy they can make sure to
08:27:56 disrupt.
08:27:58 So this is shown in little more details in this slide.
08:28:03 So these are two different snapshots of galactic Halo. So, this case is about them to love and solar masses. As a
08:28:17 registry.
08:28:19 And this shows informally offloading gas on the left of the unfolding guys on the right, and the velocity structure of the involving and offloading guys are shown on the left most panels here.
08:28:30 And you can see that then this strong episodes of all flow happens in the very center of a highly Starburst galaxy. You started imaging, the info very mildly in the center.
08:28:43 Because damage comes when you kind of spread out through the Halo, but you don't really disrupt the filaments in the outer Halo.
08:28:53 Very soon after the hot gas my propagate further all the coal, gas, it's either disrupted or radius back onto the galaxy and the filaments just re establish themselves and start providing your to the galaxy again.
08:29:08 The something similar has been seen in large scale simulations.
08:29:13 This is
08:29:16 results from Dylan Nelson from 2015. And you can also see that this outflow here might be disrupting filaments in the very inner Halo, but on the other hand might be also squeezing filaments in the very inner Halo.
08:29:30 So there's definitely some effect that we don't yet fully understand what it is but the interaction needs to be taken into account.
08:29:39 So what is important is that our flaws affect info two ways.
08:29:46 First of all, you might just interact with the enfolding gas and you might be ejected fuel outside of the galaxy so that would be kind of objective feedback, but they also prevent some of the info globally, over a long time still so that's, they have
08:30:02 also preventative at all. And this is kind of a smaller large scale simulations agree that you not only object material it also prevent some of the further info.
08:30:12 This is again an example from villain and few times that 11 solar mass Halo.
08:30:18 And there are different lines showing feedback, and no feedback simulation and you see that, then you look at actual updates of a condition.
08:30:27 Even the actual date of accretion drops by around factor of two or three with respect to know feedback so it's not only that you rejected a lot of material but you prevented.
08:30:36 some of the info to come in.
08:30:39 And finally, the info now for introduction is needed to explain.
08:30:45 Many observational trends. So, again, it's not only that we need our clothes to reject material from the galaxies. We need to do something clean following an agent This is example from Claudia and Trevor.
08:31:05 The added fire Bible feedback in Titus Alicia simulations of that two to four of our agenda of the Milky Way, like Halo.
08:31:08 And here, still our feedback eject some of the guests outside the Galaxy by the dorsal spreads out these enfolding regions. So the filaments that are available define are now much much thicker in falling region in which small satellite galaxies can blow
08:31:22 strong bits.
08:31:24 And this kind of interaction is needed to explain observable in this case, statistics of women living systems covering Lyman break Alex.
08:31:34 Alright so what does this mean well this means that also material that will be coming back at certain time, you will not be primordial.
08:31:44 So the streams and informing material retired edge of my as well, just come from on polluted the indo European medium but later times especially closer to the Jews zero.
08:31:57 Lots of the unfolding material will come from all eternity site with gas. This illustration from Ben Oppenheimer, and just shows that fraction of material that's being created late time galaxies especially a pie masses, this is this green line has come
08:32:14 from the previously ejected material.
08:32:32 It's been rejected mixed in with the rest, and then it's raining back on the gods. And this production tend to be important at late times. This is from Daniel Angliss algos are for two different scales on the left distant 11 solar mass Halo.
08:32:46 On the right, standard Bell solar mass Halo, and this just illustrates that, then you are the two to five roughly, then you're dominated by this region this color, which is financial condition from the intergalactic Bz.
08:33:02 So this is the material is kind of coming in for the first time.
08:33:11 Austria that you have two or three you started having pretty important channel which is this lighter, lighter color, part here, which is the recycling over your own beats.
08:33:15 So you're blowing beans. They go sometimes the video they do sometimes to have a video that is but there are leaning back onto the galaxy so your info has a significant component from those.
08:33:26 But then the late times going towards that achieve zero. You might also get this crazier components such as intergalactic transfer.
08:33:35 So the galaxies nearby are the ones that were falling onto your Galaxy lol a lot of in material, and now your galaxy is anything that material.
08:33:45 So it's pretty complex picture of what exactly galaxy is getting at late times. And as a consequence, a metals that
08:33:56 are being ejected initially tend to follow it been following guys as well.
08:34:01 So this seems like a visit blog but I'll just guide you quickly through it so on the left is meta listen to the outflows, and on the right is mentality of the info from a sample of simulations with high resolution simulation with fire feedback.
08:34:19 And this mentality has been scaled to the middle east of the interstellar medium of the galaxy.
08:34:33 Typical eyes some stuff out. Then you compare it to the info in the quarter of the video and you see that the info might have a little bit less metal on average, but it's very similar to what has been uploaded from the galaxies also similar with obesity
08:34:46 There still are medium in very low mass words, it can be lower, effective as a few, but because most of the condition is reactivated Vince, then you expect that these metals, is one be that different.
08:35:01 But then you go to hire an idea and you go to really elevate us. Now the differences are more significant, especially when you're focusing on these higher edge of being afraid of two to four outflows, even though the reality of us has the middle east
08:35:26 to the ICM, but the info because it's mixed with more of this primordial gas is much lower middle east to be affected or five or even lower. So further from the galaxy that the least there might be an indicator where you're flowing in and out, closer to the galaxy, you might pull up
08:35:35 some higher end is that these things but it might be more difficult.
08:35:41 Alright so let's not go towards lower shift where our situation is a little bit different so Heidi gv how strong in falling streams feeding the galaxy with higher rates we have burst the outflows and complicated info alpha region but at late time situation,
08:36:03 kind of comes down star formation becomes more continuous, and also those are not as strong anymore, at least in the, the simulations like the ones we haven't fired project.
08:36:16 And this scenario enables formation of in this, you're not destroying disk anymore you're not injecting highly MOS loaded Vince so my video can come down and form, low dispersion disk.
08:36:29 In this case, star formation is roughly steady info is also roughly continues, both at the video radius and in the inner Halo.
08:36:42 And it just nicely supplies, whatever is going on the Galaxy over long time scales over billions of years studying fault.
08:36:50 Now likely comes from the actual cooling flow in the Milky Way mass halos that were discussed by Jonathan yesterday, the tutorial.
08:37:00 So they have a halo that nicely slowly cools and just applies galaxy and that actually makes our studies maybe a little bit easier in some sense and we can start looking into finer details of how guys actually joins the galaxy.
08:37:16 I just wanted to point out that even though there is a cooling flow in the center, this is not fully isotopic situation.
08:37:24 There can still be some financial direction for the gas starts finally cooling out or it may be even condensed from the hot days in regions of the halos, this is a sample from analysis by Claudius Miriam, and I just showing lower entropy guess coming
08:37:41 from couple of preferred detection and late times. So some of these info my steal a beer, kind of elementary but it's not necessary that actually connected to the cold filaments exist.
08:37:57 Alright so this is roughly how things work in the standard case of having
08:38:06 Hydra dynamics and the stellar feedback from the standard sources.
08:38:11 But lately the been discussing a lot potential non thermal sources of feedback that can actually change the outcome for the guys info especially at late dies.
08:38:23 So just going to infuse slides. But if we discuss this alternative scenario of what might happen with a late I'm info.
08:38:32 And the reason why this might be interesting is that a couple of observational constraints indicated cosmic rays might need to escape galaxies.
08:38:42 And if they do and managed to capital to the surrounding CGM they can provide non terminal support for Halo gas, so that we don't have to support guess just be high temperature.
08:38:53 So in a simple model, where we implemented observational motivated transports parameters for cosmic rays is cosmic rays can actually do extreme change to the Milky Way mass halos and prevent large production of the hot gas to, to be there in the first
08:39:15 place.
08:39:17 So, what they do they change the density of the Halo, and they slow down the unfolding material and the conditions are such that you can completely avoid the video shock.
08:39:28 In this mass Hale's.
08:39:30 Now I wanted to point out that when you go to even higher masses that are likely to get back to the standard picture because star formation typically dies down the sources of cosmic rays might not be there.
08:39:42 The depth of potential veil is higher. And I also wanted to point out that this is strictly at load achieved. Typical know under more pressure from cosmic rays and the simulations is not dominant pioneer galaxies.
08:39:54 So this is a potential alternative scenario for the Milky Way mass halos at latex, and the consequences of skipping the video show are very dramatic so instead of having this clear shocks around the video that he was in occasionally lower temperature
08:40:10 gas penetrating to some depth and then being dominated by the heart gets deeper in your now completely dominated by this forum gas by 10 200,000 degrees and some miles showed my so this far away, but they're not really affecting what's going on in their
08:40:28 hail.
08:40:29 The other consequences that the cost make it a pressure gradient can start pushing the gas, slowly, and you might form these big things that might not be launched right from the galaxy but roughly few or even 10 kilos or six from the disc you might start
08:40:43 pushing material with 10s of kilometres per second outward.
08:40:47 And that means that the info that was already typically aligned roughly, with the Galactic plane now is going to be even much more aligned because you're kind of not the lobbyists to to exist so much in a vertical direction, and a half consequences for
08:41:04 unfolding parts which are illustrated here first of all, the scenario decreases the star formation rate of galaxies at a time so you have called her guests, but you're holding of you know internal pressure.
08:41:19 So you're actually not getting so much supply and your star formation rate drops.
08:41:25 The second of all, then you look at the enfolding announced loving gas they're completely change. First of all Oslo is much higher, especially far away from the galaxy.
08:41:36 So these other ones are ne ne ne ne super bubbles that might push the material to, maybe, few or 10s of kilo parcels but they don't go far, but far, of course, you guys can actually push you much more strongly, and then the info is typically
08:41:56 can be a little bit higher further out but it's typically much lower further towards the galaxy because you're just not allowing the gas to form this cooling flow like behavior like what we seen before.
08:42:09 So this is a better illustrated here also be the velocity of the unfolding announce loving gas So, any kind of the unfolding guys will be also slower than it used to be, and also the offloading gas tends to be pretty slow on the pencil, kilometers per
08:42:25 second.
08:42:27 Alright so, I'll come back to this picture and analyze it a little more but the couple of questions that are being asked.
08:42:35 During this workshop, were related to how does guys actually joined the disk so I wanted to go to there.
08:42:47 In the remaining time and discuss what by the happened with the readings I created material bonds with zoom in on to the galaxy itself.
08:42:53 We had this kind of funny suggestion in the old paper that it's possible that cold more gas smoothly merges into the Galactic disk like a stream of car, and during the next best way.
08:43:07 I, those kind of sentence that Neil cats come up with, we wanted to describe something that we call quotation today but we didn't know in detail how to do it.
08:43:19 So this is an example of the accredited materials shown is given Mark particles of the highest achieve galaxy from these old world where you see that the enfolding guess it's kind of turning and starting to join galaxy.
08:43:33 This was analyzing much more detail in Banner which I wish I and others.
08:43:38 Few years ago that they found something similar first of all they found that the info link cold gas has a factor of two to three higher angular momentum than the average Dark Matter Halo and then when they look at the streamlines of the guys, they see
08:43:53 that guys is trying to ally with the galaxy further out these regions that is typically 10s of killer parsecs from the galaxy, and in some cases even forms that are in like structure, especially with high energy.
08:44:07 So the guys is trying to join the disk. They outside of the disk, somehow is aligning its angular momentum and trying to become part of this bigger structure so what do you see as a start forming this itself might be only small part of the whole or physics
08:44:26 that happens there the alignment might have might be happening much further out. And you can see guys that even thousands of kilometers from the galaxy have my own additional some sign of rotation.
08:44:36 Well, the problem with these two words was imparted.
08:44:40 There were no really strong God flows.
08:44:43 So, for hydrogen galaxies, it might be a little bit more problematic, you don't have as well defined this claim the galaxies, especially a medium monster has already been they'll start might be dominate might be more affected by velocities version and
08:45:06 is not that clear but there was a sense of this quotation from the early work. So let's see how these works that lower chief. When we see galaxies like the Milky Way or nearby wonder that we can probe with both absorption and also admission type of studies,
08:45:20 for example from age one.
08:45:24 So let's talk about how guys might be accredited intergalactic this.
08:45:29 So, again, there are some examples. The love on the left, it's closer to zero, the one on the right is around.
08:45:37 In this case, it was a leftover of the cold mode and some of the cooling of the hot stuff as well but. In both cases, there was a clear sense of quotation that, then out to 50 kilo bar six or even more.
08:45:56 So guys is already trying to align with the plane and trying to rotate similar way as the galaxy. And that's being seen in these two different simulations.
08:46:20 And this is something that has been lately observed a lot with edge of especially by crystal Martin and Stephanie Hall, and others and also there is a nice work at Pine achieved by Nicola Boucher and his group I think they actually had paper last night
08:46:23 that I didn't have chance to digest. So there's this general picture that gas is quarter painting, as it's creating onto the galaxy.
08:46:33 And in a sense, this is just the statements that we didn't really have to have simulations to make because if you want to build the altar disk that have high angular momentum.
08:46:45 You kind of have to have gas that has that high angular momentum. I mean, otherwise you need to have a much bigger reservoir and lose it very strongly to, to end up there.
08:46:55 So, to illustrate this angular momentum.
08:46:58 Here is a example from fire simulation so these are four different Milky Way mass halos simulated with a fire to feedback and be different physics.
08:47:11 So in the top row, these are pure hydro simulations of something that we call fire tool. In a medium grow the edits and add into the mix, and in the last row we actually added cosmic rays.
08:47:26 So, the reason why I like cosmic rays is that they slow down star formation to be something that we observed the Milky Way was he was because community for two to three solar masses a year.
08:47:47 uncomfortable to actually look at the guys involved with your hydro, but what you see here is that
08:47:51 in the inner galaxy.
08:47:54 The compare is angular momentum specific angular momentum floats to the rotation curve over galaxy shown in this thread dash line in the inner galaxy, the gas is fully supported by rotation so that's a normal disk.
08:48:08 and that's kind of independent on the technique and the galaxy v us. And that continues to 10 or 15 k PC. So that's something we would call a galaxy it's fully rotational support structure in the stars are forming.
08:48:24 However, when you go outside of galaxy.
08:48:29 There is a.
08:48:29 Guess who's angular momentum is similar, or even a little bit higher than the author this.
08:48:35 So if anything from 20 to 50 kilo bar six fall onto the galaxy, it's more likely going to join out there these are somewhere in the outskirts than in the center just because it has such a high angular momentum would have to lose.
08:48:49 Huge fraction of its existing angular momentum to settle the party.
08:48:53 So, what I wanted to say with this blood is that you can have the hot Halo in the center like you're doing hydro, or you can have this forum.
08:49:03 Non thermal a supported material like you having cost me get a case. In both cases, the material in the inner few times of killer power six have angular momentum compatible or higher, to the outer this.
08:49:17 So once they settle is more likely going to be settled summary and certainly somebody out for this.
08:49:24 Alright so now I'm going to focus mostly on these cosmic rays halos largely for the fact that their star formation eyes are closer to what is observing.
08:49:34 Some of these results apply to Hydra rounds as well but typical rates and velocities are higher in Hydra.
08:49:43 So, because of this quotation of the inner Halo the expect things to settle pretty close to disk and now they just improved the same angular momentum load by adding is blue line that shows the unfolding guys only so this is the gas that he's going to
08:50:00 sue and joining galaxy.
08:50:02 joining galaxy. So if you see that guys the joys of the galaxy has a similar angular momentum is that as the winner Halo, on average, it might be actually slightly lower.
08:50:12 But still, similar higher than that the sketch the edge of the material is the mercury.
08:50:18 So now you see that the measure these things in these funny units. These are now in our DLA us, so we define this as being the material whose column density is higher than the the label in this.
08:50:33 And what you can actually also see here is that almost perfectly captures where the we get to this quotation.
08:50:39 So for the zero order we can just say that edges of the discard where we drop below the LA densities.
08:50:46 The second thing you see here in this blog is that the guys is not only having similar angular momentum but it's Bell align with the display of course in the galaxy alignment is close to perfect it's within few percent.
08:51:00 But then you even go to a couple of these de la di is the lady is roughly 15 or 20 depending on the Galaxy, you still see these alignment to 80 90%.
08:51:13 So the guys is not sitting perfectly you know this, it's kind of flare up or fun to like structure is trying to evil onto the other edge.
08:51:22 And now the consuming onto the kinematic profile and mass fluctuates from this material.
08:51:30 And then the top panels here I showed two examples of milk if a mass galaxies.
08:51:36 And you can see that when you're about one and a half or two, or the LA which again it's about 3040 k BC, the gas is that a nearly falling indeed about 20 kilometres per second.
08:51:49 So, most of the info won't be easily seen. If you want to find high velocity clouds or things like that, there will be a fraction, but that might be sub dominant.
08:51:57 So the infinitely material even tears does have a PC from the galaxy pretty slow, it's only thousands of kilometres per second. And then, it slows down, but ideally, but from angular momentum we know that correlates closer and closer and closer.
08:52:13 And it reaches almost full correlation somewhere between half and one or the LA.
08:52:20 After that point the gas, just sits in the galaxy that's where it ended, but it doesnt sit still.
08:52:27 You can see that systematically there's this tiny little motion of like, typically 123, kilometres per second and I'll come back to this motion. Those RG radio flows of the material within the galaxies like the military themselves and typical location
08:52:44 rates are over order of fuel solar masses, but both to find these velocities and to find the conversion rates, you have to do.
08:52:54 Life statistics so in this case we average it over. I think tense of snapshots of the galaxy because then the given time. You might even see you guys all flowing.
08:53:04 But then you average over long time scales over hundreds of million years, there's a general info signal that you can pick up. So if you look at any individual galaxy you might not see picture like this because of these very large dispersion.
08:53:18 But assuming that adding many many objects you might pick up the signal be seeing these simulations.
08:53:26 Alright, so I just going to show a few more details about it before I summarize.
08:53:43 And we had a lot of discussion about what is actually happening with this info whether it's parallel to the disclaimer or vertical. And in these fire simulations with cosmic rays, and also without cosmic rays but to a different degree, the mass flex, it's
08:53:53 it's mostly parallel to the disk, but again with large variations show me this dashed lines here, the orthogonal accretion.
08:54:02 It's a very low. Sometimes you might get some but in many cases it's actually net outflow. If you have averaging over time.
08:54:11 And we selected a subset of accreting particles randomly just to illustrate what's going on. So again, these are four different military mass halos is
08:54:24 square, the rectangular shape here at a presence this with the height of to scale heights of the gas, and the extent of one DLA radius.
08:54:46 And the particles here are followed for one or two adult diamond at the sketch so typically like half a Giga year or so before the occasion, their color coded by the radius where they joined with this bluish color meaning the edge and this kind of reddish
08:54:54 colors, meaning the center.
08:54:56 So you see the particles are all under the aligning close to this plane but not perfectly. Then there are far away, they approach the disc, they when they are very close to the disc.
08:55:11 They tend to settle into full rotation and fully joined at this graph leads point 7.8, or one hard DLA in the more compact cases more compact this so these are all similar mass but the sizes.
08:55:28 Some of the settling may occur deeper in the center, and the angles with which they settle might be higher.
08:55:35 In this particular case on the left, this is actually the galaxy that just had the merger at that point and do you see that the condition is all coming from one direction so so there's still by the leftover of what's being repeated on to the galaxy.
08:55:48 Alright so that's it obviously the pictures of the guys is not perfectly aligned with this there's definitely a spread there, but there is a global sense of rotation and the debate angular momentum works.
08:56:03 As you approach the disk, you just need to lose very little and you're going to settle into this catch.
08:56:09 So the question is, then how do we supply the star for mega regions in the very center, and that's the question we had in this conference couple of times.
08:56:22 If you're settling always at the edges, how do you get the entire nation, the situation may be more dramatic because there is like much more violent dynamics happening with the guys, but the delight times is actually this slow radio info of few kilometers
08:56:38 per second that I indicated in the last couple of slides ago.
08:56:43 And so we wanted to see if we have enough supply to kind of fuel star formation in the very center.
08:56:53 And I just going to mention that these galaxies again those are the four milky a mass galaxies, they have distribution of star formation activity that is different as a function of radius.
08:57:08 And the ones that seem to be more spread out with the radios. They have different rates of radial involvement be measured in the brain, versus outside the ones that tend to be more concentrated like this and will be.
08:57:23 They have similar at a deli unfolded throughout because all of the star formation happens close to the center.
08:57:28 So, for this case, if you measure the the lean forward a they're typically few solar masses a year.
08:57:36 And as you star formation depletes the unfolding gas that these rates drop further and further because smaller fraction of that star formation eight happens in the inner galaxy is star formation centrally concentrated that throughout this, you can see
08:57:55 of info that it's comparable to the star formation of this galaxy. Again, the one on the left here it's a kind of still ongoing merger so it has a little bit crazy mass lower rates and also dynamics.
08:58:04 I wanted I wanted to point out that to pick up the signal.
08:58:11 I guess observational colleagues can tell us if that's possible or not but you definitely need to average out the flow of galaxies.
08:58:18 Radio Lee in radio readings and also you need to have any jobs. This flow of gas over time. So this is just a snapshot.
08:58:26 At any given time color coded by a deal velocity. Within this plane of the gas for those four cases. So,
08:58:36 the densest material moves with only a few kilometers per second but there are these issues there moved around by 10, or 20, or so kilometres per second.
08:58:46 Throughout this.
08:58:47 So, if you take any galaxy at any given time, it might be hard to pick up this few kilometers per second, abl info but if you have large sophisticated galaxies there might be a way to to tease out this information and get typical ADL Floyd's of galaxies
08:59:04 over time.
08:59:07 Alright, so I have additional maybe 3040 slides that people can ask about later but to enable more time for discussion I just want to go to somebody.
08:59:24 You found that the gas info is dominated by efficient elementary hold on the creation of high energy, then cooling of the hot gas that lead times.
08:59:38 Feedback clearly affects properties of the info.
08:59:42 Details are not yet clear.
08:59:45 Seven all the groups are doing studies, as we speak, but we don't have extremely clear picture of how will then be disrupt filaments and how long is this disruption lasting and exactly how is this president of the feedback working, and the resolution
08:59:59 is still unclear, is the resolution convergence is especially important ones you have cold stuff mixed in the hot medium, as we've seen in the first few weeks, this is a steel open question even idealize simulations that are trying to get to the nitty
09:00:15 gritty of what might be going on with mixing later so it's no surprising that in the large scale cosmological simulations even zooming cosmological simulations, we don't have fully convergent picture of what's going on.
09:00:30 thing to keep in mind is that late I mean fall, often comes from large scale recycling, not always, and higher if you go you're less likely to get into this recycle component.
09:00:40 By the late times the gas info close to the galaxy might have similar Middle East the to the Oslo material and it can be similar to the general is them, but again, not, not all of it.
09:01:03 And they should worry more about these non thermal processes such as cosmic rays because even if this is extreme case and super simplified transport. They have potential to completely change the face structure of the late I'm info, even if they don't
09:01:22 that crazy leaking there might be explosive the galaxy. So we need to observational II constrain these non thermal processes, to be able to more cleanly study involving an alpha and gas. And this is something that seemed to be a consensus view from many
09:01:26 different simulations that when the guys approaches galaxy, it correlates with a disk.
09:01:40 And that creates close to this outskirts. That doesn't mean that the fun things are not also picking up some gas, it just these simulations there doesn't seem to be need to explain current star formation but might be an issue of resolving these findings.
09:01:46 And there is a way to transport the guys that it's being accredited to the outskirts, to the sun star for me regions in our galaxy. And this is through radio walls through this can we are kind of working hard to understand exactly what's being taught
09:02:01 and how it's being taught we have these smile The radio flows over time.
09:02:04 So I'll stop here.
09:02:06 Thanks.
09:02:08 Well thank you very much, I will applaud live.
09:02:12 Thanks, people can use applause icons.
09:02:16 Thank you for a very insightful talk and particularly how you connected, a number of the things people have already discussed in this conference to what you see in those simulations.
09:02:28 It is now almost three minutes after the hour. And so I give people a five minute break and reconvene in eight minutes after the hour, where we will have a panel discussion