WEBVTT 1 00:00:00.630 --> 00:00:11.190 Morgan Elowe MacLeod: So, but today we have the pleasure of having Jamie Law-Smith. Jamie is as most of you know, a new ITC fellow this year. 2 00:00:12.750 --> 00:00:20.250 Morgan Elowe MacLeod: So we have the pleasure of seeing each other in person, as well as you know, here you're on zoom and. 3 00:00:21.960 --> 00:00:22.650 Morgan Elowe MacLeod: and 4 00:00:23.700 --> 00:00:32.700 Morgan Elowe MacLeod: Before that Jamie was doing his PhD in at the University of California Santa Cruz, where he worked with ricotta ministries and. 5 00:00:33.690 --> 00:00:48.900 Morgan Elowe MacLeod: yeah Jamie take it away so again for format, we will have like the first 2025 minutes Jamie will give us an overview of what you know he's been thinking about and then we'll have time for a little bit more extended discussion. 6 00:00:49.950 --> 00:00:59.340 Morgan Elowe MacLeod: so wonderful and then on a logistical note, I just wanted to mention that this zoom call doesn't automatically mute folks as you log in. 7 00:01:00.660 --> 00:01:01.470 Morgan Elowe MacLeod: So if. 8 00:01:03.030 --> 00:01:12.690 Morgan Elowe MacLeod: If you could go ahead and mute if you're not trying to speak up right now that'll that'll be ideal awesome Thank you so much, and Jamie take it away. 9 00:01:13.800 --> 00:01:14.460 Jamie Law-Smith: Thanks Morgan. 10 00:01:19.470 --> 00:01:31.020 Jamie Law-Smith: We go so high so i'm Jamie last met and i'm very excited to be at the CFA so i'm actually not at the CFA right now i'm in Chicago but my sister my office is. 11 00:01:33.090 --> 00:01:37.290 Jamie Law-Smith: And i'm very excited to talk science with with all of you, while i'm here. 12 00:01:39.000 --> 00:01:46.230 Jamie Law-Smith: So i'm going to talk about interactions between black holes stars and galaxies. 13 00:01:47.640 --> 00:01:57.060 Jamie Law-Smith: And today i'll be talking about one particular interaction, which is that between a supermassive black hole and a star. 14 00:01:58.200 --> 00:02:01.650 Jamie Law-Smith: And also relate this to the galaxy in which it occurs. 15 00:02:03.180 --> 00:02:09.240 Jamie Law-Smith: So this diagram here is a title disruption of a star by a supermassive black hole. 16 00:02:13.650 --> 00:02:20.580 Jamie Law-Smith: So first, a few words about myself, as I think this colloquium is a bit of an opportunity to introduce myself to the Community here. 17 00:02:21.300 --> 00:02:35.670 Jamie Law-Smith: So my approach is to use stellar interactions at different scales to understand the nature of black holes the lives and deaths of stars and the dynamics and galactic centers. 18 00:02:36.870 --> 00:02:44.790 Jamie Law-Smith: So in theoretical physics i'm interested in understanding the sitter space in theories of quantum gravity such a string theory. 19 00:02:46.170 --> 00:02:52.440 Jamie Law-Smith: So this schematic shows the interactions I study at an increasing physical scale from left to right. 20 00:02:54.030 --> 00:03:01.410 Jamie Law-Smith: So at the solar radius scale I study interactions between two stars, particularly in the context of gravitational waves sources. 21 00:03:03.180 --> 00:03:08.610 Jamie Law-Smith: At the AU scale I study interactions between a star and the supermassive black hole. 22 00:03:11.130 --> 00:03:25.290 Jamie Law-Smith: At the parsecs scale I study agm discs with embedded stars so i'm interested in both the structure of the disk and the final outcome of the stars, in particular gravity waves sources in these deaths. 23 00:03:26.730 --> 00:03:31.410 Jamie Law-Smith: At the killer parsecs scale I study the host galaxies of these interactions. 24 00:03:32.910 --> 00:03:41.910 Jamie Law-Smith: i'm interested in angular momentum, transport and galactic centers and relating stellar scale processes with galaxy scale physics and global galaxy properties. 25 00:03:43.680 --> 00:03:56.070 Jamie Law-Smith: And I cosmological scales i'm interested in understanding the sitter space in the context of dark energy and theories of quantum gravity such a string theory so i'm very excited to connect this program to astrophysical data. 26 00:03:57.660 --> 00:04:04.890 Jamie Law-Smith: So in this talk i'll focus on just one of these interactions, which is that between a star and a supermassive black hole. 27 00:04:06.780 --> 00:04:10.710 Jamie Law-Smith: And i'll also say a few things about the host galaxy of this interaction. 28 00:04:14.190 --> 00:04:26.400 Jamie Law-Smith: So I also like this way of thinking about the different structures that one can study so here i'm showing binding energy on the y axis versus mass on the X axis. 29 00:04:27.060 --> 00:04:39.780 Jamie Law-Smith: And can see density is lines of constant density are indicated by these dashed lines on the diagonals so in astrophysics we like to study gravitational structures, these are the ones that are interesting. 30 00:04:41.100 --> 00:04:46.890 Jamie Law-Smith: And i've just put in read some of the different objects that I think about. 31 00:04:49.800 --> 00:04:54.720 Jamie Law-Smith: Okay, so let's talk about an interaction between a star and a supermassive black hole. 32 00:04:55.830 --> 00:04:59.370 Jamie Law-Smith: So on the left is the Milky Way plus stellar emotions from Gaia. 33 00:05:00.450 --> 00:05:04.560 Jamie Law-Smith: And we think that in the centers of most galaxies there's a massive black hole. 34 00:05:06.600 --> 00:05:13.230 Jamie Law-Smith: On the right if we zoom in by a factor of 1000 surrounding this black hole is a dense system of stars. 35 00:05:14.460 --> 00:05:18.180 Jamie Law-Smith: This is a view of our own galaxies nuclear star cluster in the infrared. 36 00:05:22.680 --> 00:05:25.380 Jamie Law-Smith: So let's zoom in another factor of 1000. 37 00:05:26.400 --> 00:05:37.500 Jamie Law-Smith: And this is a beautiful bill video from the UCLA galactic Center group and the stars in these systems trace out a complicated orbit under the combined influence of other stars and the black hole. 38 00:05:38.550 --> 00:05:44.190 Jamie Law-Smith: So the stars undergo a random walk in angular momentum space through scattering with other stars. 39 00:05:45.960 --> 00:05:56.250 Jamie Law-Smith: And every once in a while and encounter with another star will send a star on to a nearly radio it's called last Cone orbit that brings a very close to the central black hole. 40 00:05:59.400 --> 00:06:08.310 Jamie Law-Smith: And when this happens so here we're zooming in another factor of 1000 So this is the star on the left and the black hole in the Center. 41 00:06:10.230 --> 00:06:28.020 Jamie Law-Smith: So a star on one of these last Cone orbits will pass close enough to the black hole that it is ripped apart by the black holes title field, so this is a title disruption event or a TD and that's what i'm going to be talking about today. 42 00:06:29.790 --> 00:06:42.270 Jamie Law-Smith: So this is a new simulation that I developed a TD disc formation so following the star from the initial approach and disruption to return of the debrief the black hole and the formation of an increase in this. 43 00:06:43.380 --> 00:06:52.680 Jamie Law-Smith: So for the 50 notice here the dissipation here is from the nozzle shock at 30 Center is similar to the Logan Omer 1997 process. 44 00:06:54.540 --> 00:06:58.920 Jamie Law-Smith: Actually interesting late so fun fact CDs were first proposed by wheeler. 45 00:07:00.210 --> 00:07:13.260 Jamie Law-Smith: or in this in this conference note to physicist X, which we think is fine as a way to trigger the disintegration of Penrose process which the process where energy is extracted from a black hole. 46 00:07:14.310 --> 00:07:27.840 Jamie Law-Smith: And they thought that this would power, the transit agency so TVs do not work like this, we think that the transit industry is instead accretion powered or or powered by guests interactions. 47 00:07:31.110 --> 00:07:35.490 Jamie Law-Smith: Okay, so let's spend a little bit of time understanding basic title disruption theory. 48 00:07:36.720 --> 00:07:43.350 Jamie Law-Smith: So a star is disrupted when the title force across it overcomes its binding energy or itself gravity. 49 00:07:45.030 --> 00:07:53.820 Jamie Law-Smith: So this leads to definition of the title radius which depends on the mass of the black hole and the structure of the star. 50 00:07:55.410 --> 00:08:04.170 Jamie Law-Smith: So another way to think about the title radius is, if you spread the black hole over the title radius the average density is the same as star. 51 00:08:05.820 --> 00:08:18.000 Jamie Law-Smith: Okay, so we'll define beta the impact parameter as the ratio of the title radius to the Perry Center distance so higher beta is closer to the black hole. 52 00:08:19.290 --> 00:08:22.170 Jamie Law-Smith: In this example grazing encounter beta for you. 53 00:08:23.190 --> 00:08:40.260 Jamie Law-Smith: So the star coaches on a parabolic orbit in Hydra roughly parabolic orbit and hydrostatic equilibrium and it develops a quadruple distortion, as it passes through Perry Center and it's the associated torques that lead to large surface velocities and eventually break up the star. 54 00:08:40.950 --> 00:08:43.290 Jamie Law-Smith: So the star does not have time to react. 55 00:08:43.320 --> 00:08:52.050 Jamie Law-Smith: So a nice fact is that, in a TD, the passage time is approximately equal to the dynamical time of the star. 56 00:08:52.770 --> 00:09:08.550 Jamie Law-Smith: So here's this kind of order of magnitude derivation there in the Center where you can really nicely relate the passage time to to the actual to the average density of the star, which is a course related to the dynamical time of star. 57 00:09:10.650 --> 00:09:24.390 Jamie Law-Smith: And the energy required to tear the star apart is supplied by the orbital energy which at the title the title radius is greater than the binding energy by a factor of ratio of the black hole mass to the stellar mass to the two thirds. 58 00:09:26.640 --> 00:09:31.200 Jamie Law-Smith: OK, so the Center of mass is in a parabolic orbit and. 59 00:09:31.710 --> 00:09:35.700 Jamie Law-Smith: In a typical title disrupting roughly half of the debris becomes unbound. 60 00:09:36.060 --> 00:09:41.070 Jamie Law-Smith: From the system and half becomes bound to the black hole and there's often a surviving them. 61 00:09:42.450 --> 00:09:49.020 Jamie Law-Smith: So the boundary falls back towards the black hole and becomes the title disruption flare that we see. 62 00:09:50.280 --> 00:09:59.490 Jamie Law-Smith: And it's the rate of return of this bound material to the black hole or the mass fallback rate the directly informs the light, we see in a title disruption event. 63 00:10:03.420 --> 00:10:15.180 Jamie Law-Smith: So when a title disruption happens, we see a rapid increase in brightness followed by slower decay, the coincides with the nucleus of the galaxy this occurs on timescales of days to weeks. 64 00:10:16.440 --> 00:10:33.360 Jamie Law-Smith: So, through a detailed theoretical understanding of disruption itself, coupled with a comparison to well sampled observations we can learn about the properties of the disruption so black hole properties, such as its mass and spin and stellar properties that is stellar masses and ages. 65 00:10:34.410 --> 00:10:40.200 Jamie Law-Smith: We can also prob accretion or a gn and judges on time scale of weeks. 66 00:10:42.030 --> 00:10:54.540 Jamie Law-Smith: And second through the relative rates and demographics of Title disruptions, we can learn about galaxy properties so stellar populations in galactic nuclei and the dynamical mechanisms operating in galactic centers. 67 00:10:55.830 --> 00:11:03.930 Jamie Law-Smith: So both of these are important, so, for example when we're first beginning to understand supernovae the light curves all look pretty similar and it took an understanding. 68 00:11:04.230 --> 00:11:11.130 Jamie Law-Smith: of both the individual events and their birthplaces in order to understand the different mechanisms of core collapse versus thermonuclear. 69 00:11:15.600 --> 00:11:34.110 Jamie Law-Smith: Our current understanding of black holes is biased toward the most massive ones, because these live in the biggest galaxies with the largest velocity dispersion so here i'm showing the M Sigma relationship and the red box is roughly the black hole masses that T probe. 70 00:11:39.750 --> 00:11:47.970 Jamie Law-Smith: And here, showing the black hole mass function so in the local universe, for every active black hole which is the lower green line here. 71 00:11:48.660 --> 00:12:00.780 Jamie Law-Smith: There are approximately 170 quiescent black holes so that's scaled up to this upper green line so most local supermassive black holes are quiescent. 72 00:12:01.290 --> 00:12:15.450 Jamie Law-Smith: And title disruptions are really nice way to probe these black holes and again the red box is roughly the black hole masses that TVs pro so we can really investigate the black hole mass function with 10 disruptions. 73 00:12:17.490 --> 00:12:22.290 Jamie Law-Smith: And in the last 10 years the number of T detections has increased six fold. 74 00:12:23.580 --> 00:12:28.140 Jamie Law-Smith: So we're in the midst of a data explosion in TD eats and it's very exciting. 75 00:12:30.750 --> 00:12:40.890 Jamie Law-Smith: So we have well sampled for telemetry and spectroscopy for roughly 30 TD ease and we expect 10s of thousands of TVs with reuben. 76 00:12:42.510 --> 00:12:47.220 Jamie Law-Smith: So i'm just showing a few examples of the beautiful data we're now getting with TVs. 77 00:12:48.570 --> 00:12:51.600 Jamie Law-Smith: Okay, so, but what can we do with all of this information. 78 00:12:54.360 --> 00:13:05.310 Jamie Law-Smith: So one gets a very good fit to the optical UV light curves by directly using the results from our simulations, that is, the mass fallback rate from our simulations which i'll show in a little bit. 79 00:13:06.330 --> 00:13:12.000 Jamie Law-Smith: So on the Left i'm showing fits to the light curves for a few example TVs. 80 00:13:15.480 --> 00:13:22.110 Jamie Law-Smith: And this these fits allow us to constrain the black hole math so the supermassive black hole mass and many other properties. 81 00:13:22.860 --> 00:13:29.010 Jamie Law-Smith: So on the right i'm showing fits to several of these properties now this highlight black hole mass in the last column. 82 00:13:29.760 --> 00:13:40.050 Jamie Law-Smith: And we can actually measure black hole masters better than the Sigma relation, so the typical uncertainty on black hole mass determinations is a border point three decks. 83 00:13:43.620 --> 00:13:59.820 Jamie Law-Smith: Okay, so with the goal of extracting as many physical parameters as possible from each observed event we've developed over several years this stars library so stellar TD ease with abundances and realistic structures T against title disruption. 84 00:14:01.050 --> 00:14:08.550 Jamie Law-Smith: So we build stars in Mesa and we calculate their disruption in flash, which is a 3D depth of mesh or Larry and hydrogen elements. 85 00:14:10.230 --> 00:14:18.780 Jamie Law-Smith: So we have accurate stellar structures we can track the composition of the gas for an arbitrary number of elements and we use an equipment, an extended helmholtz equation upstate. 86 00:14:20.430 --> 00:14:25.920 Jamie Law-Smith: So here's a visualization of one of my simulations so on the top right you'll see the orbit of the star. 87 00:14:26.640 --> 00:14:38.100 Jamie Law-Smith: And here we're in the frame of the star zoomed in on the star as we pass period Center so you'll see title tails develop, but here this visualization does focuses on the surviving run. 88 00:14:43.770 --> 00:14:48.510 Jamie Law-Smith: Okay, so here's an example of those titled tales and the stratified density structure of the. 89 00:14:50.640 --> 00:15:04.020 Jamie Law-Smith: So I want to point out that the stellar structure is imprinted on the spread and binding energy of the debris which determines the mass fallback rate to the black hole which is then directly related to the luminosity. 90 00:15:05.040 --> 00:15:12.780 Jamie Law-Smith: evolution of the of the transition from light curve, so the stellar structure has a direct relation to the light curve that would see in Title disruptions just really. 91 00:15:16.800 --> 00:15:29.610 Jamie Law-Smith: So in this stars library we study the entire parameter space of main sequence stellar structures so in stellar mass and stellar age and also in impact parameters of distance to the black hole. 92 00:15:30.750 --> 00:15:39.810 Jamie Law-Smith: So here i'm showing mass fallback rates to the black hole so mass return to Perry Center which is related directly to the light curve and a TV. 93 00:15:40.290 --> 00:15:53.220 Jamie Law-Smith: And from simulation so each panel here is a different stellar mass and stellar age each panel is a different Star and the different lines are different impact parameters or distances to the black hole. 94 00:15:54.720 --> 00:16:09.210 Jamie Law-Smith: So we interpolate in three dimensions, so in stellar maths stellar age and distance to the black hole to provide the fallback rate for any encounter between a star and a supermassive black hole using this get help tool. 95 00:16:13.770 --> 00:16:31.410 Jamie Law-Smith: And I found that all of our simulations can be reduced to a single relationship that depends only on stellar structure characterized by the single parameter alpha, which is the ratio of the central density of the star to the average density of the star to the one third. 96 00:16:33.420 --> 00:16:41.880 Jamie Law-Smith: So we essentially characterize the stellar structure of the debt stellar density profile by this single parameter and there's actually quite a good one to one mapping between these. 97 00:16:42.360 --> 00:16:54.780 Jamie Law-Smith: And this allows us to reduce all of these simulations of different stars different ages and different distances to the black hole into single relationships just scale with stellar structure and distance to the black hole. 98 00:16:55.260 --> 00:17:06.030 Jamie Law-Smith: be characterized by beta so i'll just name some of these different quantities i'm plotting gear so in the top is the unbound mass from the star, which is related to the total energy of the transients. 99 00:17:06.900 --> 00:17:12.540 Jamie Law-Smith: The Middle is the power law decay index, which is related to the power of K of the light curves. 100 00:17:13.620 --> 00:17:18.180 Jamie Law-Smith: And the bottom is the peak mass fallback rate, which is related to the peak luminosity. 101 00:17:22.050 --> 00:17:27.540 Jamie Law-Smith: Okay, so another recording contract component of these simulations that that we have the composition of the guests. 102 00:17:28.980 --> 00:17:37.890 Jamie Law-Smith: And so the stars initial composition profile is mapped via the Hydra dynamics of the encounter to the composition of the fallback material as a function of time. 103 00:17:39.000 --> 00:17:52.800 Jamie Law-Smith: So on the left hand side i'm showing 2d slices of the maths fractions of helium along the top and carbon along the bottom at two different times the left is time equals zero right is a few dynamical times after Perry Center. 104 00:17:53.490 --> 00:17:57.150 Jamie Law-Smith: And this is for a one solar mass terminal age main sequence star. 105 00:17:58.800 --> 00:18:06.000 Jamie Law-Smith: You can see the helium enhancement and the carbon depletion in the stars core are spread into the title tables. 106 00:18:07.410 --> 00:18:20.850 Jamie Law-Smith: And this results in compositional anomalies in the fallback material so on the right, this is what i'm showing so these compositional anomalies appear before or at the time of peak fallback rate so when the event is brightest. 107 00:18:21.390 --> 00:18:39.030 Jamie Law-Smith: So the X axis here is time over time of peak which you can think of, is when the event is brightest and you can see compositional anomalies appear when this, this is a border one near peak and the the y axis is is is composition. 108 00:18:40.590 --> 00:18:52.680 Jamie Law-Smith: So we find enhancements in nitrogen and helium at peak and depletion and carbon, so these kind of things are exciting because nitrogen and other metal lines have been observed in title of disruption events spectra. 109 00:18:53.640 --> 00:19:06.570 Jamie Law-Smith: And i'll just also mentioned that with a student we've developed an analytic framework for the composition of the fallback material so to allow for a large inexpensive parameter space, so that we can then tune to the simulations. 110 00:19:08.760 --> 00:19:14.490 Jamie Law-Smith: So, how does this fall back material actually turn into the light inspector, we see in the title disruption event. 111 00:19:15.300 --> 00:19:23.280 Jamie Law-Smith: So just show this is some work we're doing in this direction, so I showed you in the beginning of simulation of Title disruption event disk formation. 112 00:19:23.850 --> 00:19:30.540 Jamie Law-Smith: And we have the chemical abundance information for all of this gas so here i'm showing the chemical structure of the debris in the chemical. 113 00:19:31.200 --> 00:19:42.720 Jamie Law-Smith: structure of a TD disk so in white is hydrogen red is helium blue is carbon and green is nitrogen, so we see this distinctly stratified chemical structure. 114 00:19:43.980 --> 00:19:51.990 Jamie Law-Smith: And, combined with ready to transfer calculations, this will allow us to connect actual hydrogen chemical structures to observed spectral lines. 115 00:19:56.130 --> 00:20:04.290 Jamie Law-Smith: So now let's just step back a little bit and think about the face space of Title disruption so here we're comparing the title radius. 116 00:20:05.580 --> 00:20:09.870 Jamie Law-Smith: To the short short radius are really the innermost bound circular orbit of black hole. 117 00:20:11.130 --> 00:20:18.900 Jamie Law-Smith: So for attend to the six solar mass black hole a typical white dwarf is too dense and so it's disrupted inside the horizon of the black hole. 118 00:20:20.190 --> 00:20:23.100 Jamie Law-Smith: and main sequence and evolve stars can be disrupted outside. 119 00:20:28.020 --> 00:20:38.580 Jamie Law-Smith: For attended the eight solar mass black hole most means sequence stars are swallowed a whole before being disrupted and only evolved stars will be disrupted outside the horizon. 120 00:20:43.410 --> 00:20:47.880 Jamie Law-Smith: Interest smaller black hole a light work can be disrupted outside the horizon. 121 00:20:50.070 --> 00:20:57.750 Jamie Law-Smith: and also for the same mass black hole each of these objects leads to very different title disruption flares and different signatures. 122 00:21:00.960 --> 00:21:06.810 Jamie Law-Smith: So this leads to this idea in this this plot is what i've called the title disruption menu. 123 00:21:07.950 --> 00:21:11.370 Jamie Law-Smith: So the X axis is the mass of the black hole. 124 00:21:12.600 --> 00:21:16.020 Jamie Law-Smith: And the y axis is the mass of the object being disrupted. 125 00:21:17.580 --> 00:21:26.040 Jamie Law-Smith: So the boundaries here are using the mass radius relationships of each of these objects and comparing the title radius to the innermost band circular orbit. 126 00:21:27.330 --> 00:21:37.620 Jamie Law-Smith: So the story here is the one needs different objects, in order to probe different mass black holes so dempster denser objects like white dorks probe less massive black holes. 127 00:21:38.040 --> 00:21:42.210 Jamie Law-Smith: Whereas more tenuous objects, like a ball of stars for more massive black holes. 128 00:21:43.200 --> 00:21:50.490 Jamie Law-Smith: And these objects, as I mentioned all have different observational signatures and their flares span many orders of magnitude in luminosity and timescale. 129 00:21:51.270 --> 00:21:58.230 Jamie Law-Smith: So we'll be using realistic models of all of these objects, in order to understand the population of 10s of thousands of tea, we expect with. 130 00:22:01.560 --> 00:22:01.740 OK. 131 00:22:03.060 --> 00:22:05.970 Jamie Law-Smith: So now i'll turn to the host galaxies. 132 00:22:07.080 --> 00:22:16.620 Jamie Law-Smith: So we've conducted the systematic study of TV host galaxies in the context of galaxies in the local universe i'll just highlight a few of the results. 133 00:22:17.760 --> 00:22:27.600 Jamie Law-Smith: So TV host galaxies appear to be over represented in rare post starburst or eight plus air quiescent bomber strong galaxies. 134 00:22:28.080 --> 00:22:36.480 Jamie Law-Smith: So these are galaxies where there's little ongoing star formation, which is the y axis here, but the stars are young, is the X axis. 135 00:22:37.440 --> 00:22:51.540 Jamie Law-Smith: So you can see the so the points here are title disruption event host galaxies the contours our reference catalog of spss galaxies and Title disruption event host galaxies are over represented in this rare region of parameter space. 136 00:22:53.700 --> 00:23:03.690 Jamie Law-Smith: So a natural question is, can we explain this with selection effects and the answer turns out to be only partial so there's something we think there's something physically going on there. 137 00:23:07.500 --> 00:23:16.590 Jamie Law-Smith: So in another galaxy evolution context TD hosts appear to live in a transition region in galaxy transformation, so the green Valley. 138 00:23:17.250 --> 00:23:35.010 Jamie Law-Smith: Between star forming spiral like galaxies you can see the the star forming main sequence and blue there and quiescent ellipticals so they're here just degrees of questions indicated by the different ones in general TV host galaxies live in this Green about in this transition region. 139 00:23:38.460 --> 00:23:45.870 Jamie Law-Smith: So we've also found that TV host galaxies have more centrally concentrated light profiles for their black hole masses. 140 00:23:46.230 --> 00:24:00.360 Jamie Law-Smith: So, irrespective of any E, plus a classification so on the Left i'm showing just a diagram of what sourcing index is here so higher source like index is more centrally concentrated light profile. 141 00:24:01.020 --> 00:24:13.410 Jamie Law-Smith: And on the right i'm showing Sir sick index versus black hole mass for TV hosts which are the points and a reference catalog of spss galaxy which access is galaxies, which is the contours. 142 00:24:14.550 --> 00:24:26.550 Jamie Law-Smith: So this could be a physical explanation for why TTS occur in these galaxies, so there are higher that could be higher stellar densities, which leads to a higher rate with to buddy interactions and that's a higher TD rate. 143 00:24:28.770 --> 00:24:36.600 Jamie Law-Smith: And you can see, this higher central concentration visually so for each TV host galaxy here which are along the top panels. 144 00:24:37.230 --> 00:24:47.850 Jamie Law-Smith: i'm showing a random spss galaxy on the bottom panels just matched on redshift and stellar mass, but with the median sourcing index of galaxies at that stellar months. 145 00:24:49.980 --> 00:25:05.070 Jamie Law-Smith: So TV host galaxies are highly centrally concentrated and there's a story here in in in in a galaxy evolution concepts that that I can go into more detail if you're interested okay. 146 00:25:07.380 --> 00:25:12.450 Jamie Law-Smith: So now to spend a few minutes discussing the work plan to do in the next few years at the ITC. 147 00:25:14.070 --> 00:25:17.520 Jamie Law-Smith: So one thing is to develop this TD machine. 148 00:25:18.900 --> 00:25:31.440 Jamie Law-Smith: Where we have end to end modeling of Title disruptions using this numerical ecosystem of different tools so starting with with stellar models to 3D Hydra dynamics. 149 00:25:32.340 --> 00:25:42.960 Jamie Law-Smith: Of the disruption and then disk formation and the gas will predict light curves and the the chemical information will predict the spectra. 150 00:25:43.410 --> 00:25:49.140 Jamie Law-Smith: Now we can use these to constrain all of the properties in a given title disruption event and make fits. 151 00:25:49.770 --> 00:26:02.010 Jamie Law-Smith: So the theoretical dream is a deterministic model predicting light curves and spectra from a handful handful of input variables so black hole mass and black hole spin inclination and stellar properties. 152 00:26:03.480 --> 00:26:22.350 Jamie Law-Smith: And I said so so reuben the estimates are reuben will discover 50,000 CDs and he rosita will discover 10,000 CDs and of course we'll have gws T and GMT to follow up these events in their host galaxies to sub second precision I wanted one or two microphones. 153 00:26:26.850 --> 00:26:35.490 Jamie Law-Smith: So the galaxy matching framework I showed earlier is general and it can be applied to the host galaxies have any transients or any type of galaxy. 154 00:26:36.690 --> 00:26:46.170 Jamie Law-Smith: So I won't describe these results here, but just as an example in work led by Sierra dud we've recently applied this framework to try to understand changing look agm. 155 00:26:47.430 --> 00:26:54.840 Jamie Law-Smith: And i'm excited to apply this framework to the host galaxies other transients and, in particular those of gravitational waves sources. 156 00:27:00.150 --> 00:27:03.600 Jamie Law-Smith: Okay, so turning to interactions between two stars. 157 00:27:05.040 --> 00:27:10.140 Jamie Law-Smith: we're going to make use of this capability we've developed for zoom in simulations. 158 00:27:10.590 --> 00:27:20.940 Jamie Law-Smith: So much like the cosmological zoom in simulations that study the large scale structure of the universe, down to the structure of galaxies but here for stars. 159 00:27:21.870 --> 00:27:33.270 Jamie Law-Smith: So this will help address this physical scale problem in Hydra DEM a model model and where there are different very disparate physical scales of interest in an interaction between two stars. 160 00:27:36.090 --> 00:27:42.150 Jamie Law-Smith: So another exciting thing is combining different approaches that are most useful over different time scales. 161 00:27:42.900 --> 00:27:54.360 Jamie Law-Smith: So this will help address this temporal scale problem in high dynamic modeling, so this is a schematic of an approach we've used recently to model, the formation of a binary neutron star. 162 00:27:56.100 --> 00:28:03.150 Jamie Law-Smith: So, starting with one D stellar evolution to using 2d methods so informed by coefficients from a different study. 163 00:28:04.140 --> 00:28:18.900 Jamie Law-Smith: To 3D Hydra dynamics for the rapid dynamical evolution and then back to one the for long term evolution so using a combination of approaches to model, the system from end to end. 164 00:28:21.510 --> 00:28:37.950 Jamie Law-Smith: And so, in addition to this T machine with with some of this machinery, I like to with some of this technology, I like to build this gravitational wave progenitor machine so i'll use this framework to study star star interactions leading to gravitational waves sources. 165 00:28:39.060 --> 00:28:44.190 Jamie Law-Smith: So here i'm showing common envelope objection, leading to a binary neutron star. 166 00:28:45.300 --> 00:28:48.180 Jamie Law-Smith: So on the left is gas density. 167 00:28:49.230 --> 00:28:52.890 Jamie Law-Smith: In the Center is velocity relative to escape velocity. 168 00:28:54.030 --> 00:29:07.710 Jamie Law-Smith: And the right is binding energy so we're seeing the new neutron star sweep through the envelope of a red giant here which will eventually lead to a binary neutron star that will merge via gravitational waves within the hubble time. 169 00:29:12.600 --> 00:29:23.550 Jamie Law-Smith: Okay, so i'm also thinking about stellar interactions embedded in agm discs, so this is a schematic of a model we're building of the structure of a gn discs with embedded stars. 170 00:29:25.320 --> 00:29:36.210 Jamie Law-Smith: So this is really exciting these the stars can be formed in situ or dynamically captured and you get a lot of Nice physics here from stars two discs. 171 00:29:36.720 --> 00:29:46.530 Jamie Law-Smith: So, as I said, i'm interested in the structure of the disc and the final outcomes of the stars and I can we can extend this model in this program to predict gravitational waves sources. 172 00:29:47.460 --> 00:30:02.520 Jamie Law-Smith: In these deaths, so it may be the large fraction of the current and future population of gravitational wave sources originate in ag and disks and there's actually a promising method to do gravitational waves cosmology when it's just mergers of two black holes. 173 00:30:06.900 --> 00:30:14.460 Jamie Law-Smith: Okay, so in theoretical physics i'm interested in understanding the Center space in theories of quantum gravity, such as string theory. 174 00:30:16.020 --> 00:30:22.800 Jamie Law-Smith: So the presently observed dark energy is consistent with a decider solution of einstein's equations. 175 00:30:24.240 --> 00:30:30.930 Jamie Law-Smith: So, shortly after the big bang as well the universe also likely went through a period of exponential expansion. 176 00:30:32.730 --> 00:30:38.400 Jamie Law-Smith: So the sitter space plays an important role and understanding our present and past the universe. 177 00:30:42.360 --> 00:30:49.650 Jamie Law-Smith: So, however it may not be possible to construct a sitter space in our current understanding of theories of quantum gravity. 178 00:30:51.330 --> 00:31:00.840 Jamie Law-Smith: So this has implications for understanding inflation and the nature of dark energy and string theory as a theory of quantum gravity. 179 00:31:02.820 --> 00:31:13.800 Jamie Law-Smith: So on the right is a diagram of Meta stable to Center space, so we may currently live in a decider minimum but it's likely, this is only met a staple. 180 00:31:18.360 --> 00:31:24.360 Jamie Law-Smith: Okay, so i'll just end here with this schematic of the different things that I think about and thank you very much. 181 00:31:28.650 --> 00:31:29.280 Morgan Elowe MacLeod: Thank you Jamie. 182 00:31:31.650 --> 00:31:34.740 Morgan Elowe MacLeod: So i'm going to stop there Courtney.