Quantifying and Understanding the Galaxy — Halo Connection May 15-19, 2017 Coordinators: Alexie Leauthaud, Risa Wechsler, and Andrew Zentner Scientific Advisors: Carlos Frenk, Marla Geha, Andrey Kravtsov, Romain Teyssier, and Martin White The formation of galaxies is still one of the key unsolved problems of astrophysics and cosmology. This is because the processes involved are complex, multi-scale, and are highly non-linear. At the same time, despite the apparent complexity of these processes, observed properties of galaxies exhibit a number of striking regularities, including tight correlations between galaxy sizes, masses, luminosities, and dynamical properties. Moreover, there is a growing empirical evidence indicating that key properties of galaxies tightly correlate with properties of extended dark matter halos in which they form. Phenomenological modeling based on such empirical correlations unlocks the predictive power of large cosmological N-body simulations, enabling astrophysicists to infer the underlying dark matter distribution in the Universe and to exploit large-scale galaxy surveys as probes of cosmological physics. The next generation of massive, wide-field surveys will observe billions of galaxies, including galaxies from the earliest epochs of their evolution. These surveys have the potential to transform our understanding of the evolution of structure in both the galaxy distribution and the dark matter distribution, and in so doing, to answer some of the most profound questions of galaxy formation and cosmology. However, maximizing the scientific impact of these forthcoming data sets depends upon bringing phenomenological models of the galaxy-dark matter halo connection to the next level of precision. This program aims to bring together experts in the statistics of the galaxy-halo connection, cosmologists, survey scientists, and observers and theorists working on galaxy evolution to foster discussions about observational probes of the galaxy-dark matter connection and to spur on the development of next-generation theoretical methods. To brainstorm and generate ideas, we will hold a conference on the galaxy-halo connection and its role in the science of large cosmological surveys on May 15-19, 2017. Quantifying and Understanding the Galaxy — Halo Connection May 15-19, 2017 ThisCoordinators: talk is online Alexie at Leauthaud, Risa Wechsler, and Andrew Zentner http://physics.ucsc.edu/~joel/GalHalo17.pdf http://online.kitp.ucsb.edu/online/galhalo-c17/ Scientific Advisors: Carlos Frenk, Marla Geha, Andrey Kravtsov, Romain Teyssier, and Martin White The formation of galaxies is still one of the key unsolved problems of astrophysics and cosmology. This is because the processes involved are complex, multi-scale, and are highly non-linear. At the same time, despite the apparent complexity of these processes, observed properties of galaxies exhibit a number of striking regularities, including tight correlations between galaxy sizes, masses, luminosities, and dynamical properties. Moreover, there is a growing empirical evidence indicatingomitting that key talks properties with no of slides galaxies online tightly correlate with properties of extended dark matter halos in which they form. Phenomenological modeling based on such empirical correlations unlocks the predictive power of large cosmological N-body simulations, enabling astrophysicists to infer the underlying dark matter distribution in the Universe and to exploit large-scale galaxy surveys as probes of cosmological physics. The next generation of massive, wide-field surveys will observe billions of galaxies, including galaxies from the earliest epochs of their evolution. These surveys have the potential to transform our understanding of the evolution of structure in both the galaxy distribution and the dark matter distribution, and in so doing, to answer some of the most profound questions of galaxy formation and cosmology. However, maximizing the scientific impact of these forthcoming data sets depends upon bringing phenomenological models of the galaxy-dark matter halo connection to the next level of precision. This program aims to bring together experts in the statistics of the galaxy-halo connection, cosmologists, survey scientists, and observers and theorists working on galaxy evolution to foster discussions about observational probes of the galaxy-dark matter connection and to spur on the development of next-generation theoretical methods. To brainstorm and generate ideas, we will hold a conference on the galaxy-halo connection and its role in the science of large cosmological surveys on May 15-19, 2017. Christoph Lee will summarize the talks about halo splashback radius Monday 3:00pm Surhud More (U Tokyo IPMU) Assembly Bias and Splashback Radius on Cluster Scales: Observational Status Tuesday 9:00am Benedikt Diemer (Harvard U) Cold Dark Matter Halo Theory/Splashback Review Friday 9:00a Philip Mansfield (U Chicago) Halo Splashback Radius m Talks & Topics That I Will Summarize Rachel Mandelbaum - Lensing, Assembly Bias Priya Natarajan - HST Frontier Fields Cluster Lensing Victor Calderon (poster) - sSSFR 2-Halo Galaxy Conformity at z ~ 0.1 Alison Coil - Galaxy Conformity at z ~ 0.2 - 1, Galaxy Clustering vs. sSFR Guinevere Kaufmann - Gas in Halos Andrey Kravtsov, Rachel Somerville, Fangzhao Jiang - RGalaxy RHalo Relation Christoph Lee (poster) - Causes and Consequences of Halo Mass Loss me - Structural Evolution in the Galaxy-Halo Connection, Halos vs. Density, Web Alyson Brooks - Abundance of Dwarf Galaxies Marla Geha - Satellites Around Galactic Analogs (SAGA Project) Priya Natarajan - Insights from Cluster Lensing Coil, Mendez, Eisenstein, Moustakas 2017 ApJ Guinevere Kaufmann - Gas in Halos Overview Guinevere Kaufmann - Gas in Halos Overview empty symbols - ratio of means filled symbols - ratio of medians gal - halo correlation gal and inner halo still have a correlation NIHAO z [0.0, 1.0] z [1.0, 2.0] z [2.0, 5.0] 2 2 2 NIHAO 1 =0.43,p=0.000 1 =0.18,p=0.071 1 =0.01,p=0.967 10− R 10− R 10− R σ =0.316 σ =0.223 σ =0.115 1.0 median 2.0 <z<5.0 log λbar0 log λbar0 log λbar0 σ =0.197 σ =0.235 σ =0.268 median 0.0 <z<0.5 log λhalo0 log λhalo0 log λhalo0 log(Mvir/M ) median 16,84% 0.8 ± 0 bar > 11.4 λ 2 2 2 10− 10− 10− 0.6 dm 0.4 λ a = 1.19,b= 0.44 a = 1.64,b= 0.85 a = 1.82,b= 0.99 , − − − − − − g λ bar 2 1 2 1 2 1 10− 10− 10− 10− 10− 10− = 0.57,p=0.615 =0.24,p=0.119 =0.31,p=0.003 R 0.2 1 λ0 1 1 10− R − halo 10− R 10− R σ =0.076 σ =0.190 σ =0.162 log λbar0 log λbar0 log λbar0 σ =0.055 σ =0.237 σ =0.263 0.0 log λhalo0 log λhalo0 log λhalo0 0 bar < 11.4 0.2 λ − 2 2 2 10− 10− 10− 0.4 − 1 0 a = 2.85,b= 1.81 a = 1.58,b= 0.86 a = 1.56,b= 0.78 10− 10 − − − − − − 2 1 2 1 2 1 r/Rvir 10− 10− 10− 10− 10− 10− λhalo0 λhalo0 λhalo0 halo fairly strong correlation between g and dm(<r) for r out to 0.2Rvir regression line: log λg = a +(1+b) log λh consistent with EAGLE (Zavala+16): the same, lack of correlation at z≥1 tight correlation between the loss of sAM of the inner (0.1Rvir) a correlation develops towards lower z (-1<b<0) DM and that of the baryons, by following Lagrangian volumes Fangzhou Jiang, Hebrew University Fangzhou Jiang, Hebrew University Alignment Is h really relevant for galaxy size? VELA NIHAOVELA VELA NIHAO NIHAOVELA VELA NIHAO 2.5 100 100 z [1.0, 2.0] 2 z [0z.0, 1[0.0).0, 1.0) KravtsovKravtsov 13 13 z [2.0, 5.0] >≈0.5 1 2 2 v 10 1 medianmedian16,84%16,84% 2.0 2 R 10 z [1z.0, 2[1.0).0, 2.0) h ± ± 2 2 / ✓ g 1 z 1 [2z.0, 35[2.0).0, 5.0) 1.5 10− 10−2 2 <R vir vir vir d cos [kpc] /r /r [kpc] [kpc] /r P/ star star star 1.0 , , star , star 0 star , e e d 0 , , e e 10 e e r r 10 r r r 10 2 2 r − 10− > 0.5 v Somerville+17 0.0 Somerville+17 medianmedian16,84% 16,84% >≈0.02<R 1.0 0.5 0.0 0.5 1.0 0.5 0.0 0.5 1.0 0.5 0.0 0.5 ± g 3 3 ± 1 1 − − cos ✓ − − cos ✓ − −10− cos103 − ✓ 3 2 2 1 1 0 100 − 10− <R1 1 2 2 bar,dm stars,dm 10− 10−gas,dm10− 10− 10− 10− 10 10 10 10 10 10 λhalo λhalo rvir [kpc]rvir [kpc] compaction strong correlation of orientation: <cos> = 0.72 (gas-DM), 0.61 (stars-DM) the mechanisms smearing out the g - h correlation should not jg jh Vvir jg RgVrot ==> Rg Rvir λhRvir randomize the alignment too much ' ' jh RvirVvir Vrot ' alignment weakens slightly towards lower-z, also seen in Illustris (Zjupa & Springel 2017) Fangzhou Jiang, Hebrew University Fangzhou Jiang, Hebrew University possible reasons for a g/h - h anti-correlation possible reasons for a g/h - h anti-correlation galaxy compaction (Dekel & Burkert 14) mergers - a system starts with low h and thus low gas - halo mergers cause h to rise - low gas -> high 1kpc (compaction) (orbital AM dominating h), while NIHAO - “Blue Nugget” (BN) forms -> high central SFR, gas depletion g is untouched yetmedian (16,84%) median (16,84%) - freshly accreted gas with high gas forms a ring - halo re-virializes -> h drops, 1.5 1.5 while g temporarily rises due to dm dm ) λ λ h / / the subsequent galaxy merger 1.0 1.0 / g cold bar cold bar h ( compaction happens λ λ 0.5 0.5 gas at a characteristic g mass scale log 9.7 0.0 0.0 Mstar≈10 Msun 0.0 0.5 1.0 1.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 11.4 ∆th [Gyr] ∆th/tvir Mvir≈10 Msun time after halo merger earlier<— compaction —> later halo galaxy Dekel+17 in prep time log ( scale factor ) merger merger Fangzhou Jiang, Hebrew University Fangzhou Jiang, Hebrew University Dark Matter Halos: Causes & Consequences of Halo Mass Loss Christoph T.