Understanding the circumgalactic medium is critical for understanding galaxy evolution. (arXiv:1903.05644v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Peeples_M/0/1/0/all/0/1">Molly S. Peeples</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Behroozi_P/0/1/0/all/0/1">Peter Behroozi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bordoloi_R/0/1/0/all/0/1">Rongmon Bordoloi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brooks_A/0/1/0/all/0/1">Alyson Brooks</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bullock_J/0/1/0/all/0/1">James S. Bullock</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Burchett_J/0/1/0/all/0/1">Joseph N. Burchett</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chen_H/0/1/0/all/0/1">Hsiao-Wen Chen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chisholm_J/0/1/0/all/0/1">John Chisholm</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Christensen_C/0/1/0/all/0/1">Charlotte Christensen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Coil_A/0/1/0/all/0/1">Alison Coil</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Corlies_L/0/1/0/all/0/1">Lauren Corlies</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Diamond_Stanic_A/0/1/0/all/0/1">Aleksandar Diamond-Stanic</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Donahue_M/0/1/0/all/0/1">Megan Donahue</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Faucher_Giguere_C/0/1/0/all/0/1">Claude-Andr&#xe9; Faucher-Gigu&#xe8;re</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ferguson_H/0/1/0/all/0/1">Henry Ferguson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fielding_D/0/1/0/all/0/1">Drummond Fielding</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fox_A/0/1/0/all/0/1">Andrew J. Fox</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+French_D/0/1/0/all/0/1">David M. French</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Furlanetto_S/0/1/0/all/0/1">Steven R. Furlanetto</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gennaro_M/0/1/0/all/0/1">Mario Gennaro</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gilbert_K/0/1/0/all/0/1">Karoline M. Gilbert</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hamden_E/0/1/0/all/0/1">Erika Hamden</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hathi_N/0/1/0/all/0/1">Nimish Hathi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hayes_M/0/1/0/all/0/1">Matthew Hayes</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Henry_A/0/1/0/all/0/1">Alaina Henry</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Howk_J/0/1/0/all/0/1">J. Christopher Howk</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hummels_C/0/1/0/all/0/1">Cameron Hummels</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Keres_D/0/1/0/all/0/1">Du&#x161;an Kere&#x161;</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kirby_E/0/1/0/all/0/1">Evan Kirby</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Koekemoer_A/0/1/0/all/0/1">Anton M. Koekemoer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lan_T/0/1/0/all/0/1">Ting-Wen Lan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lanz_L/0/1/0/all/0/1">Lauranne Lanz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Law_D/0/1/0/all/0/1">David R. Law</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lehner_N/0/1/0/all/0/1">Nicolas Lehner</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lotz_J/0/1/0/all/0/1">Jennifer M. Lotz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Martin_C/0/1/0/all/0/1">Crystal L. Martin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+McQuinn_K/0/1/0/all/0/1">Kristen McQuinn</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+McQuinn_M/0/1/0/all/0/1">Matthew McQuinn</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Munshi_F/0/1/0/all/0/1">Ferah Munshi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Oh_S/0/1/0/all/0/1">S. Peng Oh</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+OMeara_J/0/1/0/all/0/1">John M. O&#x27;Meara</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+OShea_B/0/1/0/all/0/1">Brian W. O&#x27;Shea</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pacifici_C/0/1/0/all/0/1">Camilla Pacifici</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Peek_J/0/1/0/all/0/1">J. E. G. Peek</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Postman_M/0/1/0/all/0/1">Marc Postman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Prescott_M/0/1/0/all/0/1">Moire Prescott</a>, et al. (26 additional authors not shown)

Galaxies evolve under the influence of gas flows between their interstellar
medium and their surrounding gaseous halos known as the circumgalactic medium
(CGM). The CGM is a major reservoir of galactic baryons and metals, and plays a
key role in the long cycles of accretion, feedback, and recycling of gas that
drive star formation. In order to fully understand the physical processes at
work within galaxies, it is therefore essential to have a firm understanding of
the composition, structure, kinematics, thermodynamics, and evolution of the
CGM. In this white paper we outline connections between the CGM and galactic
star formation histories, internal kinematics, chemical evolution, quenching,
satellite evolution, dark matter halo occupation, and the reionization of the
larger-scale intergalactic medium in light of the advances that will be made on
these topics in the 2020s. We argue that, in the next decade, fundamental
progress on all of these major issues depends critically on improved empirical
characterization and theoretical understanding of the CGM. In particular, we
discuss how future advances in spatially-resolved CGM observations at high
spectral resolution, broader characterization of the CGM across galaxy mass and
redshift, and expected breakthroughs in cosmological hydrodynamic simulations
will help resolve these major problems in galaxy evolution.

Galaxies evolve under the influence of gas flows between their interstellar
medium and their surrounding gaseous halos known as the circumgalactic medium
(CGM). The CGM is a major reservoir of galactic baryons and metals, and plays a
key role in the long cycles of accretion, feedback, and recycling of gas that
drive star formation. In order to fully understand the physical processes at
work within galaxies, it is therefore essential to have a firm understanding of
the composition, structure, kinematics, thermodynamics, and evolution of the
CGM. In this white paper we outline connections between the CGM and galactic
star formation histories, internal kinematics, chemical evolution, quenching,
satellite evolution, dark matter halo occupation, and the reionization of the
larger-scale intergalactic medium in light of the advances that will be made on
these topics in the 2020s. We argue that, in the next decade, fundamental
progress on all of these major issues depends critically on improved empirical
characterization and theoretical understanding of the CGM. In particular, we
discuss how future advances in spatially-resolved CGM observations at high
spectral resolution, broader characterization of the CGM across galaxy mass and
redshift, and expected breakthroughs in cosmological hydrodynamic simulations
will help resolve these major problems in galaxy evolution.

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