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DGCE SIG Seminar

Diffuse Gas in Cosmic Ecosystems Science Interest Group

DATE

Jul 27, 2023

TIME

4:00 pm EST

COMMUNITY

DGCE SIG

TYPE

Seminar

Gas Flow in the Multiphase Circumgalactic Medium

Stephanie Ho (New Mexico State University)

The reservoir of baryons and metals surrounding galaxies is known as the circumgalactic medium (CGM). The CGM plays a crucial role in the growth of galaxies; galaxies require a continuous gas supply to sustain star formation, and this gas accretion process is regulated by feedback from newly formed stars. However, observational analysis of the CGM is challenging. Not only because the low gas density makes the CGM difficult to image directly, but the CGM is also multiphase, i.e., the CGM consists of gas structures of different temperatures and densities. We will discuss recent efforts of studying the multiphase circumgalactic gas flow. In particular, we will present our work on studying the kinematics of the cool (~104 K) and warm-hot (~105.5 K) CGM of low-redshift, star-forming galaxies. For the cool gas, our results showed that although the inner CGM corotates with the galactic disk, the centrifugal force only partially supports the circumgalactic gas, implying that the angular momentum of the CGM delays accretion onto the disk. We will also present our ongoing analysis of the kinematics of the warm-hot circumgalactic gas traced by the highly ionized O VI absorption and compare that to the results from the cool gas. Finally, we will present analyses from cosmological simulations, compare that with the observed gas kinematics, and explain the observational bias that potentially affects the interpretation of observed data.

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An illustration of Sun-like star HD 181327 and its surrounding debris disk. The star is at top right. It is surrounded by a far larger debris disk that forms an incomplete ellpitical path and is cut off at right. There’s a huge cavity between the star and the disk. The debris disk is shown in shades of light gray. Toward the top and left, there are finer, more discrete points in a range of sizes. The disk appears hazier and smokier at the bottom. The star is bright white at center, with a hazy blue region around it. The background of space is black. The label Artist's Concept appears at lower left.