STRW local: Lunch Talks

Lunch Talks

Circumgalactic Gas Kinematics and Cold Gas Accretion at z=0.2

Galactic disks grow by accreting cooling gas from the circumgalactic medium (CGM). Decades of observations have also demonstrated that galaxies need a continuous gas supply to explain the star formation history and the stellar metallicity distribution of disks. However, direct observation of gas accretion onto galaxies remains sparse. I will present results of our survey that measures the kinematics of low-ionization-state gas in the CGM. We have observed quasars behind star-forming galaxies at z=0.2, and the quasar sightlines pass within 100 kpc of the foreground galaxies. We find that the Doppler shift of the circumgalactic absorption shares the same sign as the quasar side of the galactic disk, but the Doppler shifts are smaller than disk rotation predicts. The Doppler sign correlation implies the low-ionization-state gas in the inner CGM corotates with the disk. Altogether, our results indicate centrifugal force partially supports the circumgalactic gas, and therefore the angular momentum of the CGM delays accretion onto the disk. I will also discuss results from our pilot study with the EAGLE simulations that have also found cold rotating gas disks with inflowing gas. These disks extend to radii comparable to the impact parameters of our quasar sightlines around galaxies. Our analysis with EAGLE thereby further supports our inflow interpretation for the circumgalactic kinematic observations.

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Unless announced otherwise, the lunch talks start at 12:50 sharp. The approximate duration of the lunch talk is given above, and additional time will be given for questions and discussion following the presentation. Please make sure that you take ample time to pick up your lunch beforehand.

Information for Speakers and Hosts: Talks are limited to 25 minutes, with 5 additional minutes for questions. Hosts are responsible for bringing the speaker to the correct room in ample time to set up laptops etc., and for ensuring the speaker also has time for lunch.


For questions and/or suggestions concerning the lunch talks, please contact Themiya Nanayakkara () or Alvaro Hacar ()).