Séminaire de groupe ouvert à tous
Time and location: Thursday Dec 15th, 10am, Salle Galilee
Speaker : Balpreet Kaur (National Centre for Radio Astrophysics, Pune, India)
Title : Molecular gas in HI-absorption-selected galaxies at z~2
The strongest HI absorbers, the damped Lyman-alpha absorbers (DLAs), in QSO spectra indicate the presence of a gas-rich galaxy close to, or along, the QSO sightline. Identifying the HI-selected galaxies associated with DLAs provides a unique opportunity to connect the properties of high-z galaxies to those of their circumgalactic mediums, as well as to identify and characterize galaxies without a luminosity bias. We have hence been using NOEMA, the JVLA, and ALMA to carry out searches for redshifted CO emission from galaxies associated with DLAs at z>~2. Combining our results with ALMA studies from the literature, we find that the highest-metallicity DLAs tend to be associated with galaxies with very high molecular gas masses, > 5 x 10^10 solar masses, while the galaxies associated with lower-metallicity DLAs are not detected in their CO emission. We have also used the JVLA to detect, for the first time, CO(1-0) emission from high-z HI-selected galaxies, allowing us to measure the excitation of the mid-J CO rotational levels. We find that all four HI selected galaxies at z>2 with CO(1-0) studies show high excitation of the mid-J CO rotational levels, with near-thermal excitation found in the two galaxies with CO(1-0) detections. The mid-J excitation in the HI-selected galaxies is consistent with that in main-sequence and sub-mm galaxies at z>2, but significantly higher than that in main-sequence galaxies at z<2. The CO-detected galaxies are faint in our HST NUV images, indicating that they are highly obscured objects.
Topic: Kaur seminar
Time: Dec 15, 2022 10:00 AM Paris
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