Abstract / Description of output
We present a study exploring the nature and properties of the
circumgalactic medium (CGM) and its connection to the atomic gas content
in the interstellar medium (ISM) of galaxies as traced by the H i 21 cm
line. Our sample includes 45 low-z (0.026-0.049) galaxies from the
GALEX Arecibo SDSS Survey (Galaxy Evolution Explorer/Arecibo/Sloan
Digital Sky Survey). Their CGM was probed via absorption in the spectra
of background quasi-stellar objects at impact parameters of 63-231
kpc. The spectra were obtained with the Cosmic Origins Spectrograph
aboard the Hubble Space Telescope. We detected neutral hydrogen
(Lyα absorption lines) in the CGM of 92% of the galaxies. We find
that the radial profile of the CGM as traced by the Lyα equivalent
width can be fit as an exponential with a scale length of roughly the
virial radius of the dark matter halo. We found no correlation between
the orientation of the sightline relative to the galaxy’s major
axis and the Lyα equivalent width. The velocity spread of the
circumgalactic gas is consistent with that seen in the atomic gas in the
ISM. We find a strong correlation (99.8% confidence) between the gas
fraction (M(H i)/M⋆) and the impact-parameter-corrected
Lyα equivalent width. This is stronger than the analogous
correlation between corrected Lyα equivalent width and specific
star formation rate (SFR)/M⋆ (97.5% confidence). These
results imply a physical connection between the H i disk and the CGM,
which is on scales an order of magnitude larger. This is consistent with
the picture in which the H i disk is nourished by accretion of gas from
the CGM.
Original language | English |
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Pages (from-to) | 46 |
Journal | Astrophysical Journal |
Volume | 813 |
Issue number | 1 |
DOIs | |
Publication status | Published - 27 Oct 2015 |
Keywords / Materials (for Non-textual outputs)
- galaxies: halos
- galaxies: ISM
- quasars: absorption lines