Astronomy and Astrophysics – Astrophysics – Cosmology and Extragalactic Astrophysics
Scientific paper
2009-12-14
The Astrophysical Journal, Volume 713, Issue 1, pp. 131-145 (2010)
Astronomy and Astrophysics
Astrophysics
Cosmology and Extragalactic Astrophysics
16 Pages including 12 Figures and 2 Tables
Scientific paper
To search for low-redshift damped Lyman-alpha (DLA) and sub-DLA quasar absorbers, we have conducted a 21cm absorption survey of radio-loud quasars at small impact parameters to foreground galaxies selected from the Sloan Digital Sky Survey (SDSS). Here we present the first results from this survey based on observations of SDSS J104257.58+074850.5 ($z_{QSO}$ = 2.66521), a quasar at an angular separation from a foreground galaxy ($z_{gal}$ = 0.03321) of 2.5" (1.7 kpc in projection). The foreground galaxy is a low-luminosity spiral with on-going star formation (0.004 M$_{\odot}$ yr$^{-1}$ kpc$^{-2}$) and a metallicity of $-0.27 \pm 0.05$ dex. We detect 21cm absorption from the galaxy with the Green Bank Telescope (GBT), the Very Large Array (VLA), and the Very Long Baseline Array (VLBA). The absorption appears to be quiescent disk gas corotating with the galaxy and we do not find any evidence for outflowing cold neutral gas. The width of the main absorption line indicates that the gas is cold, $T_{k} < 283$ K, and the HI column is surprisingly low given the impact parameter of 1.7 kpc; we find that N(HI) $\leq 9.6 \times 10^{19}$ cm$^{-2}$ (GBT) and N(HI) $\leq 1.5 \times 10^{20}$ cm$^{-2}$ (VLBA). VLBA marginally resolves the continuum source and the absorber, and a lower limit of 27.1 $\times$ 13.9 pc is derived for the size of the absorbing cloud. In turn, this indicates a low density for a cold cloud, n(HI) $<$ 3.5 cm$^{-3}$. We hypothesize that this galaxy, which is relatively isolated, is becoming depleted in HI because it is converting its interstellar matter into stars without a replenishing source of gas, and we suggest future observations to probe this and similar galaxies.
Borthakur Sanchayeeta
Bowen David V.
Meiring Joseph. D.
Momjian Emmanuel
Tripp Todd M.
No associations
LandOfFree
Using 21cm Absorption in Small Impact Parameter Galaxy-QSO Pairs to Probe Low-Redshift Damped and Sub-Damped Lyman-alpha System does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Using 21cm Absorption in Small Impact Parameter Galaxy-QSO Pairs to Probe Low-Redshift Damped and Sub-Damped Lyman-alpha System, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Using 21cm Absorption in Small Impact Parameter Galaxy-QSO Pairs to Probe Low-Redshift Damped and Sub-Damped Lyman-alpha System will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-624220