Astronomy and Astrophysics – Astrophysics
Scientific paper
2004-04-30
Astrophys.J. 609 (2004) L53-L58
Astronomy and Astrophysics
Astrophysics
ApJL, accepted
Scientific paper
10.1086/422682
We report the discovery of two damped Ly-alpha absorption-line systems (DLAs) near redshift z=1 along a single quasar sightline (Q1727+5302) with neutral hydrogen column densities of N(HI) = (1.45\pm0.15)\times10^{21} and (2.60\pm0.20)\times10^{21} atoms/cm2. Their sightline velocity difference of 13,000 km/s corresponds to a proper separation of 106h_{70}^{-1} Mpc if interpreted as the Hubble flow (Omega_m=0.3, Omega_Lambda=0.7). The random probability of such an occurrence is significantly less than 3%. With follow-up spectroscopy, we find [Zn/H] = -0.58\pm0.15 (26.5% solar) and -1.32\pm0.28 (4.7% solar), respectively, and [Cr/H] = -1.26\pm0.15 (5.5% solar) and -1.77\pm0.28 (1.7% solar), respectively, which is evidence for depletion onto grains. Follow-up IR images show the two most likely DLA galaxy candidates to have impact parameters of 22h_{70}^{-1} kpc and 32h_{70}^{-1} kpc if near z=1. They are significantly underluminous relative to the galaxy population at z=1. To investigate the possibility of additional high-N(HI) absorbers we have searched the SDSS database for z>1 quasars within 30 arcmin of the original sightline. Five were found, and two show strong MgII-FeII absorption near z=1, consistent with classical DLA absorption approx 37% of the time, but almost always N(HI) > 10^{19} atoms/cm2. Consequently, this rare configuration of four high-N(HI) absorbers with a total sightline velocity extent of 30,600 km/s may represent a large filament-like structure stretching over a proper distance of 241h_{70}^{-1} Mpc along our sightline, and a region in space capable of harboring excessive amounts of neutral gas. Future studies of this region of the sky are encouraged.
Belfort Michele
Berk Daniel Vanden
Monier Eric M.
Nestor Daniel. B.
Rao Sandhya M.
No associations
LandOfFree
Double-Damped Lyman Alpha Absorption: A Possible Large Neutral Hydrogen Gas Filament Near Redshift z=1 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 Double-Damped Lyman Alpha Absorption: A Possible Large Neutral Hydrogen Gas Filament Near Redshift z=1, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Double-Damped Lyman Alpha Absorption: A Possible Large Neutral Hydrogen Gas Filament Near Redshift z=1 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-286635