The z=0.0912 and z=0.2212 damped Ly alpha galaxies along the sight line toward the quasar OI 363

Citation
Da. Turnshek et al., The z=0.0912 and z=0.2212 damped Ly alpha galaxies along the sight line toward the quasar OI 363, ASTROPHYS J, 553(1), 2001, pp. 288-298
Citations number
40
Categorie Soggetti
Space Sciences
Journal title
ASTROPHYSICAL JOURNAL
ISSN journal
0004637X → ACNP
Volume
553
Issue
1
Year of publication
2001
Part
1
Pages
288 - 298
Database
ISI
SICI code
0004-637X(20010520)553:1<288:TZAZDL>2.0.ZU;2-M
Abstract
New optical and infrared observations along the sight line toward the quasa r OI 363 (0738+313) are presented and discussed. Excluding quasars selectiv ely observed because they were known to be located behind gas-rich galaxies and systems which lack confirming UV spectroscopic observations of the act ual Ly alpha Line, this sight line presently contains the two lowest redshi ft classical damped Lya (DLA) quasar absorption-line systems found in surve y mode (i.e., with N-H I >2 x 10(20) atoms cm(-2)), one at z(abs) = 0.0912 and the other at z(abs) = 0.2212. Our new observations suggest identficatio ns for the DLA galaxy counterparts of these absorption-line systems. The z = 0.09 DLA galaxy appears to be an extended low surface brightness galaxy w hich is easily visible only in infrared images and shows possible rich morp hological structure. Assuming there is no contribution from the quasar host galaxy, we place an upper limit on the K-band luminosity of the z = 0.09 D LA galaxy of L-K less than or equal to 0.13L*(K) (for a cosmology with H-0 = 65 km s(-1) Mpc(-1), Omega = 1, and Lambda = 0). More realistically, a su btraction of the quasar nuclear and host light yields L(K)approximate to0.0 8L*(K). The impact parameter between the galaxy and quasar sight line is ve ry small, b < 3.6 kpc(<2"), which makes measurements difficult. The z = 0.2 2 DLA galaxy is an early-type dwarf with a K-band luminosity of L(K)approxi mate to0.1L*(K) at impact parameter b = 20 kpc. Its colors are neutral and consistent with star formation models, suggesting its formation epoch was l ess than a few Gyr ago (i.e., z(f) approximate to 0.3-0.9). Thus, it is con ceivable that its progenitor originated from the population of "faint blue galaxies" seen at moderate redshifts. In general, these results serve to su pport mounting evidence that DLA galaxies are drawn from a wide variety of gas-rich galaxy types.