2003A&A...410..785R


C.D.S. - SIMBAD4 rel 1.7 - 2021.02.26CET23:31:59

2003A&A...410..785R - Astronomy and Astrophysics, volume 410, 785-793 (2003/11-2)

Detection of molecular hydrogen at z=1.15 toward HE 0515-4414.

REIMERS D., BAADE R., QUAST R. and LEVSHAKOV S.A.

Abstract (from CDS):

A new molecular hydrogen cloud is found in the sub-damped Lyα absorber [logN(HI)=19.88±0.05] at the redshift zabs=1.15 toward the bright quasar HE 0515-4414 (zem=1.71). More than 30 absorption features in the Lyman band system of H2 are identified in the UV spectrum of this quasar obtained with the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope. The H2-bearing cloud shows a total H2 column density N(H2)=(8.7+8.7–4.0)x1016cm–2 and a fractional molecular abundance fH2=(2.3+2.3–1.1)x10–3 derived from the H2 lines arising from the J=0-5 rotational levels of the ground electronic vibrational state. The estimated rate of photodissociation at the cloud edge I0≲1.8x10–8s–1 is much higher than the mean Galactic disk value, IMW∼5.5x10–11s–1. This may indicate an enhanced star-formation activity in the z=1.15 system as compared with molecular clouds at z∼3 where I∼IMW. We also find a tentative evidence that the formation rate coefficient of H2 upon grain surfaces at z=1.15 is a factor of 10 larger than a canonical Milky Way value, RMW≃3x10–17cm3/s. The relative dust-to-gas ratio estimated from the [Cr/Zn] ratio is equal to ∼k=0.89±0.19 (in units of the mean Galactic disk value), which is in good agreement with a high molecular fraction in this system. The estimated line-of-sight size of L ∼0.25 pc may imply that the H2 is confined within small and dense filaments embedded in a more rarefied gas giving rise to the z=1.15 sub-damped Lyα absorber.

Abstract Copyright:

Journal keyword(s): cosmology: observations - quasars: absorption lines - quasars: individual: HE 0515-4414

Simbad objects: 10

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Number of rows : 10

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 QSO J0003-2603 QSO 00 03 22.9530051057 -26 03 18.306624161   18 17.53     ~ 272 0
2 LBQS 0013-0029 QSO 00 16 02.4050445836 -00 12 25.076529860   18.67 18.36     ~ 181 0
3 QSO B0347-383 QSO 03 49 43.6605705480 -38 10 30.834942758     17.3     ~ 185 0
4 QSO J0407-4410 QSO 04 07 18.0882243903 -44 10 13.989443935   17.6 17.6     ~ 89 0
5 HE 0515-4414 QSO 05 17 07.6239672230 -44 10 55.578294294 14.74 15.49 15.16     ~ 101 0
6 QSO B0528-2505 QSO 05 30 07.96279681 -25 03 29.8994010   18.17 17.34 17.7   ~ 406 0
7 QSO B0551-36 QSO 05 52 46.1825351739 -36 37 27.606597529   17.72 17.57     ~ 89 0
8 QSO B0841+129 BLL 08 44 24.2446850407 +12 45 46.527740081   18.28 18.5     ~ 109 0
9 LBQS 1232+0815 QSO 12 34 37.5507010309 +07 58 43.372966617     18.4     ~ 115 0
10 LBQS 1444+0126 QSO 14 46 53.0500684156 +01 13 55.922982686   18.71 18.38     ~ 60 0

    Equat.    Gal    SGal    Ecl

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2021.02.26-23:31:59

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