2009A&A...503..765N


C.D.S. - SIMBAD4 rel 1.7 - 2020.08.15CEST22:20:15

2009A&A...503..765N - Astronomy and Astrophysics, volume 503, 765-770 (2009/9-1)

Diffuse molecular gas at high redshift. Detection of CO molecules and the 2175 Å dust feature at z = 1.64.

NOTERDAEME P., LEDOUX C., SRIANAND R., PETITJEAN P. and LOPEZ S.

Abstract (from CDS):

We present the detection of carbon monoxide molecules (CO) at z=1.6408 towards the quasar SDSSJ160457.50+220300.5 using the Very Large Telescope Ultraviolet and Visual Echelle Spectrograph. We detected CO absorption in at least two components in the first six A-X bands and one d-X(5-0) interband system. This is the second detection of its kind along a quasar line of sight. The CO absorption profiles are well modelled by assuming rotational excitation of CO in the range 6<Tex<16K, which is consistent with or higher than the temperature of the cosmic microwave background radiation at this redshift. We derive a total CO column density of N(CO)=4x1014cm–2. The measured column densities of SI, MgI, ZnII, FeII, and SiII indicate a dust depletion pattern typical of cold gas in the Galactic disc. The background quasar spectrum is significantly reddened (u-K∼4.5mag) and exhibits a pronounced 2175Å dust absorption feature at the redshift of the CO absorber. Using a control sample of ∼500 quasars, we find that the chance probability that this feature is spurious is ∼0.3%. We show that the spectral energy distribution (SED) of the quasar is well fitted by a QSO composite spectrum reddened with a Large Magellanic Cloud supershell extinction law at the redshift of the absorber. It is noticeable that this quasar is absent from the colour-selected SDSS quasar sample. This demonstrates that our current view of the Universe may be biased against dusty sightlines. These direct observations of carbonaceous molecules and dust open up the possibility of studying the physical conditions and chemistry of diffuse molecular gas in high redshift galaxies.

Abstract Copyright:

Journal keyword(s): cosmology: observations - galaxies: ISM - quasars: absorption lines - quasars: individual: SDSSJ160457.50+220300.5

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 - 2020
#notes
1 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 9483 1
2 QSO B0235+1624 BLL 02 38 38.93010 +16 36 59.2746   16.46 15.50 15.92   ~ 1396 2
3 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 14883 1
4 RMC 136 Cl* 05 38 42.396 -69 06 03.36           ~ 1742 1
5 NAME LMC 2 Supergiant Shell sh 05 41 27 -69 22.4           ~ 169 0
6 QSO J0852+3435 QSO 08 52 44.7399141702 +34 35 40.528091733   20.42 19.70     ~ 31 1
7 [VV2006] J131903.4+431034 QSO 13 19 03.3914927801 +43 10 34.193087214   19.80 19.22     ~ 18 0
8 LBQS 1320-0006 QSO 13 23 23.7865596488 -00 21 55.237045525   18.70 18.22     ~ 75 0
9 QSO J1439+1117 QSO 14 39 12.0427554986 +11 17 40.567315542   19.27 18.92     ~ 60 1
10 2MASS J16045749+2203007 QSO 16 04 57.5081984193 +22 03 00.512725927   19.84 19.49     ~ 21 0

    Equat.    Gal    SGal    Ecl

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2020.08.15-22:20:15

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