2006A&A...449....9R


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.05CEST07:17:58

2006A&A...449....9R - Astronomy and Astrophysics, volume 449, 9-22 (2006/4-1)

Spectral shape of the UV ionizing background and OVI absorbers at z ∼1.5 towards HS 0747+4259.

REIMERS D., AGAFONOVA I.I., LEVSHAKOV S.A., HAGEN H.-J., FECHNER C., TYTLER D., KIRKMAN D. and LOPEZ S.

Abstract (from CDS):

We report on high resolution spectra of the bright QSO HS 0747+4259 (zem=1.90, V=15.8) observed to search for intermediate redshift OVI absorption systems. The spectra were obtained by means of the Space Telescope Imaging Spectrograph (STIS) at the Hubble Space Telescope (HST) and the High Resolution Echelle Spectrometer (HIRES) at the W. M. Keck telescope. We identify 16 OVI systems in the range 1.07≤z≤1.87. Among them, six systems with zabs=1.46-1.8 exhibit a sufficient number of lines of different ionic transitions to estimate the shape of the ionizing radiation field in the range 1Ryd<E<10Ryd. All recovered UV ionizing spectra are characterized by the enhanced intensity at E>3Ryd compared to the model spectrum of Haardt & Madau (1996ApJ...461...20H). This is in line with the observational evidence of a deficiency of strong Lyα absorbers with N(HI)>1015cm–2 at z<2. The UV background shows significant local variations: the spectral shape estimated at z=1.59 differs from that obtained at z=1.81 and 1.73. A possible cause of these variations is the presence of a QSO/AGN at z≃1.54-1.59 close to the line of sight. No features favoring the input of stellar radiation to the ionizing background are detected, limiting the escape fraction of the galactic UV photons to fesc<0.05.

Abstract Copyright:

Journal keyword(s): cosmology: observations - line: formation - line: profiles - galaxies: abundances - galaxies: quasars: absorption lines - galaxies: quasars: individual: HS 0747+4259

Nomenclature: Table 1: [RAL2006] QSO J0750+4252 abs N.NNNN N=24.

Status at CDS:   All or part of tables of objects will not be ingested in SIMBAD.

Simbad objects: 3

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Number of rows : 3

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 HE 0515-4414 QSO 05 17 07.6239672230 -44 10 55.578294294 14.74 15.49 15.16     ~ 97 0
2 QSO B0747+4259 QSO 07 50 54.6476110802 +42 52 19.234255219   16.43 16.23     ~ 42 0
3 [LAC2002] QSO J2233-6033 abs 1.94 ALS 22 33 37.59 -60 33 29.1           ~ 3 0

    Equat.    Gal    SGal    Ecl

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2020.07.05-07:17:58

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