J/MNRAS/391/1457 Lymanα forest in QSO pairs (Kirkman+, 2008)
The transverse proximity effect in the z∼2 Lyman α forest suggests
quasi-stellar object episodic lifetimes of ∼1Myr.
Kirkman D., Tytler D.
<Mon. Not. R. Astron. Soc., 391, 1457-1471 (2008)>
=2008MNRAS.391.1457K 2008MNRAS.391.1457K
ADC_Keywords: QSOs ; Redshifts ; Magnitudes ; H I data
Keywords: intergalactic medium - quasars: absorption lines -
cosmology: observations
Abstract:
We look for signs of the HI transverse proximity effect in the spectra
of 130 quasi-stellar object (QSO) pairs, most with transverse
separations in the plane of the sky of 0.1-3Mpc at z∼2.2. We expected
to see a decrease in Lyα forest HI absorption in the spectrum of
background QSOs near the position of foreground QSOs. Instead, we see
no change in the absorption in front of the foreground QSOs, and we
see evidence for a 50 per cent increase in the absorption out to 6Mpc
behind the foreground QSOs. Further, we see no change in the HI
absorption along the line-of-sight to the foreground QSOs, the normal
line-of-sight proximity effect. We may account for the lack of change
in the HI absorption if the effect of extra ultraviolet photons is
cancelled by higher gas density around QSOs. If so, the increase in
absorption behind the QSOs then suggests that the higher gas density
there is not cancelled by the UV radiation from the QSOs. We can
explain our observations if QSOs have had their current UV
luminosities for less than approximately a million years, a time-scale
that has been suggested for accretion disc instabilities and gas
depletion.
Description:
Our data set consists of the Lyα forest regions of the spectra
of 130 close pairs of QSOs.
We obtained the spectra for a project to measure the Alcock-Paczynski
effect with the Lyα forest.
The spectra were obtained from either Keck+LRIS (76 spectra),
Lick+KAST (26 spectra), National Optical Astronomy Observatory (NOAO)
4-m telescopes (10 spectra) or the SDSS DR5 archive (146 spectra).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 105 130 *QSO pairs
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Note on table1.dat: QSOs pairs identified as [KT2008] JHHMMSS.s+DDMMSS.s,
with [KT2008] JHHMMSS.s+DDMMSS.s A for the background QSO and
[KT2008] JHHMMSS.s+DDMMSS.s B for the foreground QSO, where
JHHMMSS.s+DDMMSS.s are the coordinates of background QSO.
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See also:
II/276 : SDSS Photometric Catalog, Release 5 (Adelman-McCarthy+, 2007)
J/ApJ/658/99 : Pairs of QSO in SDSS-DR4 (Myers+, 2007)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh Background QSO right ascension (J2000)
4- 5 I2 min RAm Background QSO right ascension (J2000)
7- 10 F4.1 s RAs Background QSO right ascension (J2000)
12 A1 --- DE- Background QSO declination sign (J2000)
13- 14 I2 deg DEd Background QSO declination (J2000)
16- 17 I2 arcmin DEm Background QSO declination (J2000)
19- 22 F4.1 arcsec DEs Background QSO declination (J2000)
24- 28 F5.3 --- zem Background QSO emission redshift
30- 33 F4.1 mag mag Background QSO magnitude in band
35- 36 A2 --- n_mag [V bJ rg] Background QSO photometric band of
the magnitude
38- 40 I3 --- S Background QSO signal-to-noise per Å at
1290Å in the QSO rest frame
42- 43 I2 h RA2h Second QSO right ascension (J2000)
45- 46 I2 min RA2m Second QSO right ascension (J2000)
48- 51 F4.1 s RA2s Second QSO right ascension (J2000)
53 A1 --- DE2- Second QSO declination sign (J2000)
54- 55 I2 deg DE2d Second QSO declination (J2000)
57- 58 I2 arcmin DE2m Second QSO declination (J2000)
60- 63 F4.1 arcsec DE2s Second QSO declination (J2000)
65- 69 F5.3 --- zem2 Second QSO emission redshift
71- 74 F4.1 mag mag2 Second QSO magnitude in band
76- 77 A2 --- n_mag2 [V bJ g] Second QSO photometric band of the
magnitude
79- 81 I3 --- S2 Second QSO signal-to-noise per Å at
1290Å in the QSO rest frame
83- 87 F5.1 arcsec Sep Angular separation on the sky between the
two QSOs
89- 92 F4.2 Mpc b Impact parameter in proper Mpc between the two
sightlines at the zem of the foreground QSO
94- 98 F5.2 10+23W/Hz LLya Estimated Lyman alpha limit luminosity
100-105 F6.1 --- OmeMax Expected ratio of the UV flux (1)
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Note (1): Expected ratio of the UV flux from the foreground QSO to the UVB,
at the point of closest approach of the background sightline to the
foreground QSO
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 05-May-2009