J/ApJ/765/137 HST survey for Lyman limit systems. II. (O'Meara+, 2013)
The HST/ACS+WFC3 survey for Lyman limit systems. II. Science.
O'Meara J.M., Prochaska J.X., Worseck G., Chen H.-W., Madau P.
<Astrophys. J., 765, 137 (2013)>
=2013ApJ...765..137O 2013ApJ...765..137O
ADC_Keywords: QSOs ; Photometry, SDSS ; Redshifts ; Spectra, ultraviolet ;
Surveys
Keywords: cosmology: observations - intergalactic medium - surveys -
quasars: absorption lines - quasars: general - ultraviolet: general
Abstract:
We present the first science results from our Hubble Space Telescope
survey for Lyman limit absorption systems (LLS) using the low
dispersion spectroscopic modes of the Advanced Camera for Surveys and
the Wide Field Camera 3. Through an analysis of 71 quasars, we
determine the incidence frequency of LLS per unit redshift and per
unit path length, l(z) and l(X), respectively, over the redshift range
1<z<2.6, and find a weighted mean of l(X)=0.29±0.05 for 2.0<z<2.5
through a joint analysis of our sample and that of Ribaudo et al.
(2011, J/ApJ/736/42). Through stacked spectrum analysis, we determine
a median (mean) value of the mean free path to ionizing radiation at
z=2.4 of λ912mfp=243(252)h-172Mpc, with an error on the
mean value of ±43h-172Mpc. We also re-evaluate the estimates of
λ912mfp from Prochaska et al. (2010, J/ApJ/718/392) and
place constraints on the evolution of λ912mfp with
redshift, including an estimate of the "breakthrough" redshift of
z=1.6. Consistent with results at higher z, we find that a significant
fraction of the opacity for absorption of ionizing photons comes from
systems with NHI≤1017.5cm-2 with a value for the total Lyman
opacity of τLymaneff=0.40±0.15. Finally, we determine that
at minimum, a 5-parameter (4 power law) model is needed to describe
the column density distribution function f(NHI,X) at z∼2.4, find
that f(NHI,X) undergoes no significant change in shape between z∼2.4
and z∼3.7, and provide our best fit model for f(NHI,X).
Description:
In Paper I (O'Meara+, 2011, Cat. J/ApJS/195/16), we reported in detail
the quasar sample and HST observations for our survey: the sample of
quasars was chosen from the SDSS Data Release 5 (Cat. II/276;
superseded by II/294) and quasars were observed with HST/ACS (Cycle
15, program ID 10878) or HST/WFC3 (Cycle 17, program ID 11594).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 55 71 Quasar sample and continuum
table2.dat 46 145 Lyman limit absorption systems (LLS) models
table6.dat 17 155 WFC3/UVIS-G280 stacked spectrum
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
J/MNRAS/435/482 : DLA system from SDSS DR5 (Jorgenson+, 2013)
J/ApJS/195/16 : Paper I: HST survey for Lyman limit systems (O'Meara+, 2011)
J/ApJ/740/91 : Lyα in galaxies around quasars (Prochaska+, 2011)
J/ApJ/736/42 : HST QSO Catalog (Ribaudo+, 2011)
J/ApJ/728/23 : GALEX UV-bright high-redshift quasars (Worseck+, 2011)
J/ApJ/718/392 : SDSS Lyman limit systems at z∼3.5 (Prochaska+, 2010)
J/A+A/505/1087 : DLAs in SDSS-DR7 (Noterdaeme+, 2009)
J/AJ/131/2766 : Quasar luminosity function from SDSS-DR3 (Richards+, 2006)
J/A+A/458/427 : Lyman alpha absorbers in 0.5<z<1.9 QSOs (Janknecht+, 2006)
J/ApJ/635/123 : The SDSS-DR3 damped Lyα survey (Prochaska+, 2005)
J/MNRAS/354/L31 : SDSS DR2 QSO and DLA properties (Murphy+, 2004)
J/MNRAS/335/555 : Lyman-alpha forest of 5 QSOs (Kim+, 2002)
J/A+A/373/757 : Lyman-Alpha Forest of 3 QSOs (Kim+, 2001)
J/ApJ/475/469 : Composite HST Spectrum of Quasars (Zheng+ 1997)
http://www.sdss.org/ : SDSS home page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Inst Instrument (1)
6- 24 A19 --- Name Quasar name (JHHMMSS.ss+DDMMSS.s)
26- 29 I4 --- Plate SDSS-DR7 plate
31- 33 I3 --- Fiber SDSS-DR7 fiber
35- 39 F5.3 --- zem [2.2/2.6] SDSS quasar emission redshift
41- 45 F5.2 mag g'mag [16.9/18.3] SDSS quasar AB g'-band magnitude
47- 51 F5.1 --- C [1/235] fitting parameter C (2)
53- 55 F3.1 --- alpha [0/3] fitting parameter α (2)
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Note (1): Quasars observed as part of our WFC3/UVIS-G280 and HST/ACS survey for
Lyman limit absorption systems (LLS) absorption (Paper I;
O'Meara+, 2011, Cat. J/ApJS/195/16). Instruments are:
WFC3 = Quasars Observed with WFC3/UVIS-G280 (Cycle 17, Program ID 11594)
ACS = Quasars Observed with ACS/PR200L (Cycle 15, Program ID 10878)
Note (2): The modeled continuum for λ<1200Å is of the form:
fcont(λ)=C.fTelfer(λ).(λ/2500Å)α,
where fTelfer is presented in Telfer et al. (2002ApJ...565..773T 2002ApJ...565..773T).
We caution the reader that these models are not meant to precisely
describe the intrinsic spectral energy distributions of the quasars,
but instead describes the flux attenuated by the Lyman series
absorption (see the text).
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- OCode Description of HST observation
16- 34 A19 --- Name Quasar name (JHHMMSS.ss+DDMMSS.s)
36- 40 F5.3 --- z [1/2.7] Reshift from absorption
42- 46 F5.2 [cm-2] logNHI [16/18.6] Log of the H I column density
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 7 F7.2 0.1nm lambda [601.9/1555.2] Wavelength; Angstroms
9- 12 F4.2 --- Flux [0.4/3.4] Normalized flux (1)
14- 17 F4.2 --- e_Flux [0/0.2] RMS in Flux (2)
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Note (1): Flux per Angstrom normalized to unity at λr=1450 Angstrom.
Note (2): With 3σ clipping from a bootstrap analysis (see text).
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History:
From electronic version of the journal
References:
O'Meara et al. Paper I. 2011ApJS..195...16O 2011ApJS..195...16O Cat. J/ApJS/195/16
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 04-Nov-2014