J/A+A/546/A67 Catalog of strong MgII absorbers (Lawther+, 2012)
Constraints on the relative sizes of intervening Mg II-absorbing clouds and
quasar emitting regions.
Lawther D., Paarup T., Schmidt M., Vestergaard M., Hjorth J., Malesani D.
<Astron. Astrophys. 546, A67 (2012)>
=2012A&A...546A..67L 2012A&A...546A..67L
ADC_Keywords: QSOs ; Equivalent widths
Keywords: quasars: emission lines - gamma-ray burst: general - ultraviolet: ISM
Abstract:
A significantly higher incidence of strong (rest equivalent width
Wr>1Å) intervening MgII absorption is observed along gamma-ray
burst (GRB) sight-lines relative to those of quasar sight-lines. A
geometrical explanation for this discrepancy has been suggested: the
ratio of the beam size of the source to the characteristic size of an
MgII absorption system can influence the observed
MgII equivalent width, if these two sizes are comparable.
We investigate whether the differing beam sizes of the continuum
source and broad-line region of Sloan Digital Sky Survey (SDSS)
quasars produce a discrepancy between the incidence of strong
MgII absorbers illuminated by the quasar continuum region and
those of absorbers illuminated by both continuum and broad-line region
light.
Description:
Here we present a catalog of strong (rest equivalent width Wr>1Å)
intervening Mg II absorbers in the SDSS Data Release 7 quasar catalog
(2010AJ....139.2360S 2010AJ....139.2360S, Cat. VII/260). The intervening absorbers were
found by a semi-automatic algorithm written in IDL - for details of
the algorithm see section 2 of our paper. A subset of the absorbers
have been visually inspected - see the MAN_OK flag in the catalog.
The number of sightlines searched, tabulated by absorber redshift,
i.e. g(z), is available as an ASCII table (for S/N>8 and S/N>15). All
analysis in our paper is based on the SNR>8 coverage, and considers
only sight-lines towards non-BAL quasars.
Any questions regarding the catalog should be sent to Daniel Lawther
(unclellama(at)gmail.com).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
mgiicat.dat 199 10367 SDSS strong MgII absorber catalog
cssn8.dat 34 220 Number of sightlines g(z) for S/N>8
cssn15.dat 34 215 Number of sightlines g(z) for S/N>15
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See also:
VII/260 : The SDSS-DR7 quasar catalog (Schneider+, 2010)
Byte-by-byte Description of file (#): mgiicat.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Spect [86/82107] Spectrum number
(order spectra were processed)
7- 11 I5 d MJD Modified Julian date of SDSS observation
13- 16 I4 --- Plate SDSS plate ID for this spectrum
18- 20 I3 --- Fiber SDSS fiber ID for this spectrum
22- 25 F4.2 --- zqso Quasar redshift (according to SDSS DR7
SpecBS pipeline)
27- 30 F4.2 0.1nm WR1 Equivalent width of MgII 2796Å line
32- 40 F9.2 0.1nm eWR1 Error on EW of MgII 2796Å line
42- 48 F7.2 0.1nm lam1 Observed wavelength of MgII 2796Å line
50- 56 F7.2 10-19W/m2/nm Amp1 Amplitude of MgII 2796Å line
58- 61 F4.2 0.1nm WId1 Observed width (sigma) of
MgII 2796Å line
63- 68 F6.2 10-19W/m2/nm Bas1 Estimated continuum flux level at
MgII 2796Å line
70- 74 F5.2 0.1nm WR2 Observed equivalent width of
MgII 2803Å line
76- 80 F5.2 0.1nm eWR2 Error on EW of MgII 2803 line
82- 88 F7.2 0.1nm lam2 Observed wavelength of MgII 2803Å line
90- 96 F7.2 10-19W/m2/nm Amp2 Amplitude of MgII 2803Å line
98-101 F4.2 0.1nm WId2 Observed width (sigma) of MgII 2803 line
103-108 F6.2 10-19W/m2/nm Bas2 Estimated continuum flux level at
MgII 2803Å line
110-114 F5.2 --- Frac1 Estimated continuum fraction of quasar
light absorbed by MgII 2796Å (1)
116-120 F5.2 --- Frac2 Estimated continuum fraction of quasar
light absorbed by MgII 2803Å (1)
122 I1 --- Bad [0/1] Flag indicating bad quasar continuum
fit if set to 1
124-127 F4.2 --- Err Error margin (in σ) of MgII doublet
separation from theoretical value
129 I1 --- Flag [0/2] Flag for unusually wide MgII
profile fits (2)
131 I1 --- Bal [0/1] Flag, 1 if spectrum is classified
as BAL by Shen et al. 2010
133-137 F5.2 --- SNR Signal-to-noise ratio around MgII 2796Å
line
139-140 I2 --- Ov Flag for overlapping MgII auto-selected
candidates
142-146 F5.2 0.1nm WRFe Equivalent width of Fe 2600Å line
(zero if no clear Fe 2600Å detection)
148-152 F5.2 0.1nm WRMgI Equivalent width of MgI line
(zero if no clear MgI detection)
154-160 F7.2 0.1nm lam.w Wavelength of weak component in composite
system (zero if no subsystems found) (3)
162 I1 --- Man [0/1] Flag, 1 if system has been visually
inspected and judged ok
164-168 F5.2 --- umag Apparent magnitude of quasar in
SDSS u imaging band
170-174 F5.2 --- gmag Apparent magnitude of quasar in
SDSS g imaging band
176-180 F5.2 --- rmag Apparent magnitude of quasar in
SDSS r imaging band
182-186 F5.2 --- imag Apparent magnitude of quasar in
SDSS i imaging band
188-192 F5.2 --- zmag Apparent magnitude of quasar in
SDSS z imaging band
194-199 F6.2 --- iMAG Absolute i magnitude of quasar, from
Schneider et al. (2010, Cat. VII/260)
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Note (1): Fraction of smoothed-spectrum (Fs) flux at centre of MgII 2796
profile that is due to continuum emission, based on a power-law fit to
the quasar continua. This was not used in our final analysis and was
therefore not thoroughly tested - use with caution in any later work,
note the flag Bad.
Note (2): This is set to 1 if the fits have a very wide Gaussian width
(greater than 3 Angstrom), and set to 2 if the ratio between Gaussian
widths is greater than 2 or less than 1. These absorbers have been
inspected visually.
Note (3): This was set to 1 by the IDL algorithm if the MgII 2803 component
appeared to overlap with another system's MgII 2796 component. All of
these have been visually inspected.
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Byte-by-byte Description of file (#): cssn15.dat cssn8.dat
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Bytes Format Units Label Explanations
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2- 5 F4.2 --- zmin Lower limit of redshift bin
7- 10 F4.2 --- zmax Upper limit of redshift bin
14- 18 I5 --- Nsp Number of spectra searched for MgII
in this z bin
22- 26 I5 --- Nsp(noBAL) Number of non-BAL spectra searched
in this z bin.
30- 34 I5 --- Nsp(wC) Number of spectra with fitted power-law
continuum in this z bin.
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Acknowledgements:
Daniel Lawther, unclellama(at)gmail.com
(End) Daniel Lawther [Dark Cosmology Centre], Patricia Vannier [CDS] 03-Aug-2012