J/ApJ/613/129 Equivalent widths of QSOs (Wise+, 2004)
Variability of narrow, associated absorption lines in moderate- and low-redshift
quasars.
Wise J.H., Eracleous M., Charlton J.C., Ganguly R.
<Astrophys. J., 613, 129-150 (2004)>
=2004ApJ...613..129W 2004ApJ...613..129W
ADC_Keywords: QSOs ; Equivalent widths ; Redshifts ; Spectra, ultraviolet
Keywords: accretion, accretion disks - galaxies: active -
quasars: absorption lines - quasars: general
Abstract:
We present the results of a search for variability in the equivalent
widths (EWs) of narrow, associated (|Δv|≤5000km/s) absorption
lines found in the UV spectra of z≤1.5 quasars. The goal of this
search was to use variability as a means of identifying absorption
lines arising in gas that is intrinsic to the quasar central engine.
We have compared archival Hubble Space Telescope (HST) Faint Object
Spectrograph (FOS) spectra of quasars with recent spectra obtained as
part of our own snapshot survey of the same objects with the Space
Telescope Imaging Spectrograph (STIS). The intervals between
observations are 4-10yr. We primarily focused on the C IV absorption
lines, although we also studied other lines available in the same
spectra (e.g., Lyα, N V, O VI).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 137 337 Line Identifications and Equivalent Width
Measurements
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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 --- Name Quasar name
16- 22 F7.5 --- z Redshift
24- 30 F7.2 0.1nm l(STIS) ? STIS observed wavelength in Angstroms
32 A1 --- l_EW(STIS) Limit flag on EW(STIS)
33- 37 F5.2 0.1nm EW(STIS) ? STIS equivalent width in Angstroms
39- 43 F5.2 0.1nm e_EW(STIS)p ? STIS Poisson noise uncertainty in Angstroms
(1)
45- 48 F4.2 0.1nm e_EW(STIS)c ? STIS continuum fit uncertainty in Angstroms
(1)
50 A1 --- f_l(STIS) STIS blend flag (2)
52- 58 F7.2 0.1nm l(FOS) ? FOS observed wavelength in Angstroms
60 A1 --- l_EW(FOS) Limit flag on EW(FOS)
61- 66 F6.2 0.1nm EW(FOS) ? FOS equivalent width in Angstroms
68- 71 F4.2 0.1nm e_EW(FOS)p ? FOS Poisson noise uncertainty in Angstroms
(1)
73- 76 F4.2 0.1nm e_EW(FOS)c ? FOS continuum fit uncertainty in Angstroms
(1)
78 A1 --- f_l(FOS) [o] Indicates FOS values out of range
80 A1 --- l_DEW Limit flag on DEW
81- 85 F5.2 0.1nm DEW ? Difference between FOS and STIS equivalent
widths in Angstroms
87 A1 --- l_DEW/sig Limit flag on DEW/sig
88- 92 F5.2 --- DEW/sig ? Deviation normalized to error (3)
94 A1 --- f_DEW/sig [u] Indicates a variable absorption line
96-100 A5 --- Line Line identification
101-102 A2 --- f_Line Flag on Line (4)
104-110 F7.2 0.1nm Wave ? Adopted rest wavelength in Angstroms
112 A1 --- f_Wave [ae] Flag on Wave (5)
114-118 F5.2 0.1nm Dlambda ? Difference between observed and expected
wavelength in Angstroms
120-126 F7.5 --- zAbs ? Redshift of the absorption-line system
128-133 I6 km/s DVel ? Velocity offset of an absorption line (6)
135 A1 --- f_DVel [u] Indicates variable absorption for DVel
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Note (1): The uncertainty is broken up into two parts, which should be added
in quadrature to give the final error bar on the equivalent width.
Note (2): A S indicates that the line listed in the STIS column is a
known blend and the EW given is the total EW of the blend. In the
same row, under the FOS column, we give the sum of the EWs of the
individual lines making up the blend, as measured in the FOS spectrum.
The rows below the total EW row in the FOS column give the EWs of the
individual lines. These lines are identified with increasing index
numbers in column 5. The corresponding rows in the STIS column are
left blank.
Note (3): The error bar was computed by adding all the relevant error bars
in quadrature.
(sig)2 = (eEW(STIS)p)2+(eEW(STIS)c)2+(eEW(FOS)p)2+(eEW(FOS)c)2
See text for more details.
Note (4): Flag on Line is defined as follows:
b = The Si IV (1393) line at zAbs=1.009 in the spectrum of EX 0302-223
is contaminated by Galactic Mg II (2803).
c = The Lyα line at zAbs=1.125 in the spectrum of QSO 0957+561A
is contaminated by Galactic Fe II (2586).
d = In the case of PG 1241+176, the Galactic Fe II (2344) line and
the O VI (1032) line at zAbs=1.2735 are blended in both the STIS
and FOS spectra.
f = The C IV doublet at zAbs=0.2014 in the spectrum of PKS 2135-14 is
slightly contaminated by the Galactic Al II (1863) line.
g = The observed lines at 2376 and 2384 in the spectrum of MRC 2251-178
are unidentified. However, they are contaminated by the Galactic
Fe II (2344 and 2374), respectively.
u = variable absorption line.
Note (5): Flag on Wave has the following meaning:
a = Mean wavelength of doublet; adopted when the doublet is unresolved
in both the FOS and STIS spectra.
e = In the case of PG 1718+481, the O VI (1037) and Fe II (2344) lines
appear to be blended with neighboring unidentified lines in both the
STIS and FOS spectra.
Note (6): A positive velocity offset indicates a redshift of the absorption
line relative to the quasar. These velocities are based on
wavelengths measured from the FOS spectra whenever possible.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Marianne Brouty [CDS] 16-Feb-2005