The Sloan Digital Sky Survey (SDSS) is one of the most ambitious and
influential surveys in the history of astronomy. Over eight years of
operations (SDSS-I, 2000-2005; SDSS-II, 2005-2008), it obtained deep,
multi-color images covering more than a quarter of the sky and created
3-dimensional maps containing more than 930,000 galaxies and more than
120,000 quasars.
SDSS data have been released to the scientific community and the general
public in annual increments, with the final public data release from SDSS-II
occurring in October 2008. That release, Data Release 7, is available
through the above website.
Meanwhile, SDSS is continuing with the Third Sloan Digital Sky Survey
(SDSS-III), a program of four new surveys using SDSS facilities. SDSS-III
began observations in July 2008 and released its first public data as Data
Release 8 to emphasize its continuity with previous SDSS releases. SDSS-III
will continue operating and releasing data through 2014.
Data Release 8 contains all images from the SDSS telescope - the largest
color image of the sky ever made. It also includes measurements for nearly
500 million stars and galaxies, and spectra of nearly two million. All the
images, measurements, and spectra are available free online.
AGNSDSSXM2 Catalog
X-ray emission from active galactic nuclei (AGN) is dominated by the
accretion disk around a supermassive black hole. The radio luminosity,
however, has not such a clear origin except in the most powerful sources
where jets are evident. The origin (and even the very existence) of the local
bi-modal distribution in radio-loudness is also a debated issue. By analyzing
X-ray, optical and radio properties of a large sample of type 1 AGN and
quasars (QSOs) up to z > 2, where the bulk of this population resides, the
authors aim to explore the interplay between radio and X-ray emission in AGN,
in order to further our knowledge on the origin of radio emission, and its
relation to accretion. They analyze a large (~800 sources) sample of type 1
AGN and QSOs selected from the 2XMMi XMM-Newton X-ray source catalog,
cross-correlated with the SDSS DR7 spectroscopic catalog, covering a redshift
range from z ~ 0.3 to z ~ 2.3. Supermassive black hole masses are estimated
from the Mg II emission line, bolometric luminosities from the X-ray data,
and radio emission or upper limits from the FIRST catalog. Most of the
sources accrete close to the Eddington limit and the distribution in
radio-loudness does not appear to have a bi-modal behavior. This study
confirms that radio-loud AGN are also X-ray loud, with an X-ray-to-optical
ratio up to twice that of radio-quiet objects, even excluding the most
extreme strongly jetted sources. By analyzing complementary radio-selected
control samples, the authors find evidence that these conclusions are not an
effect of the X-ray selection, but are likely a property of the dominant QSO
population.
The authors of this catalog conclude that their findings are best interpreted
in a context where radio emission in AGN, with the exception of a minority of
beamed sources, arises from very close to the accretion disk and is therefore
heavily linked to X-ray emission. They also speculate that the
radio-loud/radio-quiet dichotomy might either be an evolutionary effect that
developed well after the QSO peak epoch, or an effect of incompleteness in
small samples.
Basic information and derived properties are presented for the sample of
X-ray selected type 1 AGN (as well as for the 11 X-ray undetected type 1 AGN
in the "control sample"): coordinates, redshift, X-ray and radio fluxes,
optical magnitudes, from the SDSS, 2XMMi, and FIRST catalogs; continuum
luminosities at 3000 Angstroms and in the X-ray band, black hole masses,
bolometric luminosities, Eddington ratios; for the sources falling in the
FIRST field, optical fluxes at 2500 and 4400 Angstroms, X-ray-to-optical
index, radio classification, and the ratios between the radio and the UV,
optical, and X-ray fluxes.
AGNSDSSXMM Catalog
Bright XMM-Newton data are combined with the Chandra Deep Field South
observations to explore the behavior of the intrinsic AGN absorption, as a
function of redshift and luminosity. The sample consists of 359 sources
selected in the hard 2 - 8 keV band, spanning the flux range from 6 x 10-16
- 3 x 10-13 erg/cm2/s with a high rate of spectroscopic or photometric
redshift completeness (100 and 85 percent for the Chandra and XMM-Newton
data, respectively). The authors derive the column density values using X-ray
spectral fits. They find that the fraction of obscured AGN falls with
increasing luminosity in agreement with previous findings. The fraction of
obscured AGN shows an apparent increase at high redshifts (z > 2).
Simulations show that this effect can most probably be attributed to the fact
that at high redshifts the column densities are overestimated.
This table contains the subset of 153 brighter hard X-ray sources in the
XMM-Newton/Sloan Digital Sky Survey (SDSS) sample which have 2-8 keV fluxes >
3 x 10-14 erg cm-2 s-1, excluding a number of sources with extended
optical morphology and blue colors, as well as 4 sources with X-ray to
optical fluxes < 0.1 which are fit better with stellar rather than QSO
templates.
Much more information on the SDSS is available at the project's web site
at http://www.sdss.org/.
CHAMPSDSSA Catalog
The combination of the Sloan Digital Sky Survey (SDSS) and the Chandra
Multiwavelength Project (ChaMP; Green et al. 2004, ApJS, 150, 43) currently
offers the largest and most homogeneously selected sample of nearby galaxies
for investigating the relations between X-ray nuclear emission, nebular line
emission, black hole masses, and the properties of the associated stellar
populations. The authors provide X-ray spectral fits and valid uncertainties
for all the galaxies with counts ranging from 2 to 1325 (mean 76, median 19).
They present in their paper novel constraints that both X-ray luminosity LX
and X-ray spectral energy distribution bring to the galaxy evolutionary
sequence HII -> Seyfert/Transition Object -> LINER -> Passive suggested by
optical data. In particular, the authors show that both LX and Gamma, the
slope of the power law that best fits the 0.5 - 8 keV spectra, are consistent
with a clear decline in the accretion power along the sequence, corresponding
to a softening of their spectra. This implies that, at z ~ 0, or at
low-luminosity active galactic nucleus (AGN) levels, there is an
anticorrelation between Gamma and L/LEdd, opposite to the trend which is
exhibited by high-z AGN (quasars). The turning point in the Gamma - L/LEdd
LLAGN + quasars relation occurs near Gamma ~ 1.5 and L/LEdd ~ 0.01.
Interestingly, this is identical to what stellar mass X-ray binaries exhibit,
indicating that the authors have probably found the first empirical evidence
for an intrinsic switch in the accretion mode, from advection-dominated flows
to standard (disk/corona) accretion modes in supermassive black hole
accretors, similar to what has been seen and proposed to happen in stellar
mass black hole systems. The anticorrelation the authors find between Gamma
and L/LEdd may instead indicate that stronger accretion correlates with
greater absorption. Therefore, the trend for softer spectra toward more
luminous, high-redshift, and strongly accreting (L/LEdd >~ 0.01)
AGNs/quasars could simply be the result of strong selection biases reflected
in the dearth of type 2 quasar detections.
The cross-match of all ChaMP sky regions imaged by Chandra/ACIS with the SDSS
DR4 spectroscopic footprint results in a parent sample of 15,955 galaxies on
or near a chip and a subset of 199 sources that are X-ray detected. Among
those, only 107 sources have an off-axis angle (OAA) Theta <0.2 degrees and
avoid ccd=8 due to high serial readout noise; these 107 objects comprise the
main sample that the authors employ for this study and that are listed in
this table.
The authors performed direct spectral fits to the X-ray counts distribution
using the full instrument calibration, known redshift, and Galactic 21-cm
column nHGal. Source spectra were extracted from circular regions with
radii corresponding to energy encircled fractions of ~90%, while the
background region encompasses a 20 arcsec annulus, centered on the source,
with separation 4 arcsecs, from the source region. Any nearby sources were
excised, from both the source and the background regions. The spectral
fitting was done via yaxx ('Yet Another X-ray eXtractor': Aldcroft 2006,
BAAS, 38, 376), an automated script that employs the CIAO Sherpa tool. Each
spectrum was fitted in the range 0.5 - 8 keV by two different models: (1) a
single power law plus absorption fixed at the Galactic 21-cm value (model
'PL'), and (2) a fixed power law of photon index Gamma = 1.9 plus intrinsic
absorption of column nH (model 'PLfix'). For the nine objects with more than
200 counts, the authors employed a third model in which both the slope of the
power law and the intrinsic absorption were free to vary (model 'PL_abs').
GLXSDSSQS2 Catalog
A sample of ~60,000 objects from the combined Sloan Digital Sky Survey-Galaxy
Evolution Explorer (SDSS-GALEX) database with UV-optical colors that should
isolate QSOs in the redshift range 0.5 to 1.5 is discussed. The authors use
SDSS spectra of a subsample of ~ 4,500 to remove stellar and galaxy
contaminants in the sample to a very high level, based on the 7-band
photometry. In their paper, they discuss the distributions of redshift,
luminosity, and reddening of the 19,100 QSOs (~96%) that they estimate to be
present in their final sample of 19,812 point sources. This latter catalog is
available in the present table.
This paper is based on archival data from the Galaxy Evolution Explorer
(GALEX) which is operated for NASA by the California Institute of Technology
under NASA contract NAS5-98034, and on data from the SDSS.
GLXSDSSQSO Catalog
This table contains the result of an analysis of the broad-band UV and
optical properties of z ~< 3.4 quasars matched in the Galaxy Evolution
Explorer (GALEX) General Data Release 1 (GR1) and the Sloan Digital Sky
Survey (SDSS) Data Release 3 (DR3). Of the 6371 SDSS DR3 quasars covered by
204 GALEX GR1 tiles and listed in this table, 5380 (84%) have near-UV
detections, while 3034 (48%) have both near-UV and far-UV detections using a
matching radius of 7 arcseconds. Most of the DR3 sample quasars are detected
in the near-UV until z ~ 1.7, with the near-UV detection fraction dropping to
~50% by z ~ 2. Statistical tests performed on the distributions of
non-detections indicate that the optically selected quasars missed in the UV
tend to be optically faint or at high redshift. The GALEX positions are shown
to be consistent with the SDSS astrometry to within an rms scatter of 0.6 -
0.7 arcsecs in each coordinate, and the empirically determined photometric
errors from multi-epoch GALEX observations significantly exceed the Poissonian
errors quoted in the GR1 object catalogs. The UV-detected quasars are well
separated from stars in UV-optical color-color space, with the UV-optical
relative colors suggesting a marginally detected population of reddened
objects due to absorption along the line of sight or dust associated with the
quasar. The resulting spectral energy distributions (SEDs) cover ~350 - 9000
Angstroms (rest frame), where the overall median SED peaks near the
Lyman-Alpha emission line, as found in other UV quasar studies. The large
sample size allows the authors to construct median SEDs in small bins of
redshift and luminosity, and they find that the median SED becomes harder
(bluer) at UV wavelengths for quasars with lower continuum luminosity. The
detected UV-optical flux as a function of redshift is qualitatively
consistent with attenuation by intervening Lyman-absorbing clouds.
LOWZVLQVLA Catalog
This table contains results from 6-GHz Jansky Very Large Array (JVLA)
observations covering a volume-limited sample of 178 low-redshift (0.2 < z
<0.3) optically selected quasi-stellar objects (QSOs). These 176 radio
detections fall into two clear categories: (1) about 20% are radio-loud QSOs
(RLQs) with spectral luminosities of L6 >~ 1023.2 W/Hz that are primarily
generated in the active galactic nucleus (AGN) responsible for the excess
optical luminosity that defines a bona fide QSO; and (2) the remaining 80%
that are radio-quiet QSOs (RQQs) that have 1021 <~ L6 <~ 1023.2 W/Hz
and radio sizes <~ 10 kpc, and the authors suggest that the bulk of their
radio emission is powered by star formation in their host galaxies.
"Radio-silent" QSOs (L_6_<~ 1021 W/Hz) are rare, so most RQQ host galaxies
form stars faster than the Milky Way; they are not "red and dead"
ellipticals. Earlier radio observations did not have the luminosity
sensitivity of L6 <~ 1021 W/Hz that is needed to distinguish between such
RLQs and RQQs. Strong, generally double-sided radio emission spanning >> 10
kpc was found to be associated with 13 of the 18 RLQ cores with peak flux
densities of Sp > 5 mJy/beam (log(L) >~ 24). The radio luminosity function
of optically selected QSOs and the extended radio emission associated with
RLQs are both inconsistent with simple "unified" models that invoke
relativistic beaming from randomly oriented QSOs to explain the difference
between RLQs and RQQs. Some intrinsic property of the AGN or their host
galaxies must also determine whether or not a QSO appears radio-loud.
The authors have reprocessed the VLA observations of a sample of SDSS QSOs
discussed in Kimball et al. (2011, ApJ, 739, L29). These were obtained using
the VLA C configuration with a central frequency of 6 GHz and a bandwidth of
2 GHz in each of the two circular polarizations: with natural weighting the
synthesized beam width was 3.5 arcseconds FWHM. The authors generated a
catalog of radio sources associated with each QSO. They detected radio
emission at 6 GHz from all but two of the 178 color-selected SDSS QSOs
contained in this volume-limited sample of QSOs more luminous than Mi = -23
and with redshifts 0.2 < z < 0.3.
All calculations in the reference paper assume a flat LambdaCDM cosmology
with H0 = 70 km s-1 Mpc-1 and OmegaLambda = 0.7. Spectral
luminosities are specified by their source-frame frequencies, flux densities
are specified in the observer's frame, and a mean spectral index of alpha =
d(log S)/d(log nu) = -0.7 is used to make frequency conversions
OSQSONVSS Catalog
The authors used the 1.4-GHz NRAO VLA Sky Survey (NVSS) to study radio
sources in two color-selected QSO samples: a volume-limited sample of 1,313
QSOs defined by Mi < -23 in the redshift range 0.2 < z < 0.45 and a
magnitude-limited sample of 2,471 QSOs with mr <= 18.5 and 1.8 < z < 2.5.
About 10% were detected above the 2.4-mJy NVSS catalog limit and are powered
primarily by active galactic nuclei (AGNs). The space density, rho, of the
low-redshift QSOs evolves as rho ~ (1 + z)6. In both redshift ranges, the
flux-density distributions and luminosity functions of QSOs stronger than 2.4
mJy are power laws, with no features to suggest more than one kind of radio
source. Extrapolating the power laws to lower luminosities predicts the
remaining QSOs should be extremely radio quiet, but they are not. Most were
detected statistically on the NVSS images with median peak flux densities
Sp of ~ 0.3 mJy/beam and ~ 0.05 mJy/beam in the low- and high-redshift
samples, corresponding to spectral luminosities log L1.4GHz ~ 22.7 and ~
24.1 W/Hz, respectively. The authors suggest that the faint radio sources are
powered by star formation at rates dM/dt of ~ 20 M_{sun}_/yr in the moderate
luminosity (median Mi of ~ -23.4) low-redshift QSOs and dM/dt ~
500Msun/yr in the very luminous (median Mi ~ -27.5) high-redshift QSOs.
Such luminous starbursts (<log(LIR/Lsun)> ~ 11.2 and ~ 12.6,
respectively) are consistent with "quasar mode" accretion in which cold gas
flows fuel both AGN and starburst.
The SDSS DR7 QSO catalog (Schneider et al. 2010, AJ, 139, 2360) is complete
to i = 19.1 mag over a solid angle of 2.66 sr around the North Galactic Pole.
It contains the small sample of 179 color-selected QSOs defined by Mi < -23
in the narrow redshift range 0.2 < z < 0.3 studied by Kimball et al. (2011,
ApJ, 739, L29) and the larger sample of 1,313 QSOs in the wider redshift
range 0.2 < z < 0.45 discussed here. Note that these magnitudes were
calculated for an H0= 71 km/s/Mpc and OmegaM = 0.27 modern flat LambdaCDM
cosmology. The entire SDSS DR7 area is covered by the NVSS, whose source
catalog is complete for statistical purposes above a peak flux density Sp ~
2.4 mJy/beam at 1.4 GHz. In the redshift range 0.2 < z < 0.45 the 45" FWHM
(full width between half-maximum points) beam of the NVSS spans 150 - 250
kpc. There are 163 (12%) NVSS detections of the 1,313 QSOs in the redshift
range 0.2 < z < 0.45 which are listed in Table 1 of the reference paper.
The authors also chose a magnitude-limited sample of all 2,471 color-selected
DR7 QSOs brighter than mr = 18.5 in the redshift range 1.8 < z < 2.5. The
NVSS detected radio emission stronger than S = 2.4 mJy from only 191 (8%) of
them: these are listed in Table 3 of the reference paper.
This HEASARC table contains the contents of both samples described above.
It thus has 163 + 191 = 354 entries, the sum of Tables 1 and 3 from the
reference paper. To select only the entries from Table 1, the user should
select entries with redshifts from 0.2 to 0.45. To select only the entries
from Table 3, the user should select entries with redshifts > 1.8.
RASSDSSAGN Catalog
This table contains further results of a program aimed at yielding ~ 104
fully characterized optical identifications of ROSAT X-ray sources. The
program employs X-ray data from the ROSAT All Sky Survey (RASS) and both
optical imaging and spectroscopic data from the Sloan Digital Sky Survey
(SDSS). RASS/SDSS data from 5740 deg2 of sky spectroscopically covered in
SDSS Data Release 5 (DR5) provide an expanded catalog of 7000 confirmed
quasars and other active galactic nuclei (AGN) that are probable RASS
identifications. Again, in this expanded catalog the identifications as X-ray
sources are statistically secure, with only a few percent of the SDSS AGNs
likely to be randomly superposed on unrelated RASS X-ray sources. Most
identifications continue to be quasars and Seyfert 1 galaxies with 15 < m <
21 and 0.01 < z < 4, but the total sample size has grown to include very
substantial numbers of even quite rare AGN, e.g., it now includes several
hundreds of candidate X-ray-emitting BL Lac objects and narrow-line Seyfert 1
galaxies. In addition to exploring rare subpopulations, such a large total
sample may be useful when considering correlations between the X-ray and the
optical and may also serve as a resource list from which to select the
``best'' object (e.g., the X-ray-brightest AGN of a certain subclass at a
preferred redshift or luminosity) for follow-up X-ray spectral or alternate
detailed studies.
Much more information on the SDSS is available at the project's web site
at http://www.sdss.org/.
RASSDSSTAR Catalog
The ROSAT All-Sky Survey (RASS) was the first imaging X-ray survey of the
entire sky. Combining the RASS Bright and Faint Source Catalogs yields an
average of about three X-ray sources per square degree. However, while X-ray
source counterparts are known to range from distant quasars to nearby M
dwarfs, the RASS data alone are often insufficient to determine the nature of
an X-ray source. As a result, large-scale follow-up programs are required to
construct samples of known X-ray emitters. The authors use optical data
produced by the Sloan Digital Sky Survey (SDSS) to identify 709 stellar X-ray
emitters cataloged in the RASS and falling within the SDSS Data Release 1
footprint. Most of these are bright stars with coronal X-ray emission
unsuitable for SDSS spectroscopy, which is designed for fainter objects (g >
15mag). Instead, the authors use SDSS photometry, correlations with the Two
Micron All Sky Survey (2MASS) and other catalogs, and spectroscopy from the
Apache Point Observatory 3.5 m telescope to identify these stellar X-ray
counterparts. Their sample of 707 X-ray-emitting F, G, K, and M stars is one
of the largest X-ray-selected samples of such stars. The authors derive
distances to these stars using photometric parallax relations appropriate for
dwarfs on the main sequence, and use these distances to calculate their X-ray
luminosities LX. They also identify a previously unknown cataclysmic
variable (CV) as a RASS counterpart.
Much more information on the SDSS is available at the project's web site at
http://www.sdss.org/.
RASSSDSSGC Catalog
The authors use ROSAT All-Sky Survey (RASS) broad-band X-ray images and the
optical clusters identified from the Sloan Digital Sky Survey Data Release 7
(SDSS DR7) to estimate the X-ray luminosities around ~65,000 candidate galaxy
clusters with masses >~1013 h-1 Msun based on an optical to X-ray (OTX)
code that they developed. They obtain a catalog with X-ray luminosities for
all 64,646 clusters. A total of 34,522 (~53%) of these clusters have a
signal-to-noise ratio S/N > 0 after subtracting the background signal.
According to the reference paper (but see HEASARC Caveats section below),
this catalog contains 817 clusters (473 at redshift z <= 0.12) with S/N > 3
for their X-ray detections (an additional 12,629 clusters have 3 >= S/N > 1
and 21,076 clusters have 1 >= S/N > 0). The authors find about 65% of these
X-ray clusters have their most massive member located near the X-ray flux
peak; for the remaining 35%, the most massive galaxy is separated from the
X-ray peak, with the separation following a distribution expected from a
Navarro-Frenk-White profile. In the reference paper, the authors investigate
a number of correlations between the optical and X-ray properties of these
X-ray clusters, and find that the cluster X-ray luminosity is correlated with
the stellar mass (luminosity) of the clusters, as well as with the stellar
mass (luminosity) of the central galaxy and the mass of the halo, although
the scatter in these correlations is large. Comparing the properties of X-ray
clusters of similar halo masses but having different X-ray luminosities, they
find that massive haloes with masses >~1014 h-1 Msun contain a larger
fraction of red satellite galaxies when they are brighter in X-ray. An
opposite trend is found in central galaxies in relative low-mass haloes with
masses <~1014 h-1 Msun where X-ray brighter clusters have smaller
fraction of red central galaxies. Clusters with masses >~1014 h-1 Msun
that are strong X-ray emitters contain many more low-mass satellite galaxies
than weak X-ray emitters. These results are also confirmed by checking X-ray
clusters of similar X-ray luminosities but having different characteristic
stellar masses. The cluster catalog containing the optical properties of
member galaxies and the X-ray luminosity is also available at
http://gax.shao.ac.cn/data/Group.html.
The optical data used in this analysis are taken from the SDSS galaxy group
catalogs of Yang et al. (2007, ApJ, 671, 153), constructed using the adaptive
halo-based group finder of Yang et al. (2005, MNRAS, 356, 1293), here updated
to DR7. The parent galaxy catalog is the New York University Value-Added
Galaxy Catalog (NYU-VAGC; Blanton et al. 2005, AJ, 129, 2562) based on the
SDSS DR7 (Abazajian et al. 2009, ApJS, 182, 543), which contains an
independent set of significantly improved reductions.
In this study, the authors adopt a Lambda cold dark matter cosmology whose
parameters are consistent with the 7-year data release of the WMAP mission:
Omegam = 0.275, OmegaLambda = 0.725, h = H0/(100 km s-1 Mpc-1) =
0.702, and sigma8 = 0.816.
SDSSBALQS2 Catalog
This table contains a catalog of 5035 broad absorption line (BAL)
quasars (QSOs) in the Sloan Digital Sky Survey (SDSS) Data Release 5 (DR5)
QSO catalog that have absorption troughs covering a continuous velocity range
greater than or equal to 2000 km s-1. The authors have fitted ultraviolet
(UV) continua and line emission in each case, enabling them to report common
diagnostics of BAL strengths and velocities in the range from -25,000 to 0 km
s-1 for Si IV 1400 Angstroms, C IV 1549 A, Al III 1857 A, and Mg II 2799 A.
The authors calculate these diagnostics using the spectrum listed in the DR5
QSO catalog, and also for spectra from additional SDSS observing epochs when
available. They confirm and extend previous findings that BAL QSOs are more
strongly reddened in the rest-frame UV than non-BAL QSOs, and that BAL QSOs
are relatively X-ray weak compared to non-BAL QSOs. The observed BAL fraction
is dependent on the spectral signal-to-noise ratio (S/N); for higher S/N
sources, the authors find an observed BAL fraction of about 15%. BAL QSOs show
a similar Baldwin effect as for non-BAL QSOs, in that their C IV emission
equivalent widths decrease with increasing continuum luminosity. However, BAL
QSOs have weaker C IV emission in general than do non-BAL QSOs. Sources with
higher UV luminosities are more likely to have higher-velocity outflows, and
the BAL outflow velocity and UV absorption strength are correlated with
relative X-ray weakness. These results are in qualitative agreement with
models that depend on strong X-ray absorption to shield the outflow from
overionization and enable radiative acceleration. In a scenario in which BAL
trough shapes are primarily determined by outflow geometry, observed
differences in Si IV and C IV trough shapes would suggest that some
outflows have ion-dependent structure.
The authors fit SDSS spectra using the algorithm of Gibson et al. (2008, ApJ,
675, 985), which we summarize here. For QSOs at z >= 1.7, their continuum
model is a power law reddened using the Small Magellanic Cloud (SMC) reddening
curve of Pei (1992, ApJ, 395, 130). For QSOs at lower redshifts, the authors
use a fourth- or sixth-degree polynomial; in their experience this nonphysical
model is able to reproduce well the complex continuum at longer wavelengths.
They initially fit regions that are generally free from strong absorption or
emission features: 1250-1350, 1700-1800, 1950-2200, 2650-2710, 2950-3700,
3950-4050, 4140-4270, 4400-4800, 5100-6400, and > 6900 Angstroms. They then
iteratively fit the continuum, ignoring at each step wavelength bins that
deviate by more than 3 sigma from the current fit in order to exclude strong
absorption and emission features. They fit Voigt profiles to the strongest
emission lines expected in the spectrum: Si IV 1400, C IV 1549, Al III 1857,
C III 1909, and Mg II 2799. These wavelengths are taken from the SDSS vacuum
wavelength list used by the SDSS pipeline to determine emission-line
redshifts.
Much more information on the SDSS is available at the project's web site
at http://www.sdss.org/.
SDSSBALQSO Catalog
The Sloan Digital Sky Survey (SDSS) Broad Absorption Line (BAL) Quasars
Catalog (based on the 3rd SDSS Data Release) contains a total of 4784 unique
BAL quasars from the SDSS DR3 (CDS Cat. <VII/243>). An automated algorithm
was used to match a continuum to each quasar and to identify regions of flux
at least 10% below the continuum over a velocity range of at least 1000 km/s
in the C IV and Mg II absorption regions. The model continuum was selected as
the best-fit match from a set of template quasar spectra binned in
luminosity, emission line width, and redshift z, with the power-law spectral
index and amount of dust reddening as additional free parameters. The authors
characterize their sample through the traditional 'balnicity' index BI and a
revised absorption index AI, as well as through parameters such as the width,
outflow velocity, fractional depth, and number of troughs. From a sample of
16,883 quasars at 1.7 <= z <= 4.38, they identify 4386 (26.0%) quasars with
broad C IV absorption, of which 1756 (10.4%) satisfy traditional selection
criteria. From a sample of 34,973 quasars at 0.5 <= z <= 2.15, they identify
457 (1.31%) quasars with broad Mg II absorption, 191 (0.55%) of which satisfy
traditional selection criteria. They find that BAL quasars may have broader
emission lines on average than other quasars.
Much more information on the SDSS is available at the project's web site
at http://www.sdss.org/.
SDSSCVCAT Catalog
The reference paper completed the series of cataclysmic variables (CVs)
identified from the Sloan Digital Sky Survey (SDSS) I and II. The
coordinates, magnitudes, and SDSS spectra of 33 more CVs were presented.
Among the 33 are eight systems known prior to SDSS (CT Ser, DO Leo, HK Leo,
IR Com, V849 Her, V405 Peg, PG1230+226, and HS0943+1404), as well as nine
objects recently found through various photometric surveys. Among the systems
identified since the SDSS are two polar candidates, two intermediate polar
candidates, and one candidate for containing a pulsating white dwarf. A
complete summary table of the 285 CVs with spectra from SDSS I/II which were
listed in the reference paper and the 7 previous papers in the series is
contained herein.
SDSSCXOQSO Catalog
The authors have studied the spectral energy distributions and
evolution of a large sample of optically selected quasars from the Sloan
Digital Sky Survey (SDSS) that were observed in 323 Chandra images analyzed
by the Chandra Multiwavelength Project (ChaMP). Their highest-confidence
matched sample (which this HEASARC table comprises) includes 1135 X-ray
detected quasars in the redshift range 0.2 < z < 5.4, representing some 36
Msec of effective exposure. In their paper, the authors provide catalogs of
QSO properties, and describe their novel method of calculating X-ray flux
upper limits and effective sky coverage. Spectroscopic redshifts are available
for about 1/3 of the detected sample; elsewhere, redshifts are estimated
photometrically. The authors have detected 56 QSOs with redshift z > 3,
substantially expanding the known sample. They find no evidence for evolution
out to z ~ 5 for either the X-ray photon index Gamma or for the ratio of
optical/UV to X-ray flux Alpha_ox. About 10% of detected QSOs show best-fit
intrinsic absorbing columns greater than 1022 cm-2, but the fraction might
reach ~1/3 if most nondetections are absorbed. The authors confirm a
significant correlation between Alpha_ox and optical luminosity, but it
flattens or disappears for fainter (M_B >~ -23) active galactic nucleus (AGN)
alone. They report significant hardening of Gamma both toward higher X-ray
luminosity, and for relatively X-ray loud quasars. These trends may represent
a relative increase in nonthermal X-ray emission, and their findings thereby
strengthen analogies between Galactic black hole binaries and AGN. For
uniformly selected subsamples of narrow-line Seyfert 1s and narrow absorption
line QSOs, they find no evidence for unusual distributions of either
Alpha_ox or Gamma.
Much more information on the SDSS is available at the project's web site
at http://www.sdss.org/.
SDSSDR10WD Catalog
The authors report the discovery of 9,088 new spectroscopically confirmed
white dwarfs and subdwarfs in the Sloan Digital Sky Survey (SDSS) Data
Release 10 (DR10). They obtain Teff, log g and masses for
hydrogen-atmosphere white dwarf stars (DAs) and helium-atmosphere white dwarf
stars (DBs), and estimate the calcium/helium abundances for the white dwarf
stars with metallic lines (DZs) and carbon/helium for carbon-dominated
spectra (DQs). They found 1 central star of a planetary nebula, 2 new oxygen
spectra on helium-atmosphere white dwarfs, 71 DQs, 42 hot DO/PG1159s, 171
white dwarf+main-sequence star binaries, 206 magnetic DAHs, 327
continuum-dominated DCs, 397 metal-polluted white dwarfs, 450
helium-dominated white dwarfs, 647 subdwarfs and 6887 new hydrogen-dominated
white dwarf stars.
The targeted white dwarfs were required to be point sources with clean
photometry, and to have USNO-B Catalog counterparts (Monet et al.. 2003, AJ,
125, 984, CDS Cat. I/284). They were also restricted to regions inside the
DR7 imaging footprint and required to have colors within the ranges g <
19.2, (u-r) < 0.4, -1 < (u-g) < 0.3, -1 < (g-r) < 0.5 and to have low
Galactic extinction Ar < 0.5 mag. Additionally, targets that did not have
(u-r) < -0.1 and (g-r) < -0.1 were required to have USNO proper motions larger
than 2 arcseconds per century (20 milliarcseconds per year). Objects
satisfying the selection criteria that had not been observed previously by
the SDSS were denoted by the WHITEDWARF_NEW target flag, while those with
prior SDSS spectra are assigned the WHITEDWARF_SDSS flag. Some of the latter
were re-observed with BOSS in order to obtain the extended wavelength
coverage that the BOSS spectrograph offers.
The color selection used includes DA stars with temperatures above ~14,000
K, helium-atmosphere white dwarfs above ~8000 K, as well as many rarer
classes of white dwarfs. Hot subdwarfs (sdB and sdO) were targeted as well.
Note that this catalog does not include stars from the earlier SDSS white
dwarf catalogs, e.g., Eisenstein et al. (2006, ApJS, 167, 40, available in
the HEASARC database as the SDSSDWDSD table), Kleinman et al. (2013, ApJS,
205, 5, available in the HEASARC database as the SDSSDR7WD table)..
SDSSDR7WD Catalog
This table contains a new catalog of spectroscopically confirmed
white dwarf stars from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7)
spectroscopic catalog. The authors find 20,407 white dwarf spectra,
representing 19,712 stars, and provide atmospheric model fits to 14,120 DA and
1011 DB white dwarf spectra from 12,843 and 923 stars, respectively. These
numbers represent more than a factor of two increase in the total number of
white dwarf stars from the previous SDSS white dwarf catalogs based on DR4
data. The distribution of subtypes varies from previous catalogs due to the
authors' more conservative, manual classifications of each star in our catalog,
supplementing their automatic fits. In particular, they find a large number of
magnetic white dwarf stars whose small Zeeman splittings mimic increased Stark
broadening that would otherwise result in an overestimated log g if fit as a
non-magnetic white dwarf. The authors calculate mean DA and DB masses for their
clean, non-magnetic sample and find the DB mean mass is statistically larger
than that for the DAs.
This table lists the 20,407 white dwarf spectra corresponding to 19,712
distinct stars.
SDSSLASQSO Catalog
This table contains a catalog of over 130,000 quasar candidates with
near-infrared (NIR) photometric properties, with an areal coverage of
approximately 1200 deg2. This is achieved by matching the Sloan Digital Sky
Survey (SDSS) in the optical ugriz bands to the UKIRT Infrared Digital Sky
Survey (UKIDSS) Large Area Survey (LAS) in the NIR YJHK bands. The authors
match the ~1 million SDSS DR6 Photometric Quasar catalog to Data Release 3 of
the UKIDSS LAS (ULAS) and produce a catalog with 130,827 objects with
detections in one or more NIR bands, of which 74,351 objects have optical and
K-band detections and 42,133 objects have the full nine-band photometry.
The majority (~85%) of the SDSS objects were not matched simply because these
were not covered by the ULAS. The positional standard deviation of the SDSS
Quasar to ULAS matches is 0.1370 arcseconds in RA and 0.1314 arcseconds in Dec.
The authors find an absolute systematic astrometric offset between the SDSS
Quasar catalog and the UKIDSS LAS, of |RA offset| = 0.025 arcseconds and
|Dec offset| = 0.040 arcseconds; they suggest the nature of this offset to be
due to the matching of catalog, rather than image, level data. Their matched
catalog has a surface density of ~53 deg-2 for K <= 18.27 objects; tests
using this matched catalog, along with data from the UKIDSS Deep Extragalactic
Survey, imply that its limiting magnitude is i ~ 20.6. Color-redshift diagrams,
for the optical and NIR, show a close agreement between this matched catalog
and recent quasar color models at redshift z <~ 2.0, while at higher redshifts,
the models generally appear to be bluer than the mean observed quasar colors.
SDSSNBCKDE Catalog
This table contains a catalog of 1,015,082 quasar candidates selected from
the photometric imaging data of the Sloan Digital Sky Survey (SDSS) using a
non-parametric Bayesian classification kernel density estimator (NBC-KDE). It
excludes 157,075 initial candidates that were culled as known or likely
contaminants. The objects are all point sources to a limiting magnitude of i
= 21.3 from 8417 deg2 of imaging from SDSS Data Release 6 (DR6). This
sample extends the previous catalog (Paper I: Richards et al. 2004, ApJS,
155, 257) by using the latest SDSS public release data and probing both
ultraviolet (UV)-excess and high-redshift quasars. While the addition of
high-redshift candidates reduces the overall efficiency (quasars:quasar
candidates) of the catalog to ~80%, it is expected to contain no fewer than
850,000 bona fide quasars, which is ~8 times the number of the previous
sample and ~10 times the size of the largest spectroscopic quasar catalog.
Cross-matching between this photometric catalog and spectroscopic quasar
catalogs from both the SDSS and 2dF survey yields 88,879 spectroscopically
confirmed quasars. For judicious selection of the most robust UV-excess
sources (~500,000 objects in all), the efficiency is nearly 97 - more than
sufficient for detailed statistical analyses. The catalog's completeness to
type 1 (broad-line) quasars is expected to be no worse than 70%, with most
missing objects occurring at z < 0.7 and 2.5 < z < 3.0. In addition to
classification information, the authors provide photometric redshift
estimates (typically good to Delta(z) +/- 0.3 [2-sigma]) and cross-matching
with radio, X-ray, and proper-motion catalogs. Finally, the authors have
considered the catalog's utility for determining the optical luminosity
function of quasars and are able to confirm the flattening of the bright-end
slope of the quasar luminosity function at z ~ 4 as compared to z ~ 2.
Much more information on the SDSS is available at the project's web site
at http://www.sdss.org/.
SDSSNBCQSC Catalog
The Nonparametric Bayes Classifier (NBC) Quasar Candidate Catalog is a
catalog of 100,563 unresolved, UV-excess (UVX) quasar candidates with
magnitudes to as faint as 21 in the g-band from 2099 square degrees of the
Sloan Digital Sky Survey (SDSS) Data Release One (DR1) imaging data. Existing
spectra of 22,737 sources reveals that 22,191 (97.6%) are quasars; accounting
for the magnitude dependence of this efficiency, the authors estimate that
95,502 (95.0%) of the objects in the catalog are quasars. Such a high
efficiency is unprecedented in broadband surveys of quasars. This
"proof-of-concept" sample is designed to be maximally efficient, but still
has 94.7% completeness to unresolved, g ~< 19.5, UVX quasars from the DR1
quasar catalog. This efficient and complete selection is the result of the
application of a probability density type analysis to training sets that
describe the four-dimensional color distribution of stars and
spectroscopically confirmed quasars in the SDSS. Specifically, the authors
use a nonparametric Bayesian classification, based on kernel density
estimation, to parametrize the color distribution of astronomical sources -
allowing for fast and robust classification. They further supplement the
catalog by providing photometric redshifts and matches to FIRST/VLA, ROSAT,
and USNO-B sources.
Much more information on the SDSS is available at the project's web site at
http://www.sdss.org/.
SDSSQUASAR Catalog
This table contains the Data Release 12 Quasar Catalog (DR12Q) from the
Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky
Survey III (SDSS-III). This catalog includes all SDSS-III/BOSS objects that
were spectroscopically targeted as quasar candidates during the full survey
and that are confirmed as quasars via visual inspection of the spectra, have
luminosities M_i_[z=2] < -20.5 (in a LambdaCDM cosmology with H0 = 70
km/s/Mpc, OmegaM = 0.3, and OmegaLambda = 0.7), and either display at
least one emission line with a full width at half maximum (FWHM) larger than
500 km/s or, if not, have interesting/complex absorption features. The
catalog also includes previously known quasars (mostly from SDSS-I and II)
that were re-observed by BOSS. The catalog contains 297,301 quasars (272,026
are new discoveries since the beginning of SDSS-III) detected over 9376
deg2 with robust identification and redshift measured by a combination of
principal component eigenspectra. The number of quasars with z > 2.15
(184,101, of which 167,742 are new discoveries) is about an order of
magnitude greater than the number of z > 2.15 quasars known prior to BOSS.
Redshifts and FWHMs are provided for the strongest emission lines (C IV, C
III], Mg II). The catalog identifies 29,580 broad absorption line quasars and
their characteristics are listed in the file dr12qbal.dat that is available
at the CDS (http://cdsarc.u-strasbg.fr/ftp/cats/VII/279/). For each object,
the catalog presents five-band (u, g, r, i, z) CCD-based photometry with
typical accuracy of 0.03 mag together with some information on the optical
morphology and the selection criteria. When available, the catalog also
provides information on the optical variability of quasars using SDSS and
Palomar Transient Factory multi-epoch photometry. The catalog also contains
X-ray, ultraviolet, near-infrared, and radio emission properties of the
quasars, when available, from other large-area surveys. The calibrated
digital spectra, covering the wavelength region 3600-10,500 Angstrom at a
spectral resolution in the range 1300 < R < 2500, can be retrieved from the
SDSS Catalog Archive Server at http://www.sdss.org/dr12/data_access/. In
their paper, the authors also provide a supplemental list of an additional
4,841 quasars that have been identified serendipitously outside of the
superset defined to derive the main quasar catalog, available as the file
dr12qsp.dat that is available at the CDS
(http://cdsarc.u-strasbg.fr/ftp/cats/VII/279/).
This table contains the final quasar catalog of the SDSS-III/BOSS survey
resulting from five years of observations. The catalog, which the authors
call "DR12Q", contains 297,301 quasars, 184,101 of which have z > 2.15. the
authors provide robust identification from visual inspection and refined
redshift measurements based on the result of a principal component analysis
of the spectra. The present catalog contains about 80% more quasars than
their previous release (Paris et al., 2014, "DR10Q", CDS Cat. VII/270).
In SDSS-III, all fluxes in the 5 SDSS bands (u, g, r, i and z) are expressed
in terms of "nanomaggies" (nMgy), which are a convenient linear unit. These
quantities are related to standard AB magnitudes thus: an object with a flux
F given in nMgy has a Pogson magnitude (on the AB scale) m = [22.5 mag] -
2.5*log10(F). A flux of 1 Mgy is therefore close to 3631 Jy, and 1 nMgy =
~3.631 uJy (µJy).
SDSSS82CXO Catalog
This table contains some of the data from the latest release of the Stripe 82
X-ray (82X) survey point-source catalog, which currently covers 31.3 deg2
of the Sloan Digital Sky Survey (SDSS) Stripe 82 Legacy field. In total,
6,181 unique X-ray sources are significantly detected with XMM-Newton (> 5
sigma) and Chandra (> 4.5 sigma). This 31 deg2 catalog release includes
data from XMM-Newton cycle AO 13, which approximately doubled the Stripe 82X
survey area. The flux limits of the Stripe 82X survey are 8.7 x 10-16 erg
s-1 cm-2, 4.7 x 10-15 erg s-1 cm-2, and 2.1 x 10-15 erg s-1
cm^=2^ in the soft (0.5 - 2.0 keV), hard (2 - 10 keV), and full (0.5 - 10
keV) bands, respectively, with approximate half-area survey flux limits of
5.4 x 10-15 erg s-1 cm-2, 2.9 x 10-14 erg s-1 cm-2, and 1.7 x
10-14 erg s-1 cm-2, respectively. The authors matched the X-ray source
lists to available multi-wavelength catalogs, including updated matches to
the previous release of the Stripe 82X survey; 88% of the sample is matched
to a multi-wavelength counterpart. Due to the wide area of Stripe 82X and
rich ancillary multi-wavelength data, including coadded SDSS photometry,
mid-infrared WISE coverage, near-infrared coverage from UKIDSS and VISTA
Hemisphere Survey (VHS), ultraviolet coverage from GALEX, radio coverage from
FIRST, and far-infrared coverage from Herschel, as well as existing ~30%
optical spectroscopic completeness, this study is beginning to uncover rare
objects, such as obscured high-luminosity active galactic nuclei at high
redshift. The Stripe 82X point source catalog is a valuable data set for
constraining how this population grows and evolves, as well as for studying
how they interact with the galaxies in which they live. The authors derive
the XMM-Newton number counts distribution and compare it with their
previously reported Chandra log N - log S relations and other X-ray surveys.
Throughout this study, the authors adopt a cosmology of H0 = 70 km s-1
Mpc-1, OmegaM = 0.27, and Lambda = 0.73.
The XMM-Newton and Chandra X-ray sources were matched with sources in the
SDSS, WISE, UKIDSS, VHS, GALEX, FIRST and Herschel databases using the
maximum likelihood estimator (MLE) method, as discussed in detail in Section
4 of the reference paper. This table contains the list of 1,146 Chandra
sources detected in the SDSS Stripe 82. A related table SDSSS82XMM contains
the list of 5,220 XMM-Newton sources detected in the SDSS Stripe 82.
SDSSS82XMM Catalog
This table contains some of the data from the latest release of the Stripe 82
X-ray (82X) survey point-source catalog, which currently covers 31.3 deg2
of the Sloan Digital Sky Survey (SDSS) Stripe 82 Legacy field. In total,
6,181 unique X-ray sources are significantly detected with XMM-Newton (> 5
sigma) and Chandra (> 4.5 sigma). This 31 deg2 catalog release includes
data from XMM-Newton cycle AO 13, which approximately doubled the Stripe 82X
survey area. The flux limits of the Stripe 82X survey are 8.7 x 10-16 erg
s-1 cm-2, 4.7 x 10-15 erg s-1 cm-2, and 2.1 x 10-15 erg s-1
cm^=2^ in the soft (0.5 - 2.0 keV), hard (2 - 10 keV), and full (0.5 - 10
keV) bands, respectively, with approximate half-area survey flux limits of
5.4 x 10-15 erg s-1 cm-2, 2.9 x 10-14 erg s-1 cm-2, and 1.7 x
10-14 erg s-1 cm-2, respectively. The authors matched the X-ray source
lists to available multi-wavelength catalogs, including updated matches to
the previous release of the Stripe 82X survey; 88% of the sample is matched
to a multi-wavelength counterpart. Due to the wide area of Stripe 82X and
rich ancillary multi-wavelength data, including coadded SDSS photometry,
mid-infrared WISE coverage, near-infrared coverage from UKIDSS and VISTA
Hemisphere Survey (VHS), ultraviolet coverage from GALEX, radio coverage from
FIRST, and far-infrared coverage from Herschel, as well as existing ~30%
optical spectroscopic completeness, this study is beginning to uncover rare
objects, such as obscured high-luminosity active galactic nuclei at high
redshift. The Stripe 82X point source catalog is a valuable data set for
constraining how this population grows and evolves, as well as for studying
how they interact with the galaxies in which they live. The authors derive
the XMM-Newton number counts distribution and compare it with their
previously reported Chandra log N - log S relations and other X-ray surveys.
Throughout this study, the authors adopt a cosmology of H0 = 70 km s-1
Mpc-1, OmegaM = 0.27, and Lambda = 0.73.
The XMM-Newton and Chandra X-ray sources were matched with sources in the
SDSS, WISE, UKIDSS, VHS, GALEX, FIRST and Herschel databases using the
maximum likelihood estimator (MLE) method, as discussed in detail in Section
4 of the reference paper. This table contains the list of 5,220 sources
detected in the SDSS Stripe 82 in archival, AO10 and AO13 XMM-Newton
observations. A related table SDSSS82CXO contains the list of 1,146 Chandra
sources detected in the SDSS Stripe 82.
Compared to the initial version of this catalog based on the 2013 paper, in
the current version of the catalog the MLE matching between the XMM-Newton
archival and AO10 source lists and ancillary catalogs was updated to include
a 1 arcsecond systematic error added in quadrature to the emldetect reported
positional error.
SDSSUNUQSR Catalog
Large spectroscopic surveys have discovered very peculiar and hitherto
unknown types of active galactic nuclei (AGN). Such rare objects may hold
clues to the accretion history of the supermassive black holes at the centres
of galaxies. The authors aim to create a sizeable sample of unusual quasars
from the unprecedented spectroscopic database of the Sloan Digital Sky Survey
(SDSS).
This table contains a catalog of 1005 quasars with unusual spectra in the
redshift interval from 0.6 to 4.3. [HEASARC Note: the redshifts in this table
actually range from 0.497 to 4.771]. The quasars were selected from the Sloan
Digital Sky Survey Data Release 7 (Abazajian et al., 2009, ApJS, 182, 543) by
means of Kohonen self-organising maps. The spectra are dominated by either
broad absorption lines (42%), unusual red continua (27%), weak emission lines
(18%), or conspicuously strong optical and/or UV iron emission (11%). This
large sample provides a useful resource for both studying properties and
relations of/between different types of unusual quasars and selecting
particularly interesting objects, even though the compilation is not aimed at
completeness in a quantifiable sense. The spectra are grouped into seven
types. The catalogue contains the redshift, the absolute magnitude, the
spectral type, the radio loudness parameter, a peculiarity index, and some
comments on peculiar spectral features.
SDSSWDSD Catalog
This is the Sloan Digital Sky Survey (SDSS) Data Release 4 (DR4)
Catalog of White Dwarfs (WDs) and Hot Subdwarf (SD) stars. It contains 9316
spectroscopically confirmed white dwarfs which have been selected through
photometric cuts and spectroscopic modeling, backed up by a set of visual
inspections. About 6000 of the WD stars are new discoveries, roughly
doubling the number of spectroscopically confirmed WD stars. The authors
have analyzed the stars by performing temperature and surface gravity fits
to grids of pure hydrogen and helium atmospheres. Among the rare outliers
are a set of presumed helium-core DA WDs with estimated masses below
0.3 solar masses, including two candidates that may be the lowest-mass WDs
yet found. This catalog also contains a list of 928 hot SD stars.
The SDSS DR4 (Adelman-McCarthy et al. 2006, ApJS, 162, 38; see also
http://www.sdss.org/dr4/ ) contains 800,000 spectra from 4783 square degrees.
The authors have used automated techniques supplemented by visual
classification to select 13,000 candidates. An extensive analysis of
these objects has yielded 9316 white dwarfs, including 8000 DA, 713 DB,
41 DO or PG1159, 289 DC, 104 DQ, and 133 DZ types, as well as 928 hot
subdwarf stars. As well as the 10,244 primary spectra, the authors
have also presented 774 duplicate spectra of WD stars and 60 duplicate spectra
of SD stars. Thus, the present table has 11,078 (=10,244 + 774 + 60) entries.
Much more information on the SDSS is available at the project's web site
at http://www.sdss.org/.
SDSSWHLGC Catalog
Clusters of galaxies in most of the previous catalogs have
redshifts z <= 0.3. Using the photometric redshifts of galaxies from the
Sloan Digital Sky Survey Data Release 6 (SDSS DR6), the authors identify
39,716 clusters in the redshift range 0.05 < z < 0.6 with more than eight
luminous (M_r <= -21) member galaxies. Cluster redshifts are estimated
accurately with an uncertainty of less than 0.022. The contamination rate
of member galaxies is found to be roughly 20%, and the completeness of
member galaxy detection reaches ~90%. Monte Carlo simulations show that the
cluster detection rate is more than 90% for massive (M_200 > 2 x 10^14
M_sun, where M_200 is the total mass within the radius in which the mean
mass density is 200 times the critical cosmic mass density) clusters of
z <= 0.42. The false detection rate is ~5%. The authors
obtain the richness, the summed luminosity, and the gross galaxy number
within the determined radius for identified clusters. They are tightly
related to the X-ray luminosity and temperature of the clusters. Cluster
mass is related to the richness and summed luminosity with M_200 ~
R^(1.90+/-0.04)^ and M_200 ~ L_r^(1.64+/-0.03)^, respectively. In addition,
790 new candidate X-ray clusters are found by cross-identification of
these clusters with the source list of the ROSAT X-ray All-Sky Survey.
SDSSXMMQSO Catalog
This table contains the 5th Data Release Sloan Digital Sky Survey (DR5
SDSS)/XMM-Newton Quasar Survey Catalog. This catalog contains 792 SDSS DR5
quasars with optical spectra that have been observed serendipitously in the
X-rays with XMM-Newton. These quasars cover a redshift range of z = 0.11 -
5.41 and a magnitude range of i = 15.3 - 20.7. Substantial numbers of
radio-loud (70) and broad absorption line (51) quasars exist within this
sample. Significant X-ray detections at >=2 sigma account for 87% of the
sample (685 quasars), and 473 quasars are detected at >=6 sigma, sufficient
to allow X-ray spectral fits. For detected sources, ~60% have X-ray fluxes
between F(2-10 keV) = (1-10) x 10-14 erg cm-2 s-1. The authors fit a
single power law, a fixed power law with intrinsic absorption left free to
vary, and an absorbed power-law model to all quasars with X-ray
signal-to-noise ratio >= 6, resulting in a weighted mean photon index Gamma =
1.91 +/- 0.08, with an intrinsic dispersion sigma(Gamma) = 0.38. For the 55
sources (11.6%) that prefer intrinsic absorption, the authors find a weighted
mean NH = 1.5 +/- 0.3 x 1021 cm-2. They find that Gamma correlates
significantly with optical color, Delta(g-i), the optical-to-X-ray spectral
index (alphaox), and the X-ray luminosity. While the first two correlations
can be explained as artifacts of undetected intrinsic absorption, the
correlation between Gamma and X-ray luminosity appears to be a real physical
correlation, indicating a pivot in the X-ray slope.
SWSDSSQSO Catalog
The authors have compiled a catalog of optically selected quasars with
simultaneous observations in UV/optical and X-ray bands by the Swift
Gamma-ray Burst Explorer. Objects in this catalog are identified by matching
the Swift pointings with the Sloan Digital Sky Survey (SDSS) Data Release 5
(DR5) quasar catalog. The final catalog contains 843 objects, among which 637
have both Ultraviolet Optical Telescope (UVOT) and X-Ray Telescope (XRT)
observations and 354 of which are detected by both instruments. The overall
X-ray detection rate is ~ 60% which rises to ~ 85% among sources with at
least 10 ks of XRT exposure time. The authors construct the time-averaged
spectral energy distribution (SED) for each of the 354 quasars using UVOT
photometric measurements and XRT spectra. From model fits to these SEDs, they
find that the big blue bump contributes about ~ 0.3 dex to the quasar
luminosity. The authors re-visit the alphaox - L2500A relation by
selecting a clean sample with only Type 1 radio-quiet quasars; the dispersion
of this relation is reduced by at least 15% compared with studies that use
non-simultaneous UV/optical and X-ray data. They find only a weak correlation
between Lbol/LEdd and alphaUV. They do not find significant
correlations between alphax and alphaox, alphaox and alphaUV, and
alphax and log L(0.3-10 keV). The correlations between alphaUV and
alphax, alphaox and alphax, alphaox and alphaUV, Lbol/LEdd and
alphax, and Lbol/LEdd and alphaox are stronger among low-redshift
quasars, indicating that these correlations are likely driven by the changes
of SED shape with accretion state.
This quasar sample was compiled in the following steps:
1. Candidate objects for the catalog were selected as any SDSS DR5 quasar
that lie within 20 arcminutes of the center of the Swift FOV in any pointing
from launch through 2008 June.
2. XRT data were processed to obtain X-ray count rates, spectra, and spectral
parameters.
3. UVOT data were processed to obtain UV and optical photometry.
4. UVOT photometry were supplemented with measurements at other wavelengths
from published catalogs.
5. Quasar SEDs were constructed.
6. Additional parameters were calculated based on the SEDs of each quasar.
The raw sample is constructed by matching 3.5 years Swift pointings and the
SDSS DR5 quasar catalog and contains 1034 objects.
This HEASARC version of this catalog contains all 1034 objects in the "raw"
catalog. To select only the 843 objects in the "final" catalog, the user
should specify catalog_flag = 1 in any searches of this table.
XMMSDSSGCE Catalog
This table contains results from the analysis of a sample of 383 X-ray
selected galaxy groups and clusters with spectroscopic redshift measurements
(up to z ~ 0.79) from the 2XMMi/SDSS Galaxy Cluster Survey. The X-ray cluster
candidates were selected as serendipitously detected sources from the
2XMMi-DR3 catalog that were located in the footprint of the Sloan Digital Sky
Survey (SDSS-DR7). The cluster galaxies with available spectroscopic
redshifts were selected from the SDSS-DR10. The authors developed an
algorithm for identifying the cluster candidates that are associated with
spectroscopically targeted luminous red galaxies and for constraining the
cluster spectroscopic redshift. A cross-correlation of the constructed
cluster sample with published optically selected cluster catalogs yielded 264
systems with available redshifts. The present redshift measurements
(presented in reference paper III) are consistent with the published values.
The current cluster sample extends the optically confirmed cluster sample
from the authors' cluster survey by 67 objects. Moreover, it provides
spectroscopic confirmation for 78 clusters among their published cluster
sample, which previously had only photometric redshifts. Of the new cluster
sample that comprises 67 systems, 55 objects are newly X-ray discovered
clusters and 52 systems are sources newly discovered as galaxy clusters in
optical and X-ray wavelengths. Based on the measured redshifts and the fluxes
given in the 2XMMi-DR3 catalogue, the authors have estimated the X-ray
luminosities and masses of the cluster sample.
This table contains 145 entries, 67 of which are new (as of Paper III)
optically confirmed clusters (marked by values of ref_source = 'Paper III')
and 78 of which are clusters from Paper II which have now been
spectroscopically confirmed (marked by values of ref_source = 'Paper II').
The tabular information on the 530 clusters that was presented in Paper II
of this set of papers is available as the HEASARC
XMMSDSSGCS table).
The following parameters were obtained from the current optical-band cluster
detection algorithm: sdss_dr10_bcg_id, sdss_dr10_bcg_ra, sdss_dr10_bcg_dec,
bcg_rmag, redshift, num_spect_members, phot_redshift, num_phot_members, and
spatial_offset.
XMMSDSSGCS Catalog
The authors have compiled a sample of X-ray-selected galaxy groups and
clusters from the XMM-Newton Serendipitous Source Catalog (2XMMi-DR3) with
optical confirmation and redshift measurement from the Sloan Digital Sky
Survey (SDSS). In their paper, they present an analysis of the X-ray
properties of this new sample with particular emphasis on the X-ray
luminosity-temperature (LX - T) relation. The X-ray cluster candidates were
selected from the 2XMMi-DR3 catalog in the footprint of the SDSS-DR7. The
authors developed a finding algorithm to search for overdensities of galaxies
at the positions of the X-ray cluster candidates in the photometric redshift
space and to measure the redshifts of the clusters from the SDSS data. For
optically confirmed clusters with good quality X-ray data, they derived the
X-ray flux, luminosity, and temperature from proper spectral fits, while the
X-ray flux for clusters with low-quality X-ray data was obtained from the
2XMMi-DR3 catalogue. The detection algorithm provides the photometric
redshift of 530 galaxy clusters. Of these, 310 clusters have a spectroscopic
redshift for at least one member galaxy. About 75 percent of the optically
confirmed cluster sample are newly discovered X-ray clusters. Moreover, 301
systems are known as optically selected clusters in the literature while the
remainder are new discoveries in X-ray and optical bands. The optically
confirmed cluster sample spans a wide redshift range 0.03 to 0.70 (median z =
0.32). In this paper, they present the catalog of X-ray-selected galaxy
groups and clusters from the 2XMMi/SDSS galaxy cluster survey.
The catalog has two subsamples: (i) a cluster sample comprising 345 objects
with their X-ray spectroscopic temperature and flux from the spectral
fitting; (these objects are identified by having values for the table_sample
parameter of 1 in this HEASARC implementation of the catalog) and (ii) a
cluster sample consisting of 185 systems with their X-ray flux from the
2XMMi-DR3 catalog, because their X-ray data are insufficient for spectral
fitting (these objects are identified by having values for the table_sample
parameter of 2 herein). For each cluster, the catalog also provides the X-ray
bolometric luminosity and the cluster mass at R500 based on scaling
relations and the position of the likely brightest cluster galaxy (BCG). The
updated LX - T relation of the current sample with X-ray spectroscopic
parameters is presented in the paper. The authors found the slope of the LX
- T relation to be consistent with published ones. They see no evidence for
evolution in the slope and intrinsic scatter of the LX - T relation with
redshift when excluding the low-luminosity groups.
This catalog of X-ray selected galaxy clusters and groups supersedes and
subsumes the first release of the 2XMMi/SDSS Galaxy Cluster Survey,
comprising 175 clusters of galaxies, which was presented in Takey et al.
(2011, A&A, 534, A120).
