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DXRBS - ROSAT Deep X-Ray Radio Blazar Survey Catalog |
HEASARC Archive |
Overview
The authors have undertaken a survey, the Deep X-Ray Radio Blazar Survey (DXRBS), of archived, pointed ROSAT Position Sensitive Proportional Counter (PSPC) data for blazars by correlating the ROSAT WGACAT database with several publicly available radio catalogs, restricting their candidate list to serendipitous flat radio spectrum sources (Alphar <= 0.70, where SNu ~ Nu-Alphar). In their first paper (DXRBS-I), the authors discuss their survey methods, identification procedure, and first results. Their survey was found to be 95% efficient at finding flat-spectrum radio-loud quasars (FSRQs; 59 of their first 85 identifications) and BL Lacertae objects (22 of their first 85 identifications), a figure that is comparable to or greater than that achieved by other radio and X-ray survey techniques. The identifications presented therein showed that all previous samples of blazars (even when taken together) did not representatively survey the blazar population, missing critical regions of (LX, LR) parameter space within which large fractions of the blazar population lie. Particularly important was the identification of a large population of FSRQs (>=25% of DXRBS-I FSRQs) with ratios of X-ray to radio luminosity >= 10-6 (Alpharx <= 0.78). In addition, as a result of their greater sensitivity, the DXRBS-I already more than doubled the number of FSRQs in complete samples with 5-GHz (radio) luminosities between 1031.5 and 1033.5 ergs/s/Hz, and filled in the region of parameter space between X-ray-selected and radio-selected samples of BL Lac objects. The DXRBS-I was the very first sample to contain statistically significant numbers of blazars at low luminosities, approaching what should be the lower end of the FSRQ luminosity function.In DXRBS-II, the authors presented new identifications and spectra for 106 sources, including 86 radio-loud quasars, 11 BL Lacertae objects, and nine narrow-line radio galaxies. Together with the DXRBS-I objects and already-known sources, their sample now contained 298 identified objects: 234 radio-loud quasars [181 flat-spectrum quasars: FSRQ (Alphar <= 0.50) and 53 steep-spectrum quasars: SSRQ], 36 BL Lacs and 28 narrow-line radio galaxies. Redshift information is available for 96 per cent of these. Thus, the selection technique was ~90 per cent efficient at finding radio-loud quasars and BL Lacs. Reaching 5-GHz radio fluxes of ~ 50 mJy and 0.1 - 2.0 keV X-ray fluxes of a few times 10-14 erg/cm2/s, DXRBS is the faintest and largest flat-spectrum radio sample with nearly complete (~85 per cent) identification.
The DXRBS-I entries in this catalog (identified by having values of the parameter dxrbs_part equal to 1) contain data for 85 identified sources meeting the authors' selection criteria. A number of sources were serendipitously observed by ROSAT on more than one occasion, and, for completeness, the WGACAT positions and values for these multiply observed sources are listed separately, resulting in 102 DXRBS-I entries in this catalog (71 sources with 1 X-ray observation, 11 sources with 2 X-ray observations, and 3 sources with 3 X-ray observations).
The DXRBS-II entries in this catalog (identified by having values of the parameter dxrbs_part equal to 2) contain data for 106 identified sources meeting the authors' selection criteria. A number of sources were serendipitously observed by ROSAT on more than one occasion, and, for completeness, the WGACAT positions and values for these multiply observed sources are listed separately. In one case (1WGA J0513.8+0156') the source was detected twice by ROSAT and there are two possible optical counterparts: there are 2 entries for each X-ray observation corresponding to the different conterparts, resulting in a total of 4 entries for this source. There are 92 DXRBS-II sources with 1 X-ray observation, 11 sources with 2 X-ray observations, 2 sources with 4 X-ray observations and 1 source with 5 X-ray observations) resulting in 127 DXRBS-II entries for 106 sources in this catalog. Four of the DXRBS-I objects (1WGA J0421.5+1433, 1WGA J0528.5-5820, 1WGA J1057.6-7724 and 1WGA J1222.6+2934) were also included in DXRBS-II as higher signal-to-noise ratio (S/N) spectra were available. Thus, in the sum of the 2 DXRBS parts presented here, there are 229 entries corresponding to 191 newly discovered sources. The 109 previously identified blazars, 97 of which were listed in Table 6 of DXRBS-I, are not included in this table.
Catalog Bibcodes
1998AJ....115.1253P2001MNRAS.323..757L
References
The Deep X-ray Radio Blazar Survey. I. Methods and first results.
Perlman E.S., Padovani P., Giommi P., Sambruna R., Jones L.R.,
Tzioumis A., Reynolds J.
<Astron. J. 115, 1253 (1998)>
=1998AJ....115.1253P
The Deep X-Ray Radio Blazar Survey (DXRBS) - II. New identifications.
Landt H., Padovani P., Perlman E.S., Giommi P., Bignall H., Tzioumis A.
<Mon. Not. R. Astron. Soc. 323, 757 (2001)>
=2001MNRAS.323..757L
Provenance
This table was created by the HEASARC in March 2012 based on the merger of files table3.dat and table4.dat from the CDS Catalog J/AJ/115/1253 (DXRBS-I) and files table4.dat and table5.dat from the CDS Catalog J/MNRAS/323/757 (DXRBS-II). (Note that it does not include the list of 97 previously identified blazars given in table6.dat of the CDS Catalog J/AJ/115/1253.) The current DXRBS table replaced a previous version (ingested in March 1999) which included only the DXRBS-I tables 3 and 4.Parameters
Dxrbs_Part
This parameter created by the HEASARC identifies from which
part of the DXRBS the entry comes: a value of 1 indicates entries from DXRBS-I,
2 entries from DXRBS-II.
Entry_Number
This parameter created by the HEASARC uniquely identifies
sources within a given DXRBS part (I or II), and is a sequence number in
order of increasing J2000 RA. Thus, the two parameters dxrbs_part and
entry_number uniquely specify a DXRBS source.
Name
The name of the object, using the standard IAU nomenclature scheme
with the prefix of '1WGA' for WGACAT and the J2000 co-ordinates as the kernel.
RA
The Right Ascension of the X-ray source in the WGACAT database, in the
selected equinox. The co-ordinates in the original input table were J2000
equatorial coordinates and were given to a precision of 0.1 seconds of time.
Dec
The Declination of the X-ray source in the WGACAT database, in the
selected equinox. The co-ordinates in the original input table were J2000
equatorial coordinates and were given to a precision of 1 arcsecond.
LII
The Galactic Longitude of the X-ray source.
BII
The Galactic Latitude of the X-ray source.
Off_Axis
The off-axis angle of the X-ray source from the center of the PSPC
field of view, in arcminutes.
RA_Radio
The Right Ascension of the radio counterpart to the WGACAT X-ray
source in the selected equinox, in either the PMN or the GB6 Catalogs.
The co-ordinates in the original input table were J2000
equatorial coordinates and were given to a precision of 0.1 seconds of time.
Dec_Radio
The Declination of the radio counterpart to the WGACAT X-ray
source in the selected equinox, in either the PMN or the GB6 Catalogs.
The co-ordinates in the original input table were J2000
equatorial coordinates and were given to a precision of 1 arcsecond.
RA_Optical
The Right Ascension of the optical counterpart to the WGACAT
X-ray source in the selected equinox.
The co-ordinates in the original input table were J2000
equatorial coordinates and were given to a precision of 0.1 seconds of time.
Dec_Optical
The Declination of the optical counterpart to the WGACAT
X-ray source in the selected equinox.
The co-ordinates in the original input table were J2000
equatorial coordinates and were given to a precision of 1 arcsecond.
Position_Flag
This flag parameter is set to 'n' if there is a note
concerning the position of the source in the file
http://cdsarc.u-strasbg.fr/ftp/cats/J_MNRAS/323/757/notes.dat. It is thus
applicable only for DXRBS-II sources.
Xray_Opt_Offset
The offset between the X-ray and the optical positions,
in arcseconds.
Xray_Opt_Offset_Error
The rms uncertainty in the offset between the X-ray
and the optical positions, in arcseconds, given only for DXRBS-II sources.
Select_Flag
This flag parameter is set to 'N' to indicate that the source
does not meet the strict DXRBS selection criteria, given only for DXRBS-II
sources.
Source_Flag
This flag parameter is set to 'n' if there is a note
concerning the individual source in Section 3.4 of the DXRBS-II paper,
also available in the file
http://cdsarc.u-strasbg.fr/ftp/cats/J_MNRAS/323/757/notes.dat. It is thus
applicable only for DXRBS-II sources.
Count_Rate
The WGACAT ROSAT PSPC count rate of the source, in ct s-1.
For objects observed more than once by ROSAT, the count
rate, hardness ratios and X-ray flux are given for each observation.
Hardness_Ratio
The WGACAT ROSAT PSPC hardness ratio of the source, being
the ratio between the hard (0.87 - 2.0 keV) and medium (0.4 - 0.86 keV) band
count rates. (See Padovani and Giommi (1996, MNRAS, 279, 526).
For objects observed more than once by ROSAT, the count
rate, hardness ratios and X-ray flux are given for each observation. It is
available only for DXRBS-II sources.
Fx
The 0.1 - 2 keV X-ray flux of the source, in erg s-1 cm-2, not
corrected for Galactic extinction, and using a conversion factor that was
derived from the ROSAT PSPC count rate using the observed hardness ratio and
an assumed Galactic hydrogen column density. For objects observed more than
once by ROSAT, the count rate, hardness ratios and X-ray flux are given for
each observation.
Fx_Dens_1keV
The unabsorbed flux density of the source at 1 keV, in
microJansky, using a conversion factor that was derived from the ROSAT PSPC
count rate using the observed hardness ratio and an assumed Galactic hydrogen
column density.
Log_Fx_Flux_6_cm
The logarithm of the ratio between the 0.3 - 3.5 keV X-ray
flux and the radio flux at 6 cm of the source, in erg s-1 cm-2 Jy-1.
Flux_6_cm
The radio flux of the source at 6 cm, in mJy.
Spectral_Index
The radio spectral index of the source, calculated as
described in Section 2.1 of DXRBS-I and/or Section 2.2 of DXRBS-II.
Spectral_Index_Flag
This flag parameter is set to 'n' if there is a note
concerning the radio spectral index of the source in the file
http://cdsarc.u-strasbg.fr/ftp/cats/J_MNRAS/323/757/notes.dat. It is thus
applicable only for DXRBS-II sources.
BJ_Mag
The Bj (blue) magnitude of the optical counterpart (from COSMOS).
It is available only for DXRBS-II sources.
BJ_Mag_Flag
This flag parameter is set to 'n' if there is a note
concerning the Bj magnitude of the source in the file
http://cdsarc.u-strasbg.fr/ftp/cats/J_MNRAS/323/757/notes.dat. It is thus
applicable only for DXRBS-II sources.
Omag_Limit
This parameter is set to '>' if only an upper limit is available
for the corresponding parameter value.
Omag
The O-plate (blue) magnitude of the optical counterpart (from APM,
except if the corresponding flag parameter is set to 'n' in which case
see the cooresponding note for the source).
It is available only for DXRBS-II sources.
Omag_Flag
This flag parameter is set to 'n' if there is a note
concerning the O magnitude of the source in the file
http://cdsarc.u-strasbg.fr/ftp/cats/J_MNRAS/323/757/notes.dat. It is thus
applicable only for DXRBS-II sources.
Emag_Limit
This parameter is set to '>' if only an upper limit is available
for the corresponding parameter value.
Emag
The E-plate (red) magnitude of the optical counterpart (from APM,
except if the corresponding flag parameter is set to 'n' in which case
see the cooresponding note for the source).
It is available only for DXRBS-II sources.
Emag_Flag
This flag parameter is set to 'n' if there is a note
concerning the E magnitude of the source in the file
http://cdsarc.u-strasbg.fr/ftp/cats/J_MNRAS/323/757/notes.dat. It is thus
applicable only for DXRBS-II sources.
Object_Type
The object type of the source as given by the authors and
falling into one of several categories:
BL Lac BL Lacertae-type object (a sub-class of blazars)
FSRQ Flat-Spectrum Radio-Loud Quasar (a sub-class of blazars)
NLRG Narrow-Line Radio Galaxy
RG Radio Galaxy
SSRQ Steep-Spectrum Radio Quasar
A question mark indicates an uncertain classification. Full details of the
criteria used to categorize objects are given in the DXRBS-I and -II source
papers.
Redshift
The redshift of the source. This was computed, whenever possible,
by taking the mean of the values derived from the narrow lines. Where only
a single (broad) emission line was observed, it was assumed to be Mg II
2798 Angstroms. When only weak features were observed, the redshift is marked
as questionable (redshift_flag = '?') and (for DXRBS-II sources) the object is
discussed individually in Section 3.4 of the DXRBS-II source paper.
Redshift_Error
The sample standrad deviation in the redshift. No error
in the redshift is given if only 1 emission line was present in the optical
spectrum. This parameter is available only for DXRBS-II sources.
Redshift_Flag
This flag parameter is set to '?' to indicate that
the redshift is unknown (for DXRBS-I sources) or uncertain (for DXRBS-II
sources, as discussed above in the description of the redshift parameter).
Error_Radius
The error radius of the WGACAT X-ray source position,
in arcseconds.
This parameter is explicitly given only for DXRBS-I sources. For DXRBS-II
sources, it can be estimated using the value of the off-axis angle for the
source (the off_axis parameter) using the criteria given in Table 3 of
the DXRBS-II reference paper, and repeated here:
off_axis offset error_radius
(arcminutes) (arcseconds)
0 - 10 13.0
10 - 20 18.1
20 - 30 28.6
30 - 40 36.1
40 - 50 42.0
50 - 60 53.4
Ref_Position
The primary survey/catalog reference source for the accurate
positioning (identification) of the DXRBS-I source, using the following
acronyms:
APM Automatic Plate Measuring versions of the Palomar and UK
Schmidt Sky Catalogs
ATCA A snapshot survey with the Australia Telescope Compact Array
that was conducted by the authors at 3.6 and 6 cm
FIRST Faint Images of the Radio Sky at Twenty centimeters
(Becker et al. 1995, ApJS, 450, 559)
GB6 The Green Bank 6-cm Survey Catalog (Gregory et al. 1996,
ApJS, 103, 427)
NVSS NRAO VLA Sky Survey (Condon et al. 1998, AJ, 115, 1693)
OPT Optical identification
PMN Parkes-MIT-NRAO Survey (e.g., Wright et al. 1996,
ApJS, 103, 145, and papers cited therein)
TEXAS Texas Survey (Douglas et al. 1996, AJ, 111, 1945)
Optical_Error_Radius
The uncertainty in the optical counterpart position
(given only for DXRBS-I sources), in arcseconds.
Xray_Opt_Offset_Sigma
The ratio of the X-ray source to optical counterpart
positional offset to its uncertainty (xray_opt_offset/xray_opt_offset_error),
i.e., the number of sigma by which the positions disagree.
Bmag_Limit
This parameter is set to '>' if only an upper limit is available
for the corresponding parameter value.
Bmag
The B-magnitude of the optical counterpart to the DXRBS-I source,
obtained as discussed in Section 4 of DXRBS-I.
Rmag_Limit
This parameter is set to '>' if only an upper limit is available
for the corresponding parameter value.
Rmag
The R-magnitude of the optical counterpart to the DXRBS-I source,
obtained as discussed in Section 4 of DXRBS-I.
Other_Catalogs
This parameter contains coded references to other catalogs
in which the source is listed, as follows:
1: RASS Bright Source Catalog, CDS Cat. <IX/10>
2: HBQS, Homogeneous Bright QSO Survey, CDS Cat. <J/A+AS/112/347>
3: V Zwicky Catalog of Galaxies, CDS Cat. <VII/190>
4: 4C, Fourth Cambridge Survey, CDS Cat. <VIII/4>
5: Einstein Slew Survey, Elvis et al., 1992ApJS...80..257E
6: FIRST Bright Quasar Survey, See CDS Cat. <VIII/51>
7: B3, Third Bologna Survey, CDS Cat. <VIII/37>
8: Las Campanas Redshift Survey, CDS Cat. <VII/203>
Class
The HEASARC Browse object classification, based on the value of the
object_type parameter.
Contact Person
Questions regarding the DXRBS database table can be addressed to the HEASARC Help Desk.Page Author: Browse Software Development Team
Last Modified: Monday, 16-Sep-2024 17:26:39 EDT
- HEASARC Director: Dr. Andy Ptak
- NASA Official: Dr. Andy Ptak
- Web Curator: J.D. Myers
- Last Modified: 16-Sep-2024