J/MNRAS/401/1151 RASS-6dFGS catalogue (Mahony+, 2010)
The RASS-6dFGS catalogue: a sample of X-ray selected AGN from the 6dF
galaxy survey.
Mahony E.K., Croom S.M., Boyle B.J., Edge A.C., Mauch T., Sadler E.M.
<Mon. Not. R. Astron. Soc., 401, 1151-1165 (2010)>
=2010MNRAS.401.1151M 2010MNRAS.401.1151M
ADC_Keywords: Surveys ; X-ray sources ; Active gal. nuclei ; Redshifts
Keywords: catalogues - galaxies: active - X-rays: galaxies
Abstract:
We present a catalogue of 3405 X-ray sources from the ROSAT All Sky
Survey (RASS) Bright Source Catalogue which fall within the area
covered by the 6dF Galaxy Survey (6dFGS). The catalogue is count-rate
limited at 0.05cts/s in the X-ray and covers the area of sky with
δ<0° and |b|>10°. The RASS-6dFGS sample was one of the
additional target catalogues of the 6dFGS and as a result we obtained
optical spectra for 2224 (65 per cent) RASS sources. Of these, 1715
(77 per cent) have reliable redshifts with a median redshift of z=0.16
(excluding the Galactic sources). For the optically bright sources
(bJ≤17.5) in the observed sample, over 90 per cent have reliable
redshifts. The catalogue mainly comprises quasi-stellar objects (QSOs)
and active galaxies but also includes 238 Galactic sources. Of the
sources with reliable redshifts the majority are type 1 active
galactic nuclei (AGN, 69 per cent), while 12 per cent are type 2 AGN,
6 per cent absorption-line galaxies and 13 per cent are stars. We also
identify a small number of optically faint, very low redshift, compact
objects which fall outside the general trend in the bJ-z plane. The
RASS-6dFGS catalogue complements a number of Northern hemisphere
samples, particularly the ROSAT Bright Source Catalogue-NRAO VLA Sky
Survey (RBSC-NVSS) sample (Bauer et al., 2000, Cat. J/ApJS/129/547/),
and furthermore, in the same region of sky (-40°<δ<0°)
reveals an additional 561 sources that were not identified as part of
that sample. We detect 918 sources (27 per cent) of the RASS-6dFGS
sample in the radio using either the 1.4GHz NVSS or the 843MHz Sydney
University Molonglo Sky Survey (SUMSS) catalogues and find that the
detection rate changes with redshift. At redshifts larger than 1
virtually all of these sources have radio counterparts and with a
median flux density of 1.15Jy, they are much stronger than the median
flux density of 28.6mJy for the full sample. We attribute this to the
fact that the X-ray flux of these objects is being boosted by a jet
component, possibly Doppler boosted, that is only present in
radio-loud AGN. The RASS-6dFGS sample provides a large set of
homogeneous optical spectra ideal for future studies of X-ray emitting
AGN.
Description:
Objects were selected such that the dominant source of X-ray emission
originates from an AGN. The target list was selected from the southern
sources (δ≤0°) of the RBSC, a total of 9578 sources.
Sources were then checked for optical identifications via a visual
inspection process using Digitized Sky Survey (DSS) images. The
majority of the optical positions were taken from the United States
Naval Observatory (USNO) data base, with the remainder taken from
either the Automated Plate Measuring (APM) or DSS catalogues.
Positions from these latter catalogues were used when the USNO
appeared to give an incorrect position according to the DSS images.
Optical magnitudes were taken from the USNO-A2.0 catalogue (Monet
1998, Cat. I/252).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 190 3405 6dFGS-RASS AGN catalog
refs.dat 73 200 References
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See also:
VII/259 : 6dF galaxy survey final redshift release (Jones+, 2009)
IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- 6dFGS 6dFGS name (gHHMMSSs+DDMMSS)
17- 18 I2 h RAh Optical right ascension (J2000)
20- 21 I2 min RAm Optical right ascension (J2000)
23- 27 F5.2 s RAs Optical right ascension (J2000)
29 A1 --- DE- Optical declination sign (J2000)
30- 31 I2 deg DEd Optical declination (J2000)
33- 34 I2 arcmin DEm Optical declination (J2000)
36- 39 F4.1 arcsec DEs Optical declination (J2000)
41- 44 F4.1 mag bJmag ?=99.9 USNO bJ magnitude
46- 49 F4.1 mag Rmag USNO R magnitude
51 A1 --- --- [R]
52- 65 A14 --- RASS RASS name (HHMMSSs+DDMMSS, J2000)
67 A1 --- n_RASS [E.] E when X-ray source is extended (1)
69- 76 E8.3 ct/s CRate Count rate
78- 85 E8.3 ct/s e_CRate rms uncertainty on CRate
87- 94 E8.3 cm-2 N(H) Galactic hydrogen column density (2)
96-103 E8.3 mW/m2 Fx RASS (X-ray) flux (erg/s) (3)
105-112 E8.3 mW/m2 e_Fx rms uncertainty on Flux
114-120 F7.1 mJy S1.4 ?=- NVSS (1.4GHz) flux
122-129 F8.1 mJy S0.8 ?=- SUMSS (843MHz) flux
131-137 F7.4 --- z ?=- 6dFGS redshift
139-145 F7.5 --- e_z ?=- rms uncertainty on z
147 I1 --- q_z [0/6] Quality flag (4)
149-151 I3 --- ProgID ?=0 Program ID of the 6dFGS spectrum
153-156 A4 --- Class Classification from NED (G, QSO, AbLS or UvES)
158-163 F6.4 --- zNED ?=- Redshift from NED
165-169 A5 --- r_zNED Reference of the NED redshift, in refs.dat file
171-190 A20 --- Com Comments (5)
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Note (1): This is determined such that the source extent given in the RASS-BSC
is larger than 35-arcsec.
Note (2): This was calculated using the N(H) program in the HEASARC collection
which uses data from Dickey & Lockman (1990ARA&A..28..215D 1990ARA&A..28..215D) and
Kalberla et al. (2005A&A...440..775K 2005A&A...440..775K, Cat. VIII/76).
Note (3): The flux was calculated using a fixed photon index of 1.7 and the
Galactic column to determine the unabsorbed flux in the 0.1-2.4keV band.
This made use of the PIMMS program in the HEASARC collection.
Note (4): Quality flag; '0' signifies that the object wasn't observed as part
of the 6dFGS. Values 3 and 4 are regarded as reliable, and value 6 is set
for galactic sources.
Note (5): To prevent these comments from being unnecessarily complicated they
are generally self-explanatory, with the follwoing one-word entries added
during the visual inspection of the 6dFGS redshifts and should be used as
a guide only (a question mark signifies any uncertainty in the comments):
Broad = the spectrum features broad emission lines
Narrow = the spectrum has narrow emission features
Abs = the spectrum exhibits only absorption lines
BLLac = a featureless spectrum with strong continuum
Active M-star = characteristic M-star spectrum with strong Balmer emission
at z=0
WD = white dwarf star
CV = cataclysmic variable star
Neb = spectrum displays z=0 nebula emission lines
Bad splicing = refers to an error in the data reduction process when the two
arms of the spectrum (blue and red) were not matched together correctly
in the final spectrum
Fringing = fringing occasionally occurs causing strong oscillations in the
spectrum. This is due to either a small air pocket or damage in the fibre
which causes it to act like a Fabry-Perot filter. Some redshifts could
still be distinguished accurately.
Blue/red arm only = an error with either the red or blue arm during
observations resulting in only half of the spectrum being available.
Contamination = a nearby source (generally a foreground star) dominates the
spectrum, masking any optical signature of the RASS source.
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Ref Reference code
7- 25 A19 --- BibCode BibCode
27- 52 A26 --- Aut Author's name
54- 73 A20 --- Com Comments
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 30-Sep-2014