J/MNRAS/429/2143 Hidden population of AM CVns in the SDSS (Carter+, 2013)
A search for the hidden population of AM CVn binaries in the
Sloan Digital Sky Survey.
Carter P.J., Marsh T.R., Steeghs D., Groot P.J., Nelemans G., Levitan D.,
Rau A., Copperwheat C.M., Kupfer T., Roelofs G.H.A.
<Mon. Not. R. Astron. Soc. 429, 2143 (2013)>
=2013MNRAS.429.2143C 2013MNRAS.429.2143C
ADC_Keywords: Spectroscopy ; Binaries, cataclysmic ; Stars, white dwarf ;
Surveys ; QSOs
Keywords: accretion, accretion discs - binaries: close -
novae, cataclysmic variables -
stars: individual: SDSS J104325.08+563258.1 -
stars: individual: SDSS J173047.59+554518.5 -
white dwarfs
Abstract:
We present the latest results from a spectroscopic survey designed to
uncover the hidden population of AM Canum Venaticorum (AM CVn)
binaries in the photometric database of the Sloan Digital Sky Survey
(SDSS). We selected ∼2000 candidates based on their photometric
colours, a relatively small sample which is expected to contain the
majority of all AM CVn binaries in the SDSS (expected to be ∼50).
We present two new candidate AM CVn binaries discovered using this
strategy: SDSS J104325.08+563258.1 and SDSS J173047.59+554518.5. We
also present spectra of 29 new cataclysmic variables, 23 DQ white
dwarfs and 21 DZ white dwarfs discovered in this survey.
The survey is now approximately 70 per cent complete, and the
discovery of seven new AM CVn binaries indicates a lower space density
than previously predicted. From the essentially complete g∼19
sample, we derive an observed space density of (5±3)*10-7pc-3;
this is lower than previous estimates by a factor of 3.
The sample has been cross-matched with the GALEX All-Sky Imaging
Survey database, and with Data Release 9 of the UKIRT (United Kingdom
Infrared Telescope) Infrared Deep Sky Survey (UKIDSS). The addition of
UV photometry allows new colour cuts to be applied, reducing the size
of our sample to ∼1100 objects. Optimising our followup should allow
us to uncover the remaining AM CVn binaries present in the SDSS,
providing the larger homogeneous sample required to more reliably
estimate their space density.
Description:
Catalogue of the 1947 AM CVn binary candidates selected from SDSS Data
Release 7 (York+, 2000AJ....120.1579Y 2000AJ....120.1579Y; Abazajian+,
2009ApJS..182..543A 2009ApJS..182..543A) based on their photometric colours (Roelofs+,
2009MNRAS.394..367R 2009MNRAS.394..367R), together with FUV and NUV magnitudes obtained
from a cross-match with GALEX (Martin+, 2005ApJ...619L...1M 2005ApJ...619L...1M).
Identification spectra of the observed candidates cover wavelength
range ∼4000-7000Å, and were obtained at various facilities. Spectra
are supplied with relative flux calibration or normalised flux.
Classifications are based on our spectroscopy, or spectra from
subsequent SDSS data releases.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 180 1947 Target catalogue with coordinates and magnitudes
spf/* . 887 Spectra of candidates with flux calibration
sps/* . 486 Spectra of candidates with normalised flux
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See also:
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
http://www.sdss.org : SDSS Home Page
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 h RAh Right ascension (J2000)
4- 5 I2 min RAm Right ascension (J2000)
7- 11 F5.2 s RAs Right ascension (J2000)
13 A1 --- DE- Declination sign
14- 15 I2 deg DEd Declination (J2000)
17- 18 I2 arcmin DEm Declination (J2000)
20- 23 F4.1 arcsec DEs Declination (J2000)
26- 31 F6.3 mag FUVmag ? GALEX FUV magnitude
33- 37 F5.3 mag e_FUVmag ? GALEX FUVmag error
40- 45 F6.3 mag NUVmag ? GALEX NUV magnitude
47- 51 F5.3 mag e_NUVmag ? GALEX NUVmag error
54- 59 F6.3 mag umag SDSS u magnitude
61- 65 F5.3 mag e_umag SDSS umag error
68- 73 F6.3 mag gmag SDSS g magnitude
75- 79 F5.3 mag e_gmag SDSS gmag error
82- 87 F6.3 mag rmag SDSS r magnitude
89- 93 F5.3 mag e_rmag SDSS rmag error
96-101 F6.3 mag imag SDSS i magnitude
103-107 F5.3 mag e_imag SDSS imag error
110-115 F6.3 mag zmag SDSS z magnitude
117-121 F5.3 mag e_zmag SDSS zmag error
124-128 F5.3 mag Ag g band extinction (1)
131-138 A8 --- Type Spectral classification
141-152 A12 --- spFile Spectrum filename (2)
155-164 A10 "YYYY/MM/DD" Obs.date Observation date
167-174 A8 "h:m:s" Obs.time Observation time
177-180 I4 s ExpTime ? Exposure time
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Note (1): Extinction assuming full Galactic reddening according to
Schlegel et al., (1998ApJ...500..525S 1998ApJ...500..525S).
Note (2): Available files:
* Spectra with flux calibration are given a filename f*.dat, and are
in subdirectory "spf".
* Spectra without flux calibration are normalised and given a
filename s*.dat, and are in subdirectory "sps".
* The rest of the filename is formed from the first 6 digits of the
object's RA, with b,c etc. to indicate second and third objects with
similar RA. Further details of the files are supplied below.
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Byte-by-byte Description of file: spf/*
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.4 0.1nm lambda Wavelength in Angstroms (0.1nm)
12- 23 E12.6 cW/m2/nm Flux Flux at wavelength lambda, expressed in
erg/cm2/s/Å
26- 37 E12.6 cW/m2/nm e_Flux Error on flux at wavelength lambda
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Byte-by-byte Description of file: sps/*
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.4 0.1nm lambda Wavelength in Angstroms (0.1nm)
12- 23 E12.6 --- NFlux Normalised flux at wavelength lambda
26- 37 E12.6 --- e_NFlux Error on flux at wavelength lambda
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Acknowledgements:
Philip Carter, Philip.Carter(at)warwick.ac.uk
(End) Patricia Vannier [CDS] 18-Dec-2012