J/AJ/124/3042 Narrow-line Seyfert 1 galaxies from SDSS EDR (Williams+, 2002)
Narrow-line Seyfert 1 galaxies from the Sloan Digital Sky Survey
Early Data Release.
Williams R.J., Pogge R.W., Mathur S.
<Astron. J. 124, 3042 (2002)>
=2002AJ....124.3042W 2002AJ....124.3042W
ADC_Keywords: Galaxies, Seyfert ; Radio sources
Keywords: galaxies: active - galaxies: Seyfert - X-rays
Abstract:
We present a sample of 150 narrow-line Seyfert 1 galaxies (NLS1's)
found within the Sloan Digital Sky Survey (SDSS) Early Data Release
(EDR) (Stoughton et al., 2002AJ....123..485S 2002AJ....123..485S), only two of which were
previously identified as such. This substantially increases the known
number of NLS1's and provides a basic method by which to identify many
more with subsequent releases of SDSS data. With its large size and
homogeneous, well-defined selection criteria, this sample will help
alleviate two major problems that have plagued NLS1 research in the
past; namely, their relative rarity and significant differences in
selection algorithms between the known samples. Forty-five of these
SDSS-selected NLS1's are detected at energies of 0.1-2keV in the ROSAT
All-Sky Survey (RASS) and are found to have ultrasoft X-ray spectra
with photon indices of Γ≳2, in agreement with previous results
for NLS1's. However, about 10-20 of those NLS1's that were not
detected by ROSAT have optical properties very similar to the detected
objects and so should also have been detected by the RASS. This may be
due to either significant intrinsic absorption in many NLS1's, or a
significant subclass of NLS1's that have uncharacteristic,
intrinsically flatter (hence harder) X-ray spectral energy
distributions.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 52 150 NLS1s from the SDSS Early Data Release
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See also:
VII/224 : Quasars and Active Galactic Nuclei (10th Ed.) (Veron+ 2001)
IX/10 : ROSAT All-Sky Survey Bright Source Catalogue (Vosges+, 1999)
IX/29 : ROSAT All-Sky Survey Faint Source Catalog (Voges+ 2000)
J/AJ/123/567 : SDSS quasar catalog (Schneider+, 2002)
J/AJ/123/485 : SDSS: early data release (EDR) (Stoughton+, 2002)
http://archive.stsci.edu/sdss/edr_main.html : SDSS-EDR Home page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- SDSS The Sloan Digital Sky Survey Name (1)
21- 25 F5.3 --- z Redshift
27- 30 I4 km/s FWHM The Hβ Full-Width at Half-Maximum
32- 36 F5.2 --- HR1 ? The ROSAT Hardness Ratio 1 parameter (2)
38- 41 F4.2 --- e_HR1 ? Uncertainty in HR1
43- 45 F3.1 --- Gamma ? The X-ray photon index (3)
47- 49 F3.1 --- e_Gamma ? Uncertainty in Gamma
51 I1 --- Note [1/5]? Additional notes (4)
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Note (1): Where the complete name format is: SDSS JHHMMSS.ss+DDMMSS.s
Note (2): Where HR1 = (B-A)/(B+A) and A and B denote the number of counts
in the 0.1-0.4 and 0.5-2.0keV bands, respectively. Note that if there
are zero counts in band A or B, HR1 becomes +1 or -1 respectively.
Note (3): Where fE(ph/keV/cm2/s) is proportional to E-Gamma.
Note (4): Additional notes:
1 = Listed as a NLS1 in Veron-Cetty & Veron (2001, Cat. VII/224);
2 = Previously classified as a Seyfert 1 by Puchnarewicz et al.
(1992MNRAS.256..589P 1992MNRAS.256..589P);
3 = Listed as a Seyfert 1 in NED, due to reference
in Veron-Cetty & Veron (2001, Cat. VII/224);
4 = Previously listed as a NLS1 in Veron-Cetty, Veron & Goncalves
(2001A&A...372..730V 2001A&A...372..730V);
5 = Listed as a Seyfert galaxy in La Franca, Cristiani, & Barbieri
(1992AJ....103.1062L 1992AJ....103.1062L).
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History:
From electronic version of the journal
(End) James Marcout, Patricia Bauer [CDS] 20-Jan-2003