J/A+A/361/491 NGC 3109 X-ray sources (Kahabka+, 2000)
Probing the gas content of the dwarf galaxy NGC 3109 with
background X-ray sources.
Kahabka P., Puzia T.H., Pietsch W.
<Astron. Astrophys. 361, 491 (2000)>
=2000A&A...361..491K 2000A&A...361..491K
ADC_Keywords: X-ray sources
Keywords: catalogs - galaxies: individual: NGC 3109 - galaxies: active -
galaxies: ISM - radio continuum: galaxies - X-rays: galaxies
Abstract:
We established the catalog of X-ray point sources in the field of the
Magellanic-type spiral galaxy NGC 3109 (DDO 236) from two ROSAT PSPC
observations. Of the 91 X-ray sources 26 are contained within the HI
extent of NGC 3109 as derived by Jobin & Carignan
(1990AJ....100..648J 1990AJ....100..648J) with the VLA. For 10 of these we can determine
accurate hardness ratios δHR2≤0.2. We find 3 candidate AGN, 2
candidate X-ray binaries and one source which may belong to either
class. We also find 2 candidate foreground stars. In a field of 8'x8'
observed with the NTT in the I-b and and centered on the nucleus of
NGC 3109 we determine candidates for optical counterparts in the X-ray
error circle of 7 ROSAT PSPC sources. We apply a spectral fit to the
ROSAT spectrum of the X-ray brightest absorbed candidate AGN behind
NGC 3109, RX J1003.2-2607. Assuming a galactic foreground hydrogen
column density of 4.3x1020cm-2 we derive from the X-ray spectral
fit, assuming reduced metallicities (∼0.2 solar), a hydrogen column
density due to NGC 3109 of 11±75x1020cm-2. This value is
slightly larger than the hydrogen column density derived from the
21-cm observations of ∼8x1020cm-2. We estimate that the molecular
mass fraction of the gas is not larger than ∼60%.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 31 30 Shape parameters of the 5 brightest sources
within 90% confidence circle of 6 optically
matched ROSAT source coordinates.
table6.dat 88 91 ROSAT PSPC X-ray catalog of the NGC 3109 field
notes.dat 80 21 Individual notes on table6.
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See also:
IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)
IX/30 : Second ROSAT PSPC Catalog (ROSAT, 2000)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Source Source number (1)
4 I1 --- Label Label number in the source, in agreement
with label in fig. 6 (1)
6- 10 F5.2 mag Imag Instrumental I magnitude
12- 15 F4.2 mag e_Imag rms uncertainty on Imag
17- 20 F4.2 arcsec FWHM FWHM
22- 26 F5.3 --- Ell Ellipticity (1-a/b)
28- 31 F4.2 --- Class [0/1] Classification star-galaxy (2)
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Note (1): Objects are identified as [KPP2000] NN N in Simbad.
Source 59: too crowded. no reliable parameters can be given.
Note (2): Star-galaxy classification parameter of SExtraxtor:
1: point source
0: extended
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq Catalog index
4- 6 I3 --- Source Source number
7 A1 --- n_Source [*] Individual note in file notes.dat
8- 18 A11 --- RXJ RXJ number
20- 21 I2 h RAh Right ascension (J2000)
23- 24 I2 min RAm Right ascension (J2000)
26- 29 F4.1 s RAs Right ascension (J2000)
31 A1 --- DE- Declination sign (J2000)
32- 33 I2 deg DEd Declination (J2000)
35- 36 I2 arcmin DEm Declination (J2000)
38- 39 I2 arcsec DEs Declination (J2000)
41- 42 I2 arcsec e_Pos 90% confidence positional uncertainty
44- 49 F6.2 ct/ks CRT Total count rate
51- 54 F4.2 ct/ks e_CRT rms uncertainty on CRT
56- 60 F5.2 --- HR1 Soft hardness ratio
62- 65 F4.2 --- e_HR1 rms uncertainty on HR1
67- 71 F5.2 --- HR2 Hard hardness ratio
73- 76 F4.2 --- e_HR2 rms uncertainty on HR2
78- 81 I4 --- LH Likelihood ratio of existence
83- 85 I3 arcsec Ext ? Source extent in cases where the likelihood
ratio for extent is greater than 20
87- 88 I2 arcsec Delta Off-axis angle
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Byte-by-byte Description of file: notes.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Source Source number (repeated if necessary)
5- 80 A76 --- Text Text of note
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History:
Prepared via OCR at CDS.
One correction in table6 on 31-May-2001
(End) James Marcout, Patricia Bauer [CDS] 31-Jan-2001