J/ApJ/511/595 An X-Ray Survey of Galaxies in Pairs (Henriksen+, 1999)
An X-Ray Survey of Galaxies in Pairs
Henriksen M., Cousineau S.
<Astrophys. J. 511, 595 (1999)>
=1999ApJ...511..595H 1999ApJ...511..595H
ADC_Keywords: Clusters, galaxy; Surveys; X-ray sources
Mission_Name: ROSAT
Keywords: clusters: general - galaxies: interactions - surveys -
X-rays: galaxies
Abstract:
Results are reported from the first survey of X-ray emission from
galaxies in pairs. The sample consists of 52 pairs of galaxies from
the Catalog of Paired Galaxies (Cat. VII/77) whose coordinates
overlap the ROSAT Position Sensitive Proportional Counter pointed
observations. The mean observed log(Lx) for early-type pairs is
41.35±0.21, while the mean log(Lx) predicted using the
(LX-Lb) relationship for isolated early-type galaxies is 42.10±0.19.
With 95% confidence, the galaxies in pairs are underluminous in the
X-ray, compared with isolated galaxies, for the same Lb. A
significant fraction of the mixed pair sample also appears similarly
underluminous. A spatial analysis shows that the X-ray emission from
pairs of both types typically has an extent of 10 - 50 kpc, much
smaller than the group intergalactic medium, and thus likely
originates from the galaxies. CPG 564, the most X-ray luminous
early-type pair, 4.7x1042ergs/s, is an exception. The extent of
its X-ray emission, greater than 169 kpc, and HWHM, ∼80 kpc, is
comparable to that expected from an intergalactic medium. The sample
shows only a weak correlation, ∼81% confidence, between LX and
Lb, presumably due to variations in gas content within the galaxies.
No correlation between LX and the pair velocity difference
(δv), separation (δr), or far-infrared luminosity (Lfir)
is found, although the detection rate is low, 22%.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 101 52 Data for spiral galaxy pairs
table2.dat 92 16 Data for early-type galaxy pairs
table3.dat 101 36 Data for mixed galaxy pairs
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See also:
VII/77 : Catalogue of isolated pairs of galaxies in northern hemisphere
J/other/ApL/30.1 : Southern catalogue of isolated pairs extension
(Reduzzi+ 1995)
VII/113 : Catalogued Galaxies + QSOs observed in IRAS Survey,
Vers.2 (IPAC 1989)
II/156A : IRAS Faint Source Catalog, |b| > 10, Version 2.0 (Moshir+ 1989)
Byte-by-byte Description of file: table*.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- CPG Catalog of Paired Galaxies number (1)
8- 19 A12 --- Morph Galaxy morphological type from NED
21- 22 I2 h RAh Right Ascension (J2000)
24- 25 I2 min RAm Right Ascension (J2000)
27- 28 I2 s RAs Right Ascension (J2000)
30 A1 --- DE- Sign of the Declination (J2000)
31- 32 I2 deg DEd Declination (J2000)
34- 35 I2 arcmin DEm Declination (J2000)
37- 38 I2 arcsec DEs Declination (J2000)
43- 48 F6.2 arcmin Sep ? Separation of Galaxy pairs
50- 54 I5 km/s Vel Recessional velocity
56- 60 F5.2 10+36W LumB Blue luminosity (1043ergs/s)
68- 74 F7.3 10-2ct/s Cnts ? Background subtracted Xray counts
(10-2/s)
79- 83 F5.3 10-2ct/s e_Cnts ? 1 sigma error in Cnts (10-2/s)
85 A1 --- l_LumX limit on LumX
87- 92 F6.2 10+34W LumX ? Xray luminosity from 0.25-2 KeV
(1041ergs/s)
96-101 F6.2 [10-7W] LumIR ? Log of the Far IR luminosity (erg/s) (2)
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Note (1): Data in columns CPG and between RAh and LumB are based on
information from Karachentsev (1972). A Hubble constant of 50
km.s-1.Mpc-1 is used to calculate the luminosities.
Note (2): Calculated from fluxes obtained from the Catalogue of
Galaxies and Quasars Observed in the IRAS Survey, version 2.1, as well
as the Point Source Catalog and the Faint Source Catalog. The FIR
sources occur within a 25 kpc search radius centered on each of the
galaxy positions.
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History:
From ApJ electronic edition
References:
Karachentsev, I. 1972, Comm. Spec. Ap. Obs., USSR, 7, 1 (CPG)
(End) Greg Schwarz (AAS) 10-Feb-2000