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J/A+A/305/74 NGC 4565, 4656 & 5907 ROSAT observations (Vogler+ 1996)
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ROSAT observations of three edge-on spiral galaxies
Vogler A., Pietsch W., Kahabka P.T.
<Astron. Astrophys. 305, 74 (1996)>
=1996A&A...305...74V (SIMBAD/NED BibCode)
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ADC_Keywords: Galaxies, optical ; X-ray sources
Mission_Name: ROSAT
Keywords: galaxies: individual: NGC 4565 - galaxies: individual: NGC 4656 -
galaxies: individual: NGC 5907 - galaxies: spiral - X-rays: galaxies
Abstract:
The edge-on spiral galaxies NGC 4565, NGC 4656, and NGC 5907 have been
observed with the PSPC onboard ROSAT. The targets were selected for
low galactic foreground absorption to enable the detection of "soft"
X-ray emission, which is a fingerprint for the emission of a million
degree gaseous component. For NGC 4565 we find an X-ray luminosity of
1.1x10^40^erg/s . Point sources contribute 6.0x10^39^erg/s in the
bulge and 0.7x10^39^erg/s in the disk. 1.2x10^39^erg/s may be due to
diffuse X-ray emission in the bulge or disk. A nuclear source
(L_x_=2.7x10^39^erg/s) is visible. In the halo of NGC 4565 diffuse
emission with a luminosity of 2.6x10^39^erg/s was detected. The X-ray
data indicate low absorption and soft spectra. Attributing the entire
diffuse flux to emission of a hot thermal plasma, its density, mass,
and cooling time are n=0.6x10^-3cm^-3/sqrt({eta}),
m=2.2x10^7^Ms_{sun}_.sqrt({eta}) and {tau}=4.2x10^8^y.sqrt({eta}),
respectively (with the filling factor {eta}). The disturbed galaxy
NGC 4656 shows a luminosity of 1.5x10^39^erg/s, composed of a weak
nuclear point source (L_x_=1.3x10^38^erg/s), five further point
sources in the disk (L_x_=1.0x10^39^erg/s), and remaining diffuse
emission components (L_x_=0.3x10^39^erg/s). No diffuse emission could
be established in the halo of NGC 4656. NGC 5907 has an overall X-ray
luminosity of 6.5x10^39^erg/s. The only point source in the bulge
coincides with the nucleus (L_x_=2.8x10^39^erg/s), three point sources
in the disk show an integral luminosity of 3.2x10^39^erg/s. Neither
X-ray emission from SN 1940a in NGC 5907 nor diffuse halo emission
could be found. The different X-ray components for the three galaxies
are discussed and compared to results from other wavelength regimes.
Objects:
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RA (2000) DE Designation(s)
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12 36.3 +25 58 NGC 4565
12 44.2 +32 12 NGC 4656
15 15.9 +56 19 NGC 5907
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See also:
IX/11 : ROSAT Source Catalog (Voges+ 1994)
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3 94 11 Sources in bulge, disk, and halo of NGC 4565
table6 85 8 Sources in bulge, disk, and halo of NGC 4656
table7 94 7 Sources in bulge, disk, and halo of NGC 5907
table17 94 55 Serendipitous detections of sources in field A
table18 94 39 Serendipitous detections of sources in field B
table19 94 53 Serendipitous detection of sources in field C
table20 233 41 Proposed identifications of serendipitous
detections in field A, B. and C
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Byte-by-byte Description of file: table3 table6 table7 table17 table18 table19
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Bytes Format Units Label Explanations
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1- 3 A3 --- Field Field designation
5- 18 A14 --- Name Source name
20- 21 I2 h RAh Rights ascension (2000)
23- 24 I2 min RAm Rights ascension (2000)
26- 30 F5.2 s RAs Rights ascension (2000)
32 A1 --- DE- Declination sign
33- 34 I2 deg DEd Declination (2000)
36- 37 I2 arcmin DEm Declination (2000)
39- 42 F4.1 arcsec DEs Declination (2000)
44- 47 F4.1 arcsec e_Pos rms uncertainty on position
49- 54 F6.1 ---- L(Exist) Likelihood of existence
56- 61 F6.1 ct Counts Net counts in the ROSAT 0.1-2.4keV band
63- 66 F4.1 ct e_Counts rms uncertainty on Counts (1)
68- 71 F4.1 --- HR1 Hard ratio 1
73- 76 F4.1 --- HR2 Hard ratio 2
78- 81 F4.1 10-3ct/s Rate Count rate for the 0.1-2.4keV band
83- 85 F3.1 10-3ct/s e_Rate rms uncertainty on Rate
87- 89 I3 arcsec FWHMExt ? FWHM of the extent (2)
91- 94 F4.1 --- lExt ? Likelihood of extent (2)
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Note (1): In table 17, in the printed version,
Counts for A43 is 29.8 +/- -9.2.
In electronic table17, we transform e_Counts=-9.2 to 9.2
Note (2): FWHM and likelihood of extent for sources for which the extent exceeds
the PSPC PRF and for which the likelihood of extent is >=9.
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Byte-by-byte Description of file: table20
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Bytes Format Units Label Explanations
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1- 9 A9 --- Source Source name
11-144 A134 --- Candidate Candidate
146-149 F4.1 arcsec Err ? Distance of X-ray detection (1)
150 I1 arcsec Err2 ? Second value of Err (for A27 only)
151-162 A12 --- Ref References (2)
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Note (1): Distance of X-ray detection and proposed identification in arcsec,
including a 4" systematical error of the X-ray position, no error
quoted for extended objects.
Note (2): References:
PI,PII first and second PALOMAR survey
GC Gregory & Condon (1991ApJS...75.1011G)
GSC guide star catalogue from EXOSAT database,
Astrophysics Division at ESTEC
SIM SIMBAD catalogue, MPE database
HB Hewett & Burbridge (1989, A new Catalog of Quasi-Stellar
Objects, stored on magnetic tape 1989)
MB Mazarella & Balzano (1986ApJS...62..751M)
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History: Prepared via OCR at CDS.
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(End) James Marcout, Patricia Bauer [CDS] 11-Apr-1997