J/A+A/418/1 Radio continuum spectra in Virgo cluster region (Vollmer+, 2004)
Radio continuum spectra of galaxies in the Virgo cluster region.
Vollmer B., Thierbach M., Wielebinski R.
<Astron. Astrophys. 418, 1 (2004)>
=2004A&A...418....1V 2004A&A...418....1V
ADC_Keywords: Clusters, galaxy ; Galaxies, radio ; Radio continuum
Keywords: galaxies: clusters: individual: Virgo - galaxies: evolution -
galaxies: magnetic fields - radio continuum: galaxies
Abstract:
New radio continuum observations of galaxies in the Virgo cluster
region at 4.85, 8.6, and 10.55GHz are presented. These observations
are combined with existing measurements at 1.4 and 0.6GHz. The sample
includes 81 galaxies where spectra with more than two frequencies
could be derived. Galaxies that show a radio-FIR excess exhibit
central activity (HII, LINER,AGN). The four Virgo galaxies with the
highest absolute radio excess are found within 2 degrees of the center
of the cluster. Galaxies showing flat radio spectra also host active
centers. There is no clear trend between the spectral index and the
galaxy's distance to the cluster center.
Description:
We extend the galaxy sample of Niklas et al. (1995A&A...293...56N 1995A&A...293...56N) by
adding observations at 8.6GHz and enlarging the sample to 81 galaxies,
which were observed at 10.55, 8.6, 4.85GHz with the Effelsberg 100-m
telescope in December 2000, January 2001, and in August September
November 2002. Our data is complemented by 1.4GHz flux densities from
the NVSS where advantage is taken of the NVSS images to check for
source confusion and to estimate the correct source flux. In addition
0.6GHz and FIR (IRAS)data are given. The 1.4 and 0.6GHz and FIR data
are taken from the Goldmine database, which is operated by the
University of Milano-Bicocca (Gavazzi et al., 2003A&A...400..451G 2003A&A...400..451G).
Radio spectra are derived for galaxies, for which detections at at
least 3 different frequencies are available. The spectral index is
given in the catalog.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 94 81 Radio and FIR fluxes of the galaxy sample
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See also:
J/AJ/90/1681 : The Virgo Cluster Catalog (VCC) (Binggeli+, 1985)
J/A+AS/127/367 : Virgo Photometry Catalogue (VPC) (Young+ 1998)
J/A+A/343/86 : Virgo cluster radio luminosity function. I. (Gavazzi+ 1999)
J/A+A/396/449 : Hα surface photometry in Virgo (Gavazzi+, 2002)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [VCC]
4- 7 I4 --- VCC VCC number
10- 11 I2 h RAh Right ascension (B1950)
13- 14 I2 min RAm Right ascension (B1950)
16- 17 I2 s RAs Right ascension (B1950)
19 A1 --- DE- Declination sign (B1950)
20- 21 I2 deg DEd Declination (B1950)
23- 24 I2 arcmin DEm Declination (B1950)
26- 27 I2 arcsec DEs Declination (B1950)
29- 33 F5.2 deg Dist Distance to the center of the Virgo cluster
(RA = 12 28 17.7, DE = +12 40 01, B1950)
36- 39 A4 --- Mtype Morphological galaxy type
42 A1 --- Virgo [yn] Virgo cluster membership (y/n)
45- 47 I3 mJy S10.55GHz ? Flux density at 10.55GHz (2.8cm)
49- 50 I2 mJy e_S10.55GHz ? Flux density error at 10.55GHz (2.8cm)
51 A1 --- n_S10.55GHz [*] *: from Niklas et al., 1995A&A...293...56N 1995A&A...293...56N
53- 56 I4 mJy S8.6GHz ? Flux density at 8.6GHz (3.6cm)
58- 59 I2 mJy e_S8.6GHz ? Flux density error at 8.6GHz (3.6cm)
61- 64 I4 mJy S4.85GHz ? Flux density at 4.85GHz (6.0cm)
66- 67 I2 mJy e_S4.85GHz ? Flux density error at 4.85GHz (6.0cm)
68 A1 --- n_S4.85GHz [*] *: from Niklas et al., 1995A&A...293...56N 1995A&A...293...56N
70- 73 I4 mJy S1.4GHz Flux density at 1.4GHz (20cm)
75- 79 I5 mJy S0.6GHz ? Flux density at 0.6GHz (50cm)
81- 86 F6.2 10-14W/m2 FIR ? FIR flux (1)
88- 92 F5.2 --- Sp+Index ? Spectral index
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Note (1): The FIR flux is defined by Helou (1988ApJS...68..151H 1988ApJS...68..151H):
FIR = 1.26 [2.58f(60) + f(100)]
where f(60), f(100) are the IRAS flux densities expressed in Jy
and FIR is the far infra-red flux in 10-14 W/m2
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Acknowledgements: Bernd Vollmer
(End) Bernd Vollmer [CDS] 06-Apr-2004