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VLACOMACAT - VLA Coma Cluster of Galaxies 1.4-GHz Source Catalog

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Overview

This table contains results from deep 1.4-GHz Very Large Array (VLA) radio continuum observations of two ~0.5 deg2 fields in the Coma cluster of galaxies. The two fields, "Coma 1" and "Coma 3", correspond to the cluster core and the southwest infall region, and were selected on account of abundant pre-existing multiwavelength data. In their most sensitive regions, the radio data reach 0.022 mJy (22 microJy) rms per 4.4" beam, sufficient to detect (at 5-sigma) Coma member galaxies with L1.4GHz = 1.3 x 1020 W Hz-1 (1.3 x 1027 erg s-1 Hz-1). The full catalog of radio detections at and above a 4.5-sigma significance threshold is presented herein; there are 1030 of these sources which are detected at >= 5 sigma, 628 of which are within the combined Coma 1 and Coma 3 area. The authors also provide optical identifications of the radio sources using data from the Sloan Digital Sky Survey (SDSS). The depth of the radio observations allows them to detect active galactic nuclei in cluster elliptical galaxies with Mr < -20.5 (AB magnitudes), including radio detections for all cluster ellipticals with Mr < -21.8. At fainter optical magnitudes (-20.5 < Mr <~ -19), the radio sources are associated with star-forming galaxies with star formation rates as low as 0.1M_{sun}_ yr-1.

The VLA observations were performed over five days in 2006 June as program code AM868. On each of the five days, the scheduled time was centered on the transit of Coma.


Catalog Bibcode

2009AJ....137.4436M

References

A deep Very Large Array radio continuum survey of the core and outskirts
of the Coma cluster.
    Miller N.A., Hornschemeier A.E., Mobasher B.
   <Astron. J., 137, 4436-4449 (2009)>
   =2009AJ....137.4436M    (SIMBAD/NED BibCode)

Provenance

This table was created by the HEASARC in December 2011 based on CDS catalog J/AJ/137/4436 files table2.dat ('The Radio Source Catalog') and table3.dat ('Optical Counterparts to the Radio Sources'). It does not include table4.dat ('Rejected Optical Counterparts to the Radio Sources').

Parameters

Name
The radio source identification recommended by the Dictionary of Noemnclature of Celestial Objects), e.g., '[MHM2009c] CnA-nnn', where the prefix refers to Miller, Hornschemeier, Mobasher 2009) and the subsequent string is a unique source identification that the authors found useful in their analysis, the first part of which ('C1' or 'C3') presumably stands for the two fields, "Coma 1" and "Coma 3", corresponding to the cluster core and the southwest infall region.

RA
The Right Ascension of the fitted peak to the radio source in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.01 seconds of time in the original table.

Dec
The Declination of the fitted peak to the radio source in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.1 arcseconds in the original table.

LII
The Galactic Longitude of the radio source fitted peak.

BII
The Galactic Latitude of the radio source fitted peak.

SNR
The signal-to-noise ratio S/N of the radio source fitted peak. This was determined by the source identification algorithm "Seach and Destroy" (SAD) from the S/N map (see Section 2.3 of the reference paper for more details). Sources having 4.94 <S/N < 5.0 are listed as S/N = 4.9 to clarify that they are not formally 5{sigma} detections.

SNR_Flag
This parameter flags the source significance as follows:

        b = Although the peak S/N < 5 in the S/N map, the fitted value from
                  JMFIT is above a 5-sigma detection.
        c = Although the peak S/N >= 5 in the S/N map, the fitted value from
                  JMFIT is below a 5-sigma detection.
  

Flux_20_cm
The peak flux density of the radio source at 1.4 GHz, in mJy/beam (given in microJy/beam in the original table).

RMS_20_cm
The local RMS as evaluated in a 5-arcmin square box centered on the position of the radio source (this is also the error associated with the peak flux density measurement), in mJy/beam (given in microJy/beam in the original table).

Int_Flux_20_cm
The integral flux density of the radio source at 1.4 GHz, in mJy (given in microJy in the original table).

Int_Flux_20_cm_Error
The error in the radio source integral flux density at 1.4 GHz, in mJy (given in microJy in the original table).

Resolved
This flag parameter is set to 'Y' to indicate that the source was resolved, else is set to 'N' (values of 1 and 0 were used in the original table).

Resolved_Flag
This additional flag is set to 'a' to indicate that the source was extended, with the integral flux and error determined in an irregularly-shaped aperture using TVSTAT.

Near_Edge
This flag parameter is set to 'Y' to indicate that the source was within ~2.5 arcminutes of the edge of the radio mosaic, else is set to 'N' (values of 1 and 0 were used in the original table).

Comment_1
Additional comments concerning the source.

SDSS_RA
The Right Ascension of the SDSS optical counterpart to the radio source in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.01 seconds of time in the original table.

SDSS_Dec
The Declination of the SDSS optical counterpart to the radio source in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.1 arcseconds in the original table.

Vla_SDSS_Offset
The separation between the radio position and its SDSS optical counterpart, in arcseconds.

Umag
The SDSS u-band model magnitude of the SDSS optical counterpart to the radio source.

Gmag
The SDSS g-band model magnitude of the SDSS optical counterpart to the radio source.

Rmag
The SDSS r-band model magnitude of the SDSS optical counterpart to the radio source.

Imag
The SDSS i-band model magnitude of the SDSS optical counterpart to the radio source.

Zmag
The SDSS z-band model magnitude of the SDSS optical counterpart to the radio source.

SDSS_Phot_Class
The SDSS optical counterpart photometric class, where 3 = galaxy and 6 = star.

Note_Flag
This flag is set to a non-blank value of 'a' through 'h' to indicates that there is a detailed note on the source coded as follows:

    a = Radio emission is resolved, providing a likely explanation for the
        somewhat large radio-optical separation.
    b = The morphology of the extended radio emission is consistent with that
        of the optical. In the case of spiral galaxies this indicates that the
        radio emission traces the galaxy disk, whereas for elliptical galaxies
        the center of the galaxy appears to be from where the radio emission
       originates.
    c = Source appears to be the host of a radio double. The indicated
        separation is for distance from optical source to midpoint of the radio
        counterparts listed in the comment_2 parameter.
    d = Source separation is greater than 3 arcecs; see Figure 5 in the
        reference paper.
    e = Optical position for bright clump within larger galaxy.
    f = Galaxy appears to be one member of a galaxy pair.
    g = Radio emission is unresolved, but lies within the optical extent of
        the galaxy.
    h = Optical source not in SDSS catalog due to proximity to bright source,
        usually the diffraction spike of a saturated star. The position
        represents the coordinates of the peak of the object as measured
        directly in the SDSS r-band image.
  

Comment_2
Additional comments concerning the source, including NGC names for extended radio galaxies in the Coma cluster and related radio sources (see also the meaning of the note_flag = 'c' value above.


Contact Person

Questions regarding the VLACOMACAT database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 14-Dec-2011