FER2FUSRID - Fermi 2FGL Unassociated Gamma-Ray Sources Possible Radio Identifications

Overview

This table contains some of the results from an all-sky radio survey between 5- and 9-GHz of sky areas surrounding all unassociated gamma-ray objects listed in the Fermi Large Area Telescope (LAT) Second Source Catalog (2FGL). The goal of these observations is to find all new gamma-ray active galactic nucleus (AGN) associations with radio sources > 10 mJy at 8GHz. The authors observed with the Very Large Array (VLA) and the Australia Telescope Compact Array (ATCA) the areas around unassociated sources, providing localizations of weak radio point sources found in 2FGL fields at arcminute scales. They then followed up a subset of these with the Very Long Baseline Array (VLBA) and the Long Baseline Array (LBA) in order to confirm detections of radio emission on parsec-scales. The authors quantified association probabilities based on known statistics of source counts and assuming a uniform distribution of background sources. In total, they found 865 radio sources at arcsecond scales as candidates for association and detected 95 of 170 selected for follow-up observations at milliarcsecond resolution. Based on this, they obtained firm associations for 76 previously unknown gamma-ray AGNs. Comparison of these new AGN associations with the predictions from using the Wide-field Infrared Survey Explorer (WISE) color-color diagram shows that half of the associations are missed. The authors found that in 129 out of 588 gamma-ray sources observed at arcminute scales not a single radio continuum source was detected above their sensitivity limit within the 3-sigma gamma-ray localization. These "empty" fields were found to be particularly concentrated at low Galactic latitudes. The nature of these Galactic gamma-ray emitters is not yet determined.

A list of 216 target fields were observed with the VLA. The instantaneous bandwidth was split into two parts, with one half centered at 5.0 GHz (4.5 - 5.5 GHz) and the other centered at 7.3 GHz (6.8 - 7.8 GHz). The observations were made on 2012 October 26 and 2012 November 3. See section 2.1 of the reference paper for more details. These data are included in this HEASARC table.

During the first campaign with the ATCA from 2012 September 19-20, the authors observed 411 2FGL unassociated sources in a Declination range of -90 degrees to +10 degrees at 5.5 and 9 GHz. The details of this observing campaign and results have been reported by Petrov et al. (2013, MNRAS, 432, 1294: available at the HEASARC as the AT2FGLUS table). The authors detected a total of 424 point sources. In a second ATCA campaign on 2013 September 25-28, the authors re-observed sources that were detected at 5 GHz, but were not detected at 9 GHz. See section 2.2 of the reference paper for more details. These data are included in this HEASARC table.

Follow-up observations of 149 targets selected from the VLA and ATCA surveys above -30 degrees Declination were conducted with the VLBA between 2013 Feb-Aug (VCS7 project; 4.128 - 4.608 and 7.392 - 7.872 GHz simultaneously) and in 2013 Jun-Dec (campaign S5272; 7.392 - 7.872 GHz only). See section 2.3 of the reference paper for more details. These data are NOT included in this HEASARC table.

For sources with Declination below -30 degrees, the authors added 21 objects to the on-going LCS campaign being conducted using the LBA (Petrov et al. 2011, MNRAS, 414, 2528) in 2013 Mar-2013 Jun at 8.200 - 8.520 GHz. See section 2.4 of the reference paper for more details. These data are NOT included in this HEASARC table.

Catalog Bibcode

2015ApJS..217....4S

References

New associations of gamma-ray sources from the Fermi Second Source Catalog.
    Schinzel F.K., Petrov L., Taylor G.B., Mahony E.K., Edwards P.G.,
    Kovalev YU.Y.
   <Astrophys. J. Suppl. Ser., 217, 4 (2015)>
   =2015ApJS..217....4S    (SIMBAD/NED BibCode)

Provenance

This table was created by the HEASARC in May 2015 based on the union of CDS Catalog J/ApJS/217/4/ files table2.dat (the 148 'Category I' objects that were detected at 5.0/5.5 and/or 7.3/9.0 GHz within 2.7' of the 2FGL counterpart localization), table3.dat (the 501 'Category II' objects that were detected at 5.0/5.5 and/or 7.3/9.0 GHz between 2.7' and 6.5' of the 2FGL counterpart localization) and table4.dat (the 216 'Category III' objects that were detected outside of the 6.5 arcminutes but still within the 99% positional uncertainty of the 2FGL counterpart localization). It thus contains a total of 865 objects.

HEASARC Implementation

The HEASARC has created a new parameter called category to identify the table from which the entry was taken. See the Provenance section for more details.

Parameters

Category
This HEASARC-created parameter contains the 'Category' of the radio source, essentially a measure of how close the radio and gamma-ray source positions are:

  Value  Category  Meaning
    1      I       The radio source is within 2.7' of the 2FGL
                   gamma-ray source localization
    2      II      The radio source is between 2.7' and 6.5' of the 2FGL
                   gamma-ray source localization and within the 3-sigma
                   positional uncertainty of the 2FGL counterpart localization
    3      III     The radio source is beyond 6.5' of the 2FGL
                   gamma-ray source localization but still within the 99%
                   positional uncertainty of the 2FGL counterpart localization

Name
The HEASARC-created IAU-style designation of the radio source. The HEASARC has added the prefix of '[SPT2015] ATCA' for ATCA-detected radio sources and of '[SPT2015] VLA' for VLA-detected radio sources, where SPT2015 stands for Schinzel, Petrov, Taylor 2015, to the J2000.0 positional based names given in the original tables, e.g., '[SPT2015] ATCA JHHMM-DDMM' for the ATCA sources and '[SPT2015] VLA JHHMM+DDMM' for the VLA sources. The convention for the IAU names was applied to the list of all sources regardless of the category defined above. It thus allows unique identification of radio point sources using this identifier across all categories. A letter replaces the last digit of the IAU name if there were multiple separate radio sources sharing the same name. If identical names were found, the authors replaced the last digit with a letter A. If the last letter of the previous source was A, then they changed the name to B, and so forth.

Fermi_2FGL_Name
The J2000.0 position-based 2FGL designation of the gamma-ray source, e.g., '2FGL JHHMM.m+DDMMc'.

Source_Flag
This parameter contains flag(s) indicating the following note(s) concerning the radio source:

     e = a source was found in a field of extended objects;
     f = a source has spectral index flatter than -0.5 between 5 and 7/9 GHz.

RA
The Right Ascension of 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 tables.

Dec
The Declination of the radio source in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.01 arcseconds in the original tables.

LII
The Galactic Longitude of the radio source.

BII
The Galactic Latitude of the radio source.

RA_Error
The uncertainty in the Right Ascension of the radio source, in arcseconds.

Dec_Error
The uncertainty in the Declination of the radio source, in arcseconds.

Flux_5_GHz
The flux density of the radio source at 5/5.5 GHz, in mJy, corrected for beam attenuation. Flux density values provided for the "Category III" radio sources detected more than 6.5 arcminutes from the 2FGL localization but within the 3-sigma confidence of the 2FGL gamma-ray source localization. are to be considered lower limits due to beam attenuation, consequently no errors for those values are provided.

Flux_5_GHz_Error
The uncertainty in the flux density of the radio source at 5.0 (VLA) or 5.5 (ATCA) GHz, in mJy.

Flux_7_GHz
The flux density of the VLA radio source at 7.3 GHz, in mJy, corrected for beam attenuation. Flux density values provided for the "Category III" radio sources detected more than 6.5 arcminutes from the 2FGL localization but within the 3-sigma confidence of the 2FGL gamma-ray source localization. are to be considered lower limits due to beam attenuation, consequently no errors for those values are provided.

Flux_7_GHz_Error
The uncertainty in the flux density of the radio source at 7.3 GHz, in mJy.

Flux_9_GHz
The flux density of the ATCA radio source at 9.0 GHz, in mJy, corrected for beam attenuation. Flux density values provided for the "Category III" radio sources detected more than 6.5 arcminutes from the 2FGL localization but within the 3-sigma confidence of the 2FGL gamma-ray source localization. are to be considered lower limits due to beam attenuation, consequently no errors for those values are provided.

Flux_9_GHz_Error
The uncertainty in the flux density of the radio source at 9.0 GHz, in mJy.

Spectral_Index_5g
The spectral index of the radio source within the 5/5.5 GHz band: i.e., between 4.58 and 6.42 GHz for the ATCA-detected sources and between 4.5 and 5.5 GHz for the VLA-detected sources.

Spectral_Index_5g_Error
The uncertainty in the spectral index of the radio source within the 5/5.5-GHz band.

Spectral_Index_9g
The spectral index of the radio source within the 9.0 GHz ATCA band, i.e., between 8.09 and 9.92 GHz.

Spectral_Index_9g_Error
The uncertainty in the spectral index of the radio source within the 9.0 GHz ATCA band.

Spectral_Index
The spectral index of the radio source between the 5.0/5.5 and the 7.2/9.0 GHz bands.

Spectral_Index_Error
The uncertainty in the spectral index of the radio source between the 5.0/5.5 and the 7.2/9.0 GHz bands.

Offset
The angular distance in arcminutes between the gamma-ray and radio source localizations.

Offset_Sigma
The normalized separation between the gamma-ray and radio source localizations, i.e., the ratio of the separation to its 1-sigma uncertainty.

Campaign
The observing campaign in which the radio source was detected:

     V1 = VLA observations made on 2012 October 26 and 2012 November 3;
     A1 = ATCA observations made on 2012 September 19-20;
     A2 = ATCA observations made on 2013 September 25-28.

Contact Person

Questions regarding the FER2FUSRID database table can be addressed to the HEASARC Help Desk.

Page Author: Browse Software Development Team
Last Modified: Monday, 16-Sep-2024 17:27:20 EDT