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FERMILAC - Fermi LAT Second AGN Catalog

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Overview

This is the second catalog of active galactic nuclei (AGN) detected by the Fermi Large Area Telescope (LAT) in two years of scientific operation (Ackermann et al. 2011, ApJ 743, 171). The second LAT AGN catalog includes 1017 gamma-ray sources located at high Galactic latitudes (|b| > 10 degrees) that are detected with a test statistic (TS) greater than 25 (approximately 5-sigma) and associated statistically with AGNs. However, some of these are affected by analysis issues and some are associated with multiple AGNs. Consequently, we define a clean sample which includes 886 AGNs, comprising 395 BL Lacertae objects (BL Lac objects), 310 flat-spectrum radio quasars (FSRQs), 157 candidate blazars of unknown type (i.e., with broadband blazar characteristics but with no optical spectral measurement yet), 8 misaligned AGNs, 4 narrow-line Seyfert 1 (NLS1s), 10 AGNs of other types, and 2 starburst galaxies. Where possible, the blazars have been further classified based on their spectral energy distributions (SEDs) as archival radio, optical, and X-ray data permit. This second AGN catalog represents a significant improvement relative to the first LAT AGN catalog, with 52% more associated sources.

Catalog Bibcode

2011ApJ...743..171A

Bulletin

The FERMILAC database table was last updated on 15 May 2012.

References

A full description of the Second Fermi LAT AGN Catalog is given in "The Second Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope" (Ackermann et al. 2011 ApJ, 743, 171).

Provenance

This database table was created by the HEASARC in February 2010 based on the electronic data provided by the Fermi Science Support Center (FSSC) representing a combination of Tables 1, 2, and 3 of the referenced paper (Abdo et al. 2010) for the First LAT AGN Catalog.

It was updated in May 2012 to contain the Second LAT AGN Catalog, representing a combination of Tables 3, 4, 7, and 8 of the Ackermann et al. 2011 paper. Data were obtained from the 2LAC database hosted by the Agenzia Spazial Italiano Science Data Center (ASDC) at http://www.asdc.asi.it/fermi2lac/.


Parameters

Name
The source designation, 2FGL JHHMM.m+DDMM, constructed according to the IAU Specifications for Nomenclature, in which the Right Ascension and Declination have been truncated to 0.1 decimal minutes and 1', respectively. The '2' refers to the second catalog and 'FGL' represents Fermi Gamma-ray LAT.

AGN_Name
The designation of the associated AGN, as taken from one of the following astronomical catalogs:

     CRATES  Combined Radio All-sky Targeted Eight GHz Survey (Healey et al. 2007)
     CGRaBS  Candidate Gamma-Ray Blazar Survey (Healey et al. 2008)
     BZn     Roma-BZCAT (Massaro et al. 2009)
     NGC     New General Catalog (Dreyer 1887)
     PKS     Parkes Radio Sources Catalogue (Wright A.E. and Otrupcek R. 1990)
     RX      ROSAT (Bade et al. 1992)
     CLASS   Cosmic Lens All-Sky Survey (Myers et al. 2003; Browne et al. 2003)
     FRBA    Sources observed at 8.4 GHz as part of VLA program AH996
     1WGA    Catalog of ROSAT PSPC Sources (White, Giommi and Angelini 1995)
     4C      4th Cambridge Survey (Pilkington and Scott P F 1965; Gower, Scott
                  and Wills 1967)
     CXOMP   ChandraX-ray Observatory Multiwavelength Project (Kim et al. 2004)
     M       Messier (1782)
     B2,3    Second, Third Bologna Survey (Colla et al. 1970; Ficarra et al. 1985)
     Oa      Ohio Survey (Scheer & Kraus 1967; Rinsland et al. 1975)
     Ton     Tonanzintla Observatory Survey (Chavira 1958)
     1ES     Einstein Slew Survey (Elvis et al. 1992)
     TX      Texas Survey (Douglas et al. 1996)
     Mkn     Markarian (1967)
     SDSS    Sloan Digital Sky Survey
     CXOCY   Chandra X-ray Observatory, Calan Yale (Castander et al., 2003)
     ESO     European Southern Observatory (Lauberts and Valentijn 1989)
     2E      Second Einstein IPC Survey
     PG      Palomar Observatory Green Survey (Green et al., 1986)
  

RA
The Right Ascension of the associated AGN.

Dec
The Declination of the associated AGN.

LII
The Galactic Longitude of the associated AGN.

BII
the Galactic Latitude of the associated AGN.

Angular_Separation
The angular separation, in degrees, between the 2FGL source position and the position of the associated AGN.

Error_Radius
The error in the source position, in degrees, calculated from the geometric mean of the semi-major and semi-minor axes of the gamma-ray 95%-confidence region.

Optical_Class
The optical classification of the AGN, as follows:

     AGN             = Active galactic nucleus
     AGU             = Active galaxy of uncertain type
     BL Lac          = BL Lacertae object
     FSRQ            = Flat-spectrum radio quasar
     Radio Galaxy    = Active galaxy that is very luminous at radio wavelengths
     SSRQ            = Steep-spectrum radio quasar
     Starbust Galaxy = Galaxy with an exceptionally high rate of star formation
     Unindentified   = No classification determined
  

SED_Class
The classification of the AGN spectral energy distribution, based on the synchrotron peak frequency, as follows:

     LSP = low-synchrotron-peaked (sources with peak frequency < 1014 Hz)
     ISP = intermediate-synchrotron-peaked (1014 Hz < peak frequency < 1015 Hz)
     HSP = high-synchrotron-peaked (sources with peak frequency > 1015 Hz)
  

Redshift
The redshift of the AGN.

Bayesian_Prob
The Bayesian probability of the source association.

Radio_Gamma_Reliability
The reliability of the likelihood ratio for radio/gamma association.

Xray_Gamma_Reliability
The reliability of the likelihood ratio for X-ray/gamma association.

LogNLogS_Prob
The log(N)-log(S) probability of the source association.

Radio_Gamma_Likelihood
The likelihood ratio for radio/gamma association.

Xray_Gamma_Likelihood
The likelihood ratio for X-ray/gamma association.

Photon_Flux
The photon flux, in units of photons/cm2/s in the 1-100 GeV band.

Photon_Flux_Error
The 1-sigma uncertainty for the photon flux, in units of photons/cm2/s, in the 1-100 GeV band.

Spectral_Index
The photon number spectral index.

Spectral_Index_Error
The 1-sigma uncertainty for the photon spectral index.

Detection_Significance
The test statistic for detection. This is approximately equal to sigma2.

Flux_Radio
The radio flux desnsity, in mJy. These are obtained mainly from the GB6 (Gregory et al. 1996) and PMN catalogs and are at 4.85 GHz (6 cm).

Flux_Xray
This is the X-ray flux, in erg s-1 cm-2. The X-ray fluxes are derived from the ROSAT All Sky Survey (RASS) (Voges et al. 1999), Swift X-Ray Telescope, White-Giommi-Angelini (White et al. 2000), XMM (XMM-Newton Survey Science Centre 2010), and Brera Multi-scale Wavelet (Lazzati et al. 2001) catalogs. RAS, White-Giommi-Angelini & the Brera Multi-Scale wavelet catalogs are in the 0.2-2.4 keV band; XMM & Swift are in the 0.5-12 keV band (approximately).

Vmag_USNOB1
The V magnitude from the USNO-B1 catalog.

Vmag_SDSS
The V magnitude from the SDSS.

Alpha_Ro
The multi-frequency spectral index between the radio and optical bands.

Alpha_Ox
The multi-frequency spectral index between the optical and X-ray bands.

Clean_Flag
The flag 'Y' indicates that the source is in the clean sample; 'N' otherwise.

TwoFGL_Flag
The flag 'Y' indicates that the source is in the 2FGL catalog; 'N' otherwise.


Contact Person

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

Page Author: Browse Software Development Team
Last Modified: 15-May-2012