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FERMI3FHL - Third Catalog of Hard Fermi-LAT Sources (3FHL)

 HEASARC
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Overview

This is a catalog of sources detected above 10 GeV by the Fermi-Large Area Telescope (LAT) in the first 7 years of data using the Pass 8 event-level analysis. It contains 1558 objects characterized in the 10 GeV to 2 TeV energy range. The sensitivity and angular resolution are improved by factors of 3 and 2 relative to the previous LAT catalog at the same energies (1FHL). The vast majority of detected sources (79%) are extragalactic, including 16 sources located at very high redshift (z > 2). Nine percent of the sources are Galactic and 12% are unassociated (or associated with a source of unknown nature). The high-latitude sky and the Galactic plane are observed with an average sensitivity of 0.5% and 1% of the Crab Nebula flux above 10 GeV, respectively. The catalog includes 225 new gamma-ray sources. The substantial increase in the number of photons (more than 4 times relative to the 1FHL and 10 times to the 2FHL) also allows us to characterize spectral curvature for 32 sources and flux variability for 163 of them. Furthermore, we estimate that for the same energy flux limit of 10-12 erg cm2 s-1, the energy range above 10 GeV has twice as many sources as the range above 50 GeV, which confirms and quantifies the importance of lowering the energy threshold of Cherenkov telescopes as much as possible in order to increase the number of available sources.

Catalog Bibcode

2017ApJS..232...18A

Bulletin

The FERMI3FHL database table was last updated on 20 December 2017.

References

A full description of the catalog is given by the Fermi LAT team in "The Third Catalog of Hard Fermi-LAT Sources". Additional information for which is available at http://fermi.gsfc.nasa.gov/ssc/data/access/lat/3FHL/.

Provenance

This database table was first ingested by the HEASARC in December 2017 using electronic data obtained from the Fermi Science Support Center (FSSC). That data is available at http://fermi.gsfc.nasa.gov/ssc/data/access/lat/3FHL/.

Parameters

Name
The source designation, 3FHL JHHMM.m+DDMM[e], 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 '3' refers to the second catalog and 'FHL' represents "Fermi Hard LAT". A name ending with 'e' indicates an extended source.

RA
The Right Ascension of the gamma-ray source in the selected equinox.

Dec
The Declination of the gamma-ray source in the selected equinox.

LII
The Galactic Longitude of the gamma-ray source in decimal degrees.

BII
The Galactic Latitude of the gamma-ray source in decimal degrees.

Error_Radius
The position uncertainty at 95% confidence level in decimal degrees.

Roi
The region of interest number.

Significance
The gamma-ray source significance, in units of sigma.

Pivot_Energy
The energy at which the error on differential photon flux is minimal (decorrelation energy for the power-law fit). Derived from the likelihood analysis over the full band.

Flux_Density
The differential photon flux at the pivot energy. Derived from the likelihood analysis over the full band.

Flux_Density_Error
The 1-sigma error on differential photon flux at the pivot energy.

Flux
The integral photon flux between 10 GeV and 1 TeV, in photon/cm2/s.

Flux_Error
The 1-sigma uncertainty on integral photon flux between 10 GeV and 1 TeV, in photon/cm2/s.

Energy_Flux
The energy flux from 10 GeV to 1 TeV, in erg/cm2/s.

Energy_Flux_Error
The 1-sigma uncertainty on energy flux from 10 GeV to 1 TeV, in erg/cm2/s.

Curve_Significance
The significance (in sigma units) of the fit improvement between PowerLaw and LogParabola. A value greater than 9 triggers switching to the curved spectrum.

Spectrum_Type
The spectral type (PowerLaw or LogParabola).

Spectral_Index
The spectral index at the pivot energy when fitting with the LogParabola model.

Spectral_Index_Error
The 1-sigma uncertainty on the spectral index.

Beta
The curvature parameter when fitting with the LogParabola model.

Beta_Error
The 1-sigma error on beta.

Powerlaw_Index
The spectral index when fitting with the power law model.

Powerlaw_Index_Error
The 1-sigma error on the power-law index.

Flux_10_20_GeV
The integral photon flux from 10 GeV to 20 GeV, in photon/cm2/s.

Flux_10_20_GeV_Neg_Err
The lower (negative) uncertainty on integral photon flux from 10 GeV to 20 GeV, in photon/cm2/s.

Flux_10_20_GeV_Pos_Err
The upper (positive) uncertainty on integral photon flux from 10 GeV to 20 GeV, in photon/cm2/s.

nuFnu_10_20_GeV
The spectral energy distribution from 10 GeV to 20 GeV, in erg/cm2/s.

Sqrt_TS_10_20_GeV
The square root of the test statistic between 10 GeV and 20 GeV.

Flux_20_50_GeV
The integral photon flux from 20 GeV to 50 GeV, in photon/cm2/s.

Flux_20_50_GeV_Neg_Err
The lower (negative) uncertainty on integral photon flux from 20 GeV to 50 GeV, in photon/cm2/s.

Flux_20_50_GeV_Pos_Err
The upper (positive) uncertainty on integral photon flux from 20 GeV to 50 GeV, in photon/cm2/s.

nuFnu_20_50_GeV
The spectral energy distribution from 20 GeV to 50 GeV, in erg/cm2/s.

Sqrt_TS_20_50_GeV
The square root of the test statistic between 20 GeV and 50 GeV.

Flux_50_150_GeV
The integral photon flux from 50 GeV to 150 GeV, in photon/cm2/s.

Flux_50_150_GeV_Neg_Err
The lower (negative) uncertainty on integral photon flux from 50 GeV to 150 GeV, in photon/cm2/s.

Flux_50_150_GeV_Pos_Err
The upper (positive) uncertainty on integral photon flux from 50 GeV to 150 GeV, in photon/cm2/s.

nuFnu_50_150_GeV
The spectral energy distribution from 50 GeV to 150 GeV, in erg/cm2/s.

Sqrt_TS_50_150_GeV
The square root of the test statistic between 50 GeV and 150 GeV.

Flux_150_500_GeV
The integral photon flux from 150 GeV to 500 GeV, in photon/cm2/s.

Flux_150_500_GeV_Neg_Err
The lower (negative) uncertainty on integral photon flux from 150 GeV to 500 GeV, in photon/cm2/s.

Flux_150_500_GeV_Pos_Err
The upper (positive) uncertainty on integral photon flux from 150 GeV to 500 GeV, in photon/cm2/s.

nuFnu_150_500_GeV
The spectral energy distribution from 150 GeV to 500 GeV, in erg/cm2/s.

Sqrt_TS_150_500_GeV
The square root of the test statistic between 150 GeV and 500 GeV.

Flux_0p5_2_Tev
The integral photon flux from 0.5 TeV to 2 TeV, in photon/cm2/s.

Flux_0p5_2_Tev_Neg_Err
The lower (negative) uncertainty in the integral photon flux from 0.5 TeV to 2 TeV, in photon/cm2/s.

Flux_0p5_2_Tev_Pos_Err
The upper (positive) uncertainty in the integral photon flux from 0.5 TeV to 2 TeV, in photon/cm2/s.

nuFnu_0p5_2_Tev
The spectral energy distribution from 0.5 TeV to 2 TeV, in erg/cm2/s.

Sqrt_TS_0p5_2_Tev
The square root of the test statistic between 0.5 TeV to 2 TeV.

Npred
The predicted number of photons from the model.

HEP_Energy
The highest energy among photons probably coming from the source, in GeV.

HEP_Prob
The probability that the highest energy photon is coming from the source.

Num_Bayesian_Blocks
The number of Bayesian blocks from variability analysis, where 1 means that the source was non-variable and -1 means the source could not be tested.

Extended_Source_Name
The cross reference to the extended source table, if any.

Alt_GammaRay_Name
The name of the association of the 3FHL source with a source in another catalog of GeV gamma-ray sources, if any.

Tev_Assoc_Flag
This parameter can contain a flag indicating a possible association with a TeV source, coded as follows: 

      P = positional association with non-extended source in TeVCat;
      E = associated with an extended source in TeVCat;
      N = no TeV association

Assoc_TeVCat
The name of the most likely associated source in the TeVCat.

Source_Class
The astrophysical class of the counterpart of the gamma-ray source, using the schema given below, where upper-case letters are used to indicate 'identified' counterparts whereas lower-case letters indicate 'associated' counterparts. 

      agn = Non-blazar active galaxy
      bcu = Blazar candidate of uncertain type
      bin = Binary
      bll = BL Lac type of blazar
     fsrq = Flat spectrum radio quasar type of blazar
      glc = Globular cluster
      hmb = High-mass binary
    nlsy1 = Narrow-line Seyfert 1
      psr = Pulsar
      pwn = Pulsar Wind Nebula
      rdg = Radio galaxy
      sbg = Starburst galaxy
      sfr = Star-forming region
      snr = Supernova remnant
      spp = Unclear whether SNR or PWN

Assoc_Name_1
The name of identified or likely associated source.

Assoc_Name_2
The alternate name of identified or likely associated source.

Assoc_Prob_Bay
The probability of association according to the Bayesian method.

Assoc_Prob_LR
The probability of association according to the Likelihood Ratio method.

Redshift
The redshift of counterpart (negative means uncertain).

Nupeak_Obs
The observed synchrotron peak frequency, in Hz.

Contact Person

Questions regarding the FERMI3FHL database table can be addressed to the HEASARC Help Desk.
Page Author: Browse Software Development Team
Last Modified: Monday, 16-Sep-2024 17:27:23 EDT