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FERMILHESC - Fermi LAT High-Energy Source Catalog (1FHL)

 HEASARC
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Overview

This table contains the catalog of gamma-ray sources at energies above 10 GeV based on data from the Large Area Telescope (LAT) accumulated during the first 3 years of the Fermi Gamma-ray Space Telescope mission. The first Fermi-LAT catalog of > 10 GeV sources (1FHL) has 514 sources. For each source, the authors present location, spectrum, a measure of variability,and associations with cataloged sources at other wavelengths. They found that 449 (87%) could be associated with known sources, of which 393 (76% of the 1FHL sources) are active galactic nuclei. Of the 27 sources associated with known pulsars, they find 20 (12) to have significant pulsations in the range > 10 GeV (> 25 GeV). In this work, the authors also report that, at energies above 10 GeV, unresolved sources account for 27% +/- 8% of the isotropic gamma-ray background, while the unresolved Galactic population contributes only at the few percent level to the Galactic diffuse background. The authors also highlight the subset of the 1FHL sources that are the best candidates for detection at energies above 50 - 100 GeV with current and future ground-based gamma-ray observatories.

The time interval analyzed here is from the beginning of Fermi LAT science operations on 2008 August 4 (MET 239557447) to 2011 August 1 (MET 333849586), covering very nearly 3 years. In this work, the authors analyze gamma rays with energies in the range 10-500 GeV. To limit the contamination from gamma rays produced by cosmic-ray interactions in the upper atmosphere, gamma rays with zenith angles greater than 105 degrees were excluded. To further reduce the residual gamma rays from the upper atmosphere only data for time periods when the spacecraft rocking angle was less than 52 degrees were considered. See Section 2 of the reference paper for further explanations.

Catalog Bibcode

2013ApJS..209...34A

References

The First Fermi-LAT Catalog of Sources above 10 GeV.

      Ackermann M., Ajello M., Allafort A., Atwood W.B., Baldini L., Ballet J.,
      Barbiellini G., Bastieri D., Bechtol K., Belfiore A., Bellazzini R.,
      Bernieri E., Bissaldi E., Bloom E.D., Bonamente E., Brandt T.J.,
      Bregeon J., Brigida M., Bruel P., Buehler R., Burnett T.H., Buson S.,
      Caliandro G.A., Cameron R.A., Campana R., Caraveo P.A., Casandjian J.M.,
      Cavazzuti E., Cecchi C., Charles E., Chaves R.C.G., Chekhtman A.,
      Cheung C.C., Chiang J., Chiaro G., Ciprini S., Claus R., Cohen-Tanugi J.,
      Cominsky L.R., Conrad J., Cutini S., D'Ammando F., de Angelis A.,
      de Palma F., Dermer C.D., Desiante R., Digel S.W., Di Venere L.,
      Drell P.S., Drlica-Wagner A., Favuzzi C., Fegan S.J., Ferrara E.C.,
      Focke W.B., Fortin P., Franckowiak A., Funk S., Fusco P., Gargano F.,
      Gasparrini D., Gehrels N., Germani S., Giglietto N., Giommi P.,
      Giordano F., Giroletti M., Godfrey G., Gomez-Vargas G.A., Grenier I.A.,
      Guiriec S., Hadasch D., Hanabata Y., Harding A.K., Hayashida M., Hays E.,
      Hewitt J., Hill A.B., Horan D., Hughes R.E., Jogler T., Johannesson G.,
      Johnson A.S., Johnson T.J., Johnson W.N., Kamae T., Kataoka J.,
      Kawano T., Knodlseder J., Kuss M., Lande J., Larsson S., Latronico L.,
      Lemoine-Goumard M., Longo F., Loparco F., Lott B., Lovellette M.N.,
      Lubrano P., Massaro E., Mayer M., Mazziotta M.N., McEnery J.E.,
      Mehault J., Michelson P.F., Mizuno T., Moiseev A.A., Monzani M.E.,
      Morselli A., Moskalenko I.V., Murgia S., Nemmen R., Nuss E., Ohsugi T.,
      Okumura A., Orienti M., Ormes J.F., Paneque D., Perkins J.S.,
      Pesce-Rollins M., Piron F., Pivato G., Porter T.A., Raino S., Razzano M.,
      Reimer A., Reimer O., Reposeur T., Ritz S., Romani R.W., Roth M.,
      Saz Parkinson P.M., Schulz A., Sgro C., Siskind E.J., Smith D.A.,
      Spandre G., Spinelli P., Stawarz L., Strong A.W., Suson D.J.,
      Takahashi H., Thayer J.G., Thayer J.B., Thompson D.J., Tibaldo L.,
      Tinivella M., Torres D.F., Tosti G., Troja E., Uchiyama Y., Usher T.L.,
      Vandenbroucke J., Vasileiou V., Vianello G., Vitale V., Werner M.,
      Winer B.L., Wood K.S., Wood M.
      <Astrophys. J. Suppl. 209, 34 (2015)>
      =2015ApJS..209...34A

Provenance

This table was created by the HEASARC in April 2015 based on CDS Catalog J/ApJS/209/34/ files table3.dat and table7.dat.

Parameters

Name
The 1FHL catalog source name, being a J2000.0 position-based source designation registered with the CDS Dictionary of Nomenclature of Celestial Objects, viz., '1FHL JHHMM.m+DDMM', where the prefix stands for 'First Fermi Hard LAT' source.

Extent_Flag
This parameter contains a flag which is set to 'e' to indicate that the corresponding source is extended. The properties of the 18 extended 1FHL sources are listed in Table 1 of the reference paper.

RA
The Right Ascension of the gamma-ray source in the selected equinox. This was given in J2000 decimal degrees to a precision of 10-3 degrees in the original table.

Dec
The Declination of the gamma-ray source in the selected equinox. This was given in J2000 decimal degrees to a precision of 10-3 degrees in the original table.

LII
The Galactic Longitude of the gamma-ray source.

BII
The Galactic Latitude of the gamma-ray source.

Error_Semimajor_Axis
The semi-major axis of the 95%-confidence source location region (error ellipse), in degrees. This quantity is not defined for the 18 1FHL sources that have been identified as extended (extent_flag = 'e').

Error_Semiminor_Axis
The semi-minor axis of the 95%-confidence source location region (error ellipse), in degrees. This quantity is not defined for the 18 1FHL sources that have been identified as extended (extent_flag = 'e').

Error_Position_Angle
The position angle of the major axis of the 95%-confidence source location region (error ellipse), measured from North through East, in degrees. This quantity is not defined for the 18 1FHL sources that have been identified as extended (extent_flag = 'e').

Significance
The gamma-ray source significance, in units of sigma, derived from the test statistic TS = 2 Delta Log L, comparing the likelihood L with and without the source in the model, where the analysis broadly follows the same steps as the 2FGL Catalog (Nolan et al. 2012, ApJS, 199, 31).

Photon_Flux
The 10-500 GeV photon flux of the gamma-ray source, in photons cm-2 s-1.

Photon_Flux_Error
The 1-sigma uncertainty in the 10-500 GeV photon flux of the gamma-ray source, in photons cm-2 s-1.

Flux
The 10-500 GeV energy flux of the gamma-ray source, in erg cm-2 s-1. from the power-law spectral fit.

Flux_Error
The 1-sigma uncertainty in the 10-500 GeV energy flux of the gamma-ray source, in erg cm-2 s-1. from the power-law spectral fit.

Spectral_Index
The best-fit photon number power-law index, Gamma, to the 10-500 GeV spectrum of the gamma-ray source found from fitting a power-law model.

Spectral_Index_Error
The 1-sigma uncertainty in the best-fit photon number power-law index, Gamma, to the 10-500 GeV spectrum of the gamma-ray source.

Num_Bayesian_Blocks
The number of change points in the Bayesian blocks light curve analysis of the gamma-ray source, where 1 means that the source was non-variable (see Section 3.3 of the reference paper for more details).

Alt_GammaRay_Name
The name of the association of the 1FHL 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 = point-like or small angular-size TeV source;
      E = extended TeV source;
      C = good candidate for TeV detection, as defined in Section 5 of the
          reference paper.

Source_Type_1
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. As noted in Section 3.4 of the reference paper, this distinction is similar to the ones used in the 2FGL and 2LAC catalogs, and an identification is regarded as more certain than an identification. Promoting an association to an identification requires that correlated variability or source extension be found in observations at other wavelengths. Table 4 of the reference paper gives an overview of the LAT 1FHL sources classification. For 3 1FHL sources, there are associations with two distinct sources with posterior probabilities greater than 80%: in these cases, the properties of the second association are given in the parameters source_type_2, assoc_name_2, agn_optical_class_2 and sed_class_2. 

      bzb = blazar of the BL Lac type
      bzq = blazar of the FSRQ (flat spectrum radio quasar) type
      agu = active galaxy of uncertain type
     HPSR = Pulsar, identified by pulsations above 10 GeV
      PSR = Pulsar, identified by pulsations in LAT (excluding HPSR)
      psr = Pulsar, no pulsations seen in LAT yet
      snr = Supernova remnant
      pwn = Pulsar wind nebula
      spp = Unclear whether SNR or PWN
      rdg = Radio galaxy
      HMB = High-mass binary
      GAL = Normal galaxy
      SFR = Star forming region
      lbv = LBV star

Source_Type_2
The astrophysical class of the second possible association 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.

Assoc_Name_1
The identification or association of the 1FHL source. For 3 1FHL sources, there are associations with two distinct sources with posterior probabilities greater than 80%: in these cases, the properties of the second association are given in the parameters source_type_2, assoc_name_2, agn_optical_class_2 and sed_class_2.

Assoc_Name_2
The name of the second possible association of the gamma-ray source.

AGN_Optical_Class_1
The 1FHL catalog is strongly dominated by AGNs,with 393 sources associated with AGNs. For those sources, this parameter contains the optical classification of the AGN, which uses the presence/absence of emission lines to classify sources as FSRQ- or BL Lac-type. For 3 1FHL sources, there are associations with two distinct sources with posterior probabilities greater than 80%: in these cases, the properties of the second association are given in the parameters source_type_2, assoc_name_2, agn_optical_class_2 and sed_class_2.

AGN_Optical_Class_2
The optical classification of the second possible AGN association with the 1FHL source.

SED_Class_1
The 1FHL catalog is strongly dominated by AGNs,with 393 sources associated with AGNs. For those sources, this parameter contains the spectral energy distribution (SED) classification of the AGN. The authors used the convention proposed by Abdo et al. (2010, ApJ, 716, 30) and classify the AGNs as low-synchrotron-peaked (LSP), intermediate-synchrotron-peaked (ISP), and high-synchrotron-peaked (HSP) if the peak of the synchrotron emission is located below 1014 Hz, in the range of 1014 to 1015 Hz, or above 1015 Hz, respectively. This classification is complementary to the broadly used optical classification. For 3 1FHL sources, there are associations with two distinct sources with posterior probabilities greater than 80%: in these cases, the properties of the second association are given in the parameters source_type_2, assoc_name_2, agn_optical_class_2 and sed_class_2.

SED_Class_2
The SED Classification of the second possible AGN association with the 1FHL source.

Redshift
The redshift (if available) of the AGN association/identification of the 1FHL source.

Alt_Redshift
A second distinct redshift of the AGN association/identification of the 1FHL source found in the literature.

Alt_Redshift_Flag
This parameter contains a flag that is set to 'l' for three of the 1FHL sources to indicate that the corresponding second distinct redshift found in the literature for these 3 sources violates the spectroscopic lower limit as reported in Shaw et al. (2013, ApJ, 764, 135).

Class
The HEASARC Browse object classification of the gamma-ray source, based on the value of the source_type_1 parameter (q.v.).

Contact Person

Questions regarding the FERMILHESC database table can be addressed to the HEASARC Help Desk.
Page Author: Browse Software Development Team
Last Modified: Monday, 16-Sep-2024 17:27:34 EDT