VTSCat is the catalog of high-level data products from all publications of the VERITAS collaboration. The VTSCat data collection contains: high-level data like spectral flux points, light curves, spectral fits in human and machine-readable yaml and ecsv file format tabled data like upper limits tables from dark matter searches or results on the extragalactic background in ecsv file format sky maps (wherever available) in FITS file format A detailed description of VTSCat can be found in A. Acharyya et al 2023 Res. Notes AAS 7 6. Please check also the README file and all documentation linked to the README. VTSCat supplements the HEASARC catalogue of VERITAS results, accessible through this link. VTSCat is inspired and derived from gamma-cat. If you are a previous VERITAS author and would like to be associated with this repository, please send an email to G. Maier. Access: GitHub: https://github.com/VERITAS-Observatory/VERITAS-VTSCat HEASARC: https://heasarc.gsfc.nasa.gov/W3Browse/all/verimaster.html References: https://veritas.sao.arizona.edu/ VER Dictionary of Nomenclature: https://cds.u-strasbg.fr/cgi-bin/Dic-Simbad?/17350620 GitHub: https://github.com/VERITAS-Observatory/VERITAS-VTSCat HEASARC: https://heasarc.gsfc.nasa.gov/W3Browse/all/verimaster.html Research note A. Acharyya et al 2023 Res. Notes AAS 7 6; see also arXiv:2301.04498 ICRC 2021 proceedings: https://arxiv.org/abs/2108.06424

10.5281/zenodo.7593951

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VERITAS OBSERVATIONS OF DAY-SCALE FLARING OF M 87 IN 2010 APRIL

The Astrophysical Journal (2012)

E. Aliu T. Arlen T. Aune M. Beilicke W. Benbow

VERITAS has been monitoring the very-high-energy (VHE; >100GeV) gamma-ray activity of the radio galaxy M87 since 2007. During 2008, flaring activity on a timescale of a few days was observed with a peak flux of (0.70 +- 0.16) X 10^{-11} cm^{-2} s^{-1} at energies above 350GeV. In 2010 April, VERITAS detected a flare from M87 with peak flux of (2.71 +- 0.68) X 10^{-11} cm^{-2} s^{-1} for E>350GeV. The source was observed for six consecutive nights during the flare, resulting in a total of 21 hr of good quality data. The most rapid flux variation occurred on the trailing edge of the flare with an exponential flux decay time of 0.90^{+0.22}_{-0.15} days. The shortest detected exponential rise time is three times as long, at 2.87^{+1.65}_{-0.99} days. The quality of the data sample is such that spectral analysis can be performed for three periods: rising flux, peak flux, and falling flux. The spectra obtained are consistent with power-law forms. The spectral index at the peak of the flare is equal to 2.19 +- 0.07. There is some indication that the spectrum is softer in the falling phase of the flare than the peak phase, with a confidence level corresponding to 3.6 standard deviations. We discuss the implications of these results for the acceleration and cooling rates of VHE electrons in M87 and the constraints they provide on the physical size of the emitting region.

Flare

Spectral index

10.1088/0004-637x/746/2/141

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Citations (50)

THE JUNE 2008 FLARE OF MARKARIAN 421 FROM OPTICAL TO TeV ENERGIES

The Astrophysical Journal (2008)

I. Donnarumma V. Vittorini S. Vercellone E. Del Monte M. Feroci

We present optical, X-ray, high energy ($\lessapprox 30$ GeV) and very high energy ($\gtrapprox 100$ GeV; VHE) observations of the high-frequency peaked blazar Mrk 421 taken between 2008 May 24 and June 23. A high energy $\gamma$-ray signal was detected by AGILE with \sqrt{TS}=4.5 on June 9--15, with $F(E>100 \mathrm{MeV})= 42^{+14}_{-12}\times 10^{-8}$ photons cm$^{-2}$ s$^{-1}$. This flaring state is brighter than the average flux observed by EGRET by a factor of $\sim$3, but still consistent with the highest EGRET flux. In hard X-rays (20-60 keV) SuperAGILE resolved a 5-day flare (June 9-15) peaking at $\sim$ 55 mCrab. SuperAGILE, RXTE/ASM and Swift/BAT data show a correlated flaring structure between soft and hard X-rays. Hints of the same flaring behavior are also detected in the simultaneous optical data provided by the GASP-WEBT. A Swift/XRT observation near the flaring maximum revealed the highest 2-10 keV flux ever observed from this source, of 2.6 $\times 10^{-9}$ erg cm$^{-2}$ s$^{-1}$ (i.e. > 100 mCrab). A peak synchrotron energy of $\sim$3 keV was derived, higher than typical values of $\sim$0.5-1 keV. VHE observations with MAGIC and VERITAS on June 6-8 show the flux peaking in a bright state, well correlated with the X-rays. This extraordinary set of simultaneous data, covering a twelve-decade spectral range, allowed for a deep analysis of the spectral energy distribution as well as of correlated light curves. The $\gamma$-ray flare can be interpreted within the framework of the synchrotron self-Compton model in terms of a rapid acceleration of leptons in the jet.

Flare

Spectral energy distribution

10.1088/0004-637x/691/1/l13

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Citations (100)

Dark matter constraints from a joint analysis of dwarf Spheroidal galaxy observations with VERITAS

Physical review. D/Physical review. D. (2017)

S. Archambault A. Archer W. Benbow R. Bird Etienne Bourbeau

We present constraints on the annihilation cross section of weakly interacting massive particles dark matter based on the joint statistical analysis of four dwarf galaxies with VERITAS. These results are derived from an optimized photon weighting statistical technique that improves on standard imaging atmospheric Cherenkov telescope (IACT) analyses by utilizing the spectral and spatial properties of individual photon events. We report on the results of $\ensuremath{\sim}230$ hours of observations of five dwarf galaxies and the joint statistical analysis of four of the dwarf galaxies. We find no evidence of gamma-ray emission from any individual dwarf nor in the joint analysis. The derived upper limit on the dark matter annihilation cross section from the joint analysis is $1.35\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}23}\text{ }\text{ }{\mathrm{cm}}^{3}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$ at 1 TeV for the bottom quark ($b\overline{b}$) final state, $2.85\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}24}\text{ }\text{ }{\mathrm{cm}}^{3}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$ at 1 TeV for the tau lepton (${\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}}$) final state and $1.32\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}25}\text{ }\text{ }{\mathrm{cm}}^{3}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$ at 1 TeV for the gauge boson ($\ensuremath{\gamma}\ensuremath{\gamma}$) final state.

Dwarf spheroidal galaxy

Dwarf galaxy problem

10.1103/physrevd.95.082001

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Citations (112)

New GTC spectroscopic data and a statistical study to better constrain the redshift of the BL Lac RGB J2243 + 203

Monthly Notices of the Royal Astronomical Society (2018)

D. Rosa‐González H. Muriel Y. D. Mayya I. Aretxaga J. Becerra González

We present new spectroscopic data of the BL Lac RGB 2243+203, and its surroundings, obtained with the OSIRIS Multi Object Spectrograph (MOS) mounted in the Gran Telescopio Canarias (GTC). The spectra of neither the BL Lac nor its host galaxy show any spectral feature, thus hindering direct determination of its redshift. The spectroscopic redshift distribution of objects in the MOS field of view shows four galaxies with redshift between 0.5258 and 0.5288. We make use of a statistical analysis to test the possibility that the targeted BL Lac may be a member of that group. By using the spectroscopic redshifts obtained with our GTC observations, we found that this probability is between 86% and 93%.

BL Lac object

10.1093/mnras/sty3065

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Citations (5)

DISCOVERY OF VERY HIGH ENERGY GAMMA-RAY RADIATION FROM THE BL LAC 1ES 0806+524

The Astrophysical Journal (2008)

V. A. Acciari E. Aliu T. Arlen M. A. Bautista M. Beilicke

The high-frequency-peaked BL Lacertae object 1ES 0806+524, at redshift z = 0.138, was observed in the very high energy (VHE) gamma-ray regime by VERITAS between 2006 November and 2008 April. These data encompass the two- and three-telescope commissioning phases, as well as observations with the full four-telescope array. 1ES 0806+524 is detected with a statistical significance of 6.3 standard deviations from 245 excess events. Little or no measurable variability on monthly timescales is found. The photon spectrum for the period 2007 November to 2008 April can be characterized by a power law with photon index 3.6 ± 1.0stat ± 0.3sys between ∼ 300 GeV and ∼ 700 GeV. The integral flux above 300 GeV is (2.2 ± 0.5stat ± 0.4sys) × 10−12 cm−2 s−1 which corresponds to 1.8% of the Crab Nebula flux. Non-contemporaneous multiwavelength observations are combined with the VHE data to produce a broadband spectral energy distribution that can be reasonably described using a synchrotron--self-Compton model.

BL Lac object

Crab Nebula

Spectral energy distribution

10.1088/0004-637x/690/2/l126

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Citations (54)

VTSCat: The VERITAS Catalog of Gamma-Ray Observations

Zenodo (CERN European Organization for Nuclear Research) (2022)

W. Benbow A. Brill J. H. Buckley M. Capasso Jessie L. Christiansen

VTSCat is the catalog of high-level data products from all publications of the VERITAS collaboration. Most recent versions of VTSCat are available through https://doi.org/10.5281/zenodo.6988967 The VTSCat data collection contains: high-level data like spectral flux points, light curves, spectral fits in human- and machine-readable yaml and ecsv file format tabled data like upper limits tables from dark matter searches or results on the extragalactic background in ecsv file format sky maps (wherever available) in FITS file format The data collection contains results from gamma-ray measurements only. This is a pre-release for testing and early publications. A forthcoming research note will provide more details on the catalog. Please check the README file and all documentation linked to the README. VTSCat supplements the HEASARC catalogue of VERITAS results (to be published). VTSCat is inspired and derived from gamma-cat. If you are a previous VERITAS author and would like to be associated with this repository, please send an email to G. Maier. Access: GitHub: https://github.com/VERITAS-Observatory/VERITAS-VTSCat References: VERITAS: https://veritas.sao.arizona.edu/ VER Dictionary of Nomenclature: https://cds.u-strasbg.fr/cgi-bin/Dic-Simbad?/17350620

10.5281/zenodo.6163391

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Citations (1)

VizieR Online Data Catalog: Photometry/spectroscopic measurements for KA1858+4850 (Pei+, 2014)

yCat (2017)

L. Pei Aaron J. Barth G. Aldering Michael M. Briley Carla June Carroll

Source

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THE THIRD CATALOG OF ACTIVE GALACTIC NUCLEI DETECTED BY THEFERMILARGE AREA TELESCOPE

The Astrophysical Journal (2015)

M. Ackermann M. Ajello W. B. Atwood L. Baldini J. Ballet

The third catalog of active galactic nuclei (AGNs) detected by the Fermi-LAT (3LAC) is presented. It is based on the third Fermi-LAT catalog (3FGL) of sources detected between 100 MeV and 300 GeV with a Test Statistic (TS) greater than 25, between 2008 August 4 and 2012 July 31. The 3LAC includes 1591 AGNs located at high Galactic latitudes (|b|>10{\deg}), a 71% increase over the second catalog based on 2 years of data. There are 28 duplicate associations, thus 1563 of the 2192 high-latitude gamma-ray sources of the 3FGL catalog are AGNs. Most of them (98%) are blazars. About half of the newly detected blazars are of unknown type, i.e., they lack spectroscopic information of sufficient quality to determine the strength of their emission lines. Based on their gamma-ray spectral properties, these sources are evenly split between flat-spectrum radio quasars (FSRQs) and BL~Lacs. The most abundant detected BL~Lacs are of the high-synchrotron-peaked (HSP) type. About 50% of the BL~Lacs have no measured redshifts. A few new rare outliers (HSP-FSRQs and high-luminosity HSP BL~Lacs) are reported. The general properties of the 3LAC sample confirm previous findings from earlier catalogs. The fraction of 3LAC blazars in the total population of blazars listed in BZCAT remains non-negligible even at the faint ends of the BZCAT-blazar radio, optical and X-ray flux distributions, which is a clue that even the faintest known blazars could eventually shine in gamma rays at LAT-detection levels. The energy-flux distributions of the different blazar populations are in good agreement with extrapolation from earlier catalogs.

10.1088/0004-637x/810/1/14

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Citations (553)

VERITAS and Fermi-LAT Observations of TeV Gamma-Ray Sources Discovered by HAWC in the 2HWC Catalog

The Astrophysical Journal (2018)

A. U. Abeysekara A. Archer W. Benbow R. Bird Robert Brose

Abstract The High Altitude Water Cherenkov (HAWC) collaboration recently published their 2HWC catalog, listing 39 very high energy (VHE; >100 GeV) gamma-ray sources based on 507 days of observation. Among these, 19 sources are not associated with previously known teraelectronvolt (TeV) gamma-ray sources. We have studied 14 of these sources without known counterparts with VERITAS and Fermi -LAT. VERITAS detected weak gamma-ray emission in the 1 TeV–30 TeV band in the region of DA 495, a pulsar wind nebula coinciding with 2HWC J1953+294, confirming the discovery of the source by HAWC. We did not find any counterpart for the selected 14 new HAWC sources from our analysis of Fermi -LAT data for energies higher than 10 GeV. During the search, we detected gigaelectronvolt (GeV) gamma-ray emission coincident with a known TeV pulsar wind nebula, SNR G54.1+0.3 (VER J1930+188), and a 2HWC source, 2HWC J1930+188. The fluxes for isolated, steady sources in the 2HWC catalog are generally in good agreement with those measured by imaging atmospheric Cherenkov telescopes. However, the VERITAS fluxes for SNR G54.1+0.3, DA 495, and TeV J2032+4130 are lower than those measured by HAWC, and several new HAWC sources are not detected by VERITAS. This is likely due to a change in spectral shape, source extension, or the influence of diffuse emission in the source region.

Pulsar wind nebula

Crab Nebula

Astroparticle physics

10.3847/1538-4357/aade4e

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Citations (18)