VTSCat: The VERITAS Catalog of Gamma-Ray Observations

VERITAS Observations of Six Bright, Hard-Spectrum Fermi-LAT Blazars

We report on VERITAS very-high-energy (VHE; E>100 GeV) observations of six blazars selected from the Fermi Large Area Telescope First Source Catalog (1FGL). The gamma-ray emission from 1FGL sources was extrapolated up to the VHE band, taking gamma-ray absorption by the extragalactic background light into account. This allowed the selection of six bright, hard-spectrum blazars that were good candidate TeV emitters. Spectroscopic redshift measurements were attempted with the Keck Telescope for the targets without Sloan Digital Sky Survey (SDSS) spectroscopic data. No VHE emission is detected dur…

Discovery of very-high-energy emission from RGB J2243+203 and derivation of its redshift upper limit

Very-high-energy (VHE; $>$ 100 GeV) gamma-ray emission from the blazar RGB J2243+203 was discovered with the VERITAS Cherenkov telescope array, during the period between 21 and 24 December 2014. The VERITAS energy spectrum from this source can be fit by a power law with a photon index of $4.6 \pm 0.5$, and a flux normalization at 0.15 TeV of $(6.3 \pm 1.1) \times 10^{-10} ~ \textrm{cm}^{-2} \textrm{s}^{-1} \textrm{TeV}^{-1}$. The integrated \textit{Fermi}-LAT flux from 1 GeV to 100 GeV during the VERITAS detection is $(4.1 \pm 0.8) \times 10^{\textrm{-8}} ~\textrm{cm}^{\textrm{-2}}\textrm{s}^{…

Hunting for dark matter subhalos among the Fermi-LAT sources with VERITAS

The distribution of dark matter in the Galaxy, according to state-of-the-art simulations, shows not only a smooth halo component but also a rich substructure where a hierarchy of dark matter subhalos of different masses is found. We present a search for potential dark matter subhalos in our Galaxy exploiting the high (HE, 100 MeV -- 100 GeV) and very-high-energy (VHE, >100 GeV) gamma-ray bands. We assume a scenario where the dark matter is composed of weakly interacting massive particles of mass over 100 GeV, and is capable of self-annihilation into standard model products. Under such a hypoth…

STeVECat，能谱 TeV 河外星系目录

STeVECat, the Spectral TeV Extragalactic Catalog

本文开发了统一的河外甚高能伽马射线能谱目录STeVECat，汇集了1992至2021年间的403条能谱数据，支持种群研究、GeV-TeV连接及河外背景光吸收研究。

VERITAS and Fermi-LAT observations of new HAWC sources

The HAWC (High Altitude Water Cherenkov) 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, there are nineteen sources that are not associated with previously known TeV sources. We have studied fourteen 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 co…

TeV脉冲星环境目录

A catalogue of TeV pulsar environments

收集并统一了H.E.S.S.、MAGIC、VERITAS、HAWC和LHAASO等望远镜的观测数据，构建了首个TeV脉冲星环境综合目录，包含128个γ射线源与66颗脉冲星，揭示了TeV光度与特征年龄弱相关，并识别出5颗CTAO优先观测目标。

HAWC、VERITAS、Fermi-LAT与XMM-Newton对未证认超高能伽马射线源LHAASO J2108+5157的后续观测

HAWC, VERITAS, Fermi-LAT and XMM-Newton follow-up observations of the unidentified ultra-high-energy gamma-ray source LHAASO J2108+5157

该研究利用多望远镜对未证认超高能伽马射线源LHAASO J2108+5157开展观测，通过多波段数据分析揭示其能谱特性，将其解释为脉冲星风云系统并约束了磁场，为该源的物理本质提供了关键线索。

Constraints to dark matter annihilation from high-latitude HAWC unidentified sources

The $Λ$CDM cosmological framework predicts the existence of thousands of subhalos in our own Galaxy not massive enough to retain baryons and become visible. Yet, some of them may shine in gamma rays provided that the dark matter (DM) is made of weakly interacting massive particles (WIMPs), that would self-annihilate and would appear as unidentified gamma-ray sources (unIDs) in gamma-ray catalogs. Indeed, unIDs have proven to be competitive targets for DM searches with gamma rays. In this work, we focus on the three high-latitude ($|b|\geq 10^\circ$) sources present in the 2HWC catalog of the H…

Search for galactic Pevatron candidates in a population of unidentified gamma-ray sources

Lower limits on the energy cutoff for unidentified gamma-ray sources detected in the HESS galactic plane survey are derived. Additional public data from the VERITAS, HESS and Milagro experiments are used for MGRO J1908+06 to confirm the limit derived from the HESS galactic plane survey data and to enable further conclusions on the presence of spectral breaks. Five Pevatron candidates are identified in the HESS galactic plane survey. The cutoff of the gamma-ray spectrum for these sources is larger than 20 TeV at 90% confidence level. The gamma-ray sources MGRO J1908+06 and HESS J1641-463, found…

The BL-Lac gamma-ray blazar PKS 1424+240 associated with a group of galaxies at z=0.6010

PKS 1424+240 is a BL-Lac blazar with unknown redshift that was detected at high-energy gamma rays by Fermi-LAT with a hard spectrum. At VHE, it was first detected by VERITAS and later confirmed by MAGIC. Its spectral energy distribution is highly attenuated at VHE gamma rays, which is coherent with distant sources. Several estimations enabled the redshift to be constrained to the range 0.6 < z < 1.3. These results place PKS 1424+240 in the very interesting condition of being probably the most distant blazar that has been detected at VHE. The ambiguity in the redshift is still large enough to p…

利用SST-1M立体观测系统对VER J2019+368的观测

Observation of VER J2019+368 with the SST-1M stereoscopic system

本文报道了利用SST-1M立体观测系统于2024年4月至11月对未识别甚高能伽马射线源VER J2019+368区域的首次观测，重点开展形态学与光谱学研究，并评估其大视场离轴性能在探测扩展银河伽马射线源方面的能力。

Interstellar anatomy of the TeV gamma-ray peak in the IC443 supernova remnant

Supernovae remnants (SNRs) represent a major feedback source from stars on the interstellar medium of galaxies. During the latest stage of supernovae explosions, shock waves produced by the initial blast modify the chemistry of gas and dust, inject kinetic energy in the surroundings, and may alter star formation characteristics. Simultaneously, gamma-ray emission is generated by the interaction between the ambiant medium and the cosmic rays. We study the stellar and interstellar contents of IC443, an evolved shell type SNR at a distance of 1.9 kpc, with an estimated age of 30 kyr. We aim to me…