The Fourth HAWC Catalog of Very-High-Energy Gamma-Ray Sources
Instituto de Física, Universidad Nacional Autónoma de México（墨西哥国立自治大学物理研究所）；Universidad Autónoma de Chiapas（恰帕斯自治大学）；Instituto de Astronomía, Universidad Nacional Autónoma de México（墨西哥国立自治大学天体物理研究所）；Universidad de Costa Rica（哥斯达黎加大学）；Universidad Michoacana de San Nicolás de Hidalgo（米却肯圣尼古拉斯德伊达尔戈大学）；Temple University（天普大学）；Instituto Nacional de Astrofísica, Óptica y Electrónica（国家天体物理学、光学和电子学研究所）；Institute of Nuclear Physics Polish Academy of Sciences（波兰科学院核物理研究所）
R. Alfaro, C. Alvarez, E. Anita-Rangel, M. Araya, J. C. Arteaga-Velazquez, D. Avila Rojas, H. A. Ayala Solares, P. Bangale, E. Belmont-Moreno, A. Bernal, K. S. … 展开作者
R. Alfaro, C. Alvarez, E. Anita-Rangel, M. Araya, J. C. Arteaga-Velazquez, D. Avila Rojas, H. A. Ayala Solares, P. Bangale, E. Belmont-Moreno, A. Bernal, K. S. Caballero-Mora, T. Capistran, A. Carraminana, F. Carreon, S. Casanova, U. Cotti, J. Cotzomi, S. Coutino de Leon, E. De la Fuente, P. Desiati, N. Di Lalla, R. Diaz Hernandez, B. L. Dingus, M. A. DuVernois, J. C. Dıaz-Velez, K. Engel, T. Ergin, C. Espinoza, K. Fang, N. Fraija, S. Fraija, J. A. Garcıa-Gonzalez, F. Garfias, N. Ghosh, M. M. Gonzalez, J. A. Gonzalez, J. A. Goodman, S. Groetsch, D. Guevel, S. Hernandez-Cadena, F. Hueyotl-Zahuantitla, P. Huntemeyer, A. Iriarte, S. Kaufmann, D. Kieda, A. Lara, K. Leavitt, T. Lewis, H. Leon Vargas, J. T. Linnemann, A. L. Longinotti, G. Luis-Raya, O. Martinez, J. Martınez-Castro, H. Martınez-Huerta, J. A. Matthews, P. Miranda-Romagnoli, E. Moreno, M. Mostafa, M. Najafi, A. Nayerhoda, L. Nellen, R. Noriega-Papaqui, N. Omodei, M. Osorio-Archila, E. Ponce, Y. Perez Araujo, E. G. Perez-Perez, Q. Remy, A. Rodriguez Parra, D. Rosa-Gonzalez, M. Roth, H. Salazar, A. Sandoval, J. Serna-Franco, Y. Son, R. W. Springer, O. Tibolla, K. Tollefson, I. Torres, R. Torres-Escobedo, R. Turner, E. Varela, L. Villasenor, I. J. Watson, H. Wu, S. Yu, X. Zhang, H. Zhou, C. de Leon
We present an updated catalog of TeV gamma-ray sources based on the fifth pass of data from the High-Altitude Water Cherenkov (HAWC) Observatory. This release benefits from improved event reconstruction and nearly three additional years of observations. It also incorporates a systematic multi-source fitting framework, enabling more flexible and accurate modeling of the gamma-ray sky. This fitting procedure was modeled after the manual approach used in HAWC analyses of individual sources and regions, as well as other gamma-ray catalogs, like the 4FGL. In addition to more varied modeling of source morphology and spectral parameters compared to previous HAWC catalogs, this catalog uses a robust modeling of Galactic diffuse TeV emission. The fitting procedure uses both point-like and symmetric Gaussian spatial templates to model the source morphology. The spectral shape of the emission is modeled with either a simple power-law or log-parabola to explore curvature in the spectral energy distribution. We report 85 sources at the 4σ level, including 11 sources not associated with any TeVCat source using a distance-based association criterion. Distance-based association with the 1LHAASO catalog results in 22 4HWC sources without a counterpart. Additionally, there are 12 sources not associated with any physical counterpart in the Low- or High-Mass X-Ray Binary, the ATNF, or Fermi Pulsar, or SNR catalogs of sources. Five of the aforementioned sources have no counterpart in any of the catalogs searched and represent an opportunity for follow-up observations.
The HAWC observatory recently published their second source catalog with 39 very high energy gamma-ray sources based on 507 days of exposure time. Among these, there were 16 sources that are more than one degree away from any known TeV source. We studied 13 of these 16 sources with VERITAS and \textit{Fermi}-LAT data. VERITAS, an array of four imaging atmospheric Cherenkov telescopes observing gamma rays with energies higher than 85 GeV, can provide a more detailed image of the source with much shorter exposure time and with better angular resolution. With \textit{Fermi}-LAT data, we searched …
We present a systematic study of the TeV gamma-ray spectrum for the sources in the 2HWC HAWC catalog. Three spectrum models are considered in the analysis: simple power law, power law with exponential cut-off and a log-parabola. A comparison of the test statistic of nested models was performed in order to look for the best description. We used gamma-ray sky maps of 17 and 25 months of HAWC data. From the analysis, only three sources of the catalog deviate from simple power law spectrum with high significance. The corresponding parameters are given in each case.
The High Altitude Water Cherenkov (HAWC) gamma-ray observatory is carrying out a detailed survey of the northern sky at TeV energies. 2HWC J2006+341 is a newly discovered source reported by the point source search in the 2HWC HAWC Observatory Gamma Ray Catalog. Using $\sim$1038 days of HAWC data we carried out a detailed analysis of the region revealing extended emission. No emission has been detected by other TeV instruments at the location of 2HWC J2006+341. We also analyzed publicly available data from the \textit{Fermi}-LAT that show for the first time the existence of an extended GeV sour…
The High Altitude Water Cherenkov (HAWC) Observatory is a wide-field-of-view gamma-ray observatory that is optimized to detect gamma rays between ~300 GeV and several hundred TeV. The HAWC Collaboration recently released their third source catalog (3HWC), which contains 65 sources. One of these sources, the ultra-high-energy gamma-ray source 3HWC J1908+063, may exhibit a hardening of the spectral index at the highest energies (above 56 TeV). At least two populations of particles are needed to satisfactorily explain the highest energy emission. This second component could be leptonic or hadroni…
We present the first catalog of TeV gamma-ray sources realized with the recently completed High Altitude Water Cherenkov Observatory (HAWC). It is the most sensitive wide field-of-view TeV telescope currently in operation, with a 1-year survey sensitivity of ~5-10% of the flux of the Crab Nebula. With an instantaneous field of view >1.5 sr and >90% duty cycle, it continuously surveys and monitors the sky for gamma ray energies between hundreds GeV and tens of TeV. HAWC is located in Mexico at a latitude of 19 degree North and was completed in March 2015. Here, we present the 2HWC catalog, whic…
The High Altitude Water Cherenkov Gamma-Ray Observatory has been accumulating a progressively deeper exposure of the TeV sky since its inauguration in March 2015. Located at geographical latitude $+19^\circ$N, HAWC has been able to perform a deep and unbiased survey of two thirds of the sky. We analyzed three years of HAWC data searching for long term persistent emission from a redshift limited ($z\leq 0.3$) sample of active galactic nuclei drawn from the {\it Fermi}-LAT 3FHL catalog. The HAWC dataset confirms the high significance detection of the two nearest BL Lac objects, \mbox{Mrk 421} an…
We present the first catalogs of the highest-energy (above 56 TeV and 100 TeV) gamma-ray sources seen by the High Altitude Water Cherenkov (HAWC) Observatory. The wide field-of-view of HAWC naturally lends itself to unbiased all-sky surveys and newly developed event-by-event gamma-ray energy reconstruction algorithms have allowed unprecedented energy resolution. The sources presented here are the highest-energy sources ever detected. All are coincident with known lower-energy gamma-ray sources within our Galaxy. These objects may have implications for the sources of Galactic cosmic rays; since…
2HWC J1928+177 is a source recently discovered at TeV energies in the second HAWC catalog. It is coincident with the Fermi unidentified source 3FGL J1928+1739 and the pulsar PSR J1928+1746, which is 83 kyr old and located at a distance of 5 kpc with an Edot=1.6 x 10$^{36}$ erg/s. 2HWC J1928+177 is not detected by any of the IACTs currently in operation, which puts strong constrains on the morphology and spectrum of the source. There is no sign of shell-like structure in the region at other wavelengths, which in addition to the presence of a pulsar at the center, points to a Pulsar Wind Nebula …
We present a new catalog of TeV gamma-ray sources using 1523 days of data from the High Altitude Water Cherenkov (HAWC) observatory. The catalog represents the most sensitive survey of the Northern gamma-ray sky at energies above several TeV, with three times the exposure compared to the previous HAWC catalog, 2HWC. We report 65 sources detected at $\geq$ 5 sigma significance, along with the positions and spectral fits for each source. The catalog contains eight sources that have no counterpart in the 2HWC catalog, but are within $1^\circ$ of previously detected TeV emitters, and twenty source…
The H.E.S.S. collaboration recently published its Galactic Plane Survey, which is a deep survey of half of the Milky Way in TeV gamma-rays, using almost 10 years of observations. It contains 78 sources, including 16 new sources. On the other hand, the HAWC collaboration also published its 2HWC catalogue based on 507 days of data. It is the result of the first source search performed with the complete HAWC detector, covering two thirds of the sky. In this search, 39 sources have been reported, amongst them 16 detected for the first time at TeV energies. The HAWC data set doubled since then, rev…
The High Altitude Water Cherenkov Observatory (HAWC) has a wide field-of-view (FOV, $\sim$2sr) and a high duty cycle ($\sim$95\%), which make it a powerful survey and monitoring experiment for sources of TeV gamma rays. We present a systematic survey of gamma-ray sources based on the Fermi 3FHL catalog. Sources are restricted to HAWC's FOV (Declination 19$^\circ$ $\pm$ 40$^\circ$) and to extragalactic sources with redshift: 0.001 $<$ z $<$ 0.3. Extragalactic gamma-ray sources are dominated by active galactic nuclei (AGN) and TeV gamma-ray sources are mostly BL Lac-type blazars. The study of AG…
The detection of the Fermi Bubbles suggests that spiral galaxies such as the Milky Way can undergo active periods. Using gamma-ray observations, we can investigate the possibility that such structures are present in other nearby galaxies. We have analyzed the region around the Andromeda Galaxy (Messier Catalog M31) for signs of bubble-like emission using TeV gamma-ray data recorded by the High-Altitude Water Cherenkov Observatory. We fit a model consisting of two 6 kpc bubbles symmetric about and perpendicular to the M31 galactic plane and assume a power-law distribution for the gamma-ray flux…
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…
The MGRO J2019+37 region is one of the brightest sources in the sky at TeV energies. It was detected in the 2 year HAWC catalog as 2HWC J2019+367 and here we present a detailed study of this region using data from HAWC. This analysis resolves the region into two sources: HAWC J2019+368 and HAWC J2016+371. We associate HAWC J2016+371 with the evolved supernova remnant CTB 87, although its low significance in this analysis prevents a detailed study at this time. An investigation of the morphology (including possible energy dependent morphology) and spectrum for HAWC J2019+368 is the focus of thi…
An incremental version (4LAC-DR2) of the fourth catalog of active galactic nuclei (AGNs) detected by the Fermi-LAT is presented. This version is associated with the second release of the 4FGL general catalog (based on 10 years of data), where the spectral parameters, spectral energy distributions, yearly light curves, and associations have been updated for all sources. The new reported AGNs include two radio galaxies and 283 blazars. We briefly describe the properties of the new sample and outline changes affecting the previously published sample. Note: Users of this incremental release are re…
We present an incremental version (4FGL-DR2, for Data Release 2) of the fourth Fermi-LAT catalog of gamma-ray sources. Based on the first ten years of science data in the energy range from 50 MeV to 1 TeV, it uses the same analysis methods as the 4FGL catalog did for eight years of data. The spectral parameters, spectral energy distributions and associations are updated for all sources. Light curves are rebuilt for all sources with 1-year intervals (not 2-month intervals). Among the 5064 4FGL sources, 120 are formally below the detection threshold over 10 years (but are kept in the list), whil…
We present the fourth Fermi Large Area Telescope catalog (4FGL) of gamma-ray sources. Based on the first eight years of science data from the Fermi Gamma-ray Space Telescope mission in the energy range from 50 MeV to 1 TeV, it is the deepest yet in this energy range. Relative to the 3FGL catalog, the 4FGL catalog has twice as much exposure as well as a number of analysis improvements, including an updated model for the Galactic diffuse gamma-ray emission, and two sets of light curves (1-year and 2-month intervals). The 4FGL catalog includes 5064 sources above 4 sigma significance, for which we…
The fourth catalog of active galactic nuclei (AGNs) detected by the Fermi Gamma-ray Space Telescope Large Area Telescope (4LAC) between 2008 August 4 and 2016 August 2 contains 2863 objects located at high Galactic latitudes (|b|>10°). It includes 85% more sources than the previous 3LAC catalog based on 4 years of data. AGNs represent at least 79% of the high-latitude sources in the fourth Fermi-Large Area Telescope Source Catalog (4FGL), which covers the energy range from 50 MeV to 1 TeV. In addition, 344 gamma-ray AGNs are found at low Galactic latitudes. Most of the 4LAC AGNs are blazars (9…
We present the first catalog of gamma-ray sources emitting above 56 and 100 TeV with data from the High Altitude Water Cherenkov (HAWC) Observatory, a wide field-of-view observatory capable of detecting gamma rays up to a few hundred TeV. Nine sources are observed above 56 TeV, all of which are likely Galactic in origin. Three sources continue emitting past 100 TeV, making this the highest-energy gamma-ray source catalog to date. We report the integral flux of each of these objects. We also report spectra for three highest-energy sources and discuss the possibility that they are PeVatrons.
HAWC J0630+186 Could Not Be Powered by PSR J0630+19
National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；Kavli Institute for Astronomy and Astrophysics, Peking University（北京大学科维理天文与天体物理研究所）
We present the fourth in a series of catalogs of gamma-ray bursts (GRBs) observed with Fermi's Gamma-Ray Burst Monitor (Fermi-GBM). It extends the six year catalog by four more years, now covering the ten year time period from trigger enabling on 2008 July 12 to 2018 July 11. During this time period GBM triggered almost twice a day on transient events of which we identifyied 2356 as cosmic GRBs. Additional trigger events were due to solar are events, magnetar burst activities, and terrestrial gamma-ray flashes. The intention of the GBM GRB catalog series is to provide updated information to th…
The discovery of the TeV point source 2HWC J2006+341 was reported in the second HAWC gamma-ray catalog. We present a follow-up study of this source here. The TeV emission is best described by an extended source with a soft spectrum. At GeV energies, an extended source is significantly detected in Fermi-LAT data. The matching locations, sizes and spectra suggest that both gamma-ray detections correspond to the same source. Different scenarios for the origin of the emission are considered and we rule out an association to the pulsar PSR J2004+3429 due to extreme energetics required, if located a…
The latest High Altitude Water Cherenkov (HAWC) point-like source catalog up to 56 TeV reported the detection of two sources in the region of the Galactic plane at galactic longitude 52°< l < 55°, 3HWC J1930+188 and 3HWC J1928+178. The first one is associated with a known TeV source, the supernova remnant SNR G054.1+00.3. It was discovered by one of the currently operating Imaging Atmospheric Cherenkov Telescope (IACT), the Very Energetic Radiation Imaging Telescope Array System (VERITAS), detected by the High Energy Stereoscopic System (H.E.S.S.), and identified as a composite SNR. However, t…
4FHL: The Fourth Catalog of Hard Fermi-LAT Sources
Université Paris-Saclay（巴黎萨克雷大学）；Université Paris Cité（巴黎西岱大学）；CEA（法国原子能暨替代能源委员会）；CNRS（法国国家科学研究中心）；FSLAC IRL 2009（中法天文卫星联合实验室）；IAC（加那利天体物理研究所）；Istituto Nazionale di Fisica Nucleare, Sezione di Perugia（意大利国家核物理研究院佩鲁吉亚分部）；Department of Physics and Astronomy, Clemson University（克莱姆森大学物理与天文系）；Dipartimento di Fisica, Università di Trieste（的里雅斯特大学物理系）；Istituto Nazionale di Fisica Nucleare, Sezione di Trieste（意大利国家核物理研究院的里雅斯特分部）；Università di Pisa, Dipartimento di Fisica E. Fermi（比萨大学E.费米物理系）；Istituto Nazionale di Fisica Nucleare, Sezione di Pisa（意大利国家核物理研究院比萨分部）；Istituto Nazionale di Fisica Nucleare, Sezione di Bari（意大利国家核物理研究院巴里分部）；Università degli studi di Trento（特伦托大学）；Instituto de Astrofísica de Canarias（加那利天体物理研究所）；Universidad de La Laguna（拉帕拉斯大学）
TeV Gamma-Ray Emission in the DA 495 Region from HAWC Observations of J1952+2924, J1954+2837, and J1958+2848
Instituto de Física, Universidad Nacional Autónoma de México（墨西哥国立自治大学物理研究所）；Universidad Autónoma de Chiapas（奇亚帕斯自治大学）；Instituto de Astronomía, Universidad Nacional Autónoma de México（墨西哥国立自治大学天文研究所）；Universidad de Costa Rica（哥斯达黎加大学）；Universidad Michoacana de San Nicolás de Hidalgo（米却肯圣尼古拉斯德伊达尔戈大学）；Temple University（天普大学）；Michigan State University（密歇根州立大学）
The High Altitude Water Cherenkov Gamma-Ray Observatory (HAWC) continuously detects TeV photons and particles within its large field-of-view, accumulating every day a deeper exposure of two thirds of the sky. We analyzed 1523~days of HAWC live data acquired over four and a half years, in a follow-up analysis of {138} nearby ($z<0.3$) active galactic nuclei from the {\em Fermi} 3FHL catalog culminating within $40^\circ$ of the zenith at Sierra Negra, the HAWC site. This search for persistent TeV emission used a maximum-likelihood analysis assuming intrinsic power-law spectra attenuated by pair …
Sky surveys produce enormous quantities of data on extensive regions of the sky. The easiest way to access this information is through catalogues of standardised data products. {\em XMM-Newton} has been surveying the sky in the X-ray, ultra-violet, and optical bands for 20 years. The {\em XMM-Newton} Survey Science Centre has been producing standardised data products and catalogues to facilitate access to the serendipitous X-ray sky. Using improved calibration and enhanced software, we re-reduced all of the 14041 {\em XMM-Newton} X-ray observations, of which 11204 observations contained data w…
This fourth release of the RIT public catalog of numerical relativity black-hole-binary waveforms \url{http://ccrg.rit.edu/~RITCatalog} consists of 1881 accurate simulations that include 446 precessing and 611 nonprecessing quasicircular/inspiraling binary systems with mass ratios $q=m_1/m_2$ in the range $1/128\leq q\leq1$ and individual spins up to $s/m^2=0.95$; and 824 in eccentric orbits in the range $0<e\leq1$. The catalog also provides initial parameters of the binary, trajectory information, peak radiation, and final remnant black hole properties. The waveforms are corrected for the cen…
Radio-loud sources with blazar-like properties, but having a jet that does not directly point in the direction of the observer are among the most interesting classes of gamma-ray emitters. These sources are known as Misaligned Active Galactic Nuclei (MAGN). Understanding MAGN properties is useful to improve the knowledge of blazar energetics. We searched for new MAGN candidates among the remaining blazars of uncertain type detected by the Fermi Large Area Telescope (LAT) using a methodology based on characterizing their radio morphology. We identified seven new candidates associated with gamma…
Considering the shortage of comparative studies on pulse temporal characteristics between single-peaked short gamma-ray bursts (sGRBs) and double-peaked sGRBs, we examine the pulse properties of a sample of 100 BATSE sGRBs using the BATSE Time-Tagged Event (TTE) data with a 5-ms resolution. 243 individual pulses of the single-peaked, double-peaked and triple-peaked sGRBs are fitted to get their statistical properties such as the pulse asymmetry, amplitude, peak time, and pulse width, etc. For the double-peaked sGRBs, according to the overlapping ratio between two adjacent peaks, we first defin…
Investigating IceCube Neutrino Alerts with the HAWC $γ$-Ray Observatory
Instituto de Física, Universidad Nacional Autónoma de México（墨西哥国立自治大学物理研究所）；Universidad Autónoma de Chiapas（恰帕斯自治大学）；Instituto de Astronomía, Universidad Nacional Autónoma de México（墨西哥国立自治大学天文学研究所）；Universidad de Costa Rica（哥斯达黎加大学）；Universidad Michoacana de San Nicolás de Hidalgo（米却肯圣尼古拉斯德伊达尔戈大学）；Temple University（天普大学）；Michigan State University（密歇根州立大学）
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…
Recently, a few-degrees extended $γ$-ray halo in the direction of Geminga pulsar has been detected by HAWC, Milagro and Fermi-LAT. These observations can be interpreted with positrons ($e^+$) and electrons ($e^-$) accelerated by Geminga pulsar wind nebula (PWN), released in a Galactic environment with a low diffusion coefficient ($D_0$), and inverse Compton scattering (ICS) with the interstellar radiation fields. We inspect here how the morphology of the ICS $γ$-ray flux depends on the energy, the pulsar age and distance, and the strength and extension of the low-diffusion bubble. In particula…
The deepest all-sky survey available in the $γ$-ray band - the last release of the Fermi-LAT catalogue (4FGL-DR3) based on the data accumulated in 12 years, contains more than 6600 sources. The largest population among the sources is blazar subclass - 3743, $60.1\%$ of which are classified as BL Lacertae objects (BL Lacs) or Flat Spectrum Radio Quasars (FSRQs), while the rest are listed as blazar candidates of uncertain type (BCU) as their firm optical classification is lacking. The goal of this study is to classify BCUs using different machine learning algorithms which are trained on the spec…
Isolated neutron star candidates from the fourth generation XMM-Newton catalogues
Center for Lunar and Planetary Sciences, Institute of Geochemistry, Chinese Academy of Sciences（中国科学院地球化学研究所月球与行星科学中心）；Leibniz-Institut für Astrophysik Potsdam (AIP)（波茨坦阿斯特拉物理学会莱布尼茨研究所）；Université de Strasbourg, CNRS, Observatoire Astronomique de Strasbourg（斯特拉斯堡大学法国国家科学研究中心斯特拉斯堡天文台）；College of Physics, Guizhou University（贵州大学物理学院）；Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台）；Guizhou Radio Astronomical Observatory, Guizhou University（贵州大学贵州射电天文台）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；College of Astronomy and Space Sciences, University of Chinese Academy of Sciences（中国科学院大学天文与空间科学学院）
HAWC Study on the Ultra-High-Energy Gamma-Ray Emissions from the Pulsar Wind Nebula G32.64+0.53
Instituto de Física, Universidad Nacional Autónoma de México（墨西哥国立自治大学物理研究所）；Universidad Autónoma de Chiapas（恰帕斯自治大学）；Instituto de Astronomía, Universidad Nacional Autónoma de México（墨西哥国立自治大学天文研究所）；Universidad de Costa Rica（哥斯达黎加大学）；Universidad Michoacana de San Nicolás de Hidalgo（米却肯圣尼古拉斯德伊达尔戈大学）；Temple University（天普大学）；Michigan State University（密歇根州立大学）
The HAWC Collaboration released the 2HWC catalog of TeV sources, in which 19 show no association with any known high-energy (HE; E > 10 GeV) or very-high-energy (VHE; E > 300 GeV) sources. This catalog motivated follow-up studies by both the MAGIC and Fermi-LAT observatories with the aim of investigating gamma-ray emission over a broad energy band. In this paper, we report the results from the first joint work between HAWC, MAGIC and Fermi-LAT on three unassociated HAWC sources: 2HWC J2006+341, 2HWC J1907+084* and 2HWC J1852+013*. Although no significant detection was found in the HE and VHE r…
Max-Planck-Institut für Kernphysik（马克斯·普朗克核物理研究所）；Friedrich-Alexander-Universität Erlangen-Nürnberg（埃尔兰根-纽伦堡弗里德里希·阿列克山大大学）；Stockholm University（斯德哥尔摩大学）；The Oskar Klein Centre for Cosmoparticle Physics（奥斯卡·克莱因宇宙粒子物理中心）；Cherenkov Telescope Array Observatory, Science Data Management Centre (SDMC)（切伦科夫望远镜阵列观测站科学数据管理中心）
We present an incremental version (4FGL-DR3, for Data Release 3) of the fourth Fermi-LAT catalog of gamma-ray sources. Based on the first twelve years of science data in the energy range from 50 MeV to 1 TeV, it contains 6658 sources. The analysis improves on that used for the 4FGL catalog over eight years of data: more sources are fit with curved spectra, we introduce a more robust spectral parameterization for pulsars, and we extend the spectral points to 1 TeV. The spectral parameters, spectral energy distributions, and associations are updated for all sources. Light curves are rebuilt for …
An incremental version of the fourth catalog of active galactic nuclei (AGNs) detected by the Fermi-Large Area Telescope is presented. This version (4LAC-DR3) derives from the third data release of the 4FGL catalog based on 12 years of E>50 MeV gamma-ray data, where the spectral parameters, spectral energy distributions (SEDs), yearly light curves, and associations have been updated for all sources. The new reported AGNs include 587 blazar candidates and four radio galaxies. We describe the properties of the new sample and outline changes affecting the previously published one. We also introdu…
The Cygnus region of the galaxy is one of the richest regions of gas and star formation and is the brightest region of diffuse GeV emission in the northern sky. VERITAS has conducted deep observations (approximately 300 hours) in the direction of Cygnus region, reaching an average sensitivity of a few percent of the Crab nebula flux. We present the results of these observations and an analysis of over seven years of Fermi-LAT data above 1 GeV. In addition to a search for new sources in the region, we present updated spectra and morphologies of the known TeV gamma-ray sources and a study of the…
Milagro and HAWC have detected extended TeV gamma-ray emission around nearby pulsar wind nebulae (PWNe). Building on these discoveries, Linden et al. [1] identified a new source class -- TeV halos -- powered by the interactions of high-energy electrons and positrons that have escaped from the PWN, but which remain trapped in a larger region where diffusion is inhibited compared to the interstellar medium. Many theoretical properties of TeV halos remain mysterious, but empirical arguments suggest that they are ubiquitous. The key to progress is finding more halos. We outline prospects for new d…
This paper presents the results of a $\rm γ$-ray likelihood analysis over all the extreme and high synchrotron peak blazars (EHSP & HSP) from the 3HSP catalogue. We investigate 2013 multifrequency positions under the eyes of Fermi Large Area Telescope, considering 11 years of observations in the energy range between 500 MeV to 500 GeV, which results in 1160 $\rm γ$-ray signatures detected down to the TS = 9 threshold. The detections include 235 additional sources concerning the Fermi Large Area Telescope Fourth Source Catalog (4FGL), all confirmed via high-energy TS maps, and represent an impr…
We use 10 years of publicly available IceCube data to investigate the correlations between high-energy neutrinos and various Fermi-LAT gamma-ray samples. This work considers the following gamma-ray samples: the third Fermi-LAT catalog of high-energy sources(3FHL), >100GeV Fermi-LAT events, LAT 12-year source catalog(4FGL), the fourth catalog of active galactic nuclei(4LAC) and subsets of these samples. For each sample, both a single-source analysis and a stacking analysis are performed. We find no indication that the sources in these samples produce significant high-energy neutrinos. From the …
The recently published fourth Fermi Large Area Telescope source catalog (4FGL) reports 5065 gamma-ray sources in terms of direct observational gamma-ray properties. Among the sources, the largest population is the Active Galactic Nuclei (AGN), which consists of 3137 blazars, 42 radio galaxies, and 28 other AGNs. The blazar sample comprises 694 flat-spectrum radio quasars (FSRQs), 1131 BL Lac-type objects (BL Lacs), and 1312 blazar candidates of an unknown type (BCUs). The classification of blazars is difficult using optical spectroscopy given the limited knowledge with respect to their intrins…
