Publications (41)
Observations of the Unidentified TeV Gamma-Ray Source TeV J2032+4130 with the Whipple Observatory 10 m Telescope
A. Konopelko, R. W. Atkins, G. Blaylock +58
We report on observations of the sky region around the unidentified TeV gamma-ray source TeV J2032+4130 carried out with the Whipple Observatory 10 m atmospheric Cherenkov telescop…
VERITAS Observations of the gamma-Ray Binary LS I +61 303
V. A. Acciari, M. Beilicke, G. Blaylock +74
LS I +61 303 is one of only a few high-mass X-ray binaries currently detected at high significance in very high energy gamma-rays. The system was observed over several orbital cycl…
Search for Signatures of Dark Matter Annihilation in the Galactic Center with HAWC
R. Alfaro, C. Alvarez, A. Andrés +109
We conduct an indirect dark matter (DM) search in the Galactic Center, focusing on a square region within in Galactic longitude and latutide, using 2,865 days of da…
Testing the Molecular Cloud Paradigm for Ultra-High-Energy Gamma Ray Emission from the Direction of SNR G106.3+2.7
R. Alfaro, C. Alvarez, J. C. Arteaga-Velázquez +87
Supernova remnants (SNRs) are believed to be capable of accelerating cosmic rays (CRs) to PeV energies. SNR G106.3+2.7 is a prime PeVatron candidate. It is formed by a head region,…
Observation of the Galactic Center PeVatron Beyond 100 TeV with HAWC
A. Albert, R. Alfaro, C. Alvarez +99
We report an observation of ultra-high energy (UHE) gamma rays from the Galactic Center region, using seven years of data collected by the High-Altitude Water Cherenkov (HAWC) Obse…
Status of the VERITAS Observatory
J. Holder, V. A. Acciari, E. Aliu +79
VERITAS, an Imaging Atmospheric Cherenkov Telescope (IACT) system for gammma-ray astronomy in the GeV-TeV range, has recently completed its first season of observations with a full…
Discovery of Very High-Energy Gamma-Ray Radiation from the BL Lac 1ES 0806+524
VERITAS Collaboration, V. Acciari, E. Aliu +90
The high-frequency-peaked BL-Lacertae object \objectname{1ES 0806+524}, at redshift z=0.138, was observed in the very-high-energy (VHE) gamma-ray regime by VERITAS between November…
Improved Heavy Dark Matter Annihilation Search from Dwarf Galaxies with HAWC
A. Albert, R. Alfaro, C. Alvarez +103
Understanding dark matter's elusive nature is crucial for the framework of particle physics and expanding the Standard Model. This analysis utilizes the High Altitude Water Cherenk…
HAWC Performance Enhanced by Machine Learning in Gamma-Hadron Separation
R. Alfaro, C. Alvarez, A. Andrés +92
Improving gamma-hadron separation is one of the most effective ways to enhance the performance of ground-based gamma-ray observatories. With over a decade of continuous operation,…
HAWC, VERITAS, Fermi-LAT and XMM-Newton follow-up observations of the unidentified ultra-high-energy gamma-ray source LHAASO J2108+5157
The VERITAS collaboration, C. B. Adams, P. Bangale +142
We report observations of the ultra-high-energy gamma-ray source LHAASO J21085157, utilizing VERITAS, HAWC, Fermi-LAT, and XMM-Newton. VERITAS has collected 40 hours of d…
A Multi-messenger Search for Ultra-high-energy Gamma Rays in Coincidence with Neutrinos
R. Alfaro, C. Alvarez, A. Andrés +101
The last five years have shown us that ultra-high-energy (UHE; 100 TeV) gamma-ray sources are ubiquitous, but the nature of these sources remain highly uncertain. UHE gamma rays…
Modeling the Shell of Cassiopeia A to find the TeV Gamma-ray Emission Region
T. Ergin, L. Saha, P. Majumdar +2
We will present the multi-wavelength modeling of the supernova remnant Cassiopeia A's shell based on radio, X-rays, and GeV-TeV gamma rays. Our aim is to estimate the location of T…
Science Prospects for the Southern Wide-field Gamma-ray Observatory: SWGO
SWGO Collaboration, P. Abreu, R. Alfaro +303
Ground-based gamma-ray astronomy is now well established as a key observational approach to address critical topics at the frontiers of astroparticle physics and high-energy astrop…
Orbital Modulation of Gamma-Rays Beyond 100 TeV from LS 5039
R. Alfaro, M. Araya, J. C. Arteaga-Velázquez +88
Gamma-ray binaries are systems composed of a compact object orbiting a massive companion star. The interaction between these two objects can drive relativistic outflows, either jet…
Recombining Plasma & Gamma-ray Emission in the Mixed-morphology Supernova Remnant 3C 400.2
T. Ergin, A. Sezer, H. Sano +2
3C 400.2 belongs to the mixed morphology supernova remnant class, showing center-filled X-ray and shell-like radio morphology. We present a study of 3C 400.2 with archival Suzaku a…
VERITAS Observations of a Very High Energy Gamma-ray Flare from the Blazar 3C 66A
VERITAS Collaboration, V. A. Acciari, E. Aliu +87
The intermediate-frequency peaked BL Lacertae (IBL) object 3C 66A is detected during 2007 - 2008 in VHE (very high energy: E > 100 GeV) gamma-rays with the VERITAS stereoscopic arr…
Constraining the Photon Intensity of Extragalactic Background Light with the HAWC Observatory for the Blazar Mrk 421
R. Alfaro, C. Alvarez, A. Andrés +79
The blazar Mrk 421 exhibits rapid variability over a wide range of timescales. Spectral differences have been observed during the different emission states of Mrk 421. During the h…
Origin of gamma-ray emission in the shell of Cassiopeia A
L. Saha, T. Ergin, P. Majumdar +2
Non-thermal X-ray emission from the shell of Cassiopeia A (Cas A) has been an interesting subject of study, as it provides information about relativistic electrons and their accele…
HAWC Study on the Ultra-High-Energy Gamma-Ray Emissions from the Pulsar Wind Nebula G32.64+0.53
R. Alfaro, C. Alvarez, E. Anita-Rangel +108
Multi-TeV gamma-ray emission around eHWC J1850+001 (a source from the first HAWC catalog of gamma-ray sources emitting above 56 TeV) is spatially coincident with the pulsar wind ne…
Absence of TeV halos around millisecond pulsars
A. U. Abeysekara, R. Alfaro, C. Alvarez +82
TeV halos are extended very-high-energy (VHE; 0.1-100 TeV) gamma-ray emission around middle-aged pulsars. So far they have only been found around isolated pulsars, but it has been…
Study of the IC 443 region with the HAWC observatory
R. Alfaro, C. Alvarez, M. Araya +89
Supernova remnants are one potential source class considered a PeVatron (i.e. capable of accelerating cosmic rays above PeV energies). The shock fronts produced after the explosion…
The Fourth HAWC Catalog of Very-High-Energy Gamma-Ray Sources
R. Alfaro, C. Alvarez, E. Anita-Rangel +87
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 improve…
VERITAS Discovery of >200GeV Gamma-ray Emission from the Intermediate-frequency-peaked BL Lac Object W Comae
VERITAS Collaboration, V. A. Acciari, E. Aliu +80
We report the detection of very high-energy gamma-ray emission from the intermediate-frequency-peaked BL Lacertae object W Comae (z=0.102) by VERITAS. The source was observed betwe…
VERITAS observations of the BL Lac 1ES 1218+304
VERITAS Collaboration, V. A. Acciari, E. Aliu +78
The VERITAS collaboration reports the detection of very-high-energy (VHE) gamma-ray emission from the high-frequency-peaked BL Lac object 1ES 1218+304 located at a redshift of z=0.…
Studying the Supernova Remnant G31.9+0.0 in Gamma and X-Rays
T. Ergin, A. Sezer, L. Saha +2
G31.9+0.0 (3C 391) is a Galactic mixed-morphology supernova remnant observed in GeV gamma rays by Fermi Gamma Ray Space Telescope's LAT (Fermi-LAT), as well as in the 0.3-10 keV X-…
Evidence for long-term Gamma-ray and X-ray variability from the unidentified TeV source HESS J0632+057
VERITAS Collaboration, V. A. Acciari, E. Aliu +79
HESS J0632+057 is one of only two unidentified very-high-energy gamma-ray sources which appear to be point-like within experimental resolution. It is possibly associated with the m…
Constraints on Axion-Like Particles from Ultra-High-Energy Observations of 3HWC J1908+063 with HAWC
R. Alfaro, C. Alvarez, A. Andres +92
Axion-like particles (ALPs) are hypothetical particles and compelling candidates for cold dark matter. Their existence could be probed through their conversions into photons in the…
Multiwavelength Observations of LS I +61 303 with VERITAS, Swift and RXTE
VERITAS Collaboration, V. A. Acciari, E. Aliu +83
We present results from a long-term monitoring campaign on the TeV binary LSI +61 303 with VERITAS at energies above 500 GeV, and in the 2-10 keV hard X-ray bands with RXTE and Swi…
Search for joint multimessenger signals from potential galactic cosmic-ray accelerators with HAWC and IceCube
R. Alfaro, C. Alvarez, J. C. Arteaga-Velázquez +489
The origin of high-energy galactic cosmic rays is yet to be understood, but some galactic cosmic-ray accelerators can accelerate cosmic rays up to PeV energies. The high-energy cos…
Observations of the shell-type SNR Cassiopeia A at TeV energies with VERITAS
The VERITAS Collaboration, V. A. Acciari, E. Aliu +80
We report on observations of very high-energy gamma rays from the shell-type supernova remnant Cassiopeia A with the VERITAS stereoscopic array of four imaging atmospheric Cherenko…
Longtime Monitoring of TeV Radio Galaxies with HAWC
R. Alfaro, C. Alvarez, E. Anita-Rangel +85
We present the monitoring of the TeV-emitting radio galaxies M87, NGC~1275, 3C~264, and IC~310 with the High Altitude Water Cherenkov Observatory (HAWC) over a period of approximat…
Performance of the HAWC Observatory and TeV Gamma-Ray Measurements of the Crab Nebula with Improved Extensive Air Shower Reconstruction Algorithms
A . Albert, R. Alfaro, C. Alvarez +90
The High-Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory located on the side of the Sierra Negra volcano in Mexico, has been fully operational since 2015. The HAWC collaborat…
Constraints on axion-like particles from ultra-high-energy observations of M87 with the HAWC observatory
R. Alfaro, C. Alvarez, A. Andrés +95
In this work, we perform an indirect search for axion-like particles (ALPs) through their hypothesized mixing with photons in the presence of magnetic fields. ALPs are a well-motiv…
Analysis of the Emission and Morphology of the Pulsar Wind Nebula Candidate HAWC J2031+415
R. Alfaro, C. Alvarez, J. C. Arteaga-Velázquez +78
The first TeV gamma-ray source with no lower energy counterparts, TeV J2032+4130, was discovered by HEGRA. It appears in the third HAWC catalog as 3HWC J2031+415 and it is a bright…
Detection of Extended VHE Gamma Ray Emission from G106.3+2.7 with VERITAS
VERITAS Collaboration, V. A. Acciari, E. Aliu +80
We report the detection of very-high-energy (VHE) gamma-ray emission from supernova remnant (SNR) G106.3+2.7. Observations performed in 2008 with the VERITAS atmospheric Cherenkov…
Probing the star formation origin of gamma rays from 3FHL J1907.0+0713
T. Ergin, L. Saha, P. Bhattacharjee +5
Star-forming (SF) regions embedded inside giant molecular clouds (GMCs) are potential contributors to Galactic gamma rays. The gamma-ray source 3FHL J1907.0+0713 is detected with a…
Search for TeV emission from spider millisecond pulsars with HAWC
R. Alfaro, E. Anita-Rangel, M. Araya +90
Millisecond pulsars (MSPs) are observed to emit multi-wavelength radiation, from radio to GeV. Spider MSPs, which interact with their low-mass companion in close orbit (orbital per…
Spectral study of very high energy gamma rays from SS 433 with HAWC
R. Alfaro, C. Alvarez, J. C. Arteaga-Velázquez +78
Very-high-energy (0.1-100 TeV) gamma-ray emission was observed in HAWC data from the lobes of the microquasar SS 433, making them the first set of astrophysical jets that were reso…
Observation of Extended VHE Emission from the Supernova Remnant IC 443 with VERITAS
VERITAS Collaboration, V. A. Acciari, E. Aliu +90
We present evidence that the very-high-energy (VHE, E > 100 GeV) gamma-ray emission coincident with the supernova remnant IC 443 is extended. IC 443 contains one of the best-studie…
GeV Gamma-ray Counterparts of New Candidate Radio Supernova Remnants Reported in the GLEAM Survey
B. M. Mese, T. Ergin
Recently the Galactic and Extra-galactic All-sky Murchison Widefield Array survey has published 27 new candidate radio supernova remnants (SNRs) which are located within the longit…
Observation of gamma-ray emission from the galaxy M87 above 250 GeV with VERITAS
V. A. Acciari, M. Beilicke, G. Blaylock +74
The multiwavelength observation of the nearby radio galaxy M87 provides a unique opportunity to study in detail processes occurring in Active Galactic Nuclei from radio waves to Te…