S. Groetsch

Extended TeV Halos May Commonly Exist around Middle-Aged Pulsars

A. Albert, R. Alfaro, C. Alvarez +81

Extended gamma-ray emission around isolated pulsars at TeV energies, also known as TeV halos, have been found around a handful of middle-aged pulsars. The halos are significantly m…

Search for joint multimessenger signals from potential galactic cosmic-ray accelerators with HAWC and IceCube

R. Alfaro, C. Alvarez, J. C. Arteaga-VelÃ¡zquez +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…

Search for Signatures of Dark Matter Annihilation in the Galactic Center with HAWC

R. Alfaro, C. Alvarez, A. AndrÃ©s +109

We conduct an indirect dark matter (DM) search in the Galactic Center, focusing on a square region within $\pm 9^{\circ}$ 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-VelÃ¡zquez +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…

Ultra-High-Energy Gamma-Ray Bubble around Microquasar V4641 Sgr

R. Alfaro, C. Alvarez, J. C. Arteaga-VelÃ¡zquez +89

Microquasars are laboratories for the study of jets of relativistic particles produced by accretion onto a spinning black hole. Microquasars are near enough to allow detailed imagi…

astro-ph.IM2025

HAWC Performance Enhanced by Machine Learning in Gamma-Hadron Separation

R. Alfaro, C. Alvarez, A. AndrÃ©s +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 J2108 $+$ 5157, utilizing VERITAS, HAWC, Fermi-LAT, and XMM-Newton. VERITAS has collected $\sim$ 40 hours of d…

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…

A Multi-messenger Search for Ultra-high-energy Gamma Rays in Coincidence with Neutrinos

R. Alfaro, C. Alvarez, A. AndrÃ©s +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…

Orbital Modulation of Gamma-Rays Beyond 100 TeV from LS 5039

R. Alfaro, M. Araya, J. C. Arteaga-VelÃ¡zquez +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…

TeV Analysis of a Source Rich Region with HAWC Observatory: Is HESS J1809-193 a Potential Hadronic PeVatron?

A. Albert, R. Alfaro, C. Alvarez +79

HESS J1809-193 is an unidentified TeV source, first detected by the High Energy Stereoscopic System (H.E.S.S.) Collaboration. The emission originates in a source-rich region that i…

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…

Constraining the Photon Intensity of Extragalactic Background Light with the HAWC Observatory for the Blazar Mrk 421

R. Alfaro, C. Alvarez, A. AndrÃ©s +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…

Analysis of the Emission and Morphology of the Pulsar Wind Nebula Candidate HAWC J2031+415

R. Alfaro, C. Alvarez, J. C. Arteaga-VelÃ¡zquez +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…

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…

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-VelÃ¡zquez +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…

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…