Bulletin of the American Physical Society
APS April Meeting 2022
Volume 67, Number 6
Saturday–Tuesday, April 9–12, 2022; New York
Session G13: Gamma-Ray Astrophysics with HAWCRecordings Available
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Sponsoring Units: DAP Chair: Brian Rauch, Washington University, St. Louis Room: Empire |
Sunday, April 10, 2022 8:30AM - 8:42AM |
G13.00001: Real-time transient search in HAWC with improved reconstruction kwok lung fan The HAWC Observatory is a water Cherenkov observatory located in central Mexico at 4100 m above sea level. HAWC is sensitive to gamma rays with energy from a few hundred GeV to 100s of TeV. HAWC's wide field of view(~ 2 sr), large effective area and near-continuous uptime make it ideal for transient searches. Recently, HAWC's reconstruction algorithm was upgraded from Pass 4 to Pass 5, with a major improvement in sensitivity at energies below 1 TeV due to a novel noise-reduction algorithm called the multi-plane fitter. Here, we introduce the three real-time transient searches currently running in HAWC, including an untriggered GRB search, a triggered GRB/Gravitational-Wave search, and a long duration (~ days) all-sky flare search. The Pass 5 improvement on the sensitivity of real-time transient searches will be shown. |
Sunday, April 10, 2022 8:42AM - 8:54AM |
G13.00002: Searching for Gamma Rays From FRB Source Locations with the HAWC Observatory ELIJAH J Willox Fast radio bursts (FRBs) are a class of short-duration, high-fluence transients in radio wavelengths, with some sources observed to repeat, while others are single-burst. In response, there have been several multi-wavelength searches for coincident transient activity and analysis of the host environments to gain clues to the origin of these events. The recent discovery of an FRB from the direction of SGR1935+2154, a Galactic magnetar, that was observed to be flaring by Fermi and Swift-BAT encourages multi-wavelength follow-up into gamma-ray energies. The HAWC gamma-ray observatory contributes to this multi-wavelength coverage with a wide field of view and consistent live-time suited to observation of transient source locations. While attenuation of gamma rays over extragalactic distances makes long-distance flux measurements difficult, data from the HAWC observatory can provide useful first upper limits of flux from the source locations of FRBs. For each FRB in the declination band of -20 to +60, since January 1, 2016, a steady-state flux upper limit has been set, and a search for transient activity around the burst time has been conducted with upper limits also presented for this search. |
Sunday, April 10, 2022 8:54AM - 9:06AM |
G13.00003: Morphology and Spectral Study of TeV Halo Candidates, Geminga and Monogem, with the HAWC gamma-ray observatory Ramiro Torres Escobedo The origin of the local positron excess above 10 GeV reported by PAMELA, Fermi-LAT, and AMS-02 remains unclear. Dark matter particle mechanisms such as annihilation and pulsar wind nebulae are likely sources of high energy electron/positron emission. Here the extended gamma-ray regions coinciding with two nearby mid-aged pulsars, Geminga and PSR B0656+14 (Monogem) are of particular interest. The High Altitude Water Cherenkov (HAWC) collaboration previously derived a high efficiency in emission of electrons and positrons but a diffusion coefficient that differed by a factor of 100 from the average galactic value with 500 days data. This result suggested no strong contribution to the above excess from these two sources. However, this led to the concept of inverse Compton gamma-ray halos, TeV halos. With an improved point spread function (PSF) and ~1400 days of data, I present a multi-source morphology and spectral study using a halo template model that allows for the direct analysis of energy dependence in diffusion coefficient for different positron spectral indices. |
Sunday, April 10, 2022 9:06AM - 9:18AM |
G13.00004: HAWC Study of HESS J1809-193 - a PeVatron candidate in a source rich region Rishi Babu The region surrounding HESS J1809-193 is a TeV source rich region comprised of multiple source classes such as pulsars and supernovas. The very high energy gamma ray source was first observed by the High Energy Stereoscopic System (H.E.S.S.) and is marked as a potential PeVatron candidate with an extended morphology. Studies have suggested that the gamma rays follow a hadronic scenario for the source. This work analyzes the region using multiple source models containing different morphologies and energy spectra to describe the emission from the source based on the latest reconstructed data from the High Altitude Water Cherenkov(HAWC) observatory. We will present a measurement of the spectral energy distribution extending the H.E.S.S. measurement beyond 50 TeV. |
Sunday, April 10, 2022 9:18AM - 9:30AM |
G13.00005: Analysis of High-mass Microquasar LS5039 using the newest HAWC data Dezhi Huang, Chang Dong Rho The High-mass microquasar LS 5039 is a bright gamma-ray source located less than 1.5 degrees from the galactic plane. Previously the High Energy Stereoscopic System (H.E.S.S.) discovered the source with 3.9 days orbital periodicity in a very high energy gamma-ray region. However, the behavior of gamma rays beyond tens of TeV remains unclear. The High Altitude Water Cherenkov (HAWC) gamma-ray observatory has great sensitivity beyond 10 TeV, making HAWC a perfect instrument to study this source at the highest energy range. This work performs multi-source analysis using the HAWC gamma-ray sky map for which the gamma-ray energies were reconstructed with an artificial neural network. With the improved point spread function (PSF), we can disentangle microquasar LS 5039 from the complex eHWC J1825-134 region. I will present the energy spectrum of LS 5039 for energy greater than 10 TeV. |
Sunday, April 10, 2022 9:30AM - 9:42AM |
G13.00006: TeV Analysis and Energy Morphology of Probable PWN HAWC J2031+415 Ian Herzog The Cygnus Cocoon region is a complex region containing an OB star cluster that is prominent in the TeV energy range. Located in this region is HAWC J2031+415, a significant TeV gamma ray source that lays within the Fermi-LAT Cocoon. HAWC 2031+415 is believed to be a pulsar wind nebula (PWN) whose stellar counterpart is PSR J2032+4127. In this work, several modelling methods are presented to best describe the emission with the High-Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory. These models disentangle HAWC J2031+415 from the Cocoon and isolate its emission. I will present several spectral models to describe the emission of the PWN using the newest data set with significantly improved angular resolution from the HAWC observatory. Furthermore, I will present an energy morphology study of HAWC J2031+415 in 4 distinct energy bands. |
Sunday, April 10, 2022 9:42AM - 9:54AM |
G13.00007: TeV Analysis of gamma-ray source 3HWC J1843-034 Youngwan Son 3HWC J1843-034 is one of the very-high-energy gamma-ray sources that has been observed at above 56 TeV by the High Altitude Water Cherenkov (HAWC) Observatory. This source coincides with LHAASO J1843-0338, which may be associated SNR G28.6-0.1. In this work, we systematically model this source confused region with the most up-to-date HAWC data to study the morphology and spectrum of 3HWC J1843-034. Also, we compare our results with other gamma-ray experiments of various energies. |
Sunday, April 10, 2022 9:54AM - 10:06AM |
G13.00008: TeV analysis of HESS J1804-216 with the HAWC Observatory Rhiannon M Turner HESS J1804-216 has been seen in multiple wavebands, however, its origin remains uncertain. While at TeV energies this source is classified as unidentified, the Fermi-LAT measures emission associated with pulsar J1803-2137. With HAWC data, gamma-ray emission in this source region is observed with a significance above 9σ. The HAWC Observatory provides sensitivity for energies above 10 TeV which can further help identify the origin of the emission. A multi-source study reveals a point-like excess in HAWC maps near HESS J1804-216. I will present the spectral energy distribution of this source above 1 TeV. |
Sunday, April 10, 2022 10:06AM - 10:18AM |
G13.00009: Detailed Morphology study of 3HWC J1857+027 region with HAWC data and comparison with H.E.S.S. results Xiaojie Wang 3HWC J1857+027 has remained unidentified but is a pulsar wind nebula (PWN) candidate in the 3HWC catalog made by the High-Altitude Water Cherenkov Gamma-Ray Observatory (HAWC). In this region, the High Energy Stereoscopic System (H.E.S.S.) resolved two extended sources: HESS J1857+027 and HESS J1858+020, which are separated by half a degree. The multi-source fitting method based on the Multi-Mission Maximum Likelihood framework (3ML) is used to model and analysis the emission from this region in about five and half years of HAWC data. With improved performance and more accumulated statistics, we can disentangle two extended sources in the region. I will present an analysis of the gamma-ray emission in this region beyond tens of TeV. |
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