Bulletin of the American Physical Society
APS April Meeting 2019
Volume 64, Number 3
Saturday–Tuesday, April 13–16, 2019; Denver, Colorado
Session Q08: Gamma-ray Catalogs, Extended Sources, and Diffuse Emission |
Hide Abstracts |
Sponsoring Units: DAP Chair: Amy Connolly, Ohio State University Room: Sheraton Governor's Square 10 |
Monday, April 15, 2019 10:45AM - 10:57AM |
Q08.00001: The HAWC Observatory’s first catalog of sources emitting above 50 TeV and 100 TeV Kelly Malone We present the High Altitude Water Cherenkov (HAWC) Observatory’s first catalog of gamma-ray sources emitting at the highest energies (above 50 TeV and 100 TeV). HAWC consists of an array of 300 water Cherenkov detectors located in Puebla, Mexico and is well-suited to performing all-sky surveys due to its high duty cycle (>90%) and wide instantaneous field-of-view (∼2 sr). There are a total of seven sources in these catalogs: six in the Galactic plane, as well as the Crab Nebula. These sources may have implications for the sources of Galactic cosmic rays. Since Galactic CRs have been observed up to PeV energies, sources accelerating particles to these energies (“PeVatrons”) are expected to exist. The corresponding gamma-ray spectrum would be hard and extend to the highest energies without any spectral break or cutoff. We will compute the spectrum of these seven highest-energy sources and explore whether any of them can be considered PeVatron candidates. We will also consider the relevance of these highest-energy sources to probing violations of Lorentz Invariance. |
Monday, April 15, 2019 10:57AM - 11:09AM |
Q08.00002: Constraints on the Diffuse Gamma-Ray Background with HAWC Pat Harding The Diffuse Gamma-Ray Background (DGB) above 100 GeV is high-latitude emission expected to be produced by unresolved extragalactic objects such as active galactic nuclei, isotropic Galactic gamma-rays, and possible emission from dark matter annihilations or decays in the Galactic dark matter halo. The DGB has been observed up to nearly 1 TeV, but has yet to be detected at higher energies. Detections or stringent limits on the DGB above this energy would have strong multimessenger consequences, such as constraining the origin of astrophysical neutrinos observed in IceCube. The High Altitude Water Cherenkov (HAWC) observatory observes gamma rays above 100 GeV and continuously observes the sky, observing over 2/3 of the sky each day. With its high energy reach and large areal coverage, HAWC can search for the DGB at energies above 1 TeV. In order to isolate gamma-ray air showers from background hadronic showers, we will use topological cuts on HAWC air showers to create a dataset dominated by gamma-ray-like emission. In addition, due to its nearly-isotropic nature, the search for DGB emission requires non-standard background estimation methods for HAWC. We will present a limit on the DGB with HAWC as well as its implications for multimessenger and dark matter studies. |
Monday, April 15, 2019 11:09AM - 11:21AM |
Q08.00003: HAWC measurements of the Cosmic-ray Flux of three Giant Molecular Clouds Hugo Ayala The characterization of the cosmic ray flux in the Galaxy can be obtained by combining the knowledge of the distribution of gas in the Galaxy and the observation of gamma-rays. We analyze the data from the HAWC Observatory to look for gamma rays in three giant molecular clouds that are part of the Gould Belt but that are far from the galactic plane (outside the region of ±5º in galactic latitude). We can then test the paradigm that the measured local cosmic-ray flux is the same as the “sea” of cosmic rays. Due to its large field of view, and high duty cycle, HAWC is suitable to search for gamma-rays from large structures in the TeV gamma-ray regime. We present here preliminary results for the flux measurements of the Aquila, Hercules and Taurus molecular clouds. |
Monday, April 15, 2019 11:21AM - 11:33AM |
Q08.00004: The gamma Cygni Supernova Remnant at the Highest Energies Henrike Fleischhack Supernova remnants (SNRs) have long been thought to be the main source of Galactic Cosmic Rays up to PeV energies, and many of them have been shown to accelerate particles to very high energies. But which of them do indeed accelerate a significant number of protons and nuclei? And up to which energies can they accelerate these particles? Non-thermal photon emission, especially in the X-ray and gamma-ray range, is of crucial help in answering these questions. |
Monday, April 15, 2019 11:33AM - 11:45AM |
Q08.00005: On the observation of the supernova remnant IC443 with the HAWC Observatory Leah Hunt, Miguel A Mostafa The supernova remnant IC 443 is one of the most thoroughly studied, and one of the clearest examples of interaction with molecular clouds. We present the observations of IC 433 in the multi-TeV energy range using data from the High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory. IC 443 is significantly observed in the 1128 days of live-time of HAWC, ranging from November 26, 2014 to April 24, 2018, with a test statistics of 32.3 in the point-source search. The measured spectrum continues beyond 2 TeV, the maximum energy previously observed by VERITAS and MAGIC, with a photon index consistent with previous measurements. Results are presented in the context of existing models for gamma-ray production in IC 443. |
Monday, April 15, 2019 11:45AM - 11:57AM |
Q08.00006: Setting Upper Limits on the Local Burst Rate Density of Primordial Black Holes Using HAWC Alison Peisker, Kristi L Engel Primordial Black Holes (PBHs) are black holes that may have been created by density fluctuations in the early Universe and could be as large as supermassive black holes or as small as the Planck scale. It is believed that a black hole has a temperature inversely proportional to its mass and will thermally emit all species of fundamental particles via Hawking Radiation. PBHs with initial masses of ~5×10^14 g should be expiring today with bursts of high-energy gamma radiation in the GeV – TeV energy range. The High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory is sensitive to the high end of the PBH burst spectrum. With its large instantaneous field of view of ~2 sr and a duty cycle above 95%, the HAWC observatory is well suited to perform an all-sky search for PBH bursts. We performed a search on ~2.6 years of HAWC data by optimizing a previous transient search to the PBH burst energy spectrum. As this search yielded a null detection, we placed competitive upper limits at the 99% confidence level on the local PBH burst rate density. Previous studies predicting HAWC’s ability to place such a limit were surpassed, as well as limits placed by similar detectors. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700