A Search for Extended Gamma-Ray Emission from the Galactic Center with VERITAS PDF Download

Author: Nathan Kelley-Hoskins
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Matthew Gregory Buchovecky
Publisher:
ISBN:
Category :
Languages : en
Pages : 231

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Book Description
The Galactic Center (GC) is an extremely energetic region, host to a variety of powerful astronomical sources and rare astrophysical processes that emit a large flux of non-thermal radiation. The inner 375x600 pc region, called the Central Molecular Zone (CMZ), is home to the supermassive black hole Sgr A*, massive cloud complexes, supernova remnants, and likely the peak concentration of dark matter in the Galaxy. It has been studied across an extremely wide range of wavelengths by many instruments. In this dissertation, I present the results of my analysis of the very high-energy (VHE) (E > 100 GeV) gamma-ray emission from the GC using data from about 155 hours of quality observations taken with the VERITAS imaging atmospheric Cherenkov telescope. This emission includes a strong central point source VER J1745-290, coincident with the position of Sgr A*, and diffuse emission that extends along the Galactic ridge. VER J1745-290 is detected at a significance of 38 sigma, and I reconstruct its spectrum and lightcurve. Its spectrum is best fit by a power law with an index of -2.16 +/- 0.18 and flux normalization of (11.76 +/- 2.03)e-12 TeV/cm2/s at 1 TeV, and an exponential cutoff at 10.8 +/- 3.0 TeV. The exponential cutoff in its spectral shape, along with its apparent lack of variability in the very-high-energy gamma ray range favor electron models of its emission, such as the plerion model of emission from the pulsar wind nebula G359.95--0.04. I also present the results of my analysis on the morphology and, for the first time with VERITAS, the spectrum of diffuse emission in the GC. I find an approximately 52\% correlation of the gamma signal to molecular gas as traced by CS(1-0) line emission. I report an energy spectrum that is best fit by a pure power law with a hard index of -2.26 +/- 0.13, showing no evidence of a cutoff over 40 TeV. This strengthens the evidence of a potential accelerator of PeV cosmic rays being present in the GC. Using these results, I discuss the impact on current models of diffuse emission and possible connections to the central source. I also provide detections and spectra of other sources within the field of view of VERITAS.

Author: Glen Hamilton Dahlbacka
Publisher:
ISBN:
Category : Gamma rays
Languages : en
Pages : 288

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Author: Andrea Albert
Publisher: Morgan & Claypool Publishers
ISBN: 1681742691
Category : Science
Languages : en
Pages : 64

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Searching for Dark Matter with Cosmic Gamma Rays summarizes the evidence for dark matter and what we can learn about its particle nature using cosmic gamma rays. It has almost been 100 years since Fritz Zwicky first detected hints that most of the matter in the Universe that doesn't directly emit or reflect light. Since then, the observational evidence for dark matter has continued to grow. Dark matter may be a new kind of particle that is governed by physics beyond our Standard Model of particle physics. In many models, dark matter annihilation or decay produces gamma rays. There are a variety of instruments observing the gamma-ray sky from tens of MeV to hundreds of TeV. Some make deep, focused observations of small regions, while others provide coverage of the entire sky. Each experiment offers complementary sensitivity to dark matter searches in a variety of target sizes, locations, and dark matter mass scales. We review results from recent gamma-ray experiments including anomalies some have attributed to dark matter. We also discuss how our gamma-ray observations complement other dark matter searches and the prospects for future experiments.

Author: Carl E. Fichtel
Publisher:
ISBN:
Category : Gamma ray astronomy
Languages : en
Pages : 432

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Author: Silvia Celli
Publisher: Springer Nature
ISBN: 3030331245
Category : Science
Languages : en
Pages : 264

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This book addresses three “hot” topics concerning the general problem of the origin of Galactic cosmic rays, namely (1) the acceleration, propagation, and radiation of particles in supernova remnants; (2) very high energy neutrinos from the Galactic Center; and (3) the potential held by the next-generation gamma-ray and neutrino detectors CTA and KM3NeT for studying extended non-thermal sources in the Galaxy. The topics are intrinsically connected to determining the nature (“hadronic or leptonic?”) of gamma-ray emissions from young and middle-aged supernova remnants and the search for cosmic-ray PeVatrons. The results and conclusions provided here are based on extensive analytical and numerical simulations, which are formulated and presented in a straightforward format that can be readily used in the interpretations of gamma-ray and neutrino observations, as well as for confident predictions for future measurements.

Author: Alessandro De Angelis
Publisher: World Scientific
ISBN: 9812773541
Category : Science
Languages : en
Pages : 230

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Introduction -- I. Detectors for high-energy gamma-rays. First results from the MAGIC experiment / D. Bastieri for the MAGIC collaboration. H.E.S.S. / P. Vincent for the H.E.S.S. collaboration. CANGAROO / M. Mori for the CANGAROO-II, III Team. The status of VERITAS / M.K. Daniel on behalf of the VERITAS collaboration. Gamma ray bursts: recent results obtained by the SWIFT mission / G. Chinearini on behalf of the SWIFT team. Functional tests and performance characterization during the assembly phase of the modules of the AGILE silicon tracker / M. Basset [und weitere]. Status of GLAST, the gamma-ray large-area space telescope / L. Rochester on behalf of the GLAST team. Status of the ARGO-YBJ experiment / P. Camarri for the ARGO-YBJ collaboration. Gamma Air Watch (GAW) - an imaging atmospheric Cherenkov telescope large with large field of view / T. Mineo [und weitere] -- II. Topics in fundamental physics. Frontiers of high energy cosmic rays / M. Pimenta. Measurement of cosmological parameters / A. Balbi. The present and the future of cosmology with gamma ray bursts / G. Ghirlanda, G. Ghisellini. Supersymmetry breaking, extra dimensions and neutralino dark matter / A.M. Lionetto. Dark matter at [symbol]-rays / L. Pieri. Populations of subhalos in cold dark matter halos / E. Bisesi -- III. Multiwavelength observations. WEBT multifrequency support to space observations / C.M. Raiteri and M. Villata for the WEBT collaboration. REM - The Remote Observatory for GRB et al. / E. Molinari on behalf of the REM/ROSS team. Planck-LFI: operation of the scientific ground segment / F. Pasian [und weitere]. INTEGRAL three years later / L. Foschini, G. Di Cocco, G. Malaguti. XMM observations of Geminga, PSR B1055-52 and PSR B0656+14: phase resolved spectroscopy as a tool to investigate the X-[symbol] connection / P.A. Caraveo [und weitere] -- IV. Poster session. Software time-calibration of the ARGO-YBJ detector / A.K. Calabrese Melcarne for the ARGO-YBJ collaboration. Gamma-ray burst physics with GLAST / N. Omodei. Observations of blazars and EGRET sources with INTEGRAL / V. Vitale [und weitere]. A third level trigger programmable on FPGA for the gamma/hadron separation in a Cherenkov telescope using Pseudo-Zernike moments and the SVM classifier / M. Frailis [und weitere]. PulsarSpectrum: simulating gamma-ray pulsars for the GLAST mission / M. Razzano [und weitere]

Author: Thomas Brandon Stevenson
Publisher:
ISBN:
Category :
Languages : en
Pages : 215

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Galaxy Clusters (GCls) are the largest known virialized objects in the Universe. About one-third of GCls exhibit an extended radio halo associated with a population of nonthermal electrons emitting synchrotron radiation in a microgauss level magnetic field. The cooling time for the nonthermal electrons is about two orders of magnitude below the diffusion time needed to explain the radio halo, indicating that the electrons are created locally. The electrons may either be accelerated directly in the turbulent cluster medium or created as secondary products from nonthermal protons colliding with the intracluster medium. Observed gamma-ray emission can therefore resolve the contribution from these two mechanisms. Despite the empirical and theoretical motivation for the existence of gamma-ray emission from GCls, so far it remains undetected. In this talk VERITAS observations are used to analyze a 6x8 degree field of the Coma galaxy cluster and evaluate the existence of possible extended gamma-ray emission. To achieve this, a method is developed which utilizes cosmic rays as a calibration source to determine a background measurement across the full field of view. The resulting excess demonstrates a small significance of 2.7 sigma in the central 1.5 degree radius of the cluster. This observed central excess, while alone is not significant, has an angular extent in agreement with simulations and corresponds to a similar significance level seen by Fermi-LAT in the same region, and hence it is worth further investigation by VERITAS and future instruments such as CTA.

Author: T.C. Weekes
Publisher: CRC Press
ISBN: 1420033190
Category : Science
Languages : en
Pages : 234

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High energy gamma-ray photons are the prime probes of the relativistic or high-energy universe, populated by black holes, neutron stars, supernovae, quasars, and matter-antimatter annihilations. Through studying the gamma-ray sky, astrophysicists are able to better understand the formation and behavior of these exotic and energetic bodies. V

Author: Denis Bastieri
Publisher: American Institute of Physics
ISBN:
Category : Science
Languages : en
Pages : 260

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Book Description
This is the sixth edition in a series of Workshops on High Energy Gamma-Ray Experiments, following the ones held in Perugia (2002), Bari (2004), Cividale del Friuli (2005), Elba Island (2006) and Villa Mondragone (2007). The year the focus is on the region known by the acronym VHE (Very High Energy), bridging the gap between GeV and TeV. The physics that lies in this region is of the utmost importance to improve our knowledge of many different astrophysical sources like pulsars, AGNs, GRBs, and our understanding of the main components of the Extragalactic Background Light (EBL). An update is given on the current and planned research for spaceborne and ground-based experiments dedicated to the observation of the gamma-ray sky.