Searching for TeV Gamma-ray Emission from Compact Binaries with the HAWC Observatory PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Searching for TeV Gamma-ray Emission from Compact Binaries with the HAWC Observatory PDF full book. Access full book title Searching for TeV Gamma-ray Emission from Compact Binaries with the HAWC Observatory by Chang Dong Rho. Download full books in PDF and EPUB format.
Author: Chang Dong Rho Publisher: ISBN: Category : Languages : en Pages : 204
Book Description
"Astrophysical sources of very-high-energy (VHE) gamma-ray radiation provide unique information about astrophysical particle acceleration and cosmic-ray production. In particular, compact binary systems, composed of a compact object (a neutron star or black hole) in orbit with a massive stellar companion, provide an ideal environment for VHE gamma-ray production. They are not only powerful particle accelerators, but they also exhibit periodic emission that makes them excellent astrophysical laboratories. However, only a handful of binary systems have ever been observed in VHE gamma rays. Partly, this is because VHE gamma-ray binaries appear to be very rare, and part is due to observational bias. Most instruments operating at TeV are pointed and must allocate time to observing many kinds of objects. The High Altitude Water Cherenkov (HAWC) Observatory, on the other hand, has high uptime (duty cycle >95%) and a wide field of view (2 sr), making it well-suited for observing transient and time-varying sources such as binaries. HAWC is also currently the only detector that is sensitive to gamma-ray photons above 10 TeV. Collected HAWC data spanning33 months between November 2014 and January 2018 are used to analyze the known and candidate VHE gamma-ray binary systems in this work. "Microquasars" are a special subclass of X-ray binaries that are also candidate VHE gamma-ray sources. Unlike other types of binaries, compact objects in microquasars accrete matter from their companion star. This process forms an accretion disk around the compact object and relativistic jets of particles are released perpendicular to the accretion disk. This feature is very similar to active galactic nuclei (AGN), only smaller in size. Given the fact that direct observation of particle acceleration in distant AGN is very challenging, microquasars grant the valuable opportunity to model similar processes using nearby objects in our own Galaxy. SS 433 is a known microquasar that has two jets ("east" and "west") terminating in radio lobes of a surrounding supernova remnant, W 50. The recent observation of SS 433 with HAWC marked the first direct evidence of gamma-ray emission from the jets of a microquasar. Using HAWC data, we have measured a VHE flux of [formula not rendered] at the jet interaction region e1 in the east lobe and [formula not rendered] in the west lobe with a combined post-trial statistical significance of 5:4. The systematic studies used to confirm the VHE gamma-ray emission at 20 TeV from the SS 433 jet interaction regions is discussed in this work, along with a brief description of the theoretical interpretation associated with the observation. The HAWC data were also used to search for gamma rays from the known VHE binaries HESS J0632+057 and LS 5039. No emission was observed from HESS J0632+057, so we compute upper limits on its flux. Emission at low statistical significance is observed from LS 5039, which is located in a crowded region of the Galactic plane and is contaminated by gamma rays from nearby extended sources. A multiple-source analysis of the region surrounding LS 5039, as well as a time-series analysis of the light curve from LS 5039, are presented. At this time, data from HAWC are not significant enough to support multi-TeV emission from LS 5039"--Pages xi-xiii.
Author: Chang Dong Rho Publisher: ISBN: Category : Languages : en Pages : 204
Book Description
"Astrophysical sources of very-high-energy (VHE) gamma-ray radiation provide unique information about astrophysical particle acceleration and cosmic-ray production. In particular, compact binary systems, composed of a compact object (a neutron star or black hole) in orbit with a massive stellar companion, provide an ideal environment for VHE gamma-ray production. They are not only powerful particle accelerators, but they also exhibit periodic emission that makes them excellent astrophysical laboratories. However, only a handful of binary systems have ever been observed in VHE gamma rays. Partly, this is because VHE gamma-ray binaries appear to be very rare, and part is due to observational bias. Most instruments operating at TeV are pointed and must allocate time to observing many kinds of objects. The High Altitude Water Cherenkov (HAWC) Observatory, on the other hand, has high uptime (duty cycle >95%) and a wide field of view (2 sr), making it well-suited for observing transient and time-varying sources such as binaries. HAWC is also currently the only detector that is sensitive to gamma-ray photons above 10 TeV. Collected HAWC data spanning33 months between November 2014 and January 2018 are used to analyze the known and candidate VHE gamma-ray binary systems in this work. "Microquasars" are a special subclass of X-ray binaries that are also candidate VHE gamma-ray sources. Unlike other types of binaries, compact objects in microquasars accrete matter from their companion star. This process forms an accretion disk around the compact object and relativistic jets of particles are released perpendicular to the accretion disk. This feature is very similar to active galactic nuclei (AGN), only smaller in size. Given the fact that direct observation of particle acceleration in distant AGN is very challenging, microquasars grant the valuable opportunity to model similar processes using nearby objects in our own Galaxy. SS 433 is a known microquasar that has two jets ("east" and "west") terminating in radio lobes of a surrounding supernova remnant, W 50. The recent observation of SS 433 with HAWC marked the first direct evidence of gamma-ray emission from the jets of a microquasar. Using HAWC data, we have measured a VHE flux of [formula not rendered] at the jet interaction region e1 in the east lobe and [formula not rendered] in the west lobe with a combined post-trial statistical significance of 5:4. The systematic studies used to confirm the VHE gamma-ray emission at 20 TeV from the SS 433 jet interaction regions is discussed in this work, along with a brief description of the theoretical interpretation associated with the observation. The HAWC data were also used to search for gamma rays from the known VHE binaries HESS J0632+057 and LS 5039. No emission was observed from HESS J0632+057, so we compute upper limits on its flux. Emission at low statistical significance is observed from LS 5039, which is located in a crowded region of the Galactic plane and is contaminated by gamma rays from nearby extended sources. A multiple-source analysis of the region surrounding LS 5039, as well as a time-series analysis of the light curve from LS 5039, are presented. At this time, data from HAWC are not significant enough to support multi-TeV emission from LS 5039"--Pages xi-xiii.
Author: Nicole Firestone Publisher: ISBN: Category : Languages : en Pages :
Book Description
As neutrally-charged astrophysical messengers, gamma rays serve as powerful tools for determining the origins of incredibly high-energy particles from across our universe [1]. Gamma rays are considered to have the highest energy of all electromagnetic radiation, with energies spanning from 0.5 MeV to about 100 TeV [2]. Although lower-energy gamma rays can originate from within our solar system, gamma rays in the GeV and TeV ranges tend to originate from sources beyond our solar system [1]. By investigating these sources, we can understand more about the astrophysical phenomena that characterize the most extreme conditions in our universe, such as supernova remnants, gamma-ray bursts, and pulsars [3]. The High Altitude Water Cherenkov Gamma-Ray Observatory (HAWC) is one of the most sensitive gamma-ray detectors in the very high energy (VHE) regime, with the capability to observe gamma rays from 100 GeV and 100 TeV [4]. In 2017, HAWC conducted a blind search encompassing two thirds of the sky and 508 days of observations [4]. In this search, there were 16 VHE gamma-ray excesses that were unassociated with any previously discovered gamma-ray sources [4]. Now with data from 1523 days of observations, we begin to study these 16 unassociated candidate TeV sources in more detail. In this work, we update the locations of maximum significance for these candidate TeV sources and analyze the temporal progression of their significance and flux. This allows us to determine if they have faded into the diffuse gamma radiation or if they can still be considered unassociated candidate TeV sources. We then reevaluate the morphologies and spectral energy distributions of the remaining sources and discuss any recent observations from other gamma-ray observatories. We find that 10 of these 16 unassociated candidate TeV sources can still be considered candidate sources. In the future, we plan to use data from other observatories to continue to put better constrains on the morphology and spectral energy distributions for these sources and better understand their acceleration mechanisms. In addition, we plan to conduct a similar investigation with new HAWC excesses discovered with recent data from 1523 days of observations [5]. By investigating these excesses in the high-energy gamma-ray sky, we can discover and characterize new extreme astrophysical phenomena and ultimately uncover valuable information about the physical mechanisms that accelerate particles to very high energies.
Author: Matthew Rosenberg Publisher: ISBN: Category : Languages : en Pages :
Book Description
Gamma-Ray Bursts (GRBs) are brief, intense flashes of gamma rays lasting from a fraction of a second to minutes. The prompt emission from these explosive events outshines all the stars in their entire host galaxy. Thought to be produced by the core collapse of massive stars and the merger of compact stellar remnants in distant galaxies, GRBs can liberate on the order of 10^54 ergs of gravitational potential energy in just milliseconds. In addition to constituting an interesting phenomenon in their own right, these cosmic engines accelerate particles to energy scales unattainable in laboratories on Earth and thus provide a potentially interesting probe of fundamental physics as well as source candidates for ultra-high energy cosmic rays. We present recent efforts to extend the observation of GRBs beyond ~100 GeV with the High Altitude Water Cherenkov (HAWC) observatory. Located in Puebla, Mexico at a latitude of 19 degrees north and an altitude of 4100 meters above sea level, HAWC employs a 20,000 square meter array of 300 water Cherenkov detectors to observe the relativistic charged particles produced in the extensive air showers that develop upon the collision of high-energy gamma rays with Earths atmosphere. This technique provides sensitivity to ~100 GeV 100 TeV gamma rays, allows for nearly continuous operations, and achieves a wide instantaneous field of view of ~2 sr that allows for daily monitoring of the northern sky. HAWC is thus ideally suited to capture any emission above ~100 GeV from transient events like GRBs. As GRB photons above a few TeV in energy are likely to be absorbed by the extra-galactic background light before reaching Earth, HAWCs ~100 GeV 1 TeV data is of prime importance in the search for high-energy GRB emission. However, the small air-shower data necessary to achieve this lower threshold of ~100 GeV has previously been poorly modeled in HAWC simulations and has therefore not been used in past HAWC GRB searches. We will show that these modeling discrepancies were caused by an inaccurate treatment of detector noise, outline a solution that allows HAWC to achieve its lowest possible energy threshold, and present a method to reduce the impact of detector noise on HAWCs angular resolution in this newly recovered small air-shower data. Along with new GRB search algorithms, these improvements provide up to an order of magnitude improvement in HAWCs sensitivity to gamma-ray bursts. We use these new techniques to scan archival HAWC data for gamma-ray emission coincident with GRBs detected by the Fermi and Swift satellites between December 2014 and April 2018. While no significant detections were found, a comparison of our upper limits on the flux above 100 GeV from GRBs 170206A and 171120A with Fermi measurements suggests a cut-off or spectral steepening below that energy under a redshift assumption of z less than ~0.3. However, these limits are not sufficiently strict to compellingly constrain GRB models with predictions for TeV scale gamma-ray emission.
Author: Kathryne Woodle Publisher: ISBN: Category : Languages : en Pages :
Book Description
Gamma-Ray bursts (GRBs) are extremely powerful transient events that occur at cosmological distances. Observations of energy spectra of GRBs can provide information about the intervening space between the burst and Earth as well as about the source itself. GRBs have been observed up to nearly 100 GeV by satellite instruments; however, ground-based detectors are needed to provide enough exposure and statistics to determine the behavior of GRBs at those energies. The High Altitude Water Cherenkov Observatory (HAWC) is a second-generation extensive air shower detector that primarily observes very high-energy (VHE) photons, where VHE is defined as hundreds of GeV to hundreds of TeV. HAWC is built near the peak of Sierra Negra in Mexico at an altitude of 4100m. The high altitude allows the detector to observe air showers when more information is available for reconstruction. Due to its wide field of view (~2 sr) and high duty cycle (>90%), the HAWC observatory is sensitive to gamma rays in the sub-TeV to TeV energy range and can constrain the shape and cutoff of high-energy GRB spectra, especially in conjunction with observations from other detectors such as the Fermi LAT satellite. We present a likelihood-based search for VHE emission from the Fermi LAT GRBs that occurred in the field of view of HAWC during the last two years of its construction. Of the five bursts analyzed, no significant detections were observed; upper limits have been placed for each of the bursts. With less than 1/3 of the array active, the HAWC observatory limits for GRB 130702A, which is at a close redshift of z = 0.145, reach comparable sensitivity to lower energy instruments and are not limited by the EBL. With the array complete in March 2015, the sensitivity of HAWC is now greatly enhanced compared to the data analyzed in this dissertation. The future for a VHE GRB detetion by the HAWC observatory is bright.
Author: Heinrich J. Völk Publisher: Springer Science & Business Media ISBN: 9400901712 Category : Science Languages : en Pages : 447
Book Description
The `International Heidelberg Workshop on TeV Gamma-Ray Astrophysics' brought together astrophysicists from the various fields which play a role in the formation of high energy gamma-ray emission. In particular, theoretical and observational aspects of the physics and astrophysics of pulsars and quasars, the acceleration of particles at Supernova Remnants and other strong astrophysical shock fronts, and cascade processes in universal background photon fields were comprehensively discussed in more than thirty reviews by leading experts. In their entirety these reviews describe the birth of a new field of astronomy. This field concerns cosmic gamma-rays of very high energy which are observed with ground-based optical telescopes due to the Cherenkov emission of the secondary particles created by the interaction of these gamma-rays with atoms in the Earth's atmosphere. Beyond that, the workshop encompassed the latest developments and trends in theory and observation of cosmic gamma-ray sources of all energies, from nuclear gamma-ray lines in the MeV-region, through the Bremsstrahlung, Inverse Compton, and pion decay continuum emission, to gamma-rays due the decay of exotic relics from the early Universe. Audience: Specialists as well as students in physics and astrophysics and young research workers.
Author: Alison Peisker Publisher: ISBN: Category : Electronic dissertations Languages : en Pages : 152
Book Description
The universe contains many extremely energetic astrophysical sources that emit particles on timescales from fractions of a second to thousands of years. Studying these sources through gamma-ray and multi-messenger astronomy may help to reveal the answers to several remaining fundamental questions in physics. The High Altitude Water Cherenkov (HAWC) gamma-ray observatory, an extensive air shower array, is well-suited to perform transient searches due to its large field of view and high duty cycle. In this work, a catalog search of all very-high-energy gamma-ray sources in HAWC's field of view is conducted, revealing a total of 65 sources. Then a search for evaporating primordial black holes is performed. None are detected, so upper limits are set on their burst rate density. Finally, the IceCube neutrino observatory is introduced in order to perform a multi-messenger search for flaring gamma rays and neutrinos originating from the same point in the sky. None are detected, so upper limits are placed on the rate density and total energy of sources that produce both gamma rays and neutrinos. Performing these searches contributes to the understanding of the origins of cosmic rays and how astrophysical sources accelerate their particles to the high energies that are observed on Earth.
Author: Erica Heller Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Only three sources of extragalactic TeV gamma-ray emission have been observed by the High-Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory. Using a pre-selected candidate list of potential TeV-emitting BL Lac objects, we searched for TeV emission using the 2321-day dataset from the HAWC Observatory. Eleven BL Lac objects were investigated. For four of these BL Lac objects, lower energy gamma-ray data was available from the Fermi Large Area Telescope (Fermi-LAT). Using data from Fermi-LAT, we fit a simple power law model to the energy spectrum of each source and used this simple power law model to investigate the region using HAWC. We found no significant TeV gamma-ray emission from these four sources. We set upper limits on the flux from these sources at 1 TeV. For the remaining seven sources, we used three simple power law models due to the lack of lower-energy gamma-ray data. We found no significant TeV gamma-ray emission from these seven sources using all three simple power law models, and we set upper limits on the flux from these sources at 1 TeV for each model. Despite the lack of gamma-ray detection from these sources, we determine that the upper limits set using HAWC data can constrain the extrapolation of a simple power law model into the TeV energy range for three of the four sources with Fermi-LAT data. Through these investigations of BL Lac objects, we provide valuable information about the acceleration mechanisms occurring at these extreme extragalactic objects.
Author: Chang Dong Rho
Author: Chang Dong Rho
Author: Nicole Firestone
Author: Matthew Rosenberg
Author: Christopher Charles Geoffrey Bowden
Author: Miguel F Morales
Author: Kathryne Woodle
Author: 
Author: Heinrich J. Völk
Author: Alison Peisker
Author: Erica Heller