Non-thermal Emission from Supernova Remnants Observed with Suzaku and Its Implications for Cosmic-ray Acceleration PDF Download
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Author: Takaaki Tanaka
Publisher:
ISBN:
Category : Cosmic rays
Languages : en
Pages : 137
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Book Description
Author: Takaaki Tanaka
Publisher:
ISBN:
Category : Cosmic rays
Languages : en
Pages : 137
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Book Description
Author: Shiu Hang Lee
Publisher: Stanford University
ISBN:
Category :
Languages : en
Pages : 148
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Book Description
Supernova remnants (SNRs) are the only class of sources known in our Galaxy capable of providing the energy necessary to power the bulk of the Galactic cosmic-rays (CRs) below the `knee' (~ 3 PeV). They are observable across the entire frequency spectrum from radio to TeV gamma-rays, and are known to exhibit a rich variety of complex morphologies in multi-wavelength. Non-thermal emissions from SNRs in X-ray and gamma-ray arise from interaction between particles accelerated by the SNR blast wave and the surrounding medium, and are hence one of the most useful probe for the Galactic CR production process. In this thesis, we will try to obtain a fuller understanding of the origin of Galactic CRs through studying non-thermal emissions from SNRs and modelling CR injection from their astrophysical accelerators. In the first part of the thesis, we will develop a robust tool to simulate time and space-resolved broadband emission from young shell-type SNRs using coupled hydrodynamic and diffusive shock acceleration (DSA) calculations. Usually, the DSA process is expected to be highly non-linear for young SNRs due to a number of postulated coupling phenomena, which leads to the inter-correlation of the emission spectra and morphology at different wavelengths. Therefore, to gain the full picture, it is important to combine multi-wavelength observations and the relevant physical processes into a self-consistent and flexible calculation framework. By taking into account particle transport, escape, interaction and various radiative processes, our tool can predict photon emissivity in full three-dimension and multi-wavelength for any given SNR model and surrounding environment, such as in the presence of a nearby molecular cloud. Through illustrations using a few typical models for Type Ia SNR, we will demonstrate its capability of calculating results directly comparable to observations, as well as to pinpoint the gamma-ray emission mechanism, namely the leptonic and hadronic scenarios. In the second part, we will study the gamma-ray emission from a middle-aged SNR IC 443 (G189.1+3.0) using the Fermi Large Area Telescope (LAT). IC 443 has been extensively studied in the past few decades through radio to TeV gamma-ray, but high quality data in the sub-GeV to sub-TeV band, the most crucial window for constraining the origin of the high-energy emission, has still been missing. We will fill in this gap by analyzing LAT data from 200 MeV to 50 GeV using the 1st year of LAT data. Equipped with the high photon statistics available, and the excellent resolution, sensitivity and low background rate of LAT, we are able to probe the gamma-ray emission from IC 443 with minimal confusion with the backgrounds. We discovered spatially extended emission from IC 443 in the 1 - 50 GeV band for the first time, which eliminates the pulsar wind nebula (PWN) as the dominating gamma-ray emitter. We found good spatial correlation of the GeV mission with the TeV source recently detected by VERITAS, as well as a known group of ambient and shocked molecular clouds (MC). The sub-GeV to TeV broadband spectrum can be described by a power-law with a smooth break at a few GeV, the same feature also observed from several other LAT-detected middle-aged SNRs interacting with MCs. We will argue that the gamma-ray emission is most naturally explained by a neutral pion decay dominated origin, and the leptonic scenarios are disfavored. Finally, we will also discuss the major discoveries from LAT observations of other gamma-ray bright Galactic SNRs during the first 2 years of operation of Fermi. In the last part, we will construct a model of Galactic CR injection using constraints from most recent GeV and TeV observation data and CR measurements, which can provide a natural explanation for the enhanced positron flux above 10 GeV recently observed by PAMELA as compared to previous measurements. Without making speculation on `additional' positron contribution from any special nearby objects or resorting to exotic phenomena, we will look at a steady-state picture of our Galaxy in which the ensembles of SNRs and PWNe steadily inject CRs into the interstellar space. Using the GALPROP CR propagation code, the CR spectra and ratios at Earth are calculated and compared with data. Without tweaking the model parameters specifically to fit the positron data other than using observation and astrophysics-based assumptions, we will show that this steady-state model can satisfactorily reproduce the positron enhancement and other CR measurement results. Assisted by recent observations of middle-aged SNRs interacting with MCs by Fermi LAT, we are also able to set an upper-limit on the total number of these systems residing in our Galaxy. Finally, using this consistent model, we will estimate the energy budgets of the major species of Galactic CRs.
Author:
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Category :
Languages : en
Pages :
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Supernova remnants present an excellent opportunity to study the shockacceleration of relativistic particles. X-ray synchrotron emission fromrelativistic electrons should contain important information, butextracting it requires advances in models and observations. I present thefirst test of sophisticated synchrotron models against high resolutionobservations on SN 1006, the first and best example of synchrotron X-rayemission, which has been well observed at radio, X-ray and gamma-raywavelengths. Synchrotron emission can be limited at the highest energies by finite age, radiative losses or electron escape. Earlier calculations suggested thatSN 1006 was escape limited. I adapted an escape-limited synchrotron modelfor XSPEC, and demonstrated that it can account for the dominantlynonthermal integrated spectrum of SN 1006 observed by ASCA-GIS and RXTE while constraining the values of the maximum electron energy and otherparameters. Combined with TeV observations, the fits give a mean postshockmagnetic field strength of 9 microgauss and 0.7% of the supernova energyin relativistic electrons. Simultaneous thermal fits gave abundances farabove solar, as might be expected for ejecta but had not previously beenobserved. I created subsets of the escape-limited model to fit spatially resolvedASCA SIS observations. I found only small differences between thenortheast and southwest limbs. A limit of less than 9% was placed on theamount of nonthermal flux elsewhere in the remnant. Important findingsinclude the possibility that rolloff frequency may change across theremnant face, and ruling out cylindrical symmetry for SN 1006 along aNW/SE axis. These models have implications far beyond SN 1006. The only previousmodel available to describe X-ray synchrotron emission was a powerlaw. These new models are superior to powerlaws both for their robustconstraints and because they shed physical insight on the accelerationmechanism. As new instruments increase our spatial and spectral resolutio.
Author: John Danziger
Publisher: Springer Science & Business Media
ISBN: 9400972318
Category : Science
Languages : en
Pages : 597
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Book Description
IAU Symposium 101, Supernova Remnants and Their X-ray Emission, was held on the Island of San Giorgio, Venice, 30 August - 2 September 1982. It was co-sponsored by the National Research Council, Italy, the University of Padua, the Observatory of Padua, and the International Astronomical Union, and was hosted by the Cini Foundation. The contents of this volume show the wide range of disciplines that are involved in supernova remnant research. Many new results were presented, not only from the X-ray observations from the Einstein Observatory but also from observations at optical and radio wavelengths. This has led to the stimulation of theoretical work, much of which attempts to accommodate in a more unified way all of these observations. Research on supernova remnants of all ages was reported. Perhaps the most impressive part of all this work is the way in which observations at all wavelengths have extended well outside the Galaxy to other members of the Local Group and beyond. The Symposium was attended by scientists from 15 countries. Twenty five invited papers and sixty-eight shorter contributions were presented during the 4-day meeting. Thirty-three of these shorter contributions were presented in poster sessions. This volume contains almost all (89) of those contributions. They are followed by discussions which took place after each verbal presentation. Since the availability of the discussions was left to the individual contributors, they are not complete, but those contained in this volume convey some idea of the nature of the exchanges.
Author: Hidetoshi Sano
Publisher: Springer
ISBN: 4431556362
Category : Science
Languages : en
Pages : 141
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This book presents a study of the young supernova remnant RX J1713.7-3946 in order to reveal the origin of cosmic rays in our galaxy. The study focuses on the X-ray and gamma radiation from the cosmic ray electrons and protons in the supernova remnant as well as the emission from the surrounding interstellar gas measured by the NANTEN2 4-m radio telescope at Nagoya University. The gamma rays show a good spatial correspondence with the interstellar gas, which for the first time provides strong evidence of the acceleration of cosmic ray protons. Additionally, the author determines that an interaction between the supernova shockwaves and interstellar gas, referred to as “shock-cloud interaction,” promotes the efficient acceleration of cosmic ray electrons in the supernova remnant. The book reveals that the interstellar gas plays an essential role in producing the high-energy radiation and cosmic rays, offering vital new insights into the origin and behavior of galactic cosmic rays.
Author: Katie Amanda Auchettl
Publisher:
ISBN:
Category :
Languages : en
Pages : 284
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Book Description
When a star dies, it leaves a mark on its surrounding environment. The energy from the supernova explosion forms an expanding shock wave that interacts with interstellar and circumstellar material, creating what we know as a supernova remnant (SNR). If the original star has a mass that is greater than or equal to 8 solar masses, this can also lead to the formation of a rapidly rotating neutron star called a pulsar. As these objects evolve, they interact with the surrounding environment, producing non-thermal and thermal emission. For an SNR, its non-thermal emission arises from a population of relativistic particles being accelerated at the shock front of the SNR, while its thermal emission arises from the shock front heating ejecta and and swept-up interstellar medium to X-ray emitting temperatures. For pulsars, their non-thermal emission arises from relativistic particles being accelerated at the termination shock of a pulsar wind. These particles interact with surrounding magnetic fields and ambient photon fields producing synchrotron and inverse Compton emission which we observe as a pulsar wind nebula (PWN), while its thermal emission arises from the surface of the neutron star. These properties of SNRs and pulsars provide a unique window into studying the acceleration, injection, propagation and interaction of highly energetic particles called cosmic rays with the interstellar medium. In addition, they providing information about the evolution, and dynamics of these objects; properties of the shock fronts; details about the original progenitor star; and the impact that these objects have on their surroundings. The research presented here focuses on analysing the intimate connection between cosmic rays, the non-thermal emission arising from SNRs interacting with molecular clouds, and pulsar wind nebulae; as well as analysing the observational and evolutionary properties of these objects. In this thesis we model the propagation of cosmic rays through the Galaxy in an attempt to characterise a standard cosmic ray background with uncertainties, to reveal the origin of the cosmic ray electron positron anomaly. Furthermore, we analyse the gamma-ray emission from SNRs Kes 79 and MSH 11-61A, which are known to be interacting with molecular clouds, as well as the non-thermal X-ray emission arising from the PWN of PSR J1741-2054. We find that the emission from both SNRs most likely arises from the decay of neutral pions that resulted from the interaction of relativistic ions which are accelerated at the shock-front of a SNR, with ambient material. For PSR J1741-2054, we characterise the properties, minimum magnetic field and minimum energy of the particle population that produces the observed diffuse synchrotron emission that surrounds and trails the pulsar.In addition, we characterise the X-ray emission arising from Kes 79, MSH 11-61A and PSR J1741-2054, in an attempt to shed light on the origin and nature of these objects and their emission. Using X-ray data from XMM-Newton and Suzaku respectively, we probe the temperature, ionisation state, and elemental abundance of the shocked gas of each SNR. This allows us to determine their evolutionary properties, properties of the shock, and mass of the original progenitor; and constrain the density of the X-ray emitting plasma. Using Chandra, we determined the temperature of PSR J1741-2054, as well as characterised its proper motion, velocity, direction of motion, and presence of small scale structure immediately surrounding the pulsar.
Author: Timothy Robert Joubert
Publisher:
ISBN:
Category :
Languages : en
Pages : 57
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Book Description
The analysis presented in this paper incorporated photon events received during the full run time of the Fermi Gamma Space Telescope (FGST) Large Area Telescope (LAT) to date. By studying the [gamma]y emission of the supernova remnant (SNR) Kes 41 for the energy range ~ 200MeV-200GeV, the [gamma]-ray morphology and spectrum were measured. These measurements required the use of reduced log likelihood statistics mediated by the Fermi Science Tools toolkit, developed for LAT analysis. The spatial analysis of the [gamma]-ray emission was measured at 5[sigma] for the area within and around the contours established during radio measurements [25]. It also resembles Kes 41's observed, centrally bright, X-ray emission [18, 25]. Spectral analysis was also carried out and the resulting [gamma]-ray spectrum was successfully fit to a power-law model of emission consistent with [pi]0-decay, a form of non-thermal emission caused by cosmic ray acceleration. An overall approximation of the [gamma]-ray luminosity was then measured as L[gamma] = 1.94 x 1035 erg/s using a measure of the total [gamma]-ray flux. A calculation also measured the particle density associated with material interacting with Kes 41 emission as n = 0.15 particles/cm-3. This value resembles that from other calculations involving SNR-Molecular cloud interaction [22]. This interaction serves to constrain [gamma]-ray emission to the [pi]0-decay channel, so evidence of a similar density value may be evidence that the significant [gamma]-ray emission observed, was due to the acceleration of cosmic rays.
Author: Jacco Vink
Publisher: Springer Nature
ISBN: 3030552314
Category : Science
Languages : en
Pages : 532
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Book Description
Written by a leading expert, this monograph presents recent developments on supernova remnants, with the inclusion of results from various satellites and ground-based instruments. The book details the physics and evolution of supernova remnants, as well as provides an up-to-date account of recent multiwavelength results. Supernova remnants provide vital clues about the actual supernova explosions from X-ray spectroscopy of the supernova material, or from the imprints the progenitors had on the ambient medium supernova remnants are interacting with - all of which the author discusses in great detail. The way in which supernova remnants are classified, is reviewed and explained early on. A chapter is devoted to the related topic of pulsar wind nebulae, and neutron stars associated with supernova remnants. The book also includes an extended part on radiative processes, collisionless shock physics and cosmic-ray acceleration, making this book applicable to a wide variety of astronomical sub-disciplines. With its coverage of fundamental physics and careful review of the state of the field, the book serves as both textbook for advanced students and as reference for researchers in the field.
Author: Robert Brose
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Supernova remnants are believed to be the source of cosmic rays with energies up to 10^15 eV that are produced within our Galaxy. The acceleration mechanism associated with the collision-less shocks in supernova remnants - diffusive shock acceleration - predicts a spectral index of the accelerated non-thermal particles of s = 2. However, measurements of non-thermal emission in radio, X-rays and gamma-rays reveal significant deviations of the particles spectral index from the canonical value of s = 2. The youngest Galactic supernova remnant G1.9+0.3 is an interesting target for next-generation gamma-ray observatories. So far, the remnant is only detected in the radio and the X-ray bands, but its young age of ≈100 yrs and inferred shock speed of ≈ 14, 000 km/s could make it an efficient particle accelerator. I performed spherical symmetric 1D simulations with the RATPaC code, in which I simultaneously solved the transport equation for cosmic rays, the transport equation for magnetic turbulence, and the hydro-dynamical equations for ...
Author: Felix A. Aharonian
Publisher: World Scientific
ISBN: 9789812561732
Category : Science
Languages : en
Pages : 516
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Book Description
Gamma ray astronomy, the branch of high energy astrophysics that studies the sky in energetic ?-ray photons, is destined to play a crucial role in the exploration of nonthermal phenomena in the Universe in their most extreme and violent forms. The great potential of this discipline offers impressive coverage of many OC hot topicsOCO of modern astrophysics and cosmology, such as the origin of galactic and extragalactic cosmic rays, particle acceleration and radiation processes under extreme astrophysical conditions, and the search for dark matter."
