MARC details
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04489nam a2200229Ia 4500 |
| 003 - CONTROL NUMBER IDENTIFIER |
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IN-BaIIA |
| 005 - DATE AND TIME OF LATEST TRANSACTION |
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20211110122018.0 |
| 008 - FIXED-LENGTH DATA ELEMENTS--GENERAL INFORMATION |
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211028s9999 xx 000 0 eng d |
| 040 ## - CATALOGING SOURCE |
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| Transcribing agency |
IIA Library |
| 100 ## - MAIN ENTRY--PERSONAL NAME |
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| Personal name |
Paliya, Vaidehi Sharan |
| 9 (RLIN) |
37267 |
| Relator term |
Author |
| 245 #0 - TITLE STATEMENT |
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| Title |
General physical characteristics of gamma- ray emitting beamed AGNs in fermi era |
| Remainder of title |
a thesis submitted in partial fulfillment for the degree of doctor of philosophy to the dept.ment of physics, university of Calicut, Calicut |
| Statement of responsibility, etc. |
Vaidehi Sharan Paliya |
| Medium |
[Ph.D Thesis] |
| 260 ## - PUBLICATION, DISTRIBUTION, ETC. |
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| Place of publication, distribution, etc. |
Bangalore |
| Name of publisher, distributor, etc. |
Indian Institute of Astrophysics |
| Date of publication, distribution, etc. |
2016 |
| 300 ## - PHYSICAL DESCRIPTION |
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| Extent |
xiv, 153p. |
| 502 ## - DISSERTATION NOTE |
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| Degree type |
Doctor of Philosophy |
| Name of granting institution |
University of Calicut, Calicut, Kerala |
| Year degree granted |
2016 |
| 520 ## - SUMMARY, ETC. |
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| Summary, etc. |
The research work presented in this thesis is aimed to provide a detailed under-<br/>standing of the radiative processes powering the jets of the blazars, a class of AGNs<br/><br/>with jet pointed towards the line of sight to the observer. Another important aim<br/><br/>of this work is to study the multi-frequency properties of a new class of γ-ray emit-<br/>ting narrow-line Seyfert 1 (γ-NLSy1) galaxies using various observational tools and<br/><br/>to compare them with that known from powerful blazars.<br/>The goal of understanding the physical characteristics of blazars is achieved by<br/>studying the broadband flux variability and spectral energy distribution (SED)<br/>modeling of a carefully selected sample of blazars. The aim of the broadband<br/>variability study is to provide a general physical scenario, which allows one to<br/>put the observed variation from blazars across several decades of frequencies in a<br/>coherent context. Extremely fast hr scale flux variations are observed from all the<br/>sources studied here, including nearby BL Lac object Mrk 421 (z = 0.03) which<br/>showed minute scale hard X-ray (3−79 keV) flux variability during its 2013 April<br/>X-ray outburst. Moreover, by adopting a SED modeling approach, attempts are<br/>made to understand the causes of high amplitude γ-ray flux variations observed<br/>from these objects. To do this, a simple one zone leptonic emission model was also<br/>developed during the course of the thesis. The main reason of the 2014 April and<br/>2015 June γ-ray outbursts of 3C 279 (z = 0.536) and 2011 December γ-ray flare<br/>of distant blazar S5 0836+71 (z = 2.17) is found to be due to sudden acceleration<br/>of the jet. On the other hand, minute scale variability seen from Mrk 421 is<br/>explained on the basis of magnetic energy dissipation and reconnection events.<br/>The multi-wavelength observations of 3C 279 revealed that a single zone leptonic<br/>emission model successfully reproduces the γ-ray flares of 2014 April and 2015<br/>June, however, it fails to explain the uncorrelated flux variations and a hard γ-ray<br/>spectrum seen during 2013 December event. A two zone leptonic emission model<br/>is used to match the observations. All these observations hint for the presence of a variety of the radiative processes working in the 3C 279 jet (and possibly in other<br/>sources as well) and their dominance over each other, as seen during different high<br/>activity periods.<br/>The launch of the Fermi Gamma-ray space telescope in the year 2008 led to the first<br/><br/>detection of γ-ray emission with high confidence from about half-a-dozen radio-<br/>loud NLSy1 galaxies. This discovery clearly indicates the presence of relativistic<br/><br/>jets in these sources similar to that of blazars. With the motivation to understand<br/>the nature of γ-NLSy1 galaxies vis-a-vis blazars, few diagnostic tests are carried<br/>out, namely, intranight optical variability (INOV), γ-ray spectral properties, and<br/>broadband SED modeling. It is found that: (1) these sources show large amplitude<br/>(>3%) INOV with a duty cycle of about 80%, (2) their γ-ray spectra exhibit a<br/>significant curvature, and (3) their broadband SEDs have the typical double hump<br/>structure and the high energy hump can be explained due to external Compton<br/><br/>process. Thus, based on the observations covering a wide range of the electromag-<br/>netic spectrum, it can be concluded that γ-NLSy1 galaxies have all the properties<br/><br/>similar to blazars and could well be the low black hole mass counterparts of flat<br/>spectrum radio quasars.<br/> |
| 650 ## - SUBJECT ADDED ENTRY--TOPICAL TERM |
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| Topical term or geographic name entry element |
Active Galactic Nuclei |
| 9 (RLIN) |
6209 |
| 650 ## - SUBJECT ADDED ENTRY--TOPICAL TERM |
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| Topical term or geographic name entry element |
Galaxies: seyfert |
| 9 (RLIN) |
37268 |
| 650 ## - SUBJECT ADDED ENTRY--TOPICAL TERM |
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| Topical term or geographic name entry element |
Gamma rays |
| 9 (RLIN) |
2920 |
| 700 ## - ADDED ENTRY--PERSONAL NAME |
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| Personal name |
Stalin C. S. |
| Relator term |
Supervisor |
| 9 (RLIN) |
48866 |
| 856 ## - ELECTRONIC LOCATION AND ACCESS |
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| Uniform Resource Identifier |
<a href="http://prints.iiap.res.in/handle/2248/7517">http://prints.iiap.res.in/handle/2248/7517</a> |
| Link text |
Click Here to Access eThesis |
| 942 ## - ADDED ENTRY ELEMENTS (KOHA) |
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| Koha item type |
Thesis & Dissertations |
| Source of classification or shelving scheme |
Universal Decimal Classification |
