MARC details
| 000 -LEADER |
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| fixed length control field |
05652nam a2200229Ia 4500 |
| 003 - CONTROL NUMBER IDENTIFIER |
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| control field |
IN-BaIIA |
| 005 - DATE AND TIME OF LATEST TRANSACTION |
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| control field |
20211109165256.0 |
| 008 - FIXED-LENGTH DATA ELEMENTS--GENERAL INFORMATION |
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| fixed length control field |
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 |
Srivastav, S |
| 9 (RLIN) |
36982 |
| Relator term |
Author |
| 245 #0 - TITLE STATEMENT |
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| Title |
Observational studies of low redshift supernovae |
| Statement of responsibility, etc. |
S. Srivastav |
| Medium |
[Ph.D Thesis] |
| 260 ## - PUBLICATION, DISTRIBUTION, ETC. |
|---|
| Place of publication, distribution, etc. |
Bangalore |
| Name of publisher, distributor, etc. |
Indian Institute of Astrophysics |
| Date of publication, distribution, etc. |
2017 |
| 300 ## - PHYSICAL DESCRIPTION |
|---|
| Extent |
xi, 148p. |
| 502 ## - DISSERTATION NOTE |
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| Degree type |
Doctor of Philosophy |
| Name of granting institution |
Indian Institute of Astrophysics, Bangalore |
| Year degree granted |
2017 |
| 520 ## - SUMMARY, ETC. |
|---|
| Summary, etc. |
"Supernovae (SNe) are explosive transient events that mark the end stage of stellar evolution.<br/>This work presents a study of low redshift, hydrogen deficient (Type I) SNe, with emphasis<br/>on SNe of type Ia. The data were primarily obtained from the 2-metre Himalayan Chandra<br/>Telescope (HCT).<br/>SNe Ia are caused by thermonuclear disruption of accreting White Dwarfs (WDs) that<br/>have attained a mass close to the Chandrasekhar limit, rendering them unstable. In general,<br/><br/>SNe Ia follow the width-luminosity relation, making them valuable cosmic standard can-<br/>dles. However, the nature of the WD companion, i.e. exact nature of the progenitor, and the<br/><br/>details of the explosion physics remain poorly understood. The two most widely accepted<br/>progenitor scenarios include the single degenerate (where the WD has a non-degenerate<br/>companion) and double degenerate (involving merger of two WDs). In order to continue<br/>using SNe Ia effectively for high precision cosmology, it is essential to understand the<br/>explosion mechanism and the nature of the WD companion.<br/>The homogeneous nature of SNe Ia as a class of events notwithstanding, a substantial<br/>diversity is undeniably present. This diversity can be characterized through variations of<br/>light curve width, spectral indicators, bolometric properties and luminosity, and ultimately<br/>to different progenitor scenarios and explosion mechanisms. ‘Normal’ Ia events constitute<br/> ~70% of all SNe Ia and show minimal scatter in their properties, making them most useful<br/>for cosmology. A fraction of SNe Ia, termed as SN 1991T-like events, show slow declining<br/>light curves relative to normal events, and are generally overluminous. Another fraction<br/>of SNe Ia, the SN 1991bg subclass occupy the other end of the luminosity distribution,<br/>with fast declining, narrow light curves, low luminosities and very red intrinsic colours. In<br/><br/>addition, there also exist peculiar SN 2002cx-like events, whose spectra resemble 1991T-<br/>like events, but luminosities are low akin to 1991bg-like events. The diversity in SNe Ia,<br/><br/>and in particular the subclass of peculiar events, poses a challenge to theoretical progenitor<br/>and explosion models.<br/>The normal SNe Ia 2014J, 2014dg and 2011ao are studied in this work. Analytical<br/>modelling of their bolometric light curves suggests a total ejected mass of ~ 1.4 M☉, consistent with the Chandrasekhar limit. Spectroscopically, these events occupy the tightly<br/>clustered Core Normal (CN) subclass. This is consistent with the notion that normal SNe<br/>Ia originate from Chandrasekhar mass WDs, that explains the low scatter in their observed<br/>properties.<br/><br/>‘Transitional’ SNe Ia have properties intermediate to normal and extremely fast de-<br/>clining, subluminous 1991bg-like events. Transitional events thus signify a link between<br/><br/>normal and subluminous SNe Ia and hold the key to understand the progenitor scenario.<br/>Transitional SNe 2015bp, iPTF13ebh and 2003gs are studied in this work. Modelling the<br/>bolometric light curves of SNe 2015bp and 2003gs suggests a total ejected mass of ≤ 1<br/>M☉, suggesting a sub-Chandrasekhar mass WD progenitor. The early nebular spectra (~ 90<br/>days after B-band maximum) of SNe 2015bp and 2003gs show unusually well developed<br/>emission features attributable to [Ni II]. This premature emergence of nebular features also<br/><br/>indicates a small ejecta mass, consistent with the low ejecta mass inferred from the bolo-<br/>metric light curves. iPTF13ebh, on the other hand, is consistent with a Chandrasekhar mass<br/><br/>WD progenitor, indicating substantial diversity within the subclass of transitional SNe Ia.<br/><br/>The common properties of SNe Ia as a class of events are explored and various cor-<br/>relations are examined using data obtained during the course of this work and publicly<br/><br/>available data from the literature. In particular, the Swift UVOT (uvw1 − V ) colour evolu-<br/>tion is related to the decline rate parameter ∆m15(B), and therefore the intrinsic luminosity<br/><br/>for SNe Ia. The relative timing of the peak attained by (uvw1 − V ) colour curve shows a<br/>promising correlation with the decline rate parameter.<br/>Stripped envelope core collapse SNe (types Ib and Ic) form a relatively rare subclass<br/><br/>of SNe. A study of the type Ib event iPTF13bvn is presented in this work. The photomet-<br/>ric and spectroscopic characteristics of iPTF13bvn indicate a small ejecta mass, pointing<br/><br/>towards a low mass progenitor star. Fitting analytic models to the bolometric light curve<br/>also yields a small ejecta mass, thus ruling out a single, massive Wolf Rayet star as the<br/>progenitor, instead favouring a relatively low mass progenitor in a binary system.<br/><br/>Finally, future prospects in supernova astronomy are discussed in the context of up-<br/>coming wide-field, high sensitivity and high cadence surveys, and advanced observational<br/>facilities. |
| 650 ## - SUBJECT ADDED ENTRY--TOPICAL TERM |
|---|
| Topical term or geographic name entry element |
Astrophysics |
| 9 (RLIN) |
794 |
| 650 ## - SUBJECT ADDED ENTRY--TOPICAL TERM |
|---|
| Topical term or geographic name entry element |
Redshift |
| 9 (RLIN) |
8391 |
| 650 ## - SUBJECT ADDED ENTRY--TOPICAL TERM |
|---|
| Topical term or geographic name entry element |
Supernovae |
| 700 ## - ADDED ENTRY--PERSONAL NAME |
|---|
| Personal name |
Anupama G. C. |
| Relator term |
Supervisor |
| 856 ## - ELECTRONIC LOCATION AND ACCESS |
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| Uniform Resource Identifier |
<a href="http://prints.iiap.res.in/handle/2248/7521">http://prints.iiap.res.in/handle/2248/7521</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 |
