BEGIN:VCALENDAR VERSION:2.0 X-WR-CALNAME:EventsCalendar PRODID:-//hacksw/handcal//NONSGML v1.0//EN CALSCALE:GREGORIAN BEGIN:VTIMEZONE TZID:America/New_York LAST-MODIFIED:20240422T053451Z TZURL:https://www.tzurl.org/zoneinfo-outlook/America/New_York X-LIC-LOCATION:America/New_York BEGIN:DAYLIGHT TZNAME:EDT TZOFFSETFROM:-0500 TZOFFSETTO:-0400 DTSTART:19700308T020000 RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=2SU END:DAYLIGHT BEGIN:STANDARD TZNAME:EST TZOFFSETFROM:-0400 TZOFFSETTO:-0500 DTSTART:19701101T020000 RRULE:FREQ=YEARLY;BYMONTH=11;BYDAY=1SU END:STANDARD END:VTIMEZONE BEGIN:VEVENT CATEGORIES:College of Engineering,Thesis/Dissertations DESCRIPTION:Abstract: Type Ia supernovae (SNe Ia) are common lumino us astrophysical transients. SNe Ia are thought to originate from the ther monuclear runaway of a mass accreting white dwarf (WD) in binary systems. While SNe Ia have demonstrated their importance in measuring the expansion rate of the universe and the chemical evolution of galaxies, key question s about their progenitors and explosion mechanisms are still open. In rece nt years, the helium-ignited binary WD merger has emerged as a robust chan nel leading to normal SNe Ia. In this channel, two unequal mass WDs with t hin surface helium layers begin mass transfer (accretion) from the lower m ass (secondary) WD onto the higher mass (primary) WD. During this accretio n, the surface helium layer detonation on the primary can trigger another detonation near its core, which leads to complete disruption of the primar y WD. The secondary WD is impacted by the ejected material and potentially also triggers helium and core detonations. This Ph.D. thesis aims to inve stigate the end-to-end evolution of the helium-ignited binary WD merger ch annel–from the generation of physically consistent initial conditions of the binary systems to the supernova remnant phase of the ejecta. We will employ the FLASH-X hydrodynamical simulation framework to capture the full 3D evolution of the binary WD system. For accurate modeling of these syst ems, our ongoing efforts focus on improving the existing gravity solvers b y implementing flux-conservative numerical approaches for angular momentum and total energy conservation in the framework of FLASH-X. With these new developments, the resulting models will be post-processed with radiation transport codes (SuperNu, Sedona) to generate synthetic spectra. The syste matic comparison between models and observations of SNe Ia will help const rain progenitor scenarios and improve our understanding of the explosion p hysics of these events. ADVISOR(s): Dr. Robert Fisher, Department of Physi cs (Robert.fisher@umassd.edu) COMMITTEE MEMBERS: Dr. Sigal Gottlieb, Depar tment of Mathematics Dr. Vijay Varma, Department of Mathematics\nEvent pag e: https://www.umassd.edu/events/cms/eas-doctoral-proposal-defense--by-vru tant-vikasbhai-mehta.php X-ALT-DESC;FMTTYPE=text/html:

Abstract:

Type Ia supernovae (SNe Ia) are common luminous astrophysical transients. SNe I a are thought to originate from the thermonuclear runaway of a mass accret ing white dwarf (WD) in binary systems. While SNe Ia have demonstrated the ir importance in measuring the expansion rate of the universe and the chem ical evolution of galaxies\, key questions about their progenitors and exp losion mechanisms are still open. In recent years\, the helium-ignited bin ary WD merger has emerged as a robust channel leading to normal SNe Ia. In this channel\, two unequal mass WDs with thin surface helium layers begin mass transfer (accretion) from the lower mass (secondary) WD onto the hig her mass (primary) WD. During this accretion\, the surface helium layer de tonation on the primary can trigger another detonation near its core\, whi ch leads to complete disruption of the primary WD. The secondary WD is imp acted by the ejected material and potentially also triggers helium and cor e detonations.

This Ph.D. thesis aims to investigate the end-to-en d evolution of the helium-ignited binary WD merger channel–from the gene ration of physically consistent initial conditions of the binary systems t o the supernova remnant phase of the ejecta. We will employ the FLASH-X hy drodynamical simulation framework to capture the full 3D evolution of the binary WD system. For accurate modeling of these systems\, our ongoing eff orts focus on improving the existing gravity solvers by implementing flux- conservative numerical approaches for angular momentum and total energy co nservation in the framework of FLASH-X. With these new developments\, the resulting models will be post-processed with radiation transport codes (Su perNu\, Sedona) to generate synthetic spectra. The systematic comparison b etween models and observations of SNe Ia will help constrain progenitor sc enarios and improve our understanding of the explosion physics of these ev ents.

ADVISOR(s): Dr. Robert Fisher\, Department of Physics (Rober t.fisher@umassd.edu)

COMMITTEE MEMBERS: Dr. Sigal Gottlieb\, Depar tment of Mathematics Dr. Vijay Varma\, Department of Mathematics

Eve nt page: https://www.umassd.edu/events/cms /eas-doctoral-proposal-defense--by-vrutant-vikasbhai-mehta.php

DTSTAMP:20260407T130828 DTSTART;TZID=America/New_York:20260428T133000 DTEND;TZID=America/New_York:20260428T153000 LOCATION:TXT 105 SUMMARY;LANGUAGE=en-us:EAS Doctoral Proposal Defense by Vrutant Vikasbhai Mehta UID:f8dd201f77d42ac8dd23c765027de7b0@www.umassd.edu END:VEVENT END:VCALENDAR