자료유형  

 학위논문

Control Number  

0017164043

International Standard Book Number  

9798384464259

Dewey Decimal Classification Number  

523

Main Entry-Personal Name  

Bambic, Christopher J.

Publication, Distribution, etc. (Imprint  

[S.l.] : Princeton University., 2024

Publication, Distribution, etc. (Imprint  

Ann Arbor : ProQuest Dissertations & Theses, 2024

Physical Description  

178 p.

General Note  

Source: Dissertations Abstracts International, Volume: 86-04, Section: B.

General Note  

Advisor: Quataert, Eliot;Kunz, Matthew W.

Dissertation Note  

Thesis (Ph.D.)--Princeton University, 2024.

Summary, Etc.  

요약This Thesis tackles three open problems in the study of radiatively efficient accretion flows (REFs) around black holes in X-ray binary systems (XRBs) and active galactic nuclei (AGN): the thermal structure of the hard X-ray emitting "coronae" of REFs, state transitions in XRBs, and the physical mechanisms responsible for powering the prodigious luminosities of coronae. I investigate the thermodynamics of the coronal plasma, specifically, the consequences of weak Coulomb coupling between ions and rapidly cooling leptons, which may lead to separate ion and lepton temperatures and the formation of a "two-temperature" corona.Evaporation via thermal conduction from a hot corona into a colder accretion disk has been proposed as a mechanism for the soft-to-hard state transitions observed in XRBs. I use local stratified shearing-box simulations to investigate this process. My models demonstrate that weak Coulomb coupling in the surface layers of disks leads to the formation of a hot corona surrounding the colder disk. In models where magnetic-field-aligned ion thermal conduction is included, I find no evidence of disk evaporation, independent of the amount of net-vertical magnetic flux (NF) threading the accretion flow. However, simulations with NF magnetic fields launch powerful magnetocentrifugal winds, which may be able to evaporate a thin disk and form a RIAF under some conditions.The fraction of cooling in the surface layers of the disk is substantially larger for NF fields compared to zero-net-flux configurations, with moderate NF simulations radiating ≳30 percent of the flow's total luminosity via their two-temperature coronae. I show that at the order-of-magnitude level, the production and dissipation of Alfvenic turbulence in these magnetic field configurations can explain the high coronal heating efficiencies observed in luminous Seyfert galaxies and quasars.My work has implications for coronal heating in REFs threaded by NF well below the magnetically arrested disk (MAD) limit. Future observations of transient systems such as tidal disruption events (TDEs) or changing-look AGN may be able to help determine whether or not such magnetic fields are necessary to form coronae, shedding light onto the long-standing mystery of the origin of hard X-radiation from accreting black hole systems.

Subject Added Entry-Topical Term  

Astrophysics.

Subject Added Entry-Topical Term  

Plasma physics.

Subject Added Entry-Topical Term  

Astronomy.

Index Term-Uncontrolled  

Accretion

Index Term-Uncontrolled  

Coronae

Index Term-Uncontrolled  

Magnetohydrodynamics

Index Term-Uncontrolled  

Stratified shearing box

Index Term-Uncontrolled  

Thermal conduction

Index Term-Uncontrolled  

Turbulence

Added Entry-Corporate Name  

Princeton University Astrophysical Sciences

Host Item Entry  

Dissertations Abstracts International. 86-04B.

Electronic Location and Access  

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Control Number  

joongbu:654106