Pathways to Discovery in Astronomy and Astrophysics for the 2020s (2023) / Chapter Skim
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Appendix B: Report of the Panel on Compact Objects and Energetic Phenomena
Appendix B: Report of the Panel on Compact Objects and Energetic Phenomena
Pages 237-254
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From page 237... ...
If the binary companion is an ordinary star, then stellar and binary evolution can allow mass transfer and accretion from the donor companion onto the compact object, often mediated by an accretion disk. Accretion onto compact objects is an efficient power source for radiation, leading to systems called cataclysmic variables (accreting WDs)
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From page 238... ...
. • The detection of large numbers of tidal disruption events and the emergence of other important classes of astrophysical transients, including fast radio bursts and superluminous supernovae.
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From page 239... ...
The BH mass distribution, combined with the distribution and orientation of spins, may help reveal the physical origin of these BHs: do they arise from normal massive stellar binary evolution, triple/multiple star systems, or dynamical scattering in very dense stellar systems like globular clusters? That there might be gaps or breaks in the mass distribution at even higher masses may be understood as arising from known and hypothesized evolutionary pathways of single massive stars.
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From page 240... ...
Because most massive stars occur in binary or higher order multiple systems, the mass distribution of NSs and BHs constrains critically uncertain aspects of interacting binary and massive star evolution. A substantially larger sample of NS- or BH-stellar binary systems could potentially allow for an understanding of the relative rate of SN success/failure as a function of metallicity because the companion stars can be characterized in detail.
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From page 241... ...
and drive the chemical enrichment and evolution of their host galaxies. Shocks from massive stellar explosions provide a key way to constrain the still-mysterious mass-loss history of massive stars before core collapse.
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From page 242... ...
Is there EM emission before compact binary mergers, and what can it tell us about the properties of the progenitor systems? Current speculation is that fast radio bursts are also manifestations of cataclysmic events involving NSs or BHs.
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From page 243... ...
Other examples include peculiar thermonuclear SNe (e.g., type Iax) , stellar eruptions preceding core collapse, transients in the luminosity gap between classical novae and SNe, the very rapid time scales of fast and blue optical transients (FBOTs)
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From page 244... ...
are needed to map the kinetic energy structure of the ejecta, uncover the presence of relativistic jets, and map the media surrounding SNe, tidal disruption events, and NS mergers. Deep ultraviolet/optical/near-IR spectroscopy is needed to constrain the chemical composition of the ejecta, with particular emphasis on nebular phase spectroscopy and spectroscopy of distant kilonovae discovered by GW detectors.
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From page 245... ...
Relativistic jets in both long- and short-duration GRBs may be launched from either BHs or highly magnetized NSs (magnetars)
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From page 246... ...
Is this the origin of astrophysical high-energy neutrinos? An isotropic TeV/PeV neutrino background of astrophysical origin has been identified, but its origin in specific sources remains uncertain.
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From page 247... ...
WHAT SEEDS SUPERMASSIVE BLACK HOLES AND HOW DO THEY GROW? While it is well established that SMBHs and galaxies grow together over cosmic time, the physics of both what seeded SMBHs in the first place and the processes that govern their growth remain poorly understood.
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From page 248... ...
will probe the population of tidal disruption events and find binary AGNs through periodicity searches. The Roman Space Telescope will constrain the presence of IMBHs in the Local Group by discovering hyper-velocity stars.
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From page 249... ...
Mergers Coordinated observation of compact binary mergers in both GWs and EM radiation is still in its infancy. However, improvements in ground-based GW interferometers combined with aggressive EM follow-up with existing and future facilities will usher in an era of population studies of NS mergers.
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From page 250... ...
All-sky EM surveys may even facilitate PTA GW detections by initially identifying the most compact and nearby SMBH binaries, dramatically decreasing the size of the usual blind-search GW parameter space. On a somewhat longer time scale, LISA measurements of mHz GWs will detect essentially every 10 –108 M⊙ SMBH merger in the universe, providing fundamental information on SMBH evolution.
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From page 251... ...
Indeed, the expected rate is of the same order as that for core-collapse SNe. Here, the primary overlap in messengers is between the potential LISA detection of mHz GWs from the compact WD binary progenitor before explosion and information from the EM regime: MeV gamma-ray line emission from ejected nuclear products, multiwavelength continuum radiation from the SN, including nonthermal emission from shock acceleration, and possibly a direct connection to the EM progenitor, which may be identified in existing catalogues.
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From page 252... ...
The specifics of the needed capabilities for the individual messengers and EM bands are discussed in previous sections and are summarized in Table B.2. TABLE B.1 Key Science Questions and Discovery Area Question Subquestions B-Q1: What are the mass and spin distributions of B-Q1a: What do the mass and spin distributions tell us about neutron star neutron stars and stellar-mass black holes?
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From page 253... ...
; prompt public release. explosion imaging of SNe SDSS-V, ATLAS, Gaia, B-Q4: TDEs in IMBHs; binary AGN TESS, Roman, Euclid Massively multiplexed B-Q1: Noninteracting binary NSs and APOGEE, DESI, Rapid response (<1 hr)
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From page 254... ...
gravitational B-Q4: SMBH binaries other PTAs, LISA sample. Detect all merging SMBHs, localize waves B-DA: GW counterparts of EM sources loudest to <10 arcmin2.
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