Probes of the progenitors, engines and physics behind stellar collapse

2021 ◽  
Author(s):  
Chris L. Fryer
Keyword(s):  
Neutron Star ◽  
Power Source ◽  
Observational Evidence ◽  
Observational Constraints ◽  
Core Collapse ◽  
Stellar Core ◽  
Stellar Collapse ◽  
Current Paradigm ◽  
The Universe

Super-novas (SNs) are one of the most powerful explosions in the universe and astronomers have invoked the collapse of a stellar core down to a neutron star as a potential power source behind these cosmic blasts. The current paradigm behind core-collapse SN relies on convection in the region just above the newly formed neutron star. This engine was driven and confirmed by observations. We review this observational evidence, and the potential for further observational constraints in this paper.

scholarly journals Studying Supernovae under the Current Paradigm

2015 ◽  
Vol 11 (A29B) ◽  
pp. 206-207
Author(s):  
Chris L. Fryer
Keyword(s):  
Neutron Star ◽  
Observational Data ◽  
Theoretical Work ◽  
Current Understanding ◽  
Core Collapse ◽  
The Past ◽  
Physics Model ◽  
Level Of Understanding ◽  
Current Paradigm ◽  
Proto Neutron Star

AbstractThe convection-enhanced paradigm behind core-collapse supernovae (SNe) invokes a multi-physics model where convection above the proto-neutron star is able to convert the energy released in the collapse to produce the violent explosions observed as SNe. Over the past decade, the evidence in support of this engine has grown, including constraints placed by SN neutrinos, energies, progenitors and remnants. Although considerable theoretical work remains to utilize this data, our understanding of normal SNe is advancing. To achieve a deeper level of understanding, we must find ways to compare detailed simulations with the increasing set of observational data. Here we review the current constraints and how we can apply our current understanding to broaden our understanding of these powerful engines.

scholarly journals Explosions from stellar collapse

2003 ◽  
Vol 212 ◽  
pp. 377-386
Author(s):  
Chris L. Fryer
Keyword(s):  
Potential Energy ◽  
Gravitational Potential ◽  
Massive Star ◽  
Gamma Ray ◽  
Massive Stars ◽  
Power Source ◽  
Gamma Ray Bursts ◽  
Gravitational Potential Energy ◽  
Stellar Collapse ◽  
The Universe

The collapse of a massive star releases a considerable amount of gravitational potential energy. This energy is believed to be the power source of some of the largest explosions in the universe: supernovae, hypernovae, gamma-ray bursts. In this proceedings, we review the mechanisms by which the potential energy from stellar collapse can be tapped to produce these strong explosions, emphasizing how our understanding of massive stars can help constrain these mechanisms.

scholarly journals The Influence of Evolving Dark Energy on Cosmology

2005 ◽  
Vol 22 (4) ◽  
pp. 315-325 ◽  
Author(s):  
Luke Barnes ◽  
Matthew J. Francis ◽  
Geraint F. Lewis ◽  
Eric V. Linder
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Equation Of State ◽  
Cosmological Constant ◽  
Energy Exchange ◽  
Observational Evidence ◽  
Cosmological Models ◽  
Observational Constraints ◽  
Expansion Of The Universe ◽  
The Universe

AbstractObservational evidence indicating that the expansion of the universe is accelerating has surprised cosmologists in recent years. Cosmological models have sought to explain this acceleration by incorporating ‘dark energy’, of which the traditional cosmological constant is just one possible candidate. Several cosmological models involving an evolving equation of state of the dark energy have been proposed, as well as possible energy exchange to other components, such as dark matter. This paper summarizes the forms of the most prominent models and discusses their implications for cosmology and astrophysics. Finally, this paper examines the current and future observational constraints on the nature of dark energy.

scholarly journals Observational constraints on the progenitor of core-collapse supernovae

2015 ◽  
Vol 11 (A29B) ◽  
pp. 209-210
Author(s):  
Nancy Elias-Rosa
Keyword(s):  
Hydrostatic Pressure ◽  
Massive Stars ◽  
Observational Constraints ◽  
Core Collapse ◽  
Direct Information ◽  
Stellar Core ◽  
Progenitor Stars

AbstractIt is well-known that some massive stars evolve to an end state which results in the collapse of the stellar core, as the hydrostatic pressure can no longer support gravity, leading to powerful explosions called supernovae (SNe). Even with over 6000 known SNe, we have only direct information about the progenitor star for a handful of explosions. Here, I summarise the observational constraints of the massive progenitor stars of several core-collapse supernovae.

scholarly journals Millisecond Pulsars

1989 ◽  
Vol 8 ◽  
pp. 161-165
Author(s):  
J.H. Krolik
Keyword(s):  
Neutron Star ◽  
Stellar Evolution ◽  
Close Binary ◽  
Millisecond Pulsar ◽  
Millisecond Pulsars ◽  
Physical Conditions ◽  
Cast Doubt ◽  
Standard Picture ◽  
The Universe ◽  
New System

AbstractMillisecond pulsars are intrinsically interesting because they illustrate some of the most extreme physical conditions to be found anywhere in the Universe, and because their evolution exhibits several stages of great drama. It had been widely believed for several years that spin-up of an old neutron star by accretion from a close stellar companion explained their fast rotation, but the absence of companions in several cases cast doubt on that picture. This spring a millisecond pulsar in a close binary was discovered in which the companion appears to be evaporating, thus reconciling the existence of lone millisecond pulsars with the standard picture. Ongoing observations of this new system, and complementary calculations, promise to answer many of the questions remaining about this dramatic phase in stellar evolution.

scholarly journals Observational Constraints on the Surface Gravitational Redshift of a Neutron Star

2017 ◽  
Author(s):  
Masachika Iwai ◽  
Tadayasu Dotani ◽  
Masanobu Ozaki ◽  
Yoshitomo Maeda ◽  
Hideyuki Mori ◽  
...  
Keyword(s):  
Neutron Star ◽  
Gravitational Redshift ◽  
Observational Constraints

scholarly journals Does gravity operate between galaxies? Observational evidence re-examined

2010 ◽  
Vol 466 (2122) ◽  
pp. 3089-3096 ◽  
Author(s):  
Francis J. M. Farley
Keyword(s):  
Hubble Constant ◽  
Repulsive Force ◽  
Observational Evidence ◽  
Frame Of Reference ◽  
Apparent Absence ◽  
Gravitational Effects ◽  
Expanding Metric ◽  
Current Paradigm ◽  
Recession Velocity ◽  
Shed Light

The redshifts and luminosities of type 1A supernovae are conventionally fitted with the current paradigm, which holds that the galaxies are locally stationary in an expanding metric. The fit fails unless the expansion is accelerating; driven perhaps by ‘dark energy’. Is the recession of the galaxies slowed down by gravity or speeded up by some repulsive force? To shed light on this question the redshifts and apparent magnitudes of type 1A supernovae are re-analysed in a cartesian frame of reference omitting gravitational effects. The redshift is ascribed to the relativistic Doppler effect which gives the recession velocity when the light was emitted; if this has not changed, the distance reached and the luminosity follow immediately. This simple concept fits the observations surprisingly well with the Hubble constant H 0 =62.9±0.3 km s −1  Mpc −1 . It appears that the galaxies recede at unchanging velocities, so on the largest scale there is no significant intergalactic force. Reasons for the apparent absence of an intergalactic force are discussed.

scholarly journals INTERACTION BETWEEN DARK ENERGY AND DARK MATTER: OBSERVATIONAL CONSTRAINTS FROM OHD, BAO, CMB AND SNe Ia

2013 ◽  
Vol 22 (14) ◽  
pp. 1350082 ◽  
Author(s):  
SHUO CAO ◽  
NAN LIANG
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Observational Constraints ◽  
Coincidence Problem ◽  
Cosmological Constraints ◽  
Coincidence Index ◽  
Acceleration Of The Universe ◽  
Interaction Term ◽  
Negative Coupling ◽  
The Universe

In order to test if there is energy transfer between dark energy (DE) and dark matter (DM), we investigate cosmological constraints on two forms of nontrivial interaction between the DM sector and the sector responsible for the acceleration of the universe, in light of the newly revised observations including OHD, CMB, BAO and SNe Ia. More precisely, we find the same tendencies for both phenomenological forms of the interaction term Q = 3γHρ, i.e. the parameter γ to be a small number, |γ| ≈ 10-2. However, concerning the sign of the interaction parameter, we observe that γ > 0 when the interaction between dark sectors is proportional to the energy density of dust matter, whereas the negative coupling (γ < 0) is preferred by observations when the interaction term is proportional to DE density. We further discuss two possible explanations to this incompatibility and apply a quantitative criteria to judge the severity of the coincidence problem. Results suggest that the γm IDE model with a positive coupling may alleviate the coincidence problem, since its coincidence index C is smaller than that for the γd IDE model, the interacting quintessence and phantom models by four orders of magnitude.

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