Conveners
Massive white dwarfs and related phenomena: Monday block 1
- Jaziel Goulart Coelho (UTFPR)
- Banibrata Mukhopadhyay (Indian Institute of Science)
- José Domingo Arbañil Vela (Universidad Privada del Norte)
Massive white dwarfs and related phenomena: Monday block 2
- José Domingo Arbañil Vela (Universidad Privada del Norte)
- Jaziel Goulart Coelho (UTFPR)
- Banibrata Mukhopadhyay (Indian Institute of Science)
Description
This session brings together all the scientists who are interested in
white dwarf (WD) physics and astrophysics, particularly the massive WDs,
and related topics including type Ia supernova and its progenitor.
We welcome papers on the following topics and other from related topics:
1. Theoretical and observational progress in WDs
2. Very fast rotating and/or magnetized, massive WD
3. Double WD mergers
4. Importance and possible identification of strong magnetic fields in WDs
5. Chandrasekhar limit and WD mass-radius relation, and their possible
theoretical and observational violation
6. Tidal deformability in WD
7. Nuclear processes in evolution of main sequence stars evolving to WD
8. Type Ia supernova progenitor
9. Explosive events as bursts, Fast Radio Bursts (FRBs)
10. Magnetic CVs including polar and intermediate polar
11. Gravitational waves from WD systems and their future detection
I will review the properties and discuss some of the puzzling aspects of the unique binary system composed by the luminous hot subdwarf HD 49798 and a white dwarf of 1.220(8) solar masses and spin period of 13.2 s. This is one of the few massive white dwarfs with a dynamically measured mass and the one with the shortest spin period. It emits pulsed X-rays with a very soft spectrum, powered...
Double white-dwarf (DWD) mergers are relevant astrophysical sources expected to produce massive, highly-magnetized WDs, supernovae (SNe) Ia, and neutron stars (NSs). There are expected to be numerous sources in the sky, but none have been yet detected, evading the most advanced transient surveys (e.g., The Zwicky Transient Facility - ZTF). We characterize the optical transient from DWD...
Over more than a decade, along with my group members I have been
exploring the possible violation of Chandrasekhar mass-limit significantly
and possible new mass-limit(s). They are indirectly supported by some
observations of peculiar type Ia supernovae. The potential reasons behind
such a violation could be magnetic field, modified gravity, noncommutative
spacetime etc. Many other groups...
We explore in detail the time-dependent simulation for the evolution of the magnetized main sequence (MS) stars to magnetised white dwarfs (WDs) using the Cambridge Stellar evolution code: STARS. In order to do so, we have appropriately modified the said code by introducing magnetic effect and cooling. We investigate further the possible existence of stable, massive, super-Chandrasekhar WDs,...
In this research, we examine the gravitational behavior of dense astronomical bodies, specifically white dwarfs and neutron stars, using Einstein's gravitational theories. We explore the effects of deviations from spherical symmetry by applying a simplified mathematical model, incorporating the quadrupole moment to a first-order approximation [1].
Focusing on the interiors of white dwarfs, we...
In this work, we investigate the high-energy emission in SGRs/AXPs, neutron stars with extreme magnetic field, named magnetars. The observed high-energy emission in the X-rays and gamma-ray bands are explained. The outer gap accelerator model considers the generation of high-energy emission far away from the surface of the star in a combination of curvature radiation and inverse Compton...
White dwarfs are potentially the remnants of the oldest entities in the universe. They typically evolve from stars in the asymptotic giant branch, boasting initially high temperatures and masses that can reach up to $10^8 [K]$ and $1.41 M_\odot$, known as the Chandrasekhar mass limit. A recent study by Nunes, Arbañil, and Malheiro in 2021 delved into the dynamics of these massive stars,...
On June 9th, we received the news of the passing of Professor Manuel Malheiro. Malheiro was not only a colleague and advisor, but also a friend. This presentation covers our last work together and represents my homage to him.
The lack of isolated neutron stars~(NSs) rotating slower than 11 s led to the postulate of a maximum limit for their rotation period. However, the discovery of radio...
We explore the stability of this rapidly rotating WD using a modern equation of state (EoS) that accounts for electron–ion, electron–electron, and ion–ion interactions. For this EoS, we determine the mass density thresholds for the onset of pycnonuclear fusion reactions and study the impact of microscopic stability and rapid rotation on the structure and stability of WDs, considering them with...
Astrometric data presented in ATNF Pulsar Catalogue have enabled us to determine the trajectories through
the Galactic potential for different kick-velocity models of pulsars.
The system was disrupted ~0.2-0.8 Myr ago, which must correspond to the true age of at least one of the pulsars.
The implied pulsar birth velocities are consistent with the high velocities of neutron stars in...
Our understanding of the mass distribution of white dwarfs remains elusive, yet it stands as a fundamental aspect of these stellar remnants that mark the final stage of the majority of stars' lifecycles. Unravelling this distribution requires untangling the influences of the initial mass function, star formation history, and stellar evolution. The latter can be significantly altered by the...
