scholarly journals Constraints on light dark matter particles using white dwarf stars

2020 ◽  
Vol 29 (08) ◽  
pp. 2050058
Author(s):  
Grigoris Panotopoulos ◽  
Ilídio Lopes
Keyword(s):  
Dark Matter ◽  
Cross Section ◽  
Parameter Space ◽  
Globular Cluster ◽  
Upper Bound ◽  
White Dwarf ◽  
Dark Matter Particle ◽  
Dwarf Stars ◽  
White Dwarf Stars ◽  
Direct Dark Matter

We report constraints on the nucleon-dark matter particle cross-section using the internal luminosity of observed white dwarf stars in the globular cluster Messier 4. Our results cover the parameter space corresponding to relatively light dark matter particles, in the sub GeV range, which is known to be very difficult to be probed by direct dark matter searches. The additional luminosity coming from self-annihilations of dark matter particles captured inside the stars must not exceed the observed luminosity. Imposing that condition, we obtain for the spin independent cross-section of light dark matter particles (below 5[Formula: see text]GeV) on baryons [Formula: see text] the upper bound: [Formula: see text].

scholarly journals THE PHYSICS OF CRYSTALLIZATION FROM GLOBULAR CLUSTER WHITE DWARF STARS IN NGC 6397

2009 ◽  
Vol 693 (1) ◽  
pp. L6-L10 ◽  
Author(s):  
D. E. Winget ◽  
S. O. Kepler ◽  
Fabíola Campos ◽  
M. H. Montgomery ◽  
Leo Girardi ◽  
...  
Keyword(s):  
Globular Cluster ◽  
White Dwarf ◽  
Dwarf Stars ◽  
White Dwarf Stars

scholarly journals White dwarf stars: cosmic chronometers and dark matter probes

2018 ◽  
Vol 93 (4) ◽  
pp. 044002 ◽  
Author(s):  
Maurizio Salaris ◽  
Santi Cassisi
Keyword(s):  
Dark Matter ◽  
White Dwarf ◽  
Dwarf Stars ◽  
White Dwarf Stars

scholarly journals Exploring axion dark matter through radio signals from magnetic white dwarf stars

2021 ◽  
Vol 103 (11) ◽  
Author(s):  
Jin-Wei Wang ◽  
Xiao-Jun Bi ◽  
Run-Min Yao ◽  
Peng-Fei Yin
Keyword(s):  
Dark Matter ◽  
White Dwarf ◽  
Dwarf Stars ◽  
White Dwarf Stars ◽  
Radio Signals

An excess radio signal in the Abell 4038 cluster

2020 ◽  
Vol 500 (4) ◽  
pp. 5583-5588
Author(s):  
Man Ho Chan ◽  
Chak Man Lee
Keyword(s):  
Dark Matter ◽  
Spectral Data ◽  
Cross Section ◽  
Radio Signal ◽  
Dark Matter Particle ◽  
Cosmic Ray ◽  
Annihilation Cross Section ◽  
Radio Continuum ◽  
Test Statistic ◽  
Dark Matter Annihilation

ABSTRACT In the past decade, various instruments, such as the Large Area Telescope (LAT) on the Fermi Gamma Ray Space Telescope, the Alpha Magnetic Spectrometer (AMS) and the Dark Matter Particle Explorer(DAMPE), have been used to detect the signals of annihilating dark matter in our Galaxy. Although some excesses of gamma rays, antiprotons and electrons/positrons have been reported and are claimed to be dark matter signals, the uncertainties of the contributions of Galactic pulsars are still too large to confirm the claims. In this paper, we report on a possible radio signal of annihilating dark matter manifested in the archival radio continuum spectral data of the Abell 4038 cluster. By assuming a thermal annihilation cross-section and comparing the dark matter annihilation model with the null hypothesis (cosmic ray emission without dark matter annihilation), we obtain very large test statistic (TS) values, TS > 45, for four popular annihilation channels, which correspond to more than 6σ statistical preference. This reveals a possible potential signal of annihilating dark matter. In particular, our results are also consistent with the recent claims of dark matter mass, m ≈ 30–50 GeV, annihilating via the $\rm b\bar{b}$ quark channel with the thermal annihilation cross-section. However, at this time, we cannot exclude the possibility that a better background cosmic ray model could explain the spectral data without recourse to dark matter annihilations.

scholarly journals The Time Dependence of the Phases of the Harmonics Relative to the 1490 sec Fundamental in PG1346+082

1989 ◽  
Vol 114 ◽  
pp. 296-299
Author(s):  
J. L. Provencal ◽  
J. C. Clemens ◽  
G. Henry ◽  
B. P. Hine ◽  
R. E. Nather ◽  
...  
Keyword(s):  
White Dwarf ◽  
Compact Object ◽  
Detailed Knowledge ◽  
Line Profiles ◽  
Pressure Broadening ◽  
Dwarf Stars ◽  
White Dwarf Stars ◽  
Adequate Understanding ◽  
Magnitude Variation ◽  
Hydrogen Lines

White dwarf stars provide important boundary conditions for the understanding of stellar evolution. An adequate understanding of even these simple stars is impossible without detailed knowledge of their interiors. PG1346+082, an interacting binary white dwarf system, provides a unique opportunity to view the interior of one degenerate as it is brought to light in the accretion disk of the second star as the primary strips material from its less massive companion (see Wood et at. 1987).PG1346+082 is a photometric variable with a four magnitude variation over a four to five day quasi-period. A fast Fourier transform (FFT) of the light curve shows a complex, time-dependent structure of harmonics. PG1346+082 exhibits flickering – the signature of mass transfer. The optical spectra of the system contain weak emission features during minimum and broad absorption at all other times. This could be attributed to pressure broadening in the atmosphere of a compact object, or to a combination of pressure broadening and doppler broadening in a disk surrounding the compact accretor. No hydrogen lines are observed and the spectra are dominated by neutral helium. The spectra also display variable asymmetric line profiles.

scholarly journals A possible radio signal of annihilating dark matter in the Abell 4038 cluster

2019 ◽  
Vol 495 (1) ◽  
pp. L124-L128 ◽  
Author(s):  
Man Ho Chan ◽  
Chak Man Lee
Keyword(s):  
Dark Matter ◽  
Cross Section ◽  
Radio Signal ◽  
Dark Matter Particle ◽  
Cosmic Ray ◽  
Annihilation Cross Section ◽  
Radio Continuum ◽  
Test Statistic ◽  
Large Area ◽  
Dark Matter Annihilation

ABSTRACT In the past decade, some telescopes [e.g. Fermi-Large Area Telescope (LAT), Alpha Magnetic Spectrometer(AMS), and Dark Matter Particle Explorer(DAMPE)] were launched to detect the signals of annihilating dark matter in our Galaxy. Although some excess of gamma-rays, antiprotons, and electrons/positrons have been reported and claimed as dark matter signals, the uncertainties of Galactic pulsars’ contributions are still too large to confirm the claims. In this Letter, we report a possible radio signal of annihilating dark matter manifested in the archival radio continuum spectral data of the Abell 4038 cluster. By assuming the thermal annihilation cross-section and comparing the dark matter annihilation model with the null hypothesis (cosmic ray emission without dark matter annihilation), we get very large test statistic values >45 for four popular annihilation channels, which correspond to more than 6.5σ statistical preference. This provides a very strong evidence for the existence of annihilating dark matter. In particular, our results also support the recent claims of dark matter mass m ≈ 30–50 GeV annihilating via the bb̄ quark channel with the thermal annihilation cross-section.

New line profiles of sodium and potassium perturbed by helium for brown dwarf and very cool white dwarf stars

2008 ◽  
Author(s):  
M. Christova ◽  
N. F. Allard ◽  
J. F. Kielkopf ◽  
D. Homeier ◽  
F. Allard ◽  
...  
Keyword(s):  
White Dwarf ◽  
Line Profiles ◽  
Brown Dwarf ◽  
Dwarf Stars ◽  
White Dwarf Stars ◽  
Sodium And Potassium

scholarly journals A Strong Test of Electroweak Theory Using Pulsating DB White Dwarf Stars as Plasmon Neutrino Detectors

2004 ◽  
Vol 602 (2) ◽  
pp. L109-L112 ◽  
Author(s):  
D. E. Winget ◽  
D. J. Sullivan ◽  
T. S. Metcalfe ◽  
S. D. Kawaler ◽  
M. H. Montgomery
Keyword(s):  
White Dwarf ◽  
Electroweak Theory ◽  
Dwarf Stars ◽  
Neutrino Detectors ◽  
White Dwarf Stars
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