scholarly journals Neutron Stars and Dark Matter

Universe ◽  
2020 ◽  
Vol 6 (12) ◽  
pp. 222
Author(s):  
Antonino Del Popolo ◽  
Morgan Le Delliou ◽  
Maksym Deliyergiyev
Keyword(s):  
Dark Matter ◽  
Neutron Star ◽  
Neutron Stars ◽  
Cross Section ◽  
Galactic Center ◽  
Interaction Strength ◽  
Dark Matter Particle ◽  
Galactic Centre ◽  
Interaction Cross Section ◽  
Neutron Star Mass

Neutron stars change their structure with accumulation of dark matter. We study how their mass is influenced from the environment. Close to the sun, the dark matter accretion from the neutron star does not have any effect on it. Moving towards the galactic center, the density increase in dark matter results in increased accretion. At distances of some fraction of a parsec, the neutron star acquire enough dark matter to have its structure changed. We show that the neutron star mass decreases going towards the galactic centre, and that dark matter accumulation beyond a critical value collapses the neutron star into a black hole. Calculations cover cases varying the dark matter particle mass, self-interaction strength, and ratio between the pressure of dark matter and ordinary matter. This allow us to constrain the interaction cross section, σdm, between nucleons and dark matter particles, as well as the dark matter self-interaction cross section.

scholarly journals Neutron to dark matter decay in neutron stars

2018 ◽  
Vol 33 (31) ◽  
pp. 1844020 ◽  
Author(s):  
T. F. Motta ◽  
P. A. M. Guichon ◽  
A. W. Thomas
Keyword(s):  
Dark Matter ◽  
Neutron Star ◽  
Neutron Stars ◽  
Decay Width ◽  
Decay Mode ◽  
Measurement Problem ◽  
Dark Matter Particle ◽  
Neutron Decay ◽  
Astrophysical Data ◽  
The Universe

Recent proposals have suggested that a previously unknown decay mode of the neutron into a dark matter particle could solve the long lasting measurement problem of the neutron decay width. We show that, if the dark particle in neutron decay is the major component of the dark matter in the universe, this proposal is in disagreement with modern astrophysical data concerning neutron star masses.

scholarly journals The Fermi–LAT Galactic Center Excess: Evidence of Annihilating Dark Matter?

2020 ◽  
Vol 70 (1) ◽  
pp. 455-483
Author(s):  
Simona Murgia
Keyword(s):  
Dark Matter ◽  
Cross Section ◽  
Galactic Center ◽  
Dark Matter Particle ◽  
Point Sources ◽  
Current Status ◽  
Large Area ◽  
200 Gev ◽  
Γ Rays ◽  
Particle Nature

The center of the Galaxy is one of the prime targets in the search for a signal of annihilating (or decaying) dark matter. If such a signal were to be detected, it would shed light on one of the biggest mysteries in physics today: What is dark matter? Fundamental properties of the particle nature of dark matter, such as its mass, annihilation cross section, and annihilation final states, could be measured for the first time. Several experiments have searched for such a signal, and some have measured excesses that are compatible with it. A long-standing and compelling excess is observed in γ-rays by the Fermi Large Area Telescope ( Fermi–LAT). This excess is consistent with a dark matter particle with a mass of approximately 50 (up to ∼200) GeV annihilating with a velocity-averaged cross section of ∼10−26 cm3 s−1. Although a dark matter origin of the excess remains viable, other interpretations are possible. In particular, there is some evidence that the excess is produced by a population of unresolved point sources of γ-rays—for example, millisecond pulsars. In this article, I review the current status of the observation of the Fermi–LAT Galactic center excess, the possible interpretations of the excess, the evidence and counterevidence for each, and the prospects for resolving its origin with future measurements.

scholarly journals Review on Dark Matter Searches with Neutrino Telescopes

2021 ◽  
Author(s):  
Juan de Dios Zornoza
Keyword(s):  
Dark Matter ◽  
Cross Section ◽  
Galactic Center ◽  
Annihilation Cross Section ◽  
Galactic Centre ◽  
The Sun ◽  
Neutrino Telescopes ◽  
Experimental Activity ◽  
The Universe

The search for dark matter is one the hottest topics in Physics today. The fact that about 80% of the matter of the Universe is of unknown nature has triggered an intense experimental activity to detect such kind of matter and a no less intense effort on the theory side to explain it. Given the fact that we do not know well the properties of dark matter, searches from different fronts are mandatory. Neutrino telescopes are part of this experimental quest and offer specific advantages. Among the targets to look for dark matter, the Sun and the Galactic Center are the most promising ones. Neutrino telescopes have put the best limits on spin-dependent cross section of proton-WIMP scattering. Moreover, they are competitive in the constraints on the thermally averaged annihilation cross-section for high WIMP masses when looking at the Galactic Centre. Other results are also reviewed.

scholarly journals Neutron decay, dark matter and neutron stars

2019 ◽  
Vol 219 ◽  
pp. 05006
Author(s):  
D.H. Beck
Keyword(s):  
Dark Matter ◽  
Neutron Star ◽  
Neutron Stars ◽  
Nucleon Nucleon ◽  
Neutron Decay ◽  
Neutron Lifetime ◽  
Nucleon Interaction ◽  
Star Mass ◽  
Neutron Star Mass ◽  
Nucleon Nucleon Interaction

Following up on a suggestion that decay to a dark matter fermion might explain the 4σ discrepancy in the neutron lifetime, we consider the implications of such a fermion on neutron star structure. We find that including it reduces the maximum neutron star mass to well below the observed masses. In order to recover stars with the observed masses, the (repulsive) self-interactions of the dark fermion would have to be stronger than those of the nucleon-nucleon interaction.

scholarly journals Review on Indirect Dark Matter Searches with Neutrino Telescopes

Universe ◽  
2021 ◽  
Vol 7 (11) ◽  
pp. 415
Author(s):  
Juan de Dios Zornoza
Keyword(s):  
Dark Matter ◽  
Cross Section ◽  
Galactic Center ◽  
Annihilation Cross Section ◽  
Galactic Centre ◽  
The Sun ◽  
Neutrino Telescopes ◽  
Experimental Activity ◽  
The Universe

The search for dark matter is one of the hottest topics in Physics today. The fact that about 80% of the matter of the Universe is of unknown nature has triggered an intense experimental activity to detect this kind of matter and a no less intense effort on the theory side to explain it. Given the fact that we do not know the properties of dark matter well, searches from different fronts are mandatory. Neutrino telescopes are part of this experimental quest and offer specific advantages. Among the targets to look for dark matter, the Sun and the Galactic Center are the most promising ones. Considering models of dark matter densities in the Sun, neutrino telescopes have put the best limits on spin-dependent cross section of proton-WIMP scattering. Moreover, they are competitive in the constraints on the thermally averaged annihilation cross-section for high WIMP masses when looking at the Galactic Centre. Other results are also reviewed.

scholarly journals Spin-one dark matter and gamma ray signals from the galactic center

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
H. Hernández-Arellano ◽  
M. Napsuciale ◽  
S. Rodríguez
Keyword(s):  
Dark Matter ◽  
Cross Section ◽  
Gamma Ray ◽  
Galactic Center ◽  
Photon Emission ◽  
Scalar Coupling ◽  
Initial State ◽  
Internal Bremsstrahlung ◽  
Resonance Effects ◽  
State Radiation

Abstract In this work we study the possibility that the gamma ray excess (GRE) at the Milky Way galactic center come from the annihilation of dark matter with a (1, 0) ⊕ (0, 1) space-time structure (spin-one dark matter, SODM). We calculate the production of prompt photons from initial state radiation, internal bremsstrahlung, final state radiation including the emission from the decay products of the μ, τ or hadronization of quarks. Next we study the delayed photon emission from the inverse Compton scattering (ICS) of electrons (produced directly or in the prompt decay of μ, τ leptons or in the hadronization of quarks produced in the annihilation of SODM) with the cosmic microwave background or starlight. All these mechanisms yield significant contributions only for Higgs resonant exchange, i.e. for M ≈ MH /2, and the results depend on the Higgs scalar coupling to SODM, gs. The dominant mechanism at the GRE bump is the prompt photon production in the hadronization of b quarks produced in $$ \overline{D}D\to \overline{b}b $$ D ¯ D → b ¯ b , whereas the delayed photon emission from the ICS of electrons coming from the hadronization of b quarks produced in the same reaction dominates at low energies (ω < 0.3 GeV ) and prompt photons from c and τ , as well as from internal bremsstrahlung, yield competitive contributions at the end point of the spectrum (ω ≥ 30 GeV ). Taking into account all these contributions, our results for photons produced in the annihilation of SODM are in good agreement with the GRE data for gs ∈ [0.98, 1.01] × 10−3 and M ∈ [62.470, 62.505] GeV . We study the consistency of the corresponding results for the dark matter relic density, the spin-independent dark matter-nucleon cross-section σp and the cross section for the annihilation of dark matter into $$ \overline{b}b $$ b ¯ b , τ+τ−, μ+μ− and γγ, taking into account the Higgs resonance effects, finding consistent results in all cases.

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 &gt; 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 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 &gt;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 LIMITS ON THE WIMP COLD DARK MATTER INTERACTION CROSS SECTION FROM THE UK EXPERIMENT

COSMO-97 ◽  
1998 ◽  
Author(s):  
T. Ali ◽  
T. J. Sumner ◽  
J. J. Quenby ◽  
A. Bewick ◽  
N. J. T. Smith ◽  
...  
Keyword(s):  
Dark Matter ◽  
Cross Section ◽  
Cold Dark Matter ◽  
Interaction Cross Section ◽  
Matter Interaction ◽  
The Uk

General relativity and neutron stars

2016 ◽  
Vol 31 (02n03) ◽  
pp. 1641017
Author(s):  
D. G. Yakovlev
Keyword(s):  
General Relativity ◽  
Neutron Star ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Mass Measurements ◽  
Einstein Theory ◽  
Superdense Matter ◽  
Compact Binaries ◽  
Star Models ◽  
Neutron Star Mass

General Relativity affects all major aspects of neutron star structure and evolution including radiation from the surface, neutron star models, evolution in compact binaries. It is widely used for neutron star mass measurements and for studying properties of superdense matter in neutron stars. Observations of neutron stars help testing General Relativity and planning gravitational wave experiments. No deviations from Einstein Theory of Gravity have been detected so far from observations of neutron stars.

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