Effective cross section of fuzzy dark matter halos

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.

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Modeling dark matter halos with nonlinear field theories

Physical Review D ◽

10.1103/physrevd.103.103519 ◽

2021 ◽

Vol 103 (10) ◽

Author(s):

R. A. C. Correa ◽

P. H. R. S. Moraes ◽

A. de Souza Dutra ◽

O. L. Dors ◽

W. de Paula ◽

...

Keyword(s):

Dark Matter ◽

Field Theories ◽

Dark Matter Halos ◽

Nonlinear Field

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Dark matter freeze-in from semi-production

Journal of High Energy Physics ◽

10.1007/jhep06(2021)026 ◽

2021 ◽

Vol 2021 (6) ◽

Author(s):

Andrzej Hryczuk ◽

Maxim Laletin

Keyword(s):

Dark Matter ◽

Early Universe ◽

Cross Section ◽

Thermal Equilibrium ◽

Indirect Detection ◽

Production Mechanism ◽

Number Density ◽

Matter Production ◽

Relic Density ◽

Standard Formalism

Abstract We study a novel dark matter production mechanism based on the freeze-in through semi-production, i.e. the inverse semi-annihilation processes. A peculiar feature of this scenario is that the production rate is suppressed by a small initial abundance of dark matter and consequently creating the observed abundance requires much larger coupling values than for the usual freeze-in. We provide a concrete example model exhibiting such production mechanism and study it in detail, extending the standard formalism to include the evolution of dark matter temperature alongside its number density and discuss the importance of this improved treatment. Finally, we confront the relic density constraint with the limits and prospects for the dark matter indirect detection searches. We show that, even if it was never in full thermal equilibrium in the early Universe, dark matter could, nevertheless, have strong enough present-day annihilation cross section to lead to observable signals.

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On the formation and stability of fermionic dark matter halos in a cosmological framework

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3986 ◽

2020 ◽

Author(s):

Carlos R Argüelles ◽

Manuel I Díaz ◽

Andreas Krut ◽

Rafael Yunis

Keyword(s):

Black Hole ◽

Dark Matter ◽

Space Distribution ◽

Coarse Grained ◽

Dark Matter Halos ◽

The Core ◽

The Galaxy ◽

Gravitating Systems ◽

The Given ◽

First Time

Abstract The formation and stability of collisionless self-gravitating systems is a long standing problem, which dates back to the work of D. Lynden-Bell on violent relaxation, and extends to the issue of virialization of dark matter (DM) halos. An important prediction of such a relaxation process is that spherical equilibrium states can be described by a Fermi-Dirac phase-space distribution, when the extremization of a coarse-grained entropy is reached. In the case of DM fermions, the most general solution develops a degenerate compact core surrounded by a diluted halo. As shown recently, the latter is able to explain the galaxy rotation curves while the DM core can mimic the central black hole. A yet open problem is whether this kind of astrophysical core-halo configurations can form at all, and if they remain stable within cosmological timescales. We assess these issues by performing a thermodynamic stability analysis in the microcanonical ensemble for solutions with given particle number at halo virialization in a cosmological framework. For the first time we demonstrate that the above core-halo DM profiles are stable (i.e. maxima of entropy) and extremely long lived. We find the existence of a critical point at the onset of instability of the core-halo solutions, where the fermion-core collapses towards a supermassive black hole. For particle masses in the keV range, the core-collapse can only occur for Mvir ≳ E9M⊙ starting at zvir ≈ 10 in the given cosmological framework. Our results prove that DM halos with a core-halo morphology are a very plausible outcome within nonlinear stages of structure formation.

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An excess radio signal in the Abell 4038 cluster

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2895 ◽

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.

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Clustering dependence of Chandra COSMOS Legacy AGN on host galaxy properties

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320002987 ◽

2019 ◽

Vol 15 (S356) ◽

pp. 226-226

Author(s):

Viola Allevato

Keyword(s):

Dark Matter ◽

Formation Rate ◽

Stellar Mass ◽

Active Galaxies ◽

Host Galaxy ◽

Mass Star ◽

Mass Relation ◽

Dark Matter Halos ◽

X Ray

AbstractThe presence of a super massive BH in almost all galaxies in the Universe is an accepted paradigm in astronomy. How these BHs form and how they co-evolve with the host galaxy is one of the most intriguing unanswered problems in modern Cosmology and of extreme relevance to understand the issue of galaxy formation. Clustering measurements can powerfully test theoretical model predictions of BH triggering scenarios and put constraints on the typical environment where AGN live in, through the connection with their host dark matter halos. In this talk, I will present some recent results on the AGN clustering dependence on host galaxy properties, such as galaxy stellar mass, star formation rate and specific BH accretion rate, based on X-ray selected Chandra COSMOS Legacy Type 2 AGN. We found no significant AGN clustering dependence on galaxy stellar mass and specif BHAR for Type 2 COSMOS AGN at mean z ∼ 1.1, with a stellar - halo mass relation flatter than predicted for non active galaxies in the Mstar range probed by our sample. We also observed a negative clustering dependence on SFR, with AGN hosting halo mass increasing with decreasing SFR. Mock catalogs of active galaxies in hosting dark matter halos with logMh[Msun] > 12.5, matched to have the same X-ray luminosity, stellar mass and BHAR of COSMOS AGN predict the observed Mstar - Mh, BHAR - Mh and SFR-Mh relations, at z ∼ 1.

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

Monthly Notices of the Royal Astronomical Society Letters ◽

10.1093/mnrasl/slz185 ◽

2019 ◽

Vol 495 (1) ◽

pp. L124-L128 ◽

Cited By ~ 2

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.

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