scholarly journals Constraints on cross section and lifetime of dark matter with HAWC Observations of dwarf Irregular galaxies

2019 ◽  
Author(s):  
Sergio Hernández Cadena ◽  
Viviana Gammaldi ◽  
José Serna Franco ◽  
Rubén Alfaro Molina ◽  
Ekaterina Karukes ◽  
...  
2021 ◽  
Author(s):  
Viviana Gammaldi ◽  
Judit Pérez-Romero ◽  
Javier Coronado-Blázquez ◽  
Mattia Di Mauro ◽  
Miguel Angel Sánchez-Conde ◽  
...  

Author(s):  
James Binney

‘Galaxies’ describes galaxy morphology, the chemical evolution of galaxies, and stellar dynamics. A galaxy consists of a huge number of point masses—stars and dark matter—that move freely in the gravitational field that they jointly generate. The nature of a galaxy is largely determined by its luminosity, its bulge-to-disc ratio, and the ratio of its mass of cold gas to the mass in stars. Galaxies are also shaped by their environments. Dense environments are rich in elliptical and lenticular galaxies, while abnormally under-dense environments are rich in dwarf irregular galaxies. Spiral galaxies like our own tend to inhabit regions of intermediate density.


2000 ◽  
Vol 120 (6) ◽  
pp. 3027-3059 ◽  
Author(s):  
Stéphanie Côté ◽  
Claude Carignan ◽  
Kenneth C. Freeman

2021 ◽  
Vol 104 (8) ◽  
Author(s):  
V. Gammaldi ◽  
J. Pérez-Romero ◽  
J. Coronado-Blázquez ◽  
M. Di Mauro ◽  
E. V. Karukes ◽  
...  

Author(s):  
Natalia Nowak ◽  
Katarzyna Otmianowska-Mazur ◽  
Katarzyna Kulpa-Dybel ◽  
Hubert Siejkowski ◽  
Marian Soida ◽  
...  

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
H. Hernández-Arellano ◽  
M. Napsuciale ◽  
S. Rodríguez

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.


2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Andrzej Hryczuk ◽  
Maxim Laletin

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.


1998 ◽  
Vol 11 (1) ◽  
pp. 121-122
Author(s):  
Claude Carignan

Recent studies (Puche & Westpfahl 1994, Young & Lo 1996) have shown that the distribution of HI in some extreme low luminosity dwarf irregular galaxies (e.g. M81dwA, Holmberg I, Leo A) tends to have a ring-like (or shell-like) distribution which suggests that a single burst of star formation could expell most of the remaining ISM (or at least a large fraction of it) from the system. In view of this, Puche & Westpfahl (1994) suggested that in dwarf spheroidal galaxies, the HI should be found at large radii since no young stellar population is observed in most of them.


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