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We provide a new constraint on the small-scale density fluctuations, evaluating the diffuse background free-free emission from dark matter halos in the dark ages. If there exists a large amplitude of the matter density fluctuations on small…

Cosmology and Nongalactic Astrophysics · Physics 2022-05-12 Katsuya T. Abe , Teppei Minoda , Hiroyuki Tashiro

We discuss free-free radio emission from ionized gas in the intergalactic medium. Because the emissivity is proportional to the square of the electron density, the mean background is strongly sensitive to the spatial clumping of free…

Astrophysics · Physics 2009-11-10 Asantha Cooray , Steven Furlanetto

Dark matter annihilation in Galactic substructure produces diffuse gamma-ray emission of remarkably constant intensity across the sky, and in general this signal dominates over the smooth halo signal at angles greater than a few tens of…

High Energy Astrophysical Phenomena · Physics 2009-07-02 Jennifer M. Siegal-Gaskins

The current knowledge of cosmological structure formation suggests that Cold Dark Matter (CDM) halos possess a nonspherical density profile, implying that cosmic structures can be potential sources of gravitational waves via power transfer…

Astrophysics · Physics 2007-05-23 Carmelita Carbone , Carlo Baccigalupi , Sabino Matarrese

We present constraints on the density of halo dark matter candidates within the solar circle based on the anisotropy in the high energy gamma-ray background. The known galactic components of the gamma-ray background, in particular the…

Astrophysics · Physics 2007-05-23 R. Chary , E. L. Wright

(Abridged) Using high-resolution cosmological N-body simulations, we study how the density profiles of dark matter halos are affected by the filtering of the density power spectrum below a given scale length and by the introduction of a…

Astrophysics · Physics 2009-09-25 V. Avila-Reese , P. Colin , O. Valenzuela , E. D'Onghia , C. Firmani

Baryonic gas falling onto a primordial black hole (PBH) emits photons via the free-free process. These photons can contribute the diffuse free-free background radiation in the frequency range of the cosmic microwave background radiation…

Cosmology and Nongalactic Astrophysics · Physics 2021-09-09 Hiroyuki Tashiro , Katsuya T. Abe , Teppei Minoda

The majority of gamma-ray emission from Galactic dark matter annihilation is likely to be detected as a contribution to the diffuse gamma-ray background. I show that dark matter substructure in the halo of the Galaxy induces characteristic…

Astrophysics · Physics 2011-07-13 Jennifer M. Siegal-Gaskins

It is well known that annihilations in the homogeneous fluid of dark matter (DM) can leave imprints in the cosmic microwave background (CMB) anisotropy power spectrum. However, the relevance of DM annihilations in halos for cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2016-01-20 Vivian Poulin , Pasquale D. Serpico , Julien Lesgourgues

The fuzzy dark matter (FDM) scenario has received increased attention in recent years due to the small-scale challenges of the vanilla Lambda cold dark matter ($\Lambda$CDM) cosmological model and the lack of any experimental evidence for…

Cosmology and Nongalactic Astrophysics · Physics 2023-01-20 Tibor Dome , Anastasia Fialkov , Philip Mocz , Björn Malte Schäfer , Michael Boylan-Kolchin , Mark Vogelsberger

Dark matter density profiles based upon Lambda-CDM cosmology motivate an ansatz velocity distribution function with fewer high velocity particles than the Maxwell-Boltzmann distribution or proposed variants. The high velocity tail of the…

Cosmology and Nongalactic Astrophysics · Physics 2011-02-25 Mariangela Lisanti , Louis E. Strigari , Jay G. Wacker , Risa H. Wechsler

We analyze the properties of dark matter halos in the cold-plus-warm dark matter cosmologies (CWDM). We study their dependence on the fraction and velocity dispersion of the warm particle, keeping the free-streaming scale fixed. To this end…

Cosmology and Nongalactic Astrophysics · Physics 2013-01-29 Andrea V. Maccio' , Oleg Ruchayskiy , Alexey Boyarsky , Juan C. Munoz-Cuartas

We make a detailed analysis of the indirect diffuse gamma-ray signals from dark matter annihilation in the Galaxy. We include the prompt emission, as well as the emission from inverse Compton scattering whenever the annihilation products…

High Energy Astrophysical Phenomena · Physics 2012-11-14 Steve Blanchet , Julien Lavalle

This document provides a brief summary estimate of Galactic free-free emission and H-alpha emission and their relationship. Particular emphasis is placed on estimating the potential free-free emission in the region of significant confusion…

Astrophysics · Physics 2007-05-23 George F. Smoot

The $\Lambda$-CDM model of cosmology has done much to clarify our picture of the early universe. However, there are still some questions that $\Lambda$-CDM does not necessarily answer; questions such as what is the fundamental nature of…

Cosmology and Nongalactic Astrophysics · Physics 2024-06-17 Wenzer Qin

Cosmic microwave background (CMB) anisotropies and density fluctuations are calculated for flat cold dark matter (CDM) models with a wide range of parameters, i.e., $\Omega_0, h$ and $\Omega_B$ for both standard recombination and various…

Astrophysics · Physics 2009-10-22 Naoshi Sugiyama

The Fermi-LAT collaboration has recently reported the detection of angular power above the photon noise level in the diffuse gamma-ray background between 1 and 50 GeV. Such signal can be used to constrain a possible contribution from…

The Cosmic Microwave Background (CMB) physics can be used to constrain the dark energy dynamics: B modes of the polarization of the diffuse CMB emission as well as the polarized signal towards clusters of galaxies are sensitive to the…

Astrophysics · Physics 2007-05-23 Paola Andreani , Carlo Baccigalupi

We summarize the relationship between the free-free emission foreground and Galactic H-alpha emission. H-alpha observations covering nearly the entire celestial sphere are described. These data provide a template to isolate and/or remove…

Astrophysics · Physics 2008-11-26 P. R. McCullough , J. E. Gaustad , W. Rosing , D. Van Buren

[Abridged] We analyze the exchange of dark matter between halos, subhalos, and their environments in a high-resolution cosmological N-body simulation of a Lambda CDM cosmology. At each analyzed redshift z we divide the dark matter particles…

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