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We present $\gamma$-ray optical-depth calculations from a recently published extragalactic background light (EBL) model built from multiwavelength galaxy data from the Hubble Space Telescope Cosmic Assembly Near-Infrared Deep Extragalactic…

Cosmological observations precisely measure primordial variations in the density of the Universe at megaparsec and larger scales, but much smaller scales remain poorly constrained. However, sufficiently large initial perturbations at small…

Cosmology and Nongalactic Astrophysics · Physics 2024-01-29 M. S. Delos , G. Franciolini

Observations of distant gamma-ray sources are hindered by the presence of the extragalactic background light (EBL). In order to understand the physical processes that result in the observed spectrum of sources, it is imperative that a good…

High Energy Astrophysical Phenomena · Physics 2017-06-01 Thomas Armstrong , Anthony M. Brown , Paula M. Chadwick

The MACHO collaboration lensing event statistics suggest that a significant fraction of the dark galactic halo can be comprised of baryonic matter in the form of white dwarf stars with masses between 0.1 and 1.0 \Msun . Such a halo white…

Astrophysics · Physics 2009-10-28 Steven D. Kawaler

Distant BL Lacertae objects emit $\gamma$ rays which interact with the extragalactic background light (EBL), creating electron-positron pairs, and reducing the flux measured by ground-based imaging atmospheric Cherenkov telescopes (IACTs)…

High Energy Astrophysical Phenomena · Physics 2015-11-18 Justin D. Finke , Luis C. Reyes , Markos Georganopoulos , Kaeleigh Reynolds , Marco Ajello , Stephen J. Fegan , Kevin McCann

We calculate the intensity and photon spectrum of the intergalactic background light (IBL) as a function of redshift using an approach based on observational data obtained in many different wavelength bands from local to deep galaxy…

High Energy Astrophysical Phenomena · Physics 2012-12-06 Floyd W. Stecker , Matthew A. Malkan , Sean T. Scully

We present models of the extragalactic background light (EBL) based on several scenarios of galaxy formation and evolution. We have treated galaxy formation with the Press-Schecter approximation for both cold dark matter (CDM) and cold+hot…

Astrophysics · Physics 2008-02-03 Donn MacMinn , Joel R. Primack

The origin of the diffuse extragalactic, high-energy gamma-ray background (EGRB) filling the Universe remains unknown. The spectrum of this extragalactic radiation, as measured by the EGRET on-board CGRO, is well-fit by a power law across…

Astrophysics · Physics 2009-11-07 Caleb A. Scharf , Reshmi Mukherjee

We examine the most recent observational constraints arising from i) small-scale and large-scale Galactic dynamical properties, ii) star counts at faint magnitude and iii) microlensing experiments. From these constraints, we determine the…

Astrophysics · Physics 2007-05-23 D. Méra , G. Chabrier , R. Schaeffer

Very high energy (VHE, energy >~ 100 GeV) {\gamma}-rays undergo pair production with photons of the extragalactic background light (EBL). Thus, the intrinsic {\gamma}-ray flux of cosmological sources is attenuated and the Universe should be…

High Energy Astrophysical Phenomena · Physics 2013-01-11 Manuel Meyer , Dieter Horns , Martin Raue

Interactions between the extragalactic background light (EBL) and very high energy {\gamma} rays (VHE; E > 10 GeV) from cosmological sources alter their {\gamma}-ray spectrum. The stronger absorption of harder {\gamma} rays causes a…

Astrophysics of Galaxies · Physics 2018-08-21 A. M. Kudoda , A. Faltenbacher

We discuss how measurements of the absorption of $\gamma$-rays from GeV to TeV energies via pair production on the extragalactic background light (EBL) can probe important issues in galaxy formation. We use semi-analytic models (SAMs) of…

We propose a method for setting upper limits to the extragalactic background light (EBL). Our method uses simultaneous {\em Fermi}-LAT and ground-based TeV observations of blazars and is based on the assumption that the intrinsic spectral…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Markos Georganopoulos , Justin D. Finke , Luis C. Reyes

We measure the projected density profile, shape and alignment of the stellar and dark matter mass distribution in 11 strong-lens galaxies. We find that the projected dark matter density profile - under the assumption of a Chabrier stellar…

We use new studies of the cosmic evolution of star-forming galaxies to estimate the production rate of ionizing photons from hot, massive stars at low and intermediate redshifts. The luminosity function of blue galaxies in the Canada-France…

Astrophysics · Physics 2015-06-24 E. Giallongo , A. Fontana , P. Madau

We present an analysis of a deep (1$\sigma$=13 $\mu$Jy) cosmological 1.2-mm continuum map based on ASPECS, the ALMA Spectroscopic Survey in the Hubble Ultra Deep Field. In the 1 arcmin$^2$ covered by ASPECS we detect nine sources at…

Gamma-rays propagating through space are likely to be extinguished via electron-positron pair production off of the ambient extragalactic background light (EBL). The spectrum of the EBL is produced by starlight (and starlight reprocessed by…

High Energy Astrophysical Phenomena · Physics 2013-12-11 Rebecca Reesman , T. P. Walker

We present cosmological parameter measurements from the effective field theory-based full-shape analysis of the power spectrum of emission line galaxies (ELGs). First, we perform extensive tests on simulations and determine appropriate…

Cosmology and Nongalactic Astrophysics · Physics 2021-12-02 Mikhail M. Ivanov