相关论文: Metals in the Universe and Diffuse Background Radi…

We present new synthesis models of the extragalactic background light (EBL) from far infra-red (FIR) to TeV gamma-rays, with an emphasis on the extreme ultraviolet (UV) background which is responsible for the observed ionization and thermal…

The Extragalactic Background Light (EBL) that spans the UV-IR band originates from direct and dust-reprocessed starlight integrated over the history of the Universe. EBL measurements are very challenging due to foreground emission like the…

Nine metal-polluted white dwarfs are observed with medium-resolution optical spectroscopy,where photospheric abundances are determined and interpreted through comparison against solar system objects. An improved method of making such…

Very high energy (VHE, E > 30 GeV) gamma-rays are absorbed via interaction with low-energy photons from the extragalactic background light (EBL) if the involved photon energies are above the threshold for electron-positron pair creation.…

The origin of the extragalactic gamma-ray background (EGRB) is still an open question, even after nearly forty years of its discovery. The emission could originate from either truly diffuse processes or from unresolved point sources.…

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…

Context: Hot subdwarf B stars (sdBs) are considered to be core helium-burning stars with very thin hydrogen envelopes situated on or near the extreme horizontal branch (EHB). The formation of sdBs is still unclear as well as the chemical…

The bulk of the extragalactic background between 10 keV and 10 GeV is likely to be explained by the emission of Seyfert galaxies, type Ia supernovae, and blazars. However, as revealed by the INTEGRAL satellite, the bulge of our galaxy is an…

The extragalactic background light (EBL), from ultraviolet to infrared wavelengths, is predominantly due to emission from stars, accreting black holes and reprocessed light due to Galactic dust. The EBL can be studied through the imprint it…

At any given epoch, the Extragalactic Background Light (EBL) carries imprints of integrated star formation activities in the universe till that epoch. On the other hand, in order to estimate the EBL, when direct observations are not…

We discuss the contribution of the blazar population to the extragalactic background radiation across the electromagnetic (e.m.) spectrum with particular reference to the microwave, hard-X-ray and gamma-ray bands. Our estimates are based on…

Blazar emission of gamma rays and cosmic ray production of gamma rays in gas-rich clusters have been proposed recently as alternative sources of the high energy extragalactic diffuse gamma ray background radiation. We show that these…

The possibility that the major part of all extrasolar hadronic cosmic rays with energies above 10 MeV/n is of extragalactic origin is discussed. Recent observational results on the galactocentric cosmic-ray density gradient and very high…

The Fermi bubbles are gigantic gamma-ray structures in our Galaxy. The physical origin of the bubbles is still under debate. The leading scenarios can be divided into two categories. One is the nuclear star forming activity similar to…

The Cosmic Background due to the integrated radiation from galaxies over the whole life of the Universe is reviewed. We find that this background is well constrained by measurements. The total power in the background is in the range 60-93…

Annihilating dark matter (DM) has been discussed as a possible source of gamma-rays from the galactic center (GC) and contributing to the extragalactic gamma-ray background (EGB). Assuming universality of the density profile of DM halos, we…

Low and intermediate mass stars with super solar metallicities comprise a known portion of the universe. Yet yields for asymptotic giant branch (AGB) stars with metallicities greater than $Z=0.04$ do not exist in the literature. This…

Metals are found in all baryonic phases and environments, and our knowledge of their distribution `in and around galaxies' has significantly improved over the past few years. Theoretical work has shown that the fraction of metals in…

The extragalactic background light is comprised of the cumulative radiation from all galaxies across the history of the universe. The angular power spectrum of the anisotropies of such a background at near-infrared (IR) frequencies lacks of…

Despite an intense theoretical and experimental effort over the past decade, observations of the extragalactic radio background at multiple frequencies below 10 GHz are not understood in terms of known radio sources, and may represent a…