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The ultraviolet and optical background forms a baseline for any observation of the sky. It includes emission lines and scattered light from the atmosphere; resonant scattering from the Lyman lines of interplanetary hydrogen and the…

Astrophysics of Galaxies · Physics 2019-09-26 Jayant Murthy , M. S. Akshaya , S. Ravichandran

The diffuse cosmic background radiation in the GALEX far ultraviolet (FUV, 1300 \AA\ - 1700 \AA) is deduced to originate only partially in the dust-scattered radiation of FUV-emitting stars: the source of a substantial fraction of the FUV…

Astrophysics of Galaxies · Physics 2015-06-19 Richard Conn Henry , Jayant Murthy , James Overduin , Joshua Tyler

We draw attention to observational evidence indicating that a substantial fraction of the well-known cosmic celestial diffuse ultraviolet background radiation field is actually due not to dust-scattered starlight, but rather---considering…

Astrophysics of Galaxies · Physics 2018-05-25 Richard Conn Henry , Jayant Murthy , James Overduin

We have studied small scale (2 arcmin) spatial variation of the diffuse UV radiation using a set of 11 GALEX deep observations in the constellation of Draco. We find a good correlation between the observed UV background and the IR 100…

Astrophysics of Galaxies · Physics 2015-05-20 N. V. Sujatha , Jayant Murthy , Rahul Suresh , Richard Conn Henry , Luciana Bianchi

We have used Voyager and Galex observations to map the diffuse Galactic light near the Galactic equator. We find that most of the observations are relatively faint with surface brightnesses of less than 5,000 photon units. This is important…

Astrophysics of Galaxies · Physics 2020-04-14 Jayant Murthy , R. C. Henry , James Overduin

"Diffuse" gamma rays consist of several components: truly diffuse emission from the interstellar medium, the extragalactic background, whose origin is not firmly established yet, and the contribution from unresolved and faint Galactic point…

Astrophysics · Physics 2015-06-24 I. V. Moskalenko , A. W. Strong , O. Reimer

We present a map of the diffuse ultraviolet cosmic background in two wavelength bands (FUV: 1530 {\AA}; NUV: 2310 {\AA}) over almost 75% of the sky using archival data from the GALEX mission. Most of the diffuse flux is due to…

Astrophysics of Galaxies · Physics 2010-11-30 Jayant Murthy , Richard C. Henry , N. V. Sujatha

A bright UV GALEX image in the direction of a dense high galactic latitude interstellar dust cloud is examined to test (and to reject) the idea that a bright extragalactic UV background radiation field exists. A GALEX "Deep Imaging Survey"…

Astrophysics of Galaxies · Physics 2009-06-17 Richard Conn Henry

We re-examine {\em Voyager} Ultraviolet Spectrograph data used to establish upper limits to the $\lambda$ 500-900 \AA and $\lambda$ 900-1100 \AA cosmic diffuse background. The measurement of diffuse flux with the {\em Voyager} UVS data…

Astrophysics · Physics 2009-10-31 Jerry Edelstein , Stuart Bowyer , Michael Lampton

The diffuse far-ultraviolet (FUV) background has received considerable attention from astronomers since the 1970's. The initial impetus came from the hope of detecting UV radiation from the hot intergalactic medium. The central importance…

Astrophysics of Galaxies · Physics 2022-08-31 S. R. Kulkarni

It has recently become apparent that the background level of diffuse radio emission on the sky is significantly higher than the level that can result from known extragalactic radio source classes or our Galaxy given our current…

Cosmology and Nongalactic Astrophysics · Physics 2019-12-02 J. Singal

A new determination of the upper limit to the cosmic diffuse background radiation, at ~110 nm, of 300 photons s-1 cm-2 sr-1 nm-1, is placed in the context of diffuse background measurements across the entire electromagnetic spectrum,…

Astrophysics · Physics 2009-10-31 Richard C. Henry

We present an analysis of the diffuse ultraviolet (UV) background in a low latitude region near the Aquila Rift based on observations made by the Galaxy Evolution Explorer (GALEX). The UV background is at a level of about 2000 ph cm^-2 s^-1…

Astrophysics of Galaxies · Physics 2015-10-14 S. N. Jyothy , Jayant Murthy , Narayanankutty Karuppath , N. V. Sujatha

Recently, a spatially extended excess of gamma rays collected by the Fermi-LAT from the inner region of the Milky Way has been detected by different groups and with increasingly sophisticated techniques. Yet, any final conclusion about the…

High Energy Astrophysical Phenomena · Physics 2015-02-11 Francesca Calore , Ilias Cholis , Christoph Weniger

We review the current understanding of the diffuse gamma-ray background (DGRB). The DGRB is what remains of the total measured gamma-ray emission after the subtraction of the resolved sources and of the diffuse Galactic foregrounds. It is…

Cosmology and Nongalactic Astrophysics · Physics 2015-09-28 Mattia Fornasa , Miguel A. Sanchez-Conde

Ultraviolet observations from low Earth orbit (LEO) have to deal with a foreground comprised of airglow and zodiacal light which depend on the look direction and on the date and time of the observation. We have used all-sky observations…

Instrumentation and Methods for Astrophysics · Physics 2014-03-11 Jayant Murthy

If the background universe is observed through a significant amount of diffusely distributed foreground dust, then studies at optical wavelengths may be severely biased. Previous studies investigating effects of foreground dust on…

Astrophysics · Physics 2015-06-24 Frank J. Masci

We have used data from the Galaxy Evolution Explorer to study the different components of the diffuse ultraviolet background in the region between the Galactic latitudes 70-80 degree. We find an offset at zero dust column density (E(B - V)…

Astrophysics of Galaxies · Physics 2019-08-12 M. S. Akshaya , Jayant Murthy , S. Ravichandran , R. C. Henry , James Overduin

We have used GALEX observations of the North and South Galactic poles to study the diffuse ultraviolet background at locations where the Galactic light is expected to be at a minimum. We find offsets of 230 -- 290 photon units in the FUV…

Astrophysics of Galaxies · Physics 2018-05-23 M. S. Akshaya , Jayant Murthy , S. Ravichandran , R. C. Henry , James Overduin

Here is reviewed our current understanding of Galactic and extragalactic diffuse gamma-ray emission. The spectrum of the extragalactic gamma-ray background above 30 MeV can be well described by a power law with photon index s=2.1. In the…

Astrophysics · Physics 2007-05-23 Martin Pohl
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