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The diffuse high-latitude H-alpha background is widely believed to be predominantly the result of in-situ recombination of ionized hydrogen in the warm interstellar medium of the Galaxy. Instead, we show that both a substantial fraction of…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 A. N. Witt , B. Gold , F. S. Barnes , C. T. DeRoo , U. P. Vijh , G. J. Madsen

We present a multi-wavelength correlation study of diffuse ultraviolet radiation using GALEX observations towards the Aquila Rift. Apart from airglow and zodiacal emissions, we find a diffuse background of 1300 - 3700 \photu\ in the…

Astrophysics of Galaxies · Physics 2018-09-24 S. N. Jyothy , N. V. Sujatha , Narayanankutty Karuppath

The H-alpha luminosity density of galaxies is used to calculate the local diffuse radiation field at the Lyman limit as resulting from star formation in the universe. The fraction of Lyman continuum radiation leaking out from galaxies…

Astrophysics · Physics 2007-05-23 J. -M. Deharveng , S. Faisse , B. Milliard , V. Le Brun

Galaxies are surrounded by large reservoirs of gas, mostly hydrogen, fed by inflows from the intergalactic medium and by outflows due to galactic winds. Absorption-line measurements along the sightlines to bright and rare background quasars…

We present the first observations of diffuse radiation in the far ultraviolet (1000 -- 1150 \AA) from the Large Magellanic Cloud based on observations made with the {\it Far Ultraviolet Spectroscopic Explorer}. The fraction of the total…

Astrophysics of Galaxies · Physics 2015-05-19 Ananta C. Pradhan , Amit Pathak , Jayant Murthy

We present the discovery of an extended ring of ultraviolet emission surrounding the AGB star U Hya in archival observations performed by the Galaxy Evolution Explorer (GALEX). This is the third discovery of extended UV emission from a…

Solar and Stellar Astrophysics · Physics 2017-02-15 E. Sanchez , R. Montez , S. Ramstedt , K. G. Stassun

We compare the diffuse H$\alpha$ map of our Galaxy with the FUV (1370-1710\AA) continuum map. The H$\alpha$ intensity correlates well with the FUV intensity. The H$\alpha$/FUV intensity ratio increases in general with the H$\alpha$…

Astrophysics of Galaxies · Physics 2015-06-03 Kwang-Il Seon , Adolf Witt , Il-Joong Kim , Jong-Ho Shinn , Jerry Edelstein , Kyoung-Wook Min , Wonyong Han

The Galaxy Evolution Explorer (GALEX) has performed the first surveys of the sky in the Ultraviolet (UV). Its legacy is an unprecedented database with more than 200 million source measurements in far-UV (FUV) and near-UV (NUV), as well as…

Astrophysics of Galaxies · Physics 2018-02-14 Luciana Bianchi , Alberto Conti , Bernie Shiao

We report the detection of extended Ly alpha emission around individual star-forming galaxies at redshifts z = 3-6 in an ultradeep exposure of the Hubble Deep Field South obtained with MUSE on the ESO-VLT. The data reach a limiting surface…

We present a semi-empirical model for the evolving far-infrared to ultraviolet diffuse background produced by stars in galaxies. The model is designed to reproduce the results of deep galaxy surveys, and therefore may be considered as a…

Astrophysics · Physics 2009-10-31 T. M. Kneiske , K. Mannheim , D. Hartmann

I review the development of UV and EUV astronomy, covering the spectral range from 5 to 300 nm, with emphasis on sky surveys for discrete sources. I discuss studies which resulted in lists of sources observed by imaging and deliberately…

Astrophysics · Physics 2007-05-23 Noah Brosch

The estimate of the ionizing UV background through the proximity effect analysis is discussed. Taking into account the correct bending of the column density distribution which appears in high resolution high s/n data, a value of the UV…

Astrophysics · Physics 2007-05-23 E. Giallongo , S. Cristiani , S. D'Odorico , A. Fontana , S. Savaglio

We have discovered ultraviolet halos extending as far as 5{\deg} around four (of six) bright UV stars using data from the GALEX satellite. These halos are due to the scattering of the starlight from nearby thin, foreground dust clouds. We…

Astrophysics of Galaxies · Physics 2011-09-13 Jayant Murthy , Richard Conn Henry

A large fraction of the baryonic matter in the Universe is located in filaments in the intergalactic medium. However, the low surface brightness of these filaments has not yet allowed their direct detection except in very special regions in…

Astrophysics of Galaxies · Physics 2016-08-31 Marta B. Silva , Robin Kooistra , Saleem Zaroubi

We have tried to determine the flux of the ultraviolet background radiation field from the column density ratios of various ions in several absorption systems observed in the spectra of QSOs. We find that in most cases the flux is…

Astrophysics · Physics 2009-10-31 Archana Samantaray , Pushpa Khare

If damped Lyman alpha systems (DLAs) contain even modest amounts of dust, the ultraviolet luminosity of the background quasar can be severely diminished. When the spectrum is redshifted, this leads to a bias in optical surveys for DLAs.…

Astrophysics · Physics 2009-11-13 Andrew Pontzen , Max Pettini

The cosmic infrared background from galaxies should have a minimum fluctuation of the order of 10\% on angular scales probed by the DIRBE (Diffuse Infrared Background Experiment) on board COBE (Cosmic Background Explorer). We present the…

Astrophysics · Physics 2007-05-23 A. Kashlinsky , J. C. Mather , S. Odenwald , M. Hauser

The Galactic diffuse emission is potentially able to reveal much about the sources and propagation of cosmic rays (CR), their spectra and intensities in distant locations. It can possibly unveil WIMP dark matter (DM) through its…

Astrophysics · Physics 2016-08-30 I. V. Moskalenko , A. W. Strong

Lyman-alpha (Lya) photons that escape the interstellar medium of star-forming galaxies may be resonantly scattered by neutral hydrogen atoms in the circumgalactic and intergalactic media, thereby increasing the angular extent of the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Zheng Zheng , Renyue Cen , David Weinberg , Hy Trac , Jordi Miralda-Escude

We present an overview of unbiased studies of diffuse extragalactic radio sources. We use a previously developed filtering technique to remove compact sources from large surveys such as WENSS, WISH, and NVSS and examine the residual diffuse…

Astrophysics · Physics 2009-11-11 Lawrence Rudnick , Kisha M. Delain , Jeffrey A. Lemmerman