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The ARCADE 2 balloon bolometer along with a number of other instruments have detected what appears to be a radio synchrotron background at frequencies below about 3 GHz. Neither extragalactic radio sources nor diffuse Galactic emission can…

高能天体物理现象 · 物理学 2021-01-27 Martin G. H. Krause , Martin J. Hardcastle

In the next few years the classification of radio sources observed by the large surveys will be a challenging problem, and spectral index is a powerful tool for addressing it. Here we present an algorithm to estimate the spectral index of…

This work presents a detailed analysis of Cosmic Microwave Background (CMB) radiation intensity observations. The CMB is a relic of the Big Bang and its study greatly enhances our knowledge of cosmology. This work has led to new values for…

天体物理学 · 物理学 2007-05-23 Henrik P. Nordberg , George F. Smoot

Published data from long-term observations of a strip of sky at declination +5 degrees carried out at 7.6 cm on the RATAN-600 radio telescope are used to estimate some statistical properties of radio sources. Limits on the sensitivity of…

宇宙学与河外天体物理 · 物理学 2012-05-24 Yu. N. Parijskij , N. S. Soboleva , A. V. Temirova , N. N. Bursov , O. P. Zhelenkova

The X-ray background intensity around Lick count galaxies and rich clusters of galaxies is investigated in three ROSAT energy bands. It is found that the X-ray enhancements surrounding concentrations of galaxies exhibit significantly softer…

天体物理学 · 物理学 2009-11-07 A. M. Soltan , M. J. Freyberg , G. Hasinger

The radio continuum spectra of 14 star-forming galaxies are investigated by fitting nonthermal (synchrotron) and thermal (free-free) radiation laws. The underlying radio continuum measurements cover a frequency range of ~325 MHz to 24.5 GHz…

星系天体物理 · 物理学 2018-03-28 Uli Klein , Ute Lisenfeld , Simon Verley

The extragalactic background is composed of the emission from all astrophysical sources, both resolved and unresolved, in addition to any diffuse components. In the last decade, there has been significant progress in our understanding of…

宇宙学与河外天体物理 · 物理学 2025-09-23 Jonathan Biteau

Early on, extragalactic radio sources have pointed to a cosmologically evolving Universe. They were also an important piece of evidence for the existence of supermassive black holes, now thought to be a key component of galaxies. The…

高能天体物理现象 · 物理学 2018-04-06 Martin Krause

In the framework of the study of extragalactic radio sources, we will focus on the importance of the spatial resolution at different wavelengths, and of the combination of observations at different frequency bands. In particular, a…

天体物理学 · 物理学 2009-09-29 Gianfranco Brunetti

A new generation of upcoming space-based experiments will soon start to probe the spectrum of cosmic ray antiparticles with an unprecedented accuracy and, in particular, will open up a window to energies much higher than those accessible so…

天体物理学 · 物理学 2008-11-26 Torsten Bringmann , Pierre Salati

The shape of the curves defined by the counts of radio sources per unit area as a function of their flux density was one of the earliest cosmological probes. Radio source counts continue to be an area of interest, used to study the relative…

宇宙学与河外天体物理 · 物理学 2015-06-15 Ian Heywood , Matt J. Jarvis , James J. Condon

With the advent of new generation low-frequency telescopes, such as the LOw Frequency ARray (LOFAR), and improved calibration techniques, we have now started to unveil the sub GHz radio sky with unprecedented depth and sensitivity. The…

We present predictions for the counts of extragalactic sources, the contributions to fluctuations and their spatial power spectrum in each channel foreseen for the Planck Surveyor (formerly COBRAS/SAMBA) mission. The contribution to…

天体物理学 · 物理学 2009-10-30 L. Toffolatti , F. Argüeso Gómez , G. De Zotti , P. Mazzei , A. Franceschini , L. Danese , C. Burigana

We have searched the temperature maps from the COBE Differential Microwave Radiometers (DMR) first two years of data for evidence of unresolved sources. The high-latitude sky (|b| > 30\deg) contains no sources brighter than 192 uK…

天体物理学 · 物理学 2009-10-22 A. Kogut , A. J. Banday , C. L. Bennett , G. Hinshaw , K. Loewenstein , P. Lubin , G. F. Smoot , E. L. Wright

We have used VSOP space very long baseline interferometry observations to measure the brightness temperature distribution of a well-defined sub-set of the Pearson-Readhead sample of extragalactic radio sources. VLBI which is restricted to…

天体物理学 · 物理学 2009-11-06 S. J. Tingay

We present a study of diffuse extragalactic radio emission at $1.75\,$GHz from part of the ELAIS-S1 field using the Australia Telescope Compact Array. The resulting mosaic is $2.46\,$deg$^2$, with a roughly constant noise region of…

星系天体物理 · 物理学 2015-06-22 T. Vernstrom , Ray P. Norris , Douglas Scott , J. V. Wall

The density of the far infrared / submillimeter (FIR/SMM) diffuse extragalactic radiation field has recently been determined from COBE data. Nearly simultaneously, deep FIR/SMM surveys have detected substantial numbers of optically…

天体物理学 · 物理学 2009-10-31 Martin Harwit

X-ray observations of cavities and shock fronts produced by jets streaming through hot halos have significantly advanced our understanding of the energetics and dynamics of extragalactic radio sources. Radio sources at the centers of…

天体物理学 · 物理学 2007-08-29 B. R. McNamara , L. Birzan , D. A. Rafferty , P. E. J. Nulsen , C. Carilli , M. W. Wise

As a part of the ISOPHOT CIRB (Cosmic Infrared Background Radiation) project we have searched for point-like sources in eight fields mapped at two or three wavelengths between 90 and 180um. Most sources are previously unknown and based on…

天体物理学 · 物理学 2007-05-23 M. Juvela , K. Mattila , D. Lemke

Spectral variability of radio sources encodes information about the conditions of intervening media, source structure, and emission processes. With new low-frequency radio interferometers observing over wide fractional bandwidths, studies…