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Radio wavelengths offer the unique possibility of tracing the total star-formation rate in galaxies, both obscured and unobscured. As such, they may provide the most robust measurement of the star-formation history of the Universe. In this…

We have compiled a sample of 234 ultra-steep-spectrum(USS)-selected radio sources in order to find high-redshift radio galaxies (HzRGs). The sample is in the southern sky at -40 deg < DEC < -30 deg which is the overlap region of the 408-MHz…

Cosmology and Nongalactic Astrophysics · Physics 2009-11-13 J. J. Bryant , H. M. Johnston , J. W. Broderick , R. W. Hunstead , C. De Breuck , B. M. Gaensler

We constructed and presented in the first paper of this series a new sample of 84 large angular size radio galaxies by selecting from the NRAO VLA Sky Survey objects with angular size > 4', declination above +60 degrees and total flux…

Astrophysics · Physics 2009-11-07 L. Lara , I. Marquez , W. D. Cotton , L. Feretti , G. Giovannini , J. M. Marcaide , T. Venturi

This thesis reports on the application of new wide-field Very Long Baseline Interferometry (VLBI) imaging techniques using real data for the first time. These techniques are used to target three specific science areas: (i) a…

Astrophysics of Galaxies · Physics 2014-06-19 Emil Lenc

There exists a significant population of broad line, z~2 QSOs which have heavily absorbed X-ray spectra. Follow up observations in the submillimetre show that these QSOs are embedded in ultraluminous starburst galaxies, unlike most…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 M. J. Page , F. J. Carrera , J. A. Stevens , J. Ebrero , A. J. Blustin

Surveys at mm wavelengths emphasize rare classes of extragalactic radio sources characterized by spectra keeping flat or inverted up to high frequencies (such as blazars, GPS sources, advection dominated sources, or even gamma-ray burst…

Observationally, weak lensing has been served so far by optical surveys due to the much larger number densities of background galaxies achieved, which is typically by two to three orders of magnitude compared to radio. However, the high…

Instrumentation and Methods for Astrophysics · Physics 2016-03-18 Marzia Rivi , Lance Miller , Sphesihle Makhathini , Filipe Batoni Abdalla

A sample of 129 unresolved radio sources with ultrahigh linear polarization (>30 per cent) has been selected from the NRAO VLA Sky Survey. Such high average linear polarization is unusual in extragalactic sources. Higher resolution…

Astrophysics of Galaxies · Physics 2010-09-21 H. Shi , H. Liang , J. L. Han , R. W. Hunstead

Strong intergalactic shocks are a natural consequence of structure formation in the universe. They are expected to deposit large fractions of their energy in relativistic electrons (xi_e~0.05 according to SNR observations) and magnetic…

Astrophysics · Physics 2009-11-10 Uri Keshet , Eli Waxman , Abraham Loeb

Determining the energy spectrum of an electron population can give key insights into the underlying physics of a radio source; however, the lack of high resolution, broad-bandwidth observations has left many ambiguities in our understanding…

Astrophysics of Galaxies · Physics 2014-05-01 J. J. Harwood , M. J. Hardcastle , J. H. Croston , A. Stroe , R. Morganti , E. Orru

We present the Bayesian Global Sky Model (B-GSM), a new absolutely calibrated model of the diffuse Galactic foreground at frequencies below 408 MHz. We assemble a dataset of publicly available diffuse emission maps at frequencies between 45…

Instrumentation and Methods for Astrophysics · Physics 2025-04-08 George Carter , Will Handley , Mark Ashdown , Nima Razavi-Ghods

An alternative to both the tomography technique and the power spectrum approach is to search for the 21cm forest, that is the 21cm absorption features against high-z radio loud sources caused by the intervening cold neutral intergalactic…

Cosmology and Nongalactic Astrophysics · Physics 2015-01-20 Benedetta Ciardi , Susumu Inoue , Katherine J. Mack , Yidong Xu , Gianni Bernardi

A new modeling way of describing the continuous absorption of electromagnetic (EM) radiation in dense partially ionized hydrogen plasma is tested in this work. It is shown that the obtained results give a possibility of calculating spectral…

Solar and Stellar Astrophysics · Physics 2012-08-14 A. A. Mihajlov , N M Sakan , V. A. Sreckovic , Y. Vitel

We consider Thomson-like processes between dark matter dark photons and free electrons in the Milky Way. The result is a radio signal background that can be detectable with current or future radio telescope arrays. In particular, we…

High Energy Physics - Phenomenology · Physics 2025-04-08 Ariel Arza

We have completed a robotic wide-angle imaging survey of the southern sky (declination less than +15 degrees) at 656.3 nm wavelength, the H-alpha emission line of hydrogen. Each image of the resulting Southern H-Alpha Sky Survey Atlas…

Astrophysics · Physics 2008-11-26 J. E. Gaustad , P. R. McCullough , W. Rosing , D. Van Buren

In this paper, based on a 2.29 GHz VLBI all-sky survey of 613 milliarcsecond ultra-compact radio sources with $0.0035<z<3.787$, we describe a method of identifying the sub-sample which can serve as individual standard rulers in cosmology.…

Cosmology and Nongalactic Astrophysics · Physics 2018-01-08 Shuo Cao , Marek Biesiada , John Jackson , Xiaogang Zheng , Yuhang Zhao , Zong-Hong Zhu

We present a study, done with the Australian LBA, of HI absorption for two compact radio galaxies (PKS 1549-79 and PKS 1814-63). In both the radio galaxies, the HI appears to give us information about the environment in which the radio…

Astrophysics · Physics 2007-05-23 R. Morganti , T. A. Oosterloo , C. N. Tadhunter , K. A. Wills , A. Tzioumis , J. Reynolds

The Large-Aperture Experiment to Detect the Dark Age (LEDA) was designed to detect the predicted O(100)mK sky-averaged absorption of the Cosmic Microwave Background by Hydrogen in the neutral pre- and intergalactic medium just after the…

We generalize lower limits on the dark matter (DM) particle mass $m$ derived from Milky Way (MW) satellite galaxy abundances to scenarios in which DM is an ultralight scalar field produced with a field power spectrum peaked at a subhorizon…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-18 Ethan O. Nadler , Mustafa A. Amin , Risa H. Wechsler , M. Sten Delos , Andrew Benson , Vera Gluscevic

We review the statistical properties of the main populations of radio sources, as emerging from radio and millimeter sky surveys. Recent determinations of local luminosity functions are presented and compared with earlier estimates still in…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Gianfranco De Zotti , Marcella Massardi , Mattia Negrello , Jasper Wall