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We consider evolution properties of galaxies and quasars with steep radio spectrum at the decametre band from the UTR-2 catalogue. The ratios of source's monochromatic luminosities at the decametre and high-frequency bands display the…

星系天体物理 · 物理学 2016-10-19 Alla Miroshnichenko

Line intensity mapping provides a statistical approach to tracing the large-scale distribution of matter in the Universe. We apply the HI intensity mapping technique to interferometric data from the MeerKAT International GHz-Tiered…

The Planck catalogue of SZ sources limits itself to a significance threshold of 4.5 to ensure a low contamination rate by false cluster candidates. This means that only the most massive clusters at redshift z>0.5, and in particular z>0.7,…

We discuss our ATCA 18.5 and 22 GHz flux density measurements of the Southern extragalactic sources in the complete 5-GHz sample of Kuehr et al. (1981). The high-frequency (5-18.5 GHz) spectral indices of steep-spectrum sources for which we…

天体物理学 · 物理学 2009-11-11 R. Ricci , I. Prandoni , G. Gruppioni , R. J. Sault , G. De Zotti

High red-shift radio galaxies are best searched at low radio frequencies, due to its steep radio spectra. Here we present preliminary results from our programme to search for high red-shift radio galaxies to ~ 10 to 100 times fainter than…

宇宙学与河外天体物理 · 物理学 2015-05-30 Susanta Kumar Bisoi , C. H. Ishwara-Chandra , S. K. Sirothia , P. Janardhan

We present a preliminary survey of 58 radio sources within the isoplanatic patches (r < 25") of bright (11<R<12) stars suitable for use as natural guide stars with high-order adaptive optics (AO). An optical and near-infrared imaging survey…

宇宙学与河外天体物理 · 物理学 2014-11-20 B. Stalder , K. C. Chambers , William D. Vacca

Studying the radio spectral energy distribution (SED) of distant galaxies is essential for understanding their assembly and evolution over cosmic time. We present rest-frame radio SEDs of a sample of 160 starburst galaxies at redshifts 1.5…

Radio sources with steep spectra are preferentially associated with the most distant galaxies, the $\alpha-z$ relation, but the reason for this relation is an open question. The spatial distribution of spectra in high-z radio sources can be…

We present the characterisation, including a photometric redshift (photo-$z$) analysis, of the optical counterparts (CTPs) to over 45 000 bright ($S_{856\rm MHz} \geq$ 30 mJy) compact radio sources, identified across all ASKAP First Large…

We present the initial sample of redshifts for 3,839 galaxies in the MeerKAT DEEP2 field -- the deepest $\sim$1.4\,GHz radio field yet observed. Using a spectrophotometric technique combining coarse optical spectra with broadband…

星系天体物理 · 物理学 2024-04-24 A. M Matthews , D. D. Kelson , A. B. Newman , F. Camilo , J. J. Condon , W. D. Cotton , M. Dickinson , T. H. Jarrett , M. Lacy

A correlation between astrophysical high-energy neutrinos and blazars has been suggested by various authors. In particular, a likely association between IceCube events and intermediate and high-energy peaked BL Lac objects has led to a…

高能天体物理现象 · 物理学 2023-03-01 Simona Paiano , Renato Falomo , Aldo Treves , Paolo Padovani , Paolo Giommi , Riccardo Scarpa , Susanna Bisogni , Ester Marini

We examine the possibility that a claimed dependence of the FR 1/2 break value in radio luminosity on the absolute magnitude of the optical host galaxy could be due to the Malmquist bias, where a redshift-luminosity correlation appears in a…

星系天体物理 · 物理学 2014-06-18 Ashok K. Singal , Kamlesh Rajpurohit

We study the 37 brightest radio sources in the Subaru/XMM-Newton Deep Field (SXDF). We have spectroscopic redshifts for 24 of 37 objects and photometric redshifts for the remainder, yielding a median redshift z_med for the whole sample of…

天体物理学 · 物理学 2009-11-13 Eleni Vardoulaki , Steve Rawlings , Chris Simpson , David G. Bonfield , R. J. Ivison , Eduardo Ibar

We conduct the first case study towards developing optimal foreground mitigation strategies for neutral hydrogen (HI) intensity mapping using radio interferometers at low redshifts. A pipeline for simulation, foreground mitigation and power…

宇宙学与河外天体物理 · 物理学 2022-12-08 Zhaoting Chen , Laura Wolz , Richard Battye

We report in this work on a project aimed at determining Ly{\alpha} luminosity functions from z=3 to z=6. The project is based on the use of very deep photometry from the SHARDS Survey, in a set of 24 medium band filters in the GOODS-N…

宇宙学与河外天体物理 · 物理学 2012-01-24 J. M. Rodriguez-Espinosa , O. Gonzalez-Martin , J. A. Lopez-Aguerri , C. Muñoz-Tuñon , P. G. Perez-Gonzalez , A. Cava

High-redshift radio-loud quasars are used to, among other things, test the predictions of cosmological models, set constraints on black hole growth in the early universe and understand galaxy evolution. Prior to this paper, 20 extragalactic…

We present basic observational data on the 6C** sample. This is a new sample of radio sources drawn from the 151 MHz 6C survey, which was filtered with radio criteria chosen to optimize the chances of finding radio galaxies at z > 4. The…

Spectra have been obtained with the low-resolution modules of the Infrared Spectrograph (IRS) on the Spitzer Space Telescope (Spitzer) for 58 sources having f$_{\nu}$(24 micron) > 0.75 mJy. Sources were chosen from a survey of 8.2 deg$^{2}$…

We study the radio spectral properties of 2,094 star-forming galaxies (SFGs) by combining our early science data from the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) survey with VLA, GMRT radio data, and rich…

We present a 74 MHz survey of a 165 square degree region located near the north galactic pole. This survey has an unprecedented combination of both resolution (25'' FWHM) and sensitivity (RMS noise as low as 24 mJy/beam). We detect 949…

天体物理学 · 物理学 2009-11-10 A. S. Cohen , H. J. A. Rottgering , M. J. Jarvis , N. E. Kassim , T. J. W. Lazio