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We present a sample of 74 radio sources with recurrent jet activity. The sample consists of 67 galaxies, 2 quasars and 5 unidentified sources, selected from the published data or are newly recognized. The sample's redshift range is 0.002 <…

星系天体物理 · 物理学 2017-09-13 A. Kuźmicz , M. Jamrozy , D. Kozieł-Wierzbowska , M. Weżgowiec

We report results from a neutral hydrogen (HI) intensity mapping survey conducted with a Phased Array Feed (PAF) on the Parkes telescope. The survey was designed to cover ~ 380 deg^2 over the redshift range 0.3 < z < 1 (a volume of ~ 1.5…

宇宙学与河外天体物理 · 物理学 2021-03-31 Lincheng Li , Lister Staveley-Smith , Jonghwan Rhee

The recent detection of the "cosmic dawn" redshifted 21 cm signal at 78 MHz by the EDGES experiment differs significantly from theoretical predictions. In particular, the absorption trough is roughly a factor of two stronger than the most…

宇宙学与河外天体物理 · 物理学 2018-05-16 Jayce Dowell , Greg B. Taylor

The CHIME radio telescope operates in the frequency bandwidth of 400 to 800 MHz. The CHIME/FRB collaboration has a data pipeline that analyzes the data in real time, suppresses radio frequency interferences (RFI) and searches for FRBs.…

天体物理仪器与方法 · 物理学 2023-11-21 K. J. Luke

The observation of the global 21 cm signal produced by neutral hydrogen gas in the intergalactic medium (IGM) during the Dark Ages, Cosmic Dawn, and Epoch of Reionization requires measurements with extremely well-calibrated wideband…

The Ly-alpha absorption spectrum of the highest redshift quasars indicates that they are surrounded by giant HII regions, a few Mpc in size. The neutral gas around these HII regions should emit 21cm radiation in excess of the Cosmic…

天体物理学 · 物理学 2009-11-10 Stuart Wyithe , Abraham Loeb

Showing 1.4 GHz flux densities in the range of a few to a few tens of mJy, infrared-faint radio sources (IFRS) are a type of galaxy characterised by faint or absent near-infrared counterparts and consequently extreme radio-to-infrared flux…

星系天体物理 · 物理学 2015-07-22 Andreas Herzog , Ray P. Norris , Enno Middelberg , Lee R. Spitler , Christian Leipski , Quentin A. Parker

The rapid proliferation of low Earth orbit (LEO) satellite constellations has introduced a new class of radio frequency interference (RFI) that poses a fundamental challenge to modern radio astronomy. In particular, unintended…

天体物理仪器与方法 · 物理学 2026-04-20 Yujin Kim

The sensitivity of radio telescopes is becoming increasingly limited by the presence of radio frequency interference (RFI), which will worsen as the radio spectrum becomes more crowded. One context where this poses a challenge is the field…

We investigate characteristics of radio frequency interference (RFI) signals that can affect the excision potential of some interference mitigation algorithms. The techniques considered are those that modify signals from auxiliary reference…

天体物理仪器与方法 · 物理学 2010-04-01 D. A. Mitchell , J. G. Robertson

Radio frequency interference (RFI) poses a growing challenge to satellite communications, particularly in uplink channels of Low Earth Orbit (LEO) systems, due to increasing spectrum congestion and uncertainty in the location of terrestrial…

信号处理 · 电气工程与系统科学 2025-10-02 Fernando Moya Caceres , Akram Al-Hourani , Saman Atapattu , Kandeepan Sithamparanathan

We present spectroscopic observations for 64 radio galaxies having ultra steep radio spectra. Twenty-nine objects have redshifts $z>2$, the largest redshifts being almost 4. Our ultra steep spectrum (USS) criterion ($\alpha < -1$) has…

A method of radio frequency interference (RFI) suppression in radio astronomy spectral observations is described based on the analysis of the probability distribution of an instantaneous spectrum. This method allows the separation of the…

天体物理仪器与方法 · 物理学 2015-03-17 P. A. Fridman

Spectroscopic observations of a sample of 42 flat-spectrum radio sources from the Cosmic Lens All-Sky Survey (CLASS) have yielded a mean redshift of $<z> = 1.27$ with an RMS spread of 0.95, at a completeness level of 64%. The sample…

天体物理学 · 物理学 2009-10-31 D. R. Marlow , D. Rusin , N. Jackson , P. N. Wilkinson , I. W. A. Browne , L. Koopmans

Neutral hydrogen pervades the infant Universe, and its redshifted 21-cm signal allows one to chart the Universe. This signal allows one to probe astrophysical processes such as the formation of the first stars, galaxies, (super)massive…

From 1979--1996 the Green Bank Interferometer was used by the Naval Research Laboratory to monitor the flux density from 146 compact radio sources at frequencies near 2 and 8 GHz. We filter the ``light curves'' to separate intrinsic…

天体物理学 · 物理学 2009-11-11 B. Rickett , T. J. W. Lazio , F. D. Ghigo

The Low Frequency Instrument (LFI) is a radiometer array covering the 30-70 GHz spectral range on-board the ESA Planck satellite, launched on May 14th, 2009 to observe the cosmic microwave background (CMB) with unprecedented precision. In…

Active Radio Frequency Interference (RFI) mitigation becomes a necessity for radio astronomy. The solution commonly applied by the community consists in monitoring the statistics of the received signal, and flag out the detected corrupted…

信号处理 · 电气工程与系统科学 2018-09-12 Gregory Hellbourg

We present a novel neural network (NN) method for the detection and removal of Radio Frequency Interference (RFI) from the raw digitized signal in the signal processing chain of a typical radio astronomy experiment. The main advantage of…

天体物理仪器与方法 · 物理学 2022-11-30 Benjamin R. B. Saliwanchik , Anže Slosar

We present a multi-wavelength study into the nature of faint radio sources in a deep radio image with the Giant Meterwave Radio Telescope at 612\,MHz covering 1.2 deg$^2$ of the ELAIS N1 region. We detect 2800 sources above…

星系天体物理 · 物理学 2017-04-12 E. F. Ocran , A. R. Taylor , M. Vaccari , D. A. Green