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A measurable fraction ($\sim8$ per cent) of recently discovered arcmin-size circular diffuse radio sources termed as Odd Radio Circles or ORCs can be supernovae remnants in the intragroup medium, within the local group and its immediate…

Astrophysics of Galaxies · Physics 2022-04-12 A. Omar

Loop I is a nearby giant radio loop spanning over 100 degrees and centered on the Sco-Cen OB association. It may correspond to a superbubble formed by the joint action of stellar winds and supernova remnants. ROSAT observations revealed…

High Energy Astrophysical Phenomena · Physics 2019-08-13 Jean-Marc Casandjian , Isabelle Grenier

Odd Radio Circles (ORCs) are a class of low surface brightness, circular objects approximately one arcminute in diameter. ORCs were recently discovered in the Australian Square Kilometre Array Pathfinder (ASKAP) data, and subsequently…

The Odd Radio Circles are newly identified diffuse radio sources at ~1 GHz frequency, with edge-brightened nearly circular morphology, which is remarkably similar to supernova remnants although a physical association with previous…

High Energy Astrophysical Phenomena · Physics 2022-05-20 Amitesh Omar

We report the discovery of J0624-6948, a low-surface brightness radio ring, lying between the Galactic Plane and the Large Magellanic Cloud (LMC). It was first detected at 888 MHz with the Australian Square Kilometre Array Pathfinder…

Sub-arcsecond radio continuum observations of the Galactic center region at $\lambda$6 and 2cm reveal a 0.5$^{\prime\prime}$ diameter source with a shell-like morphology. This source is linearly polarized at a level of 16% at $\lambda$6cm…

Astrophysics · Physics 2009-10-30 F. Yusef-Zadeh , W. D. Cotton , S. P. Reynolds

A new class of radio source, the so-called Odd Radio Circles (ORCs), have been discovered by recent sensitive, large-area radio continuum surveys. The distances of these sources have so far relied on photometric redshifts of optical…

Astrophysics of Galaxies · Physics 2024-04-11 David Rupke , Alison Coil , Kelly Whalen , John Moustakas , Christy Tremonti , Serena Perrotta

Odd Radio Circles (ORCs) are unexpected faint circles of diffuse radio emission discovered in recent wide deep radio surveys. They are typically about one arcmin in diameter, and may be spherical shells of synchrotron emission about a…

Astrophysics of Galaxies · Physics 2021-11-03 Ray P. Norris , Evan Crawford , Peter Macgregor

A dozen of patches of polarized radio emission spanning tens of degrees in the form of coherent and stationary loops are observed at radio frequencies across the sky. Their origin is usually associated to nearby shocks, possibly arising…

In soft X-rays, the Monogem ring is an object with a diameter of 25{\deg} located in the Galactic anti-centre. It is believed to be a faint, evolved, local supernova remnant. The ring is also visible in the far-ultraviolet, and a few…

Astrophysics of Galaxies · Physics 2020-09-23 Wolfgang Reich , Patricia Reich , Xiaohui Sun

Loop I/North Polar Spur (NPS) is the giant arc structure above the Galactic plane observed at radio wavelengths ($\lesssim 10$ GHz). There has been long-standing debate about its origin. While many people believe that it black consists of…

Astrophysics of Galaxies · Physics 2025-04-08 Yanping Cong , Bin Yue , Yidong Xu , Furen Deng , Jiajun Zhang , Xuelei Chen

In this article we use 1420 MHz data to demonstrate the likely reality of Galactic radio Loops V and VI. We further estimate distances and spectral indices for both these and the four main radio loops. In the cases of Loops I - IV, radio…

Astrophysics · Physics 2009-11-13 V. Borka , J. Milogradov-Turin , D. Urošević

We have observed two fields - Field-I (l=3.2 degrees, b=-1.0 degree) and Field-II (l=356.8 degrees, b=-0.1 degree) with the Giant Metrewave Radio Telescope (GMRT) at 330 MHz. In the first field, we have studied the candidate supernova…

Astrophysics · Physics 2009-11-07 Subhashis Roy , A. Pramesh Rao

Radio continuum and radio recombination line observations of the inner degree of the galactic center reveal a rich collection of thermal and nonthermal radio structures: (a) A network of linear filaments that are oriented perpendicular to…

Astrophysics of Galaxies · Physics 2024-07-01 F. Yusef-Zadeh

Odd radio circles (ORCs) are mysterious rings of faint, diffuse emission recently discovered in radio surveys, some of which may be associated with galaxies in relatively dense environments. We propose such ORCs to be synchrotron emission…

High Energy Astrophysical Phenomena · Physics 2024-05-03 Yutaka Fujita , Norita Kawanaka , Susumu Inoue

The origin of arcmin-sized Odd Radio Circles (ORCs) found in modern all-sky radio surveys remain uncertain, with explanations ranging from starburst/AGN-driven shocks to supernova remnants (SNRs) in the low-density ambient medium. Using…

Astrophysics of Galaxies · Physics 2022-09-23 Sumit K. Sarbadhicary , Todd A. Thompson , Laura A. Lopez , Smita Mathur

The Galactic supernova remnant (SNR) Cygnus Loop emerges as an ideal laboratory for analyzing the different radiation mechanisms, as well as the particle acceleration mechanisms at different types of shocks. In order to determine radio…

High Energy Astrophysical Phenomena · Physics 2026-05-21 D. Urošević , M. Andjelić , M. D. Filipović , Z. J. Smeaton , E. Crawford , J. Raymond , D. Onić

We present three rare and striking extragalactic radio sources discovered through visual inspection of low-frequency continuum maps from LoTSS DR2 and TGSS by the RAD@home citizen-science collaboratory. The first, RAD J131346.9+500320, is…

Astrophysics of Galaxies · Physics 2025-10-03 Ananda Hota , Pratik Dabhade , Prasun Machado , Joydeep Das , Aarti Muley , Arundhati Purohit

Large-scale radio continuum surveys have good potential for discovering new Galactic supernova remnants (SNRs). Surveys of the Galactic plane are often limited in the Galactic latitude of |b| ~ 5 degree. SNRs at high latitudes, such as the…

Astrophysics of Galaxies · Physics 2014-09-05 X. Y. Gao , J. L. Han

In this paper the average brightness temperatures and surface brightnesses at 1420, 820 and 408 MHz of the six main Galactic radio-continuum loops are derived, as are their radio spectral indices. The temperatures and surface brightnesses…

Astrophysics · Physics 2008-11-26 V. Borka
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