Discovery of a radio transient in M81

Abstract

We report the discovery of a radio transient in the spiral galaxy M81. The transient was detected in early 2015 as part of a two-year survey of M81 made up of 12 epochs using the Karl G. Jansky Very Large Array. While undetected on 2014 September 12, the source was first detected on 2015 January 2, from which point it remained visible at an approximately constant luminosity of $L_R=1.5\pm 0.1\times 10^{24}$erg s${}^{-1}$ Hz${}^{-1}$ at the observing frequency of 6 GHz for at least 2 months. Assuming this is a synchrotron event with a rise-time between 2.6 and 112 days, the peak luminosity (at equipartition) corresponds to a minimum energy of $10^{44}\lesssim E_{min}\lesssim 10^{46}$erg and jet power of $P_{min}\sim 10^{39}$erg s${}^{-1}$, which are higher than most known X-ray binaries. Given its longevity, lack of short-term radio variability, and the absence of any multi-wavelength counterpart (X-ray luminosity $L_X\lesssim 10^{36}$erg s${}^{-1}$), it does not behave like known Galactic or extragalactic X-ray binaries. The M81 transient radio properties more closely resemble the unidentified radio transient 43.78+59.3 discovered in M82, which has been suggested to be a radio nebula associated with an accreting source similar to SS 433. One possibility is that both the new M81 transient and the M82 transient may be the birth of a short-lived radio bubble associated with a discrete accretion event similar to those observed from the ULX Holmberg II X-1. However, it is not possible to rule out other identifications including long-term supernova shockwave interactions with the surrounding medium from a faint supernova or a background active galaxy.

arXiv comment18 pages, 5 figures, 6 tables, accepted for publication in MNRAS

References in corpus (129)

• Astropy: A Community Python Package for Astronomy
• The NumPy array: a structure for efficient numerical computation
• The Sloan Digital Sky Survey: Technical Summary
• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• Multi-messenger Observations of a Binary Neutron Star Merger
• The SIMBAD astronomical database
• The Optical and Near-Infrared Properties of Galaxies: I. Luminosity and Stellar Mass Functions
• SDSS-III: Massive Spectroscopic Surveys of the Distant Universe, the Milky Way Galaxy, and Extra-Solar Planetary Systems
• The VizieR database of Astronomical Catalogues
• The Ninth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-III Baryon Oscillation Spectroscopic Survey
• Towards a unified model for black hole X-ray binary jets
• Astrophysics Source Code Library
• A new generation of PARSEC-COLIBRI stellar isochrones including the TP-AGB phase
• High Mass X-ray Binaries as a Star Formation Rate Indicator in Distant Galaxies
• Superluminal motion of a relativistic jet in the neutron star merger GW170817
• The ACS Nearby Galaxy Survey Treasury
• Ultraluminous X-Ray Sources
• A Radio Counterpart to a Neutron Star Merger
• Updated Nearby Galaxy Catalog
• An Intermediate-mass Black Hole of Over 500 Solar Masses in the Galaxy ESO 243-49
• The Expanded Very Large Array -- a New Telescope for New Science
• MERLIN observations of relativistic ejections from GRS 1915+105
• GRS 1915+105 and the Disc-Jet Coupling in Accreting Black Hole Systems
• A mildly relativistic wide-angle outflow in the neutron star merger GW170817
• Global Structure of Three Distinct Accretion Flows and Outflows around Black Holes through Two-Dimensional Radiation-Magnetohydrodynamic Simulations
• The Milky Way in X-rays for an outside observer: Log(N)-Log(S) and Luminosity Function of X-ray binaries from RXTE/ASM data
• Ultraluminous X-ray Sources in the Chandra and XMM-Newton Era
• Three-Dimensional General Relativistic Radiation Magnetohydrodynamical Simulation of Super-Eddington Accretion, using a new code HARMRAD with M1 Closure
• A Global Spectral Study of Black Hole X-ray Binaries
• A Radio-Selected Sample of Gamma Ray Burst Afterglows
• A Catalog of Candidate Intermediate-luminosity X-ray Objects
• An expanding radio nebula produced by a giant flare from the magnetar SGR 1806-20
• A Complete Sample of ULX Host Galaxies
• The variable radio emission from GRS 1915+105
• High Resolution Imaging of the HeII lambda 4686 Emission Line Nebula Associated with the Ultraluminous X-Ray Source in Holmberg II
• Radio Emission from an Ultraluminous X-Ray Source
• The High Resolution X-ray Spectrum of SS 433 using the Chandra HETGS
• Fast radiation mediated shocks and supernova shock breakouts
• A turnover in the radio light curve of GW170817
• New Class of High-Energy Transients from Crashes of Supernova Ejecta with Massive Circumstellar Material Shells
• Radio Detections During Two State Transitions of the Intermediate Mass Black Hole HLX-1
• Orphan GRB radio afterglows: Candidates and constraints on beaming
• The 2003 Outburst of the X-ray Transient H 1743-322: Comparisons with the Black Hole Microquasar XTE J1550-564
• A Relativistic Particle Outburst From The Soft Gamma-Ray Repeater SGR1900+14
• Time-sequenced Multi-Radio-Frequency Observations of Cygnus X-3 in Flare
• Extensive HST Ultraviolet Spectra and Multi-wavelength Observations of SN 2014J in M82 Indicate Reddening and Circumstellar Scattering by Typical Dust
• X-ray, Optical, and Radio Observations of the Type II Supernovae 1999em and 1998S
• Bright radio emission from an ultraluminous stellar-mass microquasar in M31
• The Caltech-NRAO Stripe 82 Survey (CNSS) Paper I: The Pilot Radio Transient Survey In 50 deg${}^2$
• Radio Variability of Radio Quiet and Radio Loud Quasars
• A Complete Survey of the Transient Radio Sky and Implications for Gamma-Ray Bursts, Supernovae, and other Relativistic Explosions
• The very flat radio - millimetre spectrum of Cygnus X-1
• Rapid infrared flares in GRS 1915+105 : evidence for infrared synchrotron emission
• A Deep Search for Prompt Radio Emission from Thermonuclear Supernovae with the Very Large Array
• Modulations in the radio light curve of the Type IIb Supernova 2001ig: Evidence for a Wolf-Rayet binary progenitor?
• SubmilliJansky Transients in Archival Radio Observations
• Radio Lobe Dynamics and the Environment of Microquasars
• Radio imaging observations of PSR J1023+0038 in an LMXB state
• A giant radio flare from Cygnus X-3 with associated Gamma-ray emission
• What is L*?: Anatomy of the Galaxy Luminosity Function
• A Parsec-Scale Study of the 5/15 GHz Spectral Indices of the Compact Radio Sources in M82
• Probing Cosmic-Ray Ion Acceleration with Radio-Submm and Gamma-Ray Emission from Interaction-Powered Supernovae
• Extreme Jet Ejections from the Black Hole X-ray Binary V404 Cygni
• Spectra of Black Hole Accretion Models of Ultra-Luminous X-ray Sources
• The Hardness-Intensity Diagram of Cygnus X-3: Revisiting the Radio/X-Ray States
• Black Hole Powered Nebulae and a Case Study of the Ultraluminous X-ray Source IC342 X-1
• Spatially Resolved Ultraviolet, H-alpha, Infrared, and Radio Star Formation in M81
• A Revised View of the Transient Radio Sky
• A VLA search for 5 GHz radio transients and variables at low Galactic latitudes
• A 22-year Southern Sky Survey for Transient and Variable Radio Sources using the Molonglo Observatory Synthesis Telescope
• A Study of Cepheids in M81 with the Large Binocular Telescope (Efficiently Calibrated with HST)
• Radio lobes and X-ray hot spots in the microquasar S26
• Multi-frequency Radio Measurements of SN 1987A over 22 Years
• Following the 2008 outburst decay of the black hole candidate H1743-322 in X-ray and radio
• The variability timescales and brightness temperatures of radio flares from stars to supermassive black holes
• A Re-brightening of the Radio Nebula associated with the 2004 December 27 giant flare from SGR 1806--20
• LOFAR MSSS: Detection of a low-frequency radio transient in 400 hrs of monitoring of the North Celestial Pole
• Deep MERLIN 5GHz Radio Imaging of Supernova Remnants in the M82 Starburst
• General-Relativistic Simulations of Four States of Accretion onto Millisecond Pulsars
• Swift observations of V404 Cyg during the 2015 outburst: X-ray outflows from super-Eddington accretion
• Radio Emission Associated with the ULX in Holmberg II
• Faint, Large-scale H-Alpha Filaments in the Milky Way
• Radio Emission from SN 1988Z and Very Massive Star Evolution
• Unveiling recurrent jets of the ULX Holmberg II X-1: evidence for a massive stellar-mass black hole?
• The nature of the hard state of Cygnus X-3
• NuSTAR reveals the hidden nature of SS433
• Discovery of the Luminous, Decades-Long, Extragalactic Radio Transient FIRST J141918.9+394036
• A ULX microquasar in NGC 5408?
• A highly polarised radio jet during the 1998 outburst of the black hole transient XTE J1748-288
• The peculiar mass-loss history of SN 2014C as revealed through AMI radio observations
• ROSAT observations of the dwarf starforming galaxy Holmerg II (UGC 4305)
• The evolving polarised jet of black hole candidate Swift J1745-26
• On the radio properties of the intermediate-mass black hole candidate ESO 243-49 HLX-1
• A classification of the X-ray and radio states of Cyg X-3 and their long-term correlations
• GRB orphan afterglows in present and future radio transient surveys
• Long-term monitoring of Molonglo calibrators
• An automated archival VLA transients survey
• A Search for Radio Transients in VLA Archival Images of the 3C 286 Field
• A search for long-timescale, low-frequency radio transients
• Discovery of an unusual new radio source in the star-forming galaxy M82: Faint supernova, supermassive blackhole, or an extra-galactic microquasar?
• New methods to constrain the radio transient rate: results from a survey of four fields with LOFAR
• The Arcminute Microkelvin Imager Catalogue of Gamma-ray Burst afterglows at 15.7 GHz
• Radio afterglows of a complete sample of bright Swift GRBs: predictions from present days to the SKA era
• Multiband counterparts of two eclipsing ultraluminous X-ray sources in M 51
• Tracking the variable jets of V404 Cygni during its 2015 outburst
• The Re-Acceleration of the Shock Wave in the Radio Remnant of SN 1987A
• Discovery of a Meter-Wavelength Radio Transient in the SWIRE Deep Field: 1046+59
• Swift UV/Optical Telescope Imaging of Star Forming Regions in M81 and Holmberg IX
• A search for variable and transient radio sources in the extended Chandra Deep Field South at 5.5 GHz
• Astrometric observations of X-ray binaries using very long baseline interferometry
• Spitzer Point Source Catalogs of $\sim 300,000$ Stars in Seven Nearby Galaxies
• Resolving the decades-long transient FIRST J141918.9+394036: an orphan long gamma-ray burst or a young magnetar nebula?
• Supernovae and radio transients in M 82
• Monitoring of the prompt radio emission from the unusual supernova 2004dj in NGC2403
• LOFAR 150-MHz observations of SS 433 and W 50
• Flux density variations of radio sources in M82 over the last 3 decades
• Discovery of a Luminous Radio Transient 460 pc from the Central Supermassive Black Hole in Cygnus A
• Ultraluminous X-ray Sources: Beambags and Optical Counterparts
• A New Model for the Radio Emission from SN 1994I and an Associated Search for Radio Transients in M51
• A newly discovered double-double candidate microquasar in NGC 300
• A pilot survey for transients and variables with the Australian Square Kilometre Array Pathfinder
• A Very Large Array Search for Intermediate-Mass Black Holes in Globular Clusters in M81
• The unusual radio transient in M82: an SS 433 analogue?
• Discovery, photometry, and astrometry of 49 classical nova candidates in M81 galaxy
• On the use of variability time-scales as an early classifier of radio transients and variables
• Refractive Interstellar Scintillation of Extra-galactic Radio Sources I: Expectations

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• A Late-Time Galaxy-Targeted Search for the Radio Counterpart of GW190814
• Formation of millisecond pulsars with long orbital periods by accretion-induced collapse of white-dwarfs
• VTC J095517.5+690813: A radio transient from an accretion-induced collapse of a white dwarf?
• Formulating the r-mode problem for slowly rotating neutron stars
• Multi-epoch variability of AT 2000ch (SN 2000ch) in NGC 3432 -- A radio continuum and optical study
• Radio Nebulæ from Hyper-Accreting X-ray Binaries as Common Envelope Precursors and Persistent Counterparts of Fast Radio Bursts