The Koala: A Fast Blue Optical Transient with Luminous Radio Emission from a Starburst Dwarf Galaxy at $z=0.27$

Abstract

We present ZTF18abvkwla (the "Koala"), a fast blue optical transient discovered in the Zwicky Transient Facility (ZTF) One-Day Cadence (1DC) Survey. ZTF18abvkwla has a number of features in common with the groundbreaking transient AT2018cow: blue colors at peak ($g-r\approx -0.5$ mag), a short rise time from half-max of under two days, a decay time to half-max of only three days, a high optical luminosity ($M_{g,\mathrm{peak}}\approx -20.6$mag), a hot ($\gtrsim 40,000$K) featureless spectrum at peak light, and a luminous radio counterpart. At late times ($\Delta t>80$d) the radio luminosity of ZTF18abvkwla ($\nu L_{\nu }\gtrsim 10^{40}$erg/s at 10 GHz, observer-frame) is most similar to that of long-duration gamma-ray bursts (GRBs). The host galaxy is a dwarf starburst galaxy ($M\approx 5\times 10^8{M}_{\odot }$, $\mathrm{SFR}\approx 7M_{\odot }$/yr) that is moderately metal-enriched ($\log [O/H]\approx 8.5$), similar to the hosts of GRBs and superluminous supernovae. As in AT2018cow, the radio and optical emission in ZTF18abvkwla likely arise from two separate components: the radio from fast-moving ejecta ($\Gamma \beta c>0.38c$) and the optical from shock-interaction with confined dense material ($<0.07M_{\odot }$ in $\sim 10^{15}$cm). Compiling transients in the literature with $t_{\mathrm{rise}}<5$d and $M_{\mathrm{peak}}<-20$mag, we find that a significant number are engine-powered, and suggest that the high peak optical luminosity is directly related to the presence of this engine. From 18 months of the 1DC survey, we find that transients in this rise-luminosity phase space are at least two to three orders of magnitude less common than CC SNe. Finally, we discuss strategies for identifying such events with future facilities like the Large Synoptic Survey Telescope, and prospects for detecting accompanying X-ray and radio emission.

arXiv comment27 pages, 11 figures. Resubmitted to ApJ on 13 April following comments by referee. Comments welcome!

References in corpus (105)

• Astropy: A Community Python Package for Astronomy
• Planck 2015 results. XIII. Cosmological parameters
• Stellar population synthesis at the resolution of 2003
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• The Origin of the Mass--Metallicity Relation: Insights from 53,000 Star-Forming Galaxies in the SDSS
• Correcting for the Effects of Interstellar Extinction
• The Zwicky Transient Facility: System Overview, Performance, and First Results
• Overview of the DESI Legacy Imaging Surveys
• The Zwicky Transient Facility: Data Processing, Products, and Archive
• Beaming in Gamma-Ray Bursts: Evidence for a Standard Energy Reservoir
• The Palomar Transient Factory: System Overview, Performance and First Results
• Mass Loss: Its Effect on the Evolution and Fate of High-Mass Stars
• Calibrating Extinction-Free Star Formation Rate Diagnostics with 33GHz Free-Free Emission in NGC6946
• The Zwicky Transient Facility: Science Objectives
• Long gamma-ray bursts and core-collapse supernovae have different environments
• Exploring the Optical Transient Sky with the Palomar Transient Factory
• The Host Galaxy and Redshift of the Repeating Fast Radio Burst FRB 121102
• An optical supernova associated with the X-ray flash XRF 060218
• Nearby Supernova Rates from the Lick Observatory Supernova Search. III. The Rate-Size Relation, and the Rates as a Function of Galaxy Hubble Type and Colour
• Optical Flares from the Tidal Disruption of Stars by Massive Black Holes
• Relativistic ejecta from XRF 060218 and the rate of cosmic explosions
• The Expanded Very Large Array -- a New Telescope for New Science
• The Birth of a Relativistic Outflow in the Unusual γ-ray Transient Swift J164449.3+573451
• The Fermi GBM Gamma-Ray Burst Spectral Catalog: Four Years Of Data
• The Zwicky Transient Facility: Surveys and Scheduler
• Rapidly-Evolving and Luminous Transients from Pan-STARRS1
• The Afterglows of Swift-era Gamma-Ray Bursts. I. Comparing pre-Swift and Swift era Long/Soft (Type II) GRB Optical Afterglows
• A Common Origin for Cosmic Explosions Inferred from Fireball Calorimetry
• Bolometric light curves and explosion parameters of 38 stripped-envelope core-collapse supernovae
• A Relativistic Type Ibc Supernova Without a Detected Gamma-ray Burst
• Low Luminosity Gamma-Ray Bursts as a Unique Population: Luminosity Function, Local Rate, and Beaming Factor
• A very luminous magnetar-powered supernova associated with an ultra-long gamma-ray burst
• The Observer's Guide to the Gamma-Ray Burst-Supernova Connection
• A new population of ultra-long duration gamma-ray bursts
• An embedded X-ray source shines through the aspherical AT2018cow: revealing the inner workings of the most luminous fast-evolving optical transients
• The 2nd Fermi GBM Gamma-Ray Burst Catalog: The First Four Years
• Hydrogen-Poor Superluminous Supernovae and Long-Duration Gamma-Ray Bursts Have Similar Host Galaxies
• The 3rd Fermi GBM Gamma-Ray Burst Catalog: The First Six Years
• Proper image subtraction - optimal transient detection, photometry and hypothesis testing
• The Arcminute Microkelvin Imager
• Fully-Automated Reduction of Longslit Spectroscopy with the Low Resolution Imaging Spectrometer at Keck Observatory
• The Cow: discovery of a luminous, hot and rapidly evolving transient
• The Fast, Luminous Ultraviolet Transient AT2018cow: Extreme Supernova, or Disruption of a Star by an Intermediate-Mass Black Hole?
• Calcium-rich gap transients in the remote outskirts of galaxies
• Spectroscopy of superluminous supernova host galaxies. A preference of hydrogen-poor events for extreme emission line galaxies
• The Afterglow of GRB 130427A from 1 to 10^16 GHz
• Discovery of an outflow from radio observations of the tidal disruption event ASASSN-14li
• Host-Galaxy Properties of 32 Low-Redshift Superluminous Supernovae from the Palomar Transient Factory
• Core-Collapse Supernovae and Host Galaxy Stellar Populations
• Dwarf Galaxy Starburst Statistics in the Local Volume
• GRB 060218/SN 2006aj: A Gamma-Ray Burst and Prompt Supernova at z=0.0335
• Cosmic evolution and metal aversion in super-luminous supernova host galaxies
• Radio Monitoring of the Tidal Disruption Event Swift J164449.3+573451. I. Jet Energetics and the Pristine Parsec-Scale Environment of a Supermassive Black Hole
• Real-bogus classification for the Zwicky Transient Facility using deep learning
• The Luminosity and Angular Distributions of Long GRBs
• Supernova 2006aj and the associated X-Ray Flash 060218
• Rapidly evolving transients in the Dark Energy Survey
• The GROWTH Marshal: A Dynamic Science Portal for Time-Domain Astronomy
• Radio Monitoring of the Tidal Disruption Event Swift J164449.3+573451. II. The Relativistic Jet Shuts Off and a Transition to Forward Shock X-ray/Radio Emission
• Rapidly Rising Transients in the Supernova - Superluminous Supernova Gap
• Supernovae with Two Peaks in the Optical Light Curve and the Signature of Progenitors with Low-mass Extended Envelopes
• A top-heavy stellar initial mass function in starbursts as an explanation for the high mass-to-light ratios of ultra compact dwarf galaxies
• The Zwicky Transient Facility Alert Distribution System
• AT2018cow: a luminous millimeter transient
• Are LGRBs biased tracers of star formation? Clues from the host galaxies of the Swift/BAT6 complete sample of LGRBs. I: Stellar mass at z<1
• Machine Learning for the Zwicky Transient Facility
• An unusual stellar death on Christmas Day
• Type Ibn Supernovae Show Photometric Homogeneity and Spectral Diversity at Maximum Light
• The GRB 060218/SN 2006aj event in the context of other Gamma-Ray Burst Supernovae
• Fast Radio Bursts---A Brief Review: Some Questions, Fewer Answers
• ZTF Early Observations of Type Ia Supernovae I: Properties of the 2018 Sample
• A Morphological Classification Model to Identify Unresolved PanSTARRS1 Sources: Application in the ZTF Real-Time Pipeline
• Shock breakout theory
• Long Term Radio Monitoring of SN 1993J
• Swift spectra of AT2018cow: A White Dwarf Tidal Disruption Event?
• Probing the Cosmic Gamma-Ray Burst Rate with Trigger Simulations of the Swift Burst Alert Telescope
• Radio Monitoring of the Tidal Disruption Event Swift J164449.3+573451. III. Late-time Jet Energetics and a Deviation from Equipartition
• The Radio and X-ray Luminous Type Ibc Supernova 2003L
• Discovery of a Cosmological, Relativistic Outburst via its Rapidly Fading Optical Emission
• An Early & Comprehensive Millimeter and Centimeter Wave and X-ray Study of Supernova 2011dh: A Non-Equipartition Blastwave Expanding into A Massive Stellar Wind
• A Luminous, Fast Rising UV-Transient Discovered by ROTSE: a Tidal Disruption Event?
• A Comprehensive Radio View of the Extremely Bright Gamma-Ray Burst 130427A
• Evidence for Late-stage Eruptive Mass-loss in the Progenitor to SN2018gep, a Broad-lined Ic Supernova: Pre-explosion Emission and a Rapidly Rising Luminous Transient
• X-ray Swift observations of SN 2018cow
• The Optically Unbiased Gamma-Ray Burst Host (TOUGH) Survey. VII. The Host Galaxy Luminosity Function: Probing the Relationship Between GRBs and Star Formation to Redshift $\sim 6$
• iPTF16asu: A Luminous, Rapidly-Evolving, and High-Velocity Supernova
• Signatures of Circumstellar Interaction in the Unusual Transient AT2018cow
• EVLA Observations of the Radio Evolution of SN 2011dh
• SN 2007bg: The Complex Circumstellar Environment Around One of the Most Radio-Luminous Broad-Lined Type Ic Supernovae
• FBOTs and AT2018cow following electron-capture collapse of merged white dwarfs
• Host Galaxies of Type Ic and Broad-lined Type Ic Supernovae from the Palomar Transient Factory: Implication for Jet Production
• CHANG-ES V: Nuclear Radio Outflow in a Virgo Cluster Spiral after a Tidal Disruption Event
• Highly Luminous Supernovae associated with Gamma-Ray Bursts I.: GRB 111209A/SN 2011kl in the Context of Stripped-Envelope and Superluminous Supernovae
• Are Super-Luminous supernovae and Long GRBs produced exclusively in young dense star clusters?
• IGR J12580+0134: The First Tidal Disruption Event with an Off-beam Relativistic Jet
• The Optical/NIR afterglow of GRB 111209A: Complex yet not Unprecedented
• Monte Carlo Method for Calculating Oxygen Abundances and Their Uncertainties from Strong-Line Flux Measurements
• ZTF18aalrxas: A Type IIb Supernova from a very extended low-mass progenitor
• The nearby luminous transient AT2018cow: a magnetar formed in a sub-relativistically expanding non-jetted explosion
• AT 2018cow VLBI: No Long-Lived Relativistic Outflow
• Probing dust-obscured star formation in the most massive Gamma-Ray Burst host galaxies
• Broad-lined type Ic supernova iPTF16asu: A challenge to all popular models
• ALMA Polarimetry of AT2018cow
• The Absolute Rate of LGRB Formation

Cited by in corpus (78)

• The Zwicky Transient Facility Bright Transient Survey. II. A Public Statistical Sample for Exploring Supernova Demographics
• A very luminous jet from the disruption of a star by a massive black hole
• A WC/WO star exploding within an expanding carbon-oxygen-neon nebula
• A Search for Extragalactic Fast Blue Optical Transients in ZTF and the Rate of AT2018cow-like Transients
• The Type Icn SN 2021csp: Implications for the Origins of the Fastest Supernovae and the Fates of Wolf-Rayet Stars
• Shock Cooling Emission from Extended Material Revisited
• Radio and X-ray observations of the luminous Fast Blue Optical Transient AT2020xnd
• SN2019dge: a Helium-rich Ultra-Stripped Envelope Supernova
• High-Energy Neutrinos and Gamma-Rays from Non-Relativistic Shock-Powered Transients
• Luminous Millimeter, Radio, and X-ray Emission from ZTF20acigmel (AT2020xnd)
• Circumstellar Interaction Powers the Light Curves of Luminous Rapidly Evolving Optical Transients
• Evidence for a Compact Object in the Aftermath of the Extra-Galactic Transient AT2018cow
• Shocked jets in CCSNe can power the zoo of fast blue optical transients
• Constraining the Kilonova Rate with Zwicky Transient Facility Searches Independent of Gravitational Wave and Short Gamma-ray Burst Triggers
• Model Light Curves for Type Ib and Ic Supernovae
• Fast Optical Transients from Stellar-Mass Black Hole Tidal Disruption Events in Young Star Clusters
• Shock cooling of a red-supergiant supernova at redshift 3 in lensed images
• Thermal Electrons in Mildly-relativistic Synchrotron Blast-waves
• A transient radio source consistent with a merger-triggered core collapse supernova
• Cosmological Fast Optical Transients with the Zwicky Transient Facility: A Search for Dirty Fireballs
• The Host Galaxies of Rapidly Evolving Transients in the Dark Energy Survey
• uGMRT observations of a Fast and Blue Optical Transient -- AT 2018cow
• Late-Time Radio and Millimeter Observations of Superluminous Supernovae and Long Gamma Ray Bursts: Implications for Obscured Star Formation, Central Engines, and Fast Radio Bursts
• Magnetar Engines in Fast Blue Optical Transients and Their Connections with SLSNe, SNe Ic-BL, and lGRBs
• A common envelope jets supernova (CEJSN) impostor scenario for fast blue optical transients
• A Swift Fix for Nuclear Outbursts
• A fast X-ray transient from a weak relativistic jet associated with a type Ic-BL supernova
• SN 2018gjx reveals that some SNe Ibn are SNe IIb exploding in dense circumstellar material
• Analytic Light Curves of Dense CSM Shock Breakout and Cooling
• Minutes-duration Optical Flares with Supernova Luminosities
• An environmental analysis of the fast transient AT2018cow and implications for its progenitor and late-time brightness
• Dust Echoes from Luminous Fast Blue Optical Transients
• Deciphering the unusual stellar progenitor of GRB 210704A
• Late-time Hubble Space Telescope Observations of AT 2018cow. II. Evolution of a UV bright Underlying Source 2--4 Yr Post-discovery
• CHIPS: Complete History of Interaction-Powered Supernovae
• High-Energy Neutrinos from Gamma-Ray-Faint Accretion-Powered Hypernebulae
• Late-Time Evolution and Modeling of the Off-Axis Gamma-ray Burst Candidate FIRST J141918.9+394036
• State-of-the-Art Collapsar Jet Simulations Imply Undetectable Subphotospheric Neutrinos
• A flash of polarized optical light points to an aspherical "cow"
• Particle Acceleration in Mildly Relativistic Outflows of Fast Energetic Transient Sources
• Constraining Low-luminosity Gamma-Ray Bursts as Ultra-high-energy Cosmic Ray Sources Using GRB 060218 as a Proxy
• Multimessenger astronomy with a kHz-band gravitational-wave observatory
• Wind-Reprocessed Transients from Stellar-mass Black Hole Tidal Disruption Events
• MUSSES2020J: The Earliest Discovery of a Fast Blue Ultraluminous Transient at Redshift 1.063
• A Flat-Spectrum Radio Transient at 122 Mpc consistent with an Emerging Pulsar Wind Nebula
• Simulating the tidal disruption of stars by stellar-mass black holes using moving-mesh hydrodynamics
• Neutrino Emission from Luminous Fast Blue Optical Transients
• O'TRAIN: a robust and flexible Real/Bogus classifier for the study of the optical transient sky
• Multi-wavelength observations of the Luminous Fast Blue Optical Transient AT2023fhn
• A matched-filter approach to radio variability and transients: searching for orphan afterglows in the VAST Pilot Survey
• Simulating the inflation of bubbles by late jets in core collapse supernova ejecta
• New JWST redshifts for the host galaxies of CDF-S XT1 and XT2: understanding their nature
• Radiative diffusion in a time-dependent outflow: a model for fast blue optical transients
• Late-time Hubble Space Telescope Observations of AT 2018cow. I. Further Constraints on the Fading Prompt Emission and Thermal Properties 50--60 Days Post-discovery
• Real-time Discovery of AT2020xnd: A Fast, Luminous Ultraviolet Transient with Minimal Radioactive Ejecta
• Results from the Pan-STARRS Search for Kilonovae: Contamination by Massive Stellar Outbursts
• On the optical transients from double white-dwarf mergers
• Constraints on the rate of supernovae lasting for more than a year from Subaru/Hyper Suprime-Cam
• A Population Study on the Radio Emission of Fast Blue Optical Transients
• SN 2023zaw: an ultra-stripped, nickel-poor supernova from a low-mass progenitor
• AT2019wxt: An ultra-stripped supernova candidate discovered in electromagnetic follow-up of a gravitational wave trigger
• Cosmic ray acceleration and non-thermal emission from fast luminous optical transient sources
• The Emission and Suppression of Line Features in Luminous Transients
• Searching for Radio Transients with Inverted Spectra in Epoch 1 of VLASS and VCSS, and Identification of a Sample of Candidate Relativistic Nuclear Transients
• Luminous Fast Blue Optical Transients as "Failed" Gravitational-wave Sources: Helium Core$-$Black Hole Mergers Following Delayed Dynamical Instability
• Characterising EP241107a: Multiwavelength Observations of an Einstein Probe-detected Fast X-ray Transient
• The spectra of a radiative reprocessing outflow model for fast blue optical transients
• Machine-directed gravitational-wave counterpart discovery
• The X-ray and Radio Loud Fast Blue Optical Transient AT2020mrf: Implications for an Emerging Class of Engine-Driven Massive Star Explosions
• Light-curve Modelling for The Initial Rising Phase of Rapidly-evolving Transients Powered by Continuous Outflow
• Numerical Modeling of Relativistic Effects in Synchrotron-Emitting Shocks
• Search for the Optical Counterpart of Einstein Probe Discovered Fast X-ray Transients from Lulin Observatory
• A Target Search for Fast Radio Bursts Associated with Two Fast Blue Optical Transients: AT2018cow and CSS161010
• Luminous Fast Blue Optical Transients and Type Ibn/Icn SNe from Wolf-Rayet/Black Hole Mergers
• Time Domain Astronomy with the THESEUS Satellite
• Black hole to photosphere: 3D GRMHD simulations of collapsars reveal wobbling and hybrid composition jets
• Science with a large field-of-view polarization survey: The Large Array Survey Telescope Polarization Node (LAST-P)
• AT2019ijn: a fast-rising, slow-decaying blue optical transient with exceptionally bright radio emission