The Host Galaxy and Redshift of the Repeating Fast Radio Burst FRB 121102

The precise localization of the repeating fast radio burst (FRB 121102) has provided the first unambiguous association (chance coincidence probability p ≲ 3 × 10‑4) of an FRB with an optical and persistent radio counterpart. We report on optical imaging and spectroscopy of the counterpart and find that it is an extended (0.″6–0.″8) object displaying prominent Balmer and [Oiii] emission lines. Based on the spectrum and emission line ratios, we classify the counterpart as a low-metallicity, star-forming, mr‧ = 25.1 AB mag dwarf galaxy at a redshift of z =0.19273(8), corresponding to a luminosity distance of 972 Mpc. From the angular size, the redshift, and luminosity, we estimate the host galaxy to have a diameter ≲4 kpc and a stellar mass of M* ∼ (4–7) × 107 M⊙, assuming a mass-to-light ratio between 2 to 3 M⊙L⊙‑1. Based on the Hα flux, we estimate the star formation rate of the host to be 0.4 M⊙yr‑1 and a substantial host dispersion measure (DM)depth ≲324 pc cm‑3. The net DM contribution of the host galaxy to FRB 121102 is likely to be lower than this value depending on geometrical factors. We show that the persistent radio source at FRB 121102’s location reported by Marcote et al. is offset from the galaxy’s center of light by ∼200 mas and the host galaxy does not show optical signatures for AGN activity. If FRB121102 is typical of the wider FRB population and if futureinterferometric localizations preferentially find them in dwarf galaxies with low metallicities and prominent emission lines, they would share such a preference with long gamma-ray bursts and superluminous supernovae.

[1]  F. Mannucci,et al.  Are long gamma-ray bursts biased tracers of star formation? Clues from the host galaxies of the Swift/BAT6 complete sample of LGRBs I. Stellar mass at z < 1 ? , 2014, 1409.7064.

[2]  A. Ganguly,et al.  Dense magnetized plasma associated with a fast radio burst , 2015, Nature.

[3]  J. Greene,et al.  DWARF GALAXIES WITH OPTICAL SIGNATURES OF ACTIVE MASSIVE BLACK HOLES , 2013, 1308.0328.

[4]  H. C. Chiang,et al.  HIRAX: a probe of dark energy and radio transients , 2016, Astronomical Telescopes + Instrumentation.

[5]  Nicholas B. Suntzeff,et al.  SOUTHERN SPECTROPHOTOMETRIC STANDARDS. I. , 1992 .

[6]  R. Manchester,et al.  The ATNF Pulsar Catalogue , 2003, astro-ph/0309219.

[7]  R. Manchester,et al.  The Australia Telescope National Facility Pulsar Catalogue , 2005 .

[8]  L. Kewley,et al.  Metallicity Calibrations and the Mass-Metallicity Relation for Star-forming Galaxies , 2008, 0801.1849.

[9]  P. Mészáros,et al.  A burst in a wind bubble and the impact on baryonic ejecta: high-energy gamma-ray flashes and afterglows from fast radio bursts and pulsar-driven supernova remnants , 2016, 1603.08875.

[10]  A. Fruchter,et al.  THE RELATIVE RATE OF LGRB FORMATION AS A FUNCTION OF METALLICITY , 2015, 1511.01079.

[11]  K. Horne,et al.  AN OPTIMAL EXTRACTION ALGORITHM FOR CCD SPECTROSCOPY. , 1986 .

[12]  D. Malesani,et al.  Spectroscopy of superluminous supernova host galaxies. A preference of hydrogen-poor events for extreme emission line galaxies , 2014, 1409.8331.

[13]  Prasanth H. Nair,et al.  Astropy: A community Python package for astronomy , 2013, 1307.6212.

[14]  V. Kaspi,et al.  THE McGILL MAGNETAR CATALOG , 2013, 1309.4167.

[15]  L. Kewley,et al.  The host galaxies and classification of active galactic nuclei , 2006, astro-ph/0605681.

[16]  Ž. Ivezić,et al.  THE BLUE TIP OF THE STELLAR LOCUS: MEASURING REDDENING WITH THE SLOAN DIGITAL SKY SURVEY , 2010, 1009.4933.

[17]  D. Michalik,et al.  Gaia Data Release 1 - Reference frame and optical properties of ICRF sources , 2016, 1609.07255.

[18]  C. Brogan,et al.  Low-mass black holes as the remnants of primordial black hole formation , 2012, Nature Communications.

[19]  R. Giovanelli,et al.  A DIRECT MEASUREMENT OF THE BARYONIC MASS FUNCTION OF GALAXIES AND IMPLICATIONS FOR THE GALACTIC BARYON FRACTION , 2012, 1208.5229.

[20]  Bonn,et al.  On the origin of a highly dispersed coherent radio burst , 2012, 1206.4135.

[21]  F. Jankowski,et al.  Fast Radio Transient searches with UTMOST at 843 MHz , 2016, 1601.02444.

[22]  E. Berger,et al.  NO PRECISE LOCALIZATION FOR FRB 150418: CLAIMED RADIO TRANSIENT IS AGN VARIABILITY , 2016, 1602.08434.

[23]  R. Giovanelli,et al.  A ug 2 01 2 A direct measurement of the baryonic mass function of galaxies & implications for the galactic baryon fraction , 2012 .

[24]  R. Shannon,et al.  A FAST RADIO BURST IN THE DIRECTION OF THE CARINA DWARF SPHEROIDAL GALAXY , 2014, 1412.1599.

[25]  P. McCarthy,et al.  VERY STRONG EMISSION-LINE GALAXIES IN THE WFC3 INFRARED SPECTROSCOPIC PARALLEL SURVEY AND IMPLICATIONS FOR HIGH-REDSHIFT GALAXIES, , 2011, 1109.0639.

[26]  K. Ioka,et al.  The Cosmic Dispersion Measure from Gamma-Ray Burst Afterglows: Probing the Reionization History and the Burst Environment , 2003, astro-ph/0309200.

[27]  K. Freeman,et al.  The Various Kinematics of Dwarf Irregular Galaxies in Nearby Groups and Their Dark Matter Distributions , 2000 .

[28]  R. Kennicutt,et al.  Past and Future Star Formation in Disk Galaxies , 1994 .

[29]  P. Chandra,et al.  Radio light curve of the galaxy possibly associated with FRB 150418 , 2016, 1610.09043.

[30]  L. Kewley,et al.  Theoretical Modeling of Starburst Galaxies , 2001, astro-ph/0106324.

[31]  Nrl,et al.  FRB 150418: clues to its nature from European VLBI Network and e-MERLIN observations , 2016, 1609.01419.

[32]  J. Silverman,et al.  X-RAY DETECTED ACTIVE GALACTIC NUCLEI IN DWARF GALAXIES AT 0 < z < 1 , 2016, 1603.01622.

[33]  M. Mclaughlin,et al.  A Bright Millisecond Radio Burst of Extragalactic Origin , 2007, Science.

[34]  L. Kewley,et al.  Chemical abundances in high-redshift galaxies: a powerful new emission line diagnostic , 2016, 1601.01337.

[35]  Case Western Reserve University,et al.  Dynamics of starbursting dwarf galaxies. III. A H I study of 18 nearby objects , 2014, 1404.6252.

[36]  Elaine M. Sadler,et al.  Radio sources in the 6dFGS: local luminosity functions at 1.4 GHz for star-forming galaxies and radio-loud AGN , 2007 .

[37]  Anthony L. Piro,et al.  THE IMPACT OF A SUPERNOVA REMNANT ON FAST RADIO BURSTS , 2016, 1604.04909.

[38]  Douglas P. Finkbeiner,et al.  MEASURING REDDENING WITH SLOAN DIGITAL SKY SURVEY STELLAR SPECTRA AND RECALIBRATING SFD , 2010, 1012.4804.

[39]  Matthew McQuinn,et al.  LOCATING THE “MISSING” BARYONS WITH EXTRAGALACTIC DISPERSION MEASURE ESTIMATES , 2013, 1309.4451.

[40]  K. Bannister,et al.  The magnetic field and turbulence of the cosmic web measured using a brilliant fast radio burst , 2016, Science.

[41]  Optical and radio astrometry of the galaxy associated with FRB 150418 , 2016, 1607.08257.

[42]  R. J. Reynolds Pulsar dispersion measures and H-alpha emission measures - Limits on the electron density and filling factor for the ionized interstellar gas , 1977 .

[43]  J. Mathis,et al.  The relationship between infrared, optical, and ultraviolet extinction , 1989 .

[44]  L. Ho,et al.  Detailed structural decomposition of galaxy images , 2002, astro-ph/0204182.

[45]  R. J. Reynolds,et al.  ApJ, in press Preprint typeset using L ATEX style emulateapj v. 10/09/06 THE TURBULENT WARM IONIZED MEDIUM: EMISSION MEASURE DISTRIBUTION AND MHD SIMULATIONS , 2022 .

[46]  J. I. Katz,et al.  Fast Radio Bursts---A Brief Review: Some Questions, Fewer Answers , 2016, 1604.01799.

[47]  Observatoire de la Côte d'Azur,et al.  Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties , 2016, 1609.04172.

[48]  M. Irwin,et al.  The second data release of the INT Photometric Hα Survey of the Northern Galactic Plane (IPHAS DR2) , 2014, 1406.4862.

[49]  Timothy M. Heckman,et al.  The host galaxies of active galactic nuclei , 2003 .

[50]  Nrl,et al.  A repeating fast radio burst , 2016, Nature.

[51]  L. Kewley,et al.  The Hα and Infrared Star Formation Rates for the Nearby Field Galaxy Survey , 2002, astro-ph/0208508.

[52]  K. Bannister,et al.  THE GALACTIC POSITION DEPENDENCE OF FAST RADIO BURSTS AND THE DISCOVERY OF FRB011025 , 2014, 1407.0400.

[53]  A. Keimpema,et al.  A direct localization of a fast radio burst and its host , 2017, Nature.

[54]  Max Pettini,et al.  [O III] / [N II] as an abundance indicator at high redshift , 2004, astro-ph/0401128.

[55]  J. Fynbo,et al.  A POPULATION OF MASSIVE, LUMINOUS GALAXIES HOSTING HEAVILY DUST-OBSCURED GAMMA-RAY BURSTS: IMPLICATIONS FOR THE USE OF GRBs AS TRACERS OF COSMIC STAR FORMATION , 2013, 1301.5903.

[56]  P. Vreeswijk,et al.  HOST-GALAXY PROPERTIES OF 32 LOW-REDSHIFT SUPERLUMINOUS SUPERNOVAE FROM THE PALOMAR TRANSIENT FACTORY , 2016, 1604.08207.

[57]  L. Kewley,et al.  Accepted for publication in The Astrophysical Journal Preprint typeset using L ATEX style emulateapj v. 6/22/04 HIGH-RESOLUTION MEASUREMENTS OF THE HALOS OF FOUR DARK MATTER-DOMINATED GALAXIES: DEVIATIONS FROM A UNIVERSAL DENSITY PROFILE 1 , 2004 .

[58]  Harvard-Smithsonian CfA,et al.  Using Strong Lines to Estimate Abundances in Extragalactic H II Regions and Starburst Galaxies , 2002, astro-ph/0206495.

[59]  Z. Paragi,et al.  Discovery of five low-luminosity active galactic nuclei at the centre of the Perseus cluster , 2016, 1611.05986.

[60]  E. Ofek,et al.  A real-time fast radio burst: polarization detection and multiwavelength follow-up , 2014, 1412.0342.

[61]  A. J. Levan,et al.  Long γ-ray bursts and core-collapse supernovae have different environments , 2006, Nature.

[62]  E. Bertin,et al.  SExtractor: Software for source extraction , 1996 .

[63]  O. I. Wong,et al.  WALLABY Pilot Survey: H i in the Host Galaxy of a Fast Radio Burst , 2023, The Astrophysical Journal.

[64]  R. I. Hynes,et al.  An optimal extraction of spatially blended spectra , 2001, astro-ph/0111477.

[65]  J. Condon,et al.  A CANDIDATE MASSIVE BLACK HOLE IN THE LOW-METALLICITY DWARF GALAXY PAIR MRK 709 , 2014, 1405.0278.

[66]  J. Baldwin,et al.  ERRATUM - CLASSIFICATION PARAMETERS FOR THE EMISSION-LINE SPECTRA OF EXTRAGALACTIC OBJECTS , 1981 .

[67]  Hilo,et al.  THE ELEVENTH AND TWELFTH DATA RELEASES OF THE SLOAN DIGITAL SKY SURVEY: FINAL DATA FROM SDSS-III , 2015, 1501.00963.

[68]  R. Lynch,et al.  THE REPEATING FAST RADIO BURST FRB 121102: MULTI-WAVELENGTH OBSERVATIONS AND ADDITIONAL BURSTS , 2016, 1603.08880.

[69]  C. A. Oxborrow,et al.  Planck2015 results , 2015, Astronomy &amp; Astrophysics.

[70]  R. J. Reynolds,et al.  The warm ionized medium in spiral galaxies , 2009, 0901.0941.

[71]  J. Cordes,et al.  Radio Wave Propagation and the Provenance of Fast Radio Bursts , 2016, 1605.05890.

[72]  S. Burke-Spolaor,et al.  A Population of Fast Radio Bursts at Cosmological Distances , 2013, Science.

[73]  Chien Y. Peng,et al.  DETAILED DECOMPOSITION OF GALAXY IMAGES. II. BEYOND AXISYMMETRIC MODELS , 2009, 0912.0731.

[74]  H. J. van Langevelde,et al.  The Repeating Fast Radio Burst FRB 121102 as Seen on Milliarcsecond Angular Scales , 2017, 1701.01099.

[75]  Susumu Inoue Probing the cosmic reionization history and local environment of gamma‐ray bursts through radio dispersion , 2003 .

[76]  S. Burke-Spolaor,et al.  Five new fast radio bursts from the HTRU high-latitude survey at Parkes: First evidence for two-component bursts , 2015, 1511.07746.

[77]  X. Siemens,et al.  UvA-DARE ( Digital Academic Repository ) Fast Radio Burst Discovered in the Arecibo Pulsar ALFA Survey , 2014 .

[78]  D. Schlegel,et al.  Maps of Dust Infrared Emission for Use in Estimation of Reddening and Cosmic Microwave Background Radiation Foregrounds , 1998 .