The host of GRB 171205A in 3D

A resolved multiwavelength study of a rare grand-design spiral GRB host

¹ Astronomical Institute, Czech Academy of Sciences, Fričova 298, Ondřejov, Czech Republic
² Université de la Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, 06304 Nice, France
³ Aix Marseille Univ., CNRS, CNES, LAM, Marseille, France
⁴ INAF, Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, 80131 Napoli, Italy
⁵ DARK, Niels Bohr Institute, University of Copenhagen, Jagtvej 128, 2200-N Copenhagen, Denmark
⁶ Astronomical Observatory Institute, Faculty of Physics, Adam Mickiewicz University, ul. Słoneczna 36, 60-286 Poznań, Poland
⁷ Department of Astrophysics/IMAPP, Radboud University, 6525 AJ Nijmegen, The Netherlands
⁸ David A. Dunlap Department of Astronomy & Astrophysics, University of Toronto, 50 St. George St., Toronto, Ontario M5S 3H4, Canada
⁹ Centro Astronómico Hispano-Alemán, Observatorio de Calar Alto, Sierra de los Filabres, 4550 Gérgal, Spain
¹⁰ 3 Dunlap Institute for Astrophysics & Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4, Canada
¹¹ Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
¹² Cosmic Dawn Center, Niels Bohr Institute, University of Copenhagen, Jagtvej 128, 2200-N Copenhagen, Denmark
¹³ INAF, Osservatorio Astronomico di Brera, Via Bianchi, Merate, Italy
¹⁴ Space Science Data Center (SSDC) – Agenzia Spaziale Italiana (ASI), 00133 Roma, Italy
¹⁵ INAF – Osservatorio Astronomico di Roma, Via Frascati 33, 00040 Monte Porzio Catone, Italy
¹⁶ Clemson University, Department of Physics and Astronomy, Clemson, SC 29634-0978, USA
¹⁷ Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, 107 Reykjavík, Iceland
¹⁸ University of Messina, MIFT Department, Via F. S. D’Alcontres 31, Papardo, 98166 Messina, Italy
¹⁹ Astronomical Institute Anton Pannekoek, University of Amsterdam, 1090 GE Amsterdam, The Netherlands
²⁰ INAF – Osservatorio di Astrofisica e Scienza dello Spazio, Via Piero Gobetti 93/3, 40129 Bologna, Italy
²¹ Department of Physics, University of Bath, Bath BA2 7AY, UK
²² Centre for Astrophysics Research, University of Hertfordshire, Hatfield AL10 9AB, UK
²³ School of Mathematical and Physical Sciences, Macquarie University, NSW 2109, Australia
²⁴ ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO-3D), Australia

Received: 3 October 2023
Accepted: 2 July 2024

Abstract

Long GRB hosts at z < 1 are usually low-mass, low-metallicity star-forming galaxies. Here we present the most detailed, spatially resolved study of the host of GRB 171205A so far, a grand-design barred spiral galaxy at z = 0.036. Our analysis includes MUSE integral field spectroscopy complemented with high-spatial-resolution UV/VIS HST imaging and CO(1−0) and H I 21 cm data. The GRB is located in a small star-forming region in a spiral arm of the galaxy at a deprojected distance of ∼8 kpc from the center. The galaxy shows a smooth negative metallicity gradient and the metallicity at the GRB site is half solar, slightly below the mean metallicity at the corresponding distance from the center. Star formation in this galaxy is concentrated in a few H II regions between 5 and 7 kpc from the center and at the end of the bar, inwards from the GRB region; however the H II region hosting the GRB is in the top 10% of the regions with the highest specific star-formation rate. The stellar population at the GRB site has a very young component (< 5 Myr) that contributes a significant part of the light. Ionized and molecular gas show only minor deviations at the end of the bar. A parallel study found an asymmetric H I distribution and some additional gas near the position of the GRB, which might explain the star-forming region of the GRB site. Our study shows that long GRBs can occur in many types of star-forming galaxies; however the actual GRB sites have consistently low metallicity, high star formation rates, and a young population. Furthermore, gas inflow or interactions triggering the star formation producing the GRB progenitor might not be evident in ionized or even molecular gas but only in H I.