GRB 190114C in the nuclear region of an interacting galaxy -- A detailed host analysis using ALMA, HST and VLT

Abstract

GRB 190114C is the first GRB for which the detection of very-high energy emission up to the TeV range has been reported. It is still unclear whether environmental properties might have contributed to the production of these very high-energy photons, or if it is solely related to the released GRB emission. The relatively low redshift of the GRB (z=0.425) allows us to study the host galaxy of this event in detail, and to potentially identify idiosyncrasies that could point to progenitor characteristics or environmental properties responsible for such a unique event. We use ultraviolet, optical, infrared and submillimetre imaging and spectroscopy obtained with HST, VLT and ALMA to obtain an extensive dataset on which the analysis of the host galaxy is based. The host system is composed of a close pair of interacting galaxies (Delta v = 50 km s^-1), both of which are well-detected by ALMA in CO(3-2). The GRB occurred within the nuclear region (~170 pc from the centre) of the less massive but more star-forming galaxy of the pair. The host is more massive (log(M/M_odot)=9.3) than average GRB hosts at that redshift and the location of the GRB is rather unique. The enhanced star-formation rate was probably triggered by tidal interactions between the two galaxies. Our ALMA observations indicate that both host galaxy and companion have a high molecular gas fraction, as has been observed before in interacting galaxy pairs. The location of the GRB within the core of an interacting galaxy with an extinguished line-of-sight is indicative of a denser environment than typically observed for GRBs and could have been crucial for the generation of the very-high-energy photons that were observed.

A&A, in press, 11 pages

References in corpus (14)

• Constraining the Low-Mass Slope of the Star Formation Sequence at 0.5<z<2.5
• Long gamma-ray bursts and core-collapse supernovae have different environments
• A decade of Gamma-Ray Bursts observed by $Fermi$-LAT: The 2${}^{nd}$ GRB catalog
• Observation of inverse Compton emission from a long $\gamma$-ray burst
• The optically unbiased GRB host (TOUGH) survey. I. Survey design and catalogs
• Long Gamma-Ray Bursts and Type Ic Core Collapse Supernovae Have Similar Locations in Hosts
• Signatures of a jet cocoon in early spectra of a supernova associated with a $\gamma$-ray burst
• A Consistent Study of Metallicity Evolution at 0.8 < z < 2.6
• High Energy Afterglow from Gamma-ray Bursts
• ALLSMOG: an APEX Low-redshift Legacy Survey for MOlecular Gas. I - molecular gas scaling relations, and the effect of the CO/H2 conversion factor
• Are LGRBs biased tracers of star formation? Clues from the host galaxies of the $Swift$/BAT6 complete sample of bright LGRBs III: Stellar masses, star formation rates and metallicities at $z>1$
• Two gamma-ray bursts from dusty regions with little molecular gas
• GRB 980425 host: [CII], [OI] and CO lines reveal recent enhancement of star formation due to atomic gas inflow
• Herschel observations of gamma-ray burst host galaxies: implications for the topology of the dusty interstellar medium

Cited by in corpus (4)

• The variable absorption in the X-ray spectrum of GRB 190114C
• Probing the physical properties of the intergalactic medium using gamma-ray bursts
• GRB host galaxies with strong H${}_2$ absorption: CO-dark molecular gas at the peak of cosmic star formation
• Jitter radiation: towards TeV-photons of gamma-ray bursts