Michałowski, Michał J.21; Hunt, L. K.4; Palazzi, E.4; Savaglio, S.5; Gentile, G.22; Rasmussen, Jesper1; Baes, M.21; Basa, S.7; Bianchi, S.4; Berta, S.5; Burlon, D.23; Ceron, J. M. Castro9; Covino, S.4; Cuby, J. -G.7; D'Elia, V.10; Ferrero, P.11; Götz, D.12; Hjorth, J.13; Koprowski, M. P.24; Borgne, D. Le15; Floc'h, E. Le12; Malesani, D.13; Murphy, T.23; Pian, E.4; Piranomonte, S.4; Rossi, A.16; Sollerman, J.25; Tanvir, N. R.26; Postigo, A. de Ugarte19; Watson, D.13; van der Werf, P.20; Vergani, S. D.4; Xu, D.13
1 Department of Physics, Technical University of Denmark2 Plasma Physics and Fusion Energy, Department of Physics, Technical University of Denmark3 Ghent University4 National Institute for Astrophysics5 Max Planck Institute6 Vrije Universiteit Brussel7 Aix Marseille Universite8 University of Sydney9 European Space Astronomy Centre and European Space Agency10 ASI Science Data Center11 Universidad de La Laguna12 University Paris Diderot - Paris 713 University of Copenhagen14 University of Edinburgh15 Pierre and Marie Curie University - University of Paris VI16 Thüringer Landessternwarte Tautenburg17 Stockholm University18 University of Leicester19 Instituto de Astrofísica de Andalucía20 Leiden University21 Ghent University22 Vrije Universiteit Brussel23 University of Sydney24 University of Edinburgh25 Stockholm University26 University of Leicester
Gamma-ray bursts (GRBs) have been proposed as a tool to study star formation in the Universe, so it is crucial to investigate whether their host galaxies and immediate environments are in any way special compared with other star-forming galaxies. Here we present spatially resolved maps of dust emission of the host galaxy of the closest known GRB 980425 at z=0.0085 using our new high-resolution observations from Herschel, APEX, ALMA and ATCA. We modeled the spectral energy distributions of the host and of the star-forming region displaying the Wolf-Rayet signatures in the spectrum (WR region), located 800 pc away from the GRB position. The host is characterised by low dust content and high fraction of UV-visible star-formation, similar to other dwarf galaxies. Such galaxies are abundant in the local universe, so it is not surprising to find a GRB in one of them, assuming the correspondence between the GRB rate and star-formation. The WR region contributes substantially to the host emission at the far-infrared, millimeter and radio wavelengths and we propose this to be a consequence of its high gas density. If dense environments are also found close to the positions of other GRBs, then the ISM density should also be considered as an important factor influencing whether a given stellar population can produce a GRB, in a similar way as metallicity.
Astronomy and Astrophysics, 2014, Vol 562, Issue A70