Outflows from dwarf starbursts are ubiquitous: kinematics of z<0.3 GRB-SN hosts resolved with FLAMES. (arXiv:1904.05935v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Thone_C/0/1/0/all/0/1">C. C. Thöne</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Izzo_L/0/1/0/all/0/1">L. Izzo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Flores_H/0/1/0/all/0/1">H. Flores</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Postigo_A/0/1/0/all/0/1">A. de Ugarte Postigo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vergani_S/0/1/0/all/0/1">S. D. Vergani</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Christensen_L/0/1/0/all/0/1">L. Christensen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Covino_S/0/1/0/all/0/1">S. Covino</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Valle_M/0/1/0/all/0/1">M. Della Valle</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hammer_F/0/1/0/all/0/1">F. Hammer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Melandri_A/0/1/0/all/0/1">A. Melandri</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Puech_M/0/1/0/all/0/1">M. Puech</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rodrigues_M/0/1/0/all/0/1">M. A. Rodrigues</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gorosabel_J/0/1/0/all/0/1">J. Gorosabel</a>
The hosts of long duration gamma-ray bursts are predominantly starburst
galaxies at subsolar metallicity. At redshifts z<1, this implies that most of
them are low-mass dwarf galaxies similar to the populations of blue compact
dwarfs and dwarf irregulars. What triggers the massive star-formation needed
for producing a GRB progenitor is still largely unknown, as are the resolved
gas properties and kinematics of these galaxies and their formation history.
Here we present a sample of six spatially resolved GRB hosts at z<0.3 observed
with 3D spectroscopy at high spectral resolution (R=8,000-13,000) using
FLAMES/VLT. We analyze the resolved gas kinematics in the full and the
abundances in a subsample. Only two galaxies show a regular disk-like rotation
field, two are dispersion dominated and the others have several narrow emission
components associated with different parts of the galaxy, which might indicate
recent mergers. All galaxies show evidence for broad components underlying the
main narrow emission with FWHM of 150-300 km/s. This broad component is more
metal rich than the narrow components, blueshifted and follows a different
velocity structure. We find a weak correlation between the star-formation rate
and the FHWM of the broad component, its flux relative to the narrow component
and the maximum outflow velocity of the gas, but we not find any correlation
with the star-formation density, metallicity or stellar mass. We associate this
broad component with a metal rich outflow from star-forming regions in the
host. The GRB is not found at the brightest or most extreme region of the host
but is always associated with a star-forming region showing a clear wind
component. Our study shows the great potential of 3D spectroscopy to study the
star-formation processes in galaxies hosting extreme transients, the need for
high S/N and the dangers using un- or only partially resolved data.
The hosts of long duration gamma-ray bursts are predominantly starburst
galaxies at subsolar metallicity. At redshifts z<1, this implies that most of
them are low-mass dwarf galaxies similar to the populations of blue compact
dwarfs and dwarf irregulars. What triggers the massive star-formation needed
for producing a GRB progenitor is still largely unknown, as are the resolved
gas properties and kinematics of these galaxies and their formation history.
Here we present a sample of six spatially resolved GRB hosts at z<0.3 observed
with 3D spectroscopy at high spectral resolution (R=8,000-13,000) using
FLAMES/VLT. We analyze the resolved gas kinematics in the full and the
abundances in a subsample. Only two galaxies show a regular disk-like rotation
field, two are dispersion dominated and the others have several narrow emission
components associated with different parts of the galaxy, which might indicate
recent mergers. All galaxies show evidence for broad components underlying the
main narrow emission with FWHM of 150-300 km/s. This broad component is more
metal rich than the narrow components, blueshifted and follows a different
velocity structure. We find a weak correlation between the star-formation rate
and the FHWM of the broad component, its flux relative to the narrow component
and the maximum outflow velocity of the gas, but we not find any correlation
with the star-formation density, metallicity or stellar mass. We associate this
broad component with a metal rich outflow from star-forming regions in the
host. The GRB is not found at the brightest or most extreme region of the host
but is always associated with a star-forming region showing a clear wind
component. Our study shows the great potential of 3D spectroscopy to study the
star-formation processes in galaxies hosting extreme transients, the need for
high S/N and the dangers using un- or only partially resolved data.
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