J/A+A/602/A85 SN 1998bw MUSE datacube (Kruehler+, 2017)
Hot gas around SN 1998bw: Inferring the progenitor from its environment.
Kruehler T., Kuncarayakti H., Schady P., Anderon J.P., Galbany L.,
Gensior J.
<Astron. Astrophys. 602, A85 (2017)>
=2017A&A...602A..85K 2017A&A...602A..85K (SIMBAD/NED BibCode)
ADC_Keywords: Gamma rays
Keywords: galaxies: ISM - galaxies: abundances - galaxies: star formation -
gamma-ray burst: general - gamma-ray burst: individual: GRB 980425
Abstract:
Spatially resolved spectroscopy of the environments of explosive
transients carries detailed information about the physical properties
of the stellar population that gave rise to the explosion, and thus
the progenitor itself. Here, we present new observations of
ESO184-G82, the galaxy hosting the archetype of the γ-ray
burst/supernova connection, GRB 980425/SN 1998bw, obtained with the
integral field spectrograph MUSE mounted at the Very Large Telescope.
These observations have yielded detailed maps of emission-line
strength for various nebular lines along with physical parameters such
as dust extinction, stellar age, and oxygen abundance on spatial
scales of 160pc. The immediate environment of GRB 980425 is young
5-8Myr) and consistent with a mildly extinguished (AV∼0.1mag)
progenitor of zero-age main-sequence mass between 25 M☉ and 40
M☉ and an oxygen abundance 12+log(O=H)∼8.2 (Z∼0.3Z☉),
which is slightly lower than that of an integrated measurement of the
whole galaxy (12+log(O=H)∼8.3) and a prominent nearby HII region
(12+log(O/H)∼8.4). This region is significantly younger than the
explosion site, and we argue that a scenario in which the GRB
progenitor formed in this environment and was subsequently ejected
appears very unlikely. We show that empirical strong-line methods
based on [O iii] and/or [N ii] are inadequate to produce accurate maps
of oxygen abundance at the level of detail of our MUSE observation as
these methods strongly depend on the ionization state of the gas. The
metallicity gradient in ESO184-G82 is -0.06dex/kpc,
indicating that the typical offsets of at most few kpc for cosmological
GRBs on average have a small impact on oxygen abundance measurements
at higher redshift.
Description:
The ESO184-G82 data cube (SN1998bwastphotcube.fits) is a
multi-dimensional fits file with a primary header and two extensions:
The primary header contains only the fits headers.
The first fits extension (DATA) contains the observed flux values in
units of 10-20erg/cm^2/s/Å. The dimensions of the cube
are 320x324x3682 where the first two are celestial coordinates (RA,
DEC), and the last one the wavelength coordinate.
The second fits extension (STAT) contains the estimated variance in
units of 10-40erg-2cm-4s-2Å-2
Objects:
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RA (2000) DE Designation(s)
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19 35 03.17 -52 50 46.1 SN1998bw = GRB 980425
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 126 2 Information on datacude
SN1998bw.fits 2880 1060456 Datacude (2.9G)
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 22 F3.1 arcsec/pix scale Scale of the image
24- 26 I3 --- Nx Number of pixels along X-axis
28- 30 I3 --- Ny Number of pixels along Y-axis
32- 35 I4 --- Nz Number of slices
37- 43 F7.2 0.1nm blambda Lower value of wavelength interval
45- 51 F7.2 0.1nm Blambda Upper value of wavelength interval
53- 59 F7.5 0.1nm dlambda Wavelenght resolution
61- 67 I7 Kibyte size Size of FITS file
69- 81 A13 --- FileName Name of FITS file
83-126 A44 --- Title Title of the FITS file extension
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Acknowledgements:
Thomas Kruehler, kruehler(at)mpe.mpg.de
(End) Patricia Vannier [CDS] 18-May-2017