J/A+A/674/A210 Starburst galaxy UM 462 datacube (Monreal-Ibero+, 2023)
UM462, a local green pea galaxy analogue under the MUSE magnifying glass.
Monreal-Ibero A., Weilbacher P.M., Micheva G., Kollatschny W., Maseda M.
<Astron. Astrophys. 674, A210 (2023)>
=2023A&A...674A.210M 2023A&A...674A.210M (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies ; Spectroscopy ; Optical ; Infrared
Keywords: galaxies: starburst - galaxies: dwarf - galaxies: individual: UM 462 -
galaxies: ISM - galaxies: abundances -
galaxies: kinematics and dynamics
Abstract:
Stellar feedback in high-redshift galaxies plays an important, if not
dominant, role in the re-ionisation epoch of the Universe. Because of
their extreme star formation (SF), the relatively closer green pea
(GP) galaxies are postulated as favorite local laboratories, and
analogues to those high-redshift galaxies. However, at their typical
redshift of z∼0.2, the most intimate interaction between stars and the
surrounding interstellar medium cannot be disentangled. Detailed
studies of blue compact dwarf (BCD) galaxies sharing properties with
GP galaxies are necessary to anchor our investigations on them.
We want to study in detail UM462, which is a BCD with emission line
ratios and equivalent widths, stellar mass, and metallicity similar to
those observed in GP galaxies, and thus it is ideally suited as a
corner stone and reference galaxy.
We use high-quality optical integral field spectroscopy data obtained
with MUSE on the ESO Very Large Telescope. Results. The electron
density (ne) and temperature (Te) were mapped. Median Te decreases
according to the sequence [SIII]->[NII]->HeI. Furthermore, Te([SIII])
values are ∼13000K, and uniform within the uncertainties over an
area of ∼20"x8" (∼1.4kpcx0.6kpc). The total oxygen abundance by
means of the direct method is 12+log(O/H)∼8.02 and homogenous all
over the galaxy within the uncertainties, which is in stark contrast
with the metallicities derived from several strong line methods. This
result calls for a systematic study to identify the best strategy to
determine reliable metallicities at any location within a galaxy. The
strong line ratios used in the BPT diagrams and other ratios tracing
the ionisation structure were mapped. They are compatible with plasma
ionised by massive hot stars. However, there is a systematic excess in
the [OI]/Hα ratio, suggesting an additional mechanism or a
complex relative configuration of gas and stars. The velocity field
for the ionised gas presents receding velocities in the east and
approaching velocities in the west and south-west with velocity
differences of Dv∼40km/s, but it is not compatible with simple
rotation. The most striking feature is a velocity stratification in
the area towards the north with redder velocities in the high
ionisation lines and bluer velocities in the low ionisation lines.
This is the only area with velocity dispersions clearly above the MUSE
instrumental width, and it is surrounded by two ∼1kpc-long structures
nicknamed 'the horns'. We interpret the observational evidence in
that area as a fragmented super-bubble fruit of the stellar feedback
and it may constitute a preferred channel through which Lyman
continuum photons from the youngest generation of stars can escape.
The galaxy luminosity is dominated by a young (i.e. ∼6Myr) stellar
population that contributes only 10% to the stellar mass, as derived
from the modelling of the stellar continuum. The most recent SF seems
to propagate from the outer to the inner parts of the galaxy, and then
from east to west. We identified a supernova remnant and Wolf-Rayet
stars - as traced by the red bump - that support this picture. The
direction of the propagation implies the presence of younger
Wolf-Rayet stars at the maximum in Ha. These may be detected by deep
observations of the blue bump (not covered here).
The ensemble of results exemplifies the potential of 2D detailed
spectroscopic studies of dwarf star-forming galaxies at high spatial
resolution as a key reference for similar studies on primeval
galaxies.
Description:
The dwarf starburst galaxy UM 462 (Mrk 1307) was observed as part of a
backup target for the MUSE Guaranteed Time Observations (GTO)
programme at the Very Large Telescope on the night of 17 April 2018.
We provide here our reduced data cube, once cut and corrected from
Galactic extinction, as described in Sect. 2 in Monreal-Ibero et al.
2023, and used in that work. It covers an area of 52.8"x63.2", with a
sampling of 0.2" and a spectral range of 4749.79-9349.79Å with a
sampling of 1.25Å/pix.
Objects:
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RA (2000) DE Designation(s)
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11 52 37.18 -02 28 09.8 UM 462 = Mrk 1307
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 156 1 Information on fits datacube
fits/* . 1 fits datacube
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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 pixels along Z-axis
37- 57 A21 "datime" Obs.date Observation date
59- 65 F7.2 0.1nm bAWAV Lower value of wavelength interval
67- 73 F7.2 0.1nm BAWAV Upper value of wavelength interval
75- 78 F4.2 0.1nm/pix dAWAV Wavelength sampling
80- 86 I7 Kibyte size Size of FITS file
88-112 A25 --- FileName Name of FITS file, in subdirectory fits
114-156 A43 --- Title Title of the FITS file
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Acknowledgements:
Ana Monreal-Ibero, monreal(at)strw.leidenuniv.nl
(End) Patricia Vannier [CDS] 19-Jun-2023