Mapping UV properties throughout the cosmic horseshoe: Lessons from VLT-MUSE
Publication Date
2018-05Journal Title
Monthly Notices of the Royal Astronomical Society
ISSN
0035-8711
Publisher
Oxford University Press (OUP)
Volume
476
Issue
2
Pages
1726-1740
Type
Article
This Version
VoR
Metadata
Show full item recordCitation
James, B., Auger, M., Pettini, M., Stark, D., Belokurov, V., & Carniani, S. (2018). Mapping UV properties throughout the cosmic horseshoe: Lessons from VLT-MUSE. Monthly Notices of the Royal Astronomical Society, 476 (2), 1726-1740. https://doi.org/10.1093/mnras/sty315
Abstract
We present the first spatially-resolved rest-frame UV study of the
gravitationally lensed galaxy, the 'Cosmic Horseshoe' (J1148+1930) at z=2.38.
Our gravitational lens model shows that the system is made up of four
star-forming regions, each ~4-8 kpc^2 in size, from which we extract four
spatially exclusive regional spectra. We study the interstellar and wind
absorption lines, along with CIII] doublet emission lines, in each region to
investigate any variation in emission/absorption line properties. The mapped
CIII] emission shows distinct kinematical structure, with velocity offsets of
~+/-50 km/s between regions suggestive of a merging system, and a variation in
equivalent width that indicates a change in ionisation parameter and/or
metallicity between the regions. Absorption line velocities reveal a range of
outflow strengths, with gas outflowing between -200<v(km/s)<-50 relative to the
systemic velocity of that region. Interestingly, the strongest gas outflow
appears to emanate from the most diffuse star-forming region. The
star-formation rates remain relatively constant (~8-16 M_sol/yr), mostly due to
large uncertainties in reddening estimates. As such, the outflows appear to be
'global' rather than 'locally' sourced. We measure electron densities with a
range of log(Ne)=3.92-4.36 cm^-3, and point out that such high densities may be
common when measured using the CIII] doublet due to its large critical density.
Overall, our observations demonstrate that while it is possible to trace
variations in large scale gas kinematics, detecting inhomogeneities in physical
gas properties and their effects on the outflowing gas may be more difficult.
This study provides important lessons for the spatially-resolved rest-frame UV
studies expected with future observatories, such as JWST.
Sponsorship
BLJ thanks support from the European Space Agency (ESA) and SC acknowledges nancial support from the Science & Technology Facilities Council (STFC). The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement no. 308024.
Funder references
Science and Technology Facilities Council (ST/M001172/1)
European Research Council (308024)
Science and Technology Facilities Council (ST/K004182/1)
Science and Technology Facilities Council (ST/N000927/1)
Embargo Lift Date
2100-01-01
Identifiers
External DOI: https://doi.org/10.1093/mnras/sty315
This record's URL: https://www.repository.cam.ac.uk/handle/1810/275076
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