29 research outputs found
Alien Registration- Eagle, Olive P. (Portland, Cumberland County)
https://digitalmaine.com/alien_docs/21405/thumbnail.jp
Alien Registration- Eagle, Olive P. (Portland, Cumberland County)
https://digitalmaine.com/alien_docs/21405/thumbnail.jp
Alien Registration- Brinchman, Arnold F. (Portland, Cumberland County)
https://digitalmaine.com/alien_docs/21342/thumbnail.jp
Alien Registration- Brinchman, Arnold F. (Portland, Cumberland County)
https://digitalmaine.com/alien_docs/21342/thumbnail.jp
The MUSE-Wide Survey: Survey Description and First Data Release
We present the MUSE-Wide survey, a blind, 3D spectroscopic survey in the
CANDELS/GOODS-S and CANDELS/COSMOS regions. Each MUSE-Wide pointing has a depth
of 1 hour and hence targets more extreme and more luminous objects over 10
times the area of the MUSE-Deep fields (Bacon et al. 2017). The legacy value of
MUSE-Wide lies in providing "spectroscopy of everything" without photometric
pre-selection. We describe the data reduction, post-processing and PSF
characterization of the first 44 CANDELS/GOODS-S MUSE-Wide pointings released
with this publication. Using a 3D matched filtering approach we detected 1,602
emission line sources, including 479 Lyman- (Lya) emitting galaxies
with redshifts . We cross-match the emission line
sources to existing photometric catalogs, finding almost complete agreement in
redshifts and stellar masses for our low redshift (z < 1.5) emitters. At high
redshift, we only find ~55% matches to photometric catalogs. We encounter a
higher outlier rate and a systematic offset of z0.2 when
comparing our MUSE redshifts with photometric redshifts. Cross-matching the
emission line sources with X-ray catalogs from the Chandra Deep Field South, we
find 127 matches, including 10 objects with no prior spectroscopic
identification. Stacking X-ray images centered on our Lya emitters yielded no
signal; the Lya population is not dominated by even low luminosity AGN. A total
of 9,205 photometrically selected objects from the CANDELS survey lie in the
MUSE-Wide footprint, which we provide optimally extracted 1D spectra of. We are
able to determine the spectroscopic redshift of 98% of 772 photometrically
selected galaxies brighter than 24th F775W magnitude. All the data in the first
data release - datacubes, catalogs, extracted spectra, maps - are available on
the website https://musewide.aip.de. [abridged]Comment: 25 pages 15+1 figures. Accepted, A&A. Comments welcom
Galaxy Collisions - Dawn of a New Era
The study of colliding galaxies has progressed rapidly in the last few years,
driven by observations with powerful new ground and space-based instruments.
These instruments have used for detailed studies of specific nearby systems,
statistical studies of large samples of relatively nearby systems, and
increasingly large samples of high redshift systems. Following a brief summary
of the historical context, this review attempts to integrate these studies to
address the following key issues. What role do collisions play in galaxy
evolution, and how can recently discovered processes like downsizing resolve
some apparently contradictory results of high redshift studies? What is the
role of environment in galaxy collisions? How is star formation and nuclear
activity orchestrated by the large scale dynamics, before and during merger?
Are novel modes of star formation involved? What are we to make of the
association of ultraluminous X-ray sources with colliding galaxies? To what do
degree do mergers and feedback trigger long-term secular effects? How far can
we push the archaeology of individual systems to determine the nature of
precursor systems and the precise effect of the interaction? Tentative answers
to many of these questions have been suggested, and the prospects for answering
most of them in the next few decades are good.Comment: 44 pages, 9 figures, review article in press for Astrophysics Update
Vol.
Extremely metal-poor star-forming galaxies. New detections and general morphological and photometric properties
(abridged) We present long-slit spectroscopy with the 3.6m ESO telescope of
eight HII regions in seven star-forming (SF) dwarf galaxies, discovered in SDSS
DR4 and 6dFGRS. In addition, we use SDSS imaging data to study the photometric
structure of the sample galaxies. From the 3.6m telescope spectra, we determine
the oxygen abundance of these systems to be 7.3<12+log(O/H)<7.6, placing them
among the most metal-poor SF galaxies ever discovered. Our photometric analysis
reveals a moderately blue, stellar host galaxy in all sample galaxies. The
detection of a stellar host in all galaxies studied here and all previously
studied extremely metal-deficient SF galaxies implies that they are unlikely to
be forming their first generation of stars. With regard to the structural
properties of their host galaxy, we demonstrate that these systems are
indistinguishable from blue compact dwarf (BCD) galaxies. However, in contrast
to the majority (>90%) of BCDs that are characterised by red elliptical host
galaxies, extremely metal-poor SF dwarfs (hereafter XBCDs) reveal moderately
blue and irregular hosts. This is consistent with a young evolutionary status
and in the framework of standard star formation histories implies that several
XBCDs formed most of their stellar mass in the past 2 Gyr. A large fraction of
XBCDs reveal a cometary morphology due to the presence of intense SF activity
at one edge of an elongated host galaxy with a gradually decreasing surface
brightness towards its antipodal end.Comment: 20 pages, 32 Postscript figures, accepted by Astronomy & Astrophysic
Microangiopathic complications in type 1 diabetes mellitus: differences in severity when isolated or associated with autoimmune polyendocrinopathies
Alien Registration- Eagle, Olive P. (Portland, Cumberland County)
https://digitalmaine.com/alien_docs/21405/thumbnail.jp
Alien Registration- Brinchman, Arnold F. (Portland, Cumberland County)
https://digitalmaine.com/alien_docs/21342/thumbnail.jp