55 research outputs found
Revisiting FUSE O VI Emission in Galaxy Halos
A significant fraction of baryons in galaxies are in the form of diffuse gas
of the circumgalactic medium (CGM). One critical component of the multi-phases
of CGM, the so-called "coronal" warm-hot phase gas ( K)
traced by O VI 1031.93, 1037.62 \r{A} resonance lines, has rarely been detected
in emission from galaxy halos other than Milky Way. Here we report four
additional detections of O VI emission gas in the halos of nearby edge-on
galaxies, NGC 4631 and NGC 891, using archival Far Ultraviolet Spectroscopic
Explorer data and an updated data pipeline. We find the most intense O VI
emission to be from fields forming a vertical line near the center of NGC 4631,
despite the close proximity to the disk of two other fields. The detected O VI
emission surface brightness are about 1.1 to
3.9 ergs s cm arcsec. The
spatial distribution of the five 30" 30" O VI detection fields in NGC
4631 can be interpreted as the existence of filamentary structures of more
intense O VI emission superimposed within a diffuse and faint O VI halo in
star-forming galaxies. Volume-filled O VI emission mapping is greatly needed to
determine the structure and prevalence of warm-hot gas and the role it plays in
the cycling of gas between the galaxy disk and the halo. Finally, we present
the sensitivity of future funded and proposed UV missions (LUVOIR-A, LUVOIR-B,
CETUS, and Aspera) to the detection of diffuse and faint O VI emission in
nearby galaxy halos.Comment: 12 pages, 5 figures, accepted for publication in Ap
FIREBall-2: flight preparation of a proven balloon payload to image the intermediate redshift circumgalactic medium
FIREBall-2 is a stratospheric balloon-borne 1-m telescope coupled to a UV
multi-object slit spectrograph designed to map the faint UV emission
surrounding z~0.7 galaxies and quasars through their Lyman-alpha line emission.
This spectro-imager had its first launch on September 22nd 2018 out of Ft.
Sumner, NM, USA. Because the balloon was punctured, the flight was abruptly
interrupted. Instead of the nominal 8 hours above 32 km altitude, the
instrument could only perform science acquisition for 45 minutes at this
altitude. In addition, the shape of the deflated balloon, combined with a full
Moon, revealed a severe off-axis scattered light path, directly into the UV
science detector and about 100 times larger than expected. In preparation for
the next flight, and in addition to describing FIREBall-2's upgrade, this paper
discusses the exposure time calculator (ETC) that has been designed to analyze
the instrument's optimal performance (explore the instrument's limitations and
subtle trade-offs)
Extreme Ultraviolet Reflective Grating Characterization and Simulationsfor the Aspera SmallSat Mission
The Aspera SmallSat mission is designed to detect and map the warm-hot gaseous component of the halos of nearby galaxies through long-slit spectroscopy of the ionized O VI emission line (103.2 nm) for the first time. The Aspera Rowland circle type spectrograph uses a toroidal grating coated with a multilayer film consisting of aluminum, lithium fluoride, and magnesium fluoride capping to optimize reflectivity in the extreme ultraviolet (EUV) waveband from 103 to 104nm. We discuss the grating characterization test setup at the University of Arizona (UA), which will validate the multilayer coating and grating efficiency in a UV vacuum chamber. We also simulate the reflectivity of the multilayer thin film coating using IMD IDL software to compare simulated results with measured reflectivity. Additionally, non-sequential ray trace simulations and 3D CAD modeling are used for verification of the test setup. Finally, the implications of the differences between the measured and simulated reflectivity and grating efficiencies are considered, including impact to the mission
The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment
The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in
operation since July 2014. This paper describes the second data release from
this phase, and the fourteenth from SDSS overall (making this, Data Release
Fourteen or DR14). This release makes public data taken by SDSS-IV in its first
two years of operation (July 2014-2016). Like all previous SDSS releases, DR14
is cumulative, including the most recent reductions and calibrations of all
data taken by SDSS since the first phase began operations in 2000. New in DR14
is the first public release of data from the extended Baryon Oscillation
Spectroscopic Survey (eBOSS); the first data from the second phase of the
Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2),
including stellar parameter estimates from an innovative data driven machine
learning algorithm known as "The Cannon"; and almost twice as many data cubes
from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous
release (N = 2812 in total). This paper describes the location and format of
the publicly available data from SDSS-IV surveys. We provide references to the
important technical papers describing how these data have been taken (both
targeting and observation details) and processed for scientific use. The SDSS
website (www.sdss.org) has been updated for this release, and provides links to
data downloads, as well as tutorials and examples of data use. SDSS-IV is
planning to continue to collect astronomical data until 2020, and will be
followed by SDSS-V.Comment: SDSS-IV collaboration alphabetical author data release paper. DR14
happened on 31st July 2017. 19 pages, 5 figures. Accepted by ApJS on 28th Nov
2017 (this is the "post-print" and "post-proofs" version; minor corrections
only from v1, and most of errors found in proofs corrected
- …