Discovery of high-ionization far-ultraviolet line emission from the interstellar medium

1990 ◽  
Vol 350 ◽  
pp. 242 ◽  
Author(s):  
Christopher Martin ◽  
Stuart Bowyer
Keyword(s):  
Interstellar Medium ◽  
Line Emission ◽  
High Ionization ◽  
Far Ultraviolet

scholarly journals Challenges and Techniques for Simulating Line Emission

Galaxies ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 100 ◽  
Author(s):  
Karen Olsen ◽  
Andrea Pallottini ◽  
Aida Wofford ◽  
Marios Chatzikos ◽  
Mitchell Revalski ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Emission Line ◽  
Line Emission ◽  
Emission Lines ◽  
Synthetic Spectra ◽  
Recent Advances ◽  
The Future ◽  
Important Quality ◽  
Circumgalactic Medium

Modeling emission lines from the millimeter to the UV and producing synthetic spectra is crucial for a good understanding of observations, yet it is an art filled with hazards. This is the proceedings of “Walking the Line”, a 3-day conference held in 2018 that brought together scientists working on different aspects of emission line simulations, in order to share knowledge and discuss the methodology. Emission lines across the spectrum from the millimeter to the UV were discussed, with most of the focus on the interstellar medium, but also some topics on the circumgalactic medium. The most important quality of a useful model is a good synergy with observations and experiments. Challenges in simulating line emission are identified, some of which are already being worked upon, and others that must be addressed in the future for models to agree with observations. Recent advances in several areas aiming at achieving that synergy are summarized here, from micro-physical to galactic and circum-galactic scale.

The Interstellar Medium in the Far Ultraviolet

2009 ◽  
Author(s):  
J. Christopher Howk ◽  
Michael E. Van Steenberg ◽  
George Sonneborn ◽  
H. Warren Moos ◽  
William P. Blair
Keyword(s):  
Interstellar Medium ◽  
Far Ultraviolet

scholarly journals Local star-forming dwarf galaxies as windows on reionization-era stellar populations

2019 ◽  
Vol 15 (S352) ◽  
pp. 316-316
Author(s):  
Peter Senchyna
Keyword(s):  
Line Emission ◽  
Stellar Populations ◽  
Star Forming ◽  
Star Models ◽  
Relative Paucity ◽  
High Ionization ◽  
Low Metallicity ◽  
Nearby Galaxies ◽  
A New Technique

AbstractThe recent detections of high-ionization nebular line emission from species including CIV in a number of z > 6 galaxies have highlighted substantial deficiencies in our understanding of metal poor stars. Prominent nebular CIV has never been detected in purely star-forming systems locally, and the massive star models used to model this emission in photoionization codes have not been empirically calibrated below the metallicity of the SMC (20% solar). As a result, we are presently entirely unprepared to correctly interpret nebular emission from metal-poor stars observed with JWST and ALMA in the reionization era. We present results from a multi-pronged ongoing local ultraviolet/optical observation campaign with HST/COS, Keck/ESI, and MMT designed to address this issue by locating and characterizing stellar populations capable of powering such high-ionization emission. This work has already demonstrated that strong nebular CIV can be powered by extremely metal-poor (< 10% solar) massive stars, indicating that we may already have evidence of such low-metallicity populations in the reionization era. However, CIV at the equivalent widths detected at z > 6 remains elusive locally, potentially in part due to the relative paucity of known nearby galaxies at these metallicities with massive stellar populations comparable to those in z > 6 systems. We present a new technique to locate such nearby galaxies, and results from optical follow-up which indicate that a substantial population of highly star- forming metal-poor galaxies likely resides just below the detection limits of previous large spectroscopic surveys.

scholarly journals Polyaromatic disordered carbon grains as carriers of the UV bump: Far-UV to mid-IR spectroscopy of laboratory analogs

2017 ◽  
Vol 607 ◽  
pp. A73 ◽  
Author(s):  
L. Gavilan ◽  
K. C. Le ◽  
T. Pino ◽  
I. Alata ◽  
A. Giuliani ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Interstellar Dust ◽  
Vacuum Ultraviolet ◽  
Interstellar Extinction ◽  
Electronic Transitions ◽  
Mid Infrared ◽  
Pressure Experiment ◽  
Circumstellar Extinction ◽  
Integrated Intensities ◽  
Far Ultraviolet

Context. A multiwavelength study of laboratory carbons with varying degrees of hydrogenation and sp2 hybridization is required to characterize the structure of the carbonaceous carriers of interstellar and circumstellar extinction. Aims. We study the spectral properties of carbonaceous dust analogs from the far-ultraviolet to the mid-infrared and correlate features in both spectral ranges to the aromatic/aliphatic degree. Methods. Analogs to carbonaceous interstellar dust encountered in various phases of the interstellar medium have been prepared in the laboratory. These are amorphous hydrogenated carbons (a-C:H), analogs to the diffuse interstellar medium component, and soot particles, analogs to the polyaromatic component. Thin films (d < 100 nm) have been measured in transmission in the vacuum-ultraviolet (VUV; 120–210 nm) within the atmospheric pressure experiment (APEX) chamber of the DISCO beam line at the SOLEIL synchrotron radiation facility. Spectra of these films were further measured through the UV-Vis (210 nm–1 μm) and in the mid-infrared (3–15 μm). Results. Tauc optical gaps, Eg, are derived from the visible spectra. The major spectral features are fitted through the VUV to the mid-infrared to obtain positions, full-widths at half maximum (FWHM), and integrated intensities. These are plotted against the position of the π-π∗ electronic transitions peak. Unidentified or overlapping features in the UV are identified by correlations with complementary infrared data. A correlation between the optical gap and position of the π-π∗ electronic transitions peak is found. The latter is also correlated to the position of the sp3 carbon defect band at ~8 μm, the aromatic C=C stretching mode position at ~6 μm, and the H/C ratio. Conclusions. Ultraviolet and infrared spectroscopy of structurally diverse carbon samples are used to constrain the nanostructural properties of carbon carriers of both circumstellar and interstellar extinction, such as the associated coherent lengths and the size of polyaromatic units. Our study suggests that carriers of the interstellar UV bump should exhibit infrared bands akin to the A/B classes of the aromatic infrared bands, while the circumstellar bump carriers should exhibit bands corresponding to the B/C classes.

scholarly journals What do Gamma Rays tell us about the ISM?: New Insight from the Compton Observatory

1996 ◽  
Vol 169 ◽  
pp. 437-446 ◽  
Author(s):  
Hans Bloemen
Keyword(s):  
Interstellar Medium ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Line Emission ◽  
Cosmic Ray ◽  
Gamma Ray Astronomy ◽  
Early Results ◽  
The Galaxy ◽  
Γ Ray ◽  
Insight Into

Gamma-ray astronomy has become a rich field of research and matured significantly since the launch of NASA's Compton Gamma Ray Observatory in April 1991. Studies of the diffuse γ-ray emission of the Galaxy can now be performed in far more detail and extended into the MeV regime, including both continuum and line emission. These studies provide unique insight into various aspects of the interstellar medium, in particular of the cosmic-ray component. This paper gives a brief review on the diffuse Galactic γ-ray emission and summarizes early results and prospects from the Compton Observatory.

scholarly journals Observations of [OI]63 μm line emission in main-sequence galaxies at z ∼ 1.5

2020 ◽  
Vol 499 (2) ◽  
pp. 1788-1794
Author(s):  
J Wagg ◽  
M Aravena ◽  
D Brisbin ◽  
I Valtchanov ◽  
C Carilli ◽  
...  
Keyword(s):  
Field Strength ◽  
Interstellar Medium ◽  
Radiation Field ◽  
Uv Radiation ◽  
Main Sequence ◽  
Line Emission ◽  
The Other ◽  
Low Density ◽  
Star Forming ◽  
Neutral Gas

ABSTRACT We present Herschel–PACS spectroscopy of four main-sequence star-forming galaxies at z ∼ 1.5. We detect [OI]63 μm line emission in BzK-21000 at z = 1.5213, and measure a line luminosity, $L_{\rm [O\, {\small I}]63\, \mu m} = (3.9\pm 0.7)\times 10^9$ L⊙. Our PDR modelling of the interstellar medium in BzK-21000 suggests a UV radiation field strength, G ∼ 320G0, and gas density, n ∼ 1800 cm−3, consistent with previous LVG modelling of the molecular CO line excitation. The other three targets in our sample are individually undetected in these data, and we perform a spectral stacking analysis which yields a detection of their average emission and an [O i]63 μm line luminosity, $L_{\rm [O\, {\small I}]63\, \mu m} = (1.1\pm 0.2)\times 10^9$ L⊙. We find that the implied luminosity ratio, $L_{\rm [O\, {\small I}]63\, \mu m}/L_{\rm IR}$, of the undetected BzK-selected star-forming galaxies broadly agrees with that of low-redshift star-forming galaxies, while BzK-21000 has a similar ratio to that of a dusty star-forming galaxy at z ∼ 6. The high [O i]63 μm line luminosities observed in BzK-21000 and the z ∼ 1−3 dusty and sub-mm luminous star-forming galaxies may be associated with extended reservoirs of low density, cool neutral gas.

scholarly journals Detection of Escaping Lyman Continuum Radiation in Two Local Starbursts Using FUSE

2006 ◽  
Vol 2 (S235) ◽  
pp. 316-316
Author(s):  
E. Leitet ◽  
N. Bergvall ◽  
B-G Andersson ◽  
E. Zackrisson
Keyword(s):  
Interstellar Medium ◽  
Starburst Galaxies ◽  
Compact Galaxy ◽  
Archival Data ◽  
Continuum Radiation ◽  
Neutral Gas ◽  
Lyman Continuum ◽  
Profile Fitting ◽  
First Results ◽  
Far Ultraviolet

AbstractWe present the detection of escaping Lyman Continuum (LyC) radiation from two local starburst galaxies, Tol 1247-232 and Tol 0440-381, using archival data from the Far Ultraviolet Spectroscopic Explorer (FUSE). From profile fitting of metal lines, high densities of neutral gas were derived for both galaxies, implying that the LyC radiation is escaping from holes in the interstellar medium. The first results for one of the galaxies, Tol 1247-232, give an escape fraction (fesc) of 17–35%. These new detections, together with that of the blue compact galaxy Haro 11 in Bergvall et al. (2006) where fesc between 4–10% was found, will have a feedback on cosmic reionization models.

Carbon and oxygen X-ray line emission from the interstellar medium

1982 ◽  
Vol 253 ◽  
pp. 131 ◽  
Author(s):  
H. W. Schnopper ◽  
J. P. Delvaille ◽  
R. Rocchia ◽  
C. Blondel ◽  
C. Cheron ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Line Emission ◽  
X Ray
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