| 1. |
- Aalto, Susanne, 1964
(author)
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Astrochemistry and star formation in nearby galaxies: From galaxy disks to hot nuclei
- 2016
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In: EAS Publications Series. - : EDP Sciences. - 1633-4760 .- 1638-1963. - 9782759820221 ; 75-76, s. 73-80
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Conference paper (peer-reviewed)abstract
- Studying the molecular phase of the interstellar medium in galaxies is fundamental for the understanding of the onset and evolution of compact and extended star formation, and of the growth of supermassive black holes. Molecular line emission is an excellent tracer of chemical, physical and dynamical conditions in the cold neutral gas. Key molecules in extragalactic studies are e.g. HCN, HCO+, HC3N, SiO, CH3OH, H2O. Furthermore, we can use IR excited molecular emission to probe the very inner regions of luminous infrared galaxies allowing us to get past the optically thick dust barrier of the compact obscured nuclei where lines of CO, HCN and HCO+ in their vibrational ground state (?=0) may be self-absorbed. Finally, molecular outflows and their chemistry are briefly discussed-including new ALMA results on for example the outflow of the lenticular galaxy NGC1377 and a study of the chemistry of the outflow of the quasar Mrk231.
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| 2. |
- Costagliola, Francesco, 1981, et al.
(author)
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Exploring the molecular chemistry and excitation in obscured LIRGs: An ALMA mm-wave spectral scan of NGC 4418
- 2016
-
In: EAS Publications Series. - : EDP Sciences. - 1633-4760 .- 1638-1963. - 9782759820221 ; 75-76, s. 67-68
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Conference paper (peer-reviewed)abstract
- The compact, obscured nuclei (CON) of luminous infrared galaxies (LIRG) combine large molecular columns with intense infrared (IR), ultra-violet (UV), and X-radiation and represent ideal laboratories for the study of the chemistry of the interstellar medium (ISM) under extreme conditions. Here we present the first ALMA wide-band spectral scan of a dusty LIRG, the CON NGC 4418. We derive molecular abundances and compare them with other Galactic and extragalactic sources. Our spectral scan confirms that the chemical complexity in the nucleus of NGC 4418 is one of the highest ever observed outside our Galaxy. We suggest that the galaxy may be a template for a new kind of chemistry and excitation, typical of CON.
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| 3. |
- Mangum, J. G., et al.
(author)
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Densitometry and Thermometry of Starburst Galaxies
- 2016
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In: EAS Publications Series. - : EDP Sciences. - 1633-4760 .- 1638-1963. - 9782759820221 ; 75-76, s. 61-65
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Conference paper (peer-reviewed)abstract
- With a goal toward deriving the physical conditions in external galaxies, we have conducted a survey and subsequent high spatial resolution imaging of formaldehyde (H2CO) and ammonia (NH3) emission and absorption in a sample of starburst galaxies. In this article we present the results from a subset of this survey which focuses on high spatial resolution measurements of volume density-and kinetic temperature-sensitive transitions of the H2CO molecule. The volume density structure toward the nuclear region of NGC 253 has been derived from ? ≠4 arcsec NRAO Very Large Array (VLA) measurements of the 110-111 and 211-212 K-doublet transitions of H2CO. The kinetic temperature structure toward NGC 253 and NGC 4945 has been derived from ? ≠0.5-1.0 arcsec measurements of the H2CO 3K-1K+1-2K-1K+1 (near 218 GHz) and 5K-1K+1-4K-1K+1 (near 365 GHz) transitions acquired using the Atacama Large Millimeter/submillimeter Array (ALMA). These measurements have allowed us to characterize the dense gas and kinetic temperature structure within these star forming galaxies, which is a first step toward associating dense star-forming gas and the heating processes at work within galaxies.
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| 4. |
- Baan, Willem A., et al.
(author)
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Dense Molecular Gas in Luminous Infrared Galaxies: Diagnosing the ISM
- 2008
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In: EAS Publications Series. - : EAS, EDP Sciences. - 1633-4760 .- 1638-1963. ; 31, s. 111-114
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Journal article (peer-reviewed)abstract
- The behavior of molecular tracers of the high-density star-forming ISM provides a diagnostics tool for luminous FIR galaxies. All molecules react differently to the physical and chemical environment and their collective behavior is indicative of the excitation of the ISM and its evolutionary state. This paper describes efforts to diagnose the nuclear medium through multiple-molecule studies.
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| 5. |
- Edgar, Brian, 1945-, et al.
(author)
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The new potential for the Weyl tensor in n dimensions : wave equation and gauge
- 2008
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In: Spanish Relativity Meeting 2007,2007. - Spain : EDR. ; , s. 245-248
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Conference paper (peer-reviewed)abstract
- Although the Lanczos potential (a (2,1) form, L) for the Weyl tensor does not exist in dimensions greater than four, a new potential (a (2,3) form, P, which coincides with the double dual of L in four dimensions) has recently been shown to exist in all dimensions. In this talk we discuss the structure of its wave equation which is obtained from the Bianchi identities, and the related question of gauge.
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| 6. |
- Farzone, M., et al.
(author)
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What is the origin of the water vapour signatures in red giant stars?
- 2013
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In: EAS Publications Series. - : EDP Sciences. - 1633-4760 .- 1638-1963. - 9782759809974 ; 60, s. 155-159
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Conference paper (peer-reviewed)abstract
- We investigate the occurrence of water vapour signatures in a total of 10 red giants in the solar neighbourhood at mid-infrared wavelengths (12 pm). With the use of high resolution spectra from TEXES and synthesized spectra based on MARCS model atmospheres, we analyse the differences and discuss plausible causes. These include abundance adjustments, the addition of non-photospheric components (MOLspheres) and a different temperature profile.
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| 7. |
- Feiden, Gregory, 1986-, et al.
(author)
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Magnetic Field Induced Radius Inflation of Low-Mass Stars
- 2013
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In: Binary 2013: Setting a new standard in the analysis of binary stars.. - : EDP Sciences.
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Conference paper (other academic/artistic)abstract
- We present results obtained using the magnetic Dartmouth stellar evolution code that address the possibility that magnetic fields are inflating low-mass stars in detached eclipsing binaries. While it seems plausible that magnetic fields are inflating stars with radiative cores, the level of inflation observed among fully convective stars appears too large to be explained by magnetic fields. We provide an alternative explanation, stellar metallicity, and propose observations that can help further constrain stellar models.
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| 8. |
- Holl, Berry, et al.
(author)
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Characterizing the Astrometric Errors in the Gaia Catalogue
- 2011
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In: EAS Publications Series. - : EDP Sciences. - 1633-4760 .- 1638-1963. ; 45:GAIA: At the Frontiers of Astrometry, s. 117-122
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Journal article (peer-reviewed)abstract
- Accurate characterization of the errors in the global astrometric solution for Gaia is essential for making optimal use of the catalogue data. We investigate the structure of the covariance between the estimated astrometric parameters by studying the properties of the astrometric least squares solution. We find that astrometric errors can be separated in a star and an attitude part, due to the estimation of the star and attitude parameters respectively. Hence the covariances can be separated in a star, an attitude and a cross term. This is demonstrated using our scalable simulation tool AGISLab, where the covariances are estimated statistically using Monte Carlo techniques.
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| 9. |
- Lammers, U., et al.
(author)
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News on Seeking Gaia's Astrometric Core Solution with AGIS
- 2011
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In: EAS Publications Series. - : EDP Sciences. - 1633-4760 .- 1638-1963. ; 45:GAIA: At the Frontiers of Astrometry, s. 123-126
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Journal article (peer-reviewed)abstract
- We report on recent new developments around the Astrometric Global Iterative Solution system. This includes the availability of an efficient Conjugate Gradient solver and the Generic Astrometric Calibration scheme that had been proposed a while ago. The number of primary stars to be included in the core solution is now believed to be significantly higher than the 100 Million that served as baseline until now. Cloud computing services are being studied as a possible cost-effective alternative to running AGIS on dedicated computing hardware at ESAC during the operational phase.
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| 10. |
- Lindegren, Lennart, et al.
(author)
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Basic principles of scanning space astrometry
- 2011
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In: EAS Publications Series. - : EDP Sciences. - 1633-4760 .- 1638-1963. ; 45:GAIA: At the Frontiers of Astrometry, s. 109-114
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Journal article (peer-reviewed)abstract
- We outline the basic principles of scanning space astrometry, such as represented by Hipparcos, Gaia, and some other astrometric satellites planned or proposed. We explain the need for large-angle measurements, why these are essentially one-dimensional, how it is possible to determine absolute parallaxes, and why a Hipparcos-type scanning law is favourable. We discuss the choice of the basic angle between the two viewing directions, the principle of self-calibration, and why the resulting numerical problem must be difficult to solve.
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