Search Publications
Astrometric measurement techniques
Reffert, Sabine
This contribution reviews the various principles which form the basis of astrometric measurements, such as meridian circle observations, imaging techniques, scanning satellites and interferometry. Various projects which employ those techniques are described, e.g. the Multichannel Astrometric Photometer, the Fine Guidance Sensors onboard the Hubble…
A new view on the ISM of galaxies: Far-infrared and submillimetre spectroscopy with Herschel
Wilson, Christine D.; Baes, Maarten; Madden, Suzanne C. +2 more
The FIR/submm window is amongst the least explored spectral regions of the electromagnetic spectrum. It is, however, a key to study the general properties of the interstellar medium of galaxies, as it contains important spectral line diagnostics from the neutral, ionized and molecular ISM. The Herschel Space Observatory, successfully launched on 1…
Positron astronomy with SPI/INTEGRAL
Knödlseder, J.; Schanne, S.; Cordier, B. +7 more
We provide an overview of positron astronomy results that have been obtained using the INTEGRAL spectrometer SPI, and discuss their implications for the still mysterious origin of positrons in our Galaxy. It has long been known that the 511 keV positron annihilation emission is strongest from the central region of our Galaxy. Recently, it has been…
The Cygnus region: A laboratory for nucleosynthesis
Martin, Pierrick; Knödlseder, Jürgen; Meynet, Georges
We have observed the Cygnus region in the gamma-ray decay lines of 26Al and 60Fe with the INTEGRAL/SPI spectrometer. A study of the morphology of the 1809 keV emission from 26Al suggests an emission region centered about the massive star cluster Cyg OB2, with a characteristic size between 6° and 9° or possibly high…
A molecular gas study of low luminosity radio galaxies
Prandoni, I.; Wilson, T. L.; de Ruiter, H. R. +3 more
We discuss CO spectral line data of a volume-limited sample of 23 nearby ( z < 0.03) low luminosity radio galaxies, selected from the B2 catalogue. We investigate whether the CO properties of our sample are correlated with the properties of the host galaxy, and in particular with the dust component. We find strong evidences for a physical link …
Cold and hot gas in the most HI deficient compact groups
Yun, Min S.; Verdes-Montenegro, Lourdes; Borthakur, Sanchayeeta +2 more
Dense groups of galaxies should be prime sites for galaxy interactions and mergers, and their evolution has been the subject of controversy for 25 years. In order to explain the HI deficiency found in compact groups of galaxies we previously proposed an evolutionary scenario in which the amount of HI decreases with the secular evolutionary state o…
Witnessing the formation of a brightest cluster galaxy at z > 2
Ford, Holland C.; Miley, George K.; Overzier, Roderik A.
We present deep observations taken with the HST advanced camera for surveys of the central massive galaxy in a forming cluster at z = 2.2. The galaxy hosting the powerful radio source MRC 1138-262 is associated with one of the most extensive merger systems known in the early universe. Our HST/ACS image shows many star-forming galaxies merging with…
Ionized gas in starbursts: Case study of M82 and a note on NGC 1275
Gallagher, J. S.
Starbursts can be considered as galaxies where the normal self-regulation between the densities of young stars and the state of the ISM has broken down. This contribution briefly examines how intense modes of star formation influence the ISM, primarily as measured through properties of the warm ionized gas.
Winds from super star clusters: The interstellar environment in the starburst core of M82
Smith, L. J.; Westmoquette, M. S.
We present HST/STIS spectroscopy for two slit positions crossing the starburst core of M82, sampling both clusters and ionized gas at optical wavelengths. The spectra have a spatial resolution of ∼2 pc at M82, allowing us to probe the conditions within the starburst environment in unprecedented detail. The data provide new insights into young clus…
Black hole masses from reverberation mapping
Peterson, Bradley M.; Bentz, Misty C.
We review briefly how black hole masses are measured directly using reverberation mapping and indirectly through scaling relationships based on reverberation results, in particular through broad-line region radius-luminosity relationships. We discuss the nature and origin of uncertainties in these measurements, and outline current and future effor…