On-axis spectroscopy of the host galaxies of 20 optically luminous quasars at z ~ 0.3
By G. Letawe, Pierre Magain, F. Courbin, P. Jablonka, K. Jahnke, G. Meylan, L. Wisotzki. 2006
42 citations recorded by the source corpus.
We present the analysis of a sample of 20 bright low-redshift quasars (M B < - 23 and z < 0.35) observed spectroscopically with the Very Large Telescope (VLT). The Focal Reducer/low dispersion Spectrograph (FORS1) spectra, obtained in Multi-Object Spectroscopy (MOS) mode, allow to observe simultaneously the quasars and several reference stars used to spatially deconvolve the data. Applying the Magain, Courbin & Sohy (MCS) deconvolution method, we are able to separate the individual spectra of the quasar and of the underlying host galaxy. Contrary to some previous claims, we find that luminous quasars are not exclusively hosted by massive ellipticals. Most quasar host galaxies harbour large amounts of gas, irrespective of their morphological type. Moreover, the stellar content of half of the hosts is a young Sc-like population, associated with a rather low-metallicity interstellar medium. A significant fraction of the galaxies contain gas ionized at large distances by the quasar radiation. This large distance ionization is always associated with signs of gravitational interactions (as detected from images or disturbed rotation curves). The spectra of the quasars themselves provide evidence that gravitational interactions bring dust and gas in the immediate surrounding of the super massive black hole, allowing to feed it. The quasar activity might thus be triggered (1) in young gas-rich spiral galaxies by local events and (2) in more evolved galaxies by gravitational interactions or collisions. The latter mechanism gives rises to the most powerful quasars. Finally, we derive mass models for the isolated spiral host galaxies and we show that the most reliable estimators of the systemic redshift in the quasar spectrum are the tips of the Ha and Hβ lines.
Subfields: Astronomy and Astrophysics, Instrumentation, AI for Physical Sciences
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Citations in the corpus
- Generative Adversarial Networks recover features in astrophysical images of galaxies beyond the deconvolution limit (2017, background): “Deconvolution has long been known as an ‘ill-posed’ inverse problem because there is often no unique solution if one follows the signal processing approach of backwards modelling (Magain et al. 1998, 2007; Letawe et al. 2007, 2008; Cantale et al. 2016).”
- A Cosmological Framework for the Co-Evolution of Quasars, Supermassive Black Holes, and Elliptical Galaxies. I. Galaxy Mergers and Quasar Activity (2007, background): “…have the youngest host stellar populations (Jahnke et al. 2004a;VandenBerk et al. 2006) and the greatest prominence of postmerger tidal features and disturbances (Canalizo & Stockton 2001; Kauffmann et al. 2003; Hutchings et al. 2003, 2006; Hutchings 2003; Zakamska et al. 2006; Letawe et al. 2007).”
- The ZipML Framework for Training Models with End-to-End Low Precision: The Cans, the Cannots, and a Little Bit of Deep Learning (2016, background): “Deconvolution has long been known as an “ill-posed” inverse problem because there is often no unique solution if one follows the signal processing approach of backwards modelling [32, 31, 25, 26, 8].”
- Properties of flat-spectrum radio-loud Narrow-Line Seyfert 1 Galaxies (2014, background): “The contribution of the host galaxy in objects atz> 0.1 is typically less than 10% (Letawe et al. 2007).”