Slit and integral-field optical spectroscopy of the enigmatic quasar HE 0450–2958

Letawe, Géraldine; Magain, Pierre; Courbin, F.

doi:10.1051/0004-6361:20078725

Cited by 11 publications

(37 citation statements)

References 20 publications

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“…Using VLT/FORS and VLT/VIMOS data, Letawe et al (2008) found several clouds of highly ionized gas along the radio axis defined by Feain et al (2007). With our sub-arcsecond 5-GHz imaging, we can determine a more precise angle for the radio axis, that remains aligned with these clouds.…”

Section: First Evidence For a Bipolar Outflow In He0450−2958mentioning

confidence: 87%

“…The B1-B4 patches of radio emission spatially coincide with these emission line regions. B1, ∼10 kpc from the quasar, is associated spatially with Em3/Em4 and R3 from Letawe et al (2008). B2, the blob detected 1 kpc to the west of the quasar by HST, was found to have AGN-ionized gas according to line diagnostic diagrams.…”

Section: First Evidence For a Bipolar Outflow In He0450−2958mentioning

confidence: 92%

“…B3 lies too close to the quasar emission, so it was not observed by VLT. B4 (Gal2/Gal3 in Letawe et al 2008) shows a mix of stars and ionized gas. They have also observed two other emission line regions (Em1 and Em2) ∼10 kpc north and south of the quasar that were not detected by the JVLA at radio frequencies.…”

Section: First Evidence For a Bipolar Outflow In He0450−2958mentioning

confidence: 99%

“…The halo of ionized gas surrounding the quasar (Letawe et al 2008) is evidence of significant energy input from the AGN, in the form of radiative feedback, that may also have contributed to depleting the gas reservoir of the quasar host galaxy. At least two parallel lines of evidence (signatures of strong AGN feedback, plus matching SFR estimates for the companion SFG from spatially resolved radio data and unresolved FIR, see Section 4.2.1) hence suggest that ULIRG-like activity should be regarded as an upper limit to the host galaxy SFR.…”

Section: Disentangling Sf and Agn Activity In The Quasarmentioning

confidence: 99%

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Further evidence for a quasar-driven jet impacting its neighbour galaxy: The saga of HE0450-2958 continues

Molnár¹,

Sargent²,

Elbaz³

et al. 2017

Mon. Not. R. Astron. Soc.

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HE0450−2958, an interacting quasar-starburst galaxy pair at z = 0.285, is one of the bestknown examples of strong star formation activity in the presence of a quasar-driven jet. We present new multiband Karl G. Jansky Very Large Array-imaging covering 1-6 GHz and reaching an angular resolution of up to 0.6 arcsec (a sixfold improvement over existing radio data). We confirm the previous detection of a spatially extended radio component around the quasar, indicating that there is ongoing star formation activity in the quasar host galaxy. For the first time, we directly detect a jet-like bipolar outflow from the quasar aligned with its companion star-forming galaxy (SFG) and several blobs of ionized gas in its vicinity identified in previous studies. Within the companion SFG, we find evidence for a flattening of the synchrotron spectral index towards the point of intersection with the jet axis, further suggesting that the outflow may actually be impacting its interstellar medium. We discuss two possible mechanisms that could have triggered the starburst in the companion SFG: a wet-dry merger with the quasar and jet-induced star formation. While triggering through interaction-driven gas dynamics cannot be excluded with current data, our new observations make HE0450−2958 a strong candidate for jet-induced star formation, and one of the rare links between local systems (like Minkowski's Object or Centaurus A) and the high-z regime where radio-optical alignments suggest that this phenomenon could be more common.

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Section: First Evidence For a Bipolar Outflow In He0450−2958mentioning

confidence: 87%

Section: First Evidence For a Bipolar Outflow In He0450−2958mentioning

confidence: 92%

Section: First Evidence For a Bipolar Outflow In He0450−2958mentioning

confidence: 99%

Section: Disentangling Sf and Agn Activity In The Quasarmentioning

confidence: 99%

See 2 more Smart Citations

Further evidence for a quasar-driven jet impacting its neighbour galaxy: The saga of HE0450-2958 continues

Molnár¹,

Sargent²,

Elbaz³

et al. 2017

Mon. Not. R. Astron. Soc.

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“…Dynamics, BPT diagrams, and more are thus derived from the host-alone spectra. The method is fully described and applied to HE 0450−2958 by Letawe et al (2008b). Up-todate synthesis on this object is described by Elbaz et al (2009).…”

Section: Spectroscopymentioning

confidence: 99%

The Power of Deconvolution for Study of QSO Host Galaxies

Letawe¹,

Letawe²,

Magain³

2009

Proc. IAU

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Abstract. The major challenge in studying QSO host galaxies is to remove the QSO contribution, which often outshines the whole system. Our group has acquired the technical ability to handle such data, for images and slit spectroscopy, as well as integral field spectroscopy. We review here the major techniques developed by our team, and their latest applications. We are open for collaboration with other teams to spread the use of these powerful techniques.Keywords. techniques: image processing, spectroscopy, galaxies: active, quasars: general Spectroscopy: We apply the Magain, Courbin, & Sohy (1998) deconvolution routines to the separation of the quasar and host galaxy. In addition to detailed analysis of integrated host and quasar spectra (Letawe et al. 2007), we combine the information from spatially resolved slit spectra to high-resolution imaging from HST/ACS (Letawe et al. 2008a). These studies clarify the role of interaction in bringing gas and dust to the nucleus and reveal the dominance of host galaxies containing young stellar populations and ionized gas as well as the broad nuclear Hα reflected line far from the nucleus. The peculiar source HE 0450−2958 (Magain et al. 2005) has been a focus of this work.Integral field spectroscopy: Based on VLT IFU observations of quasars, we remove the nuclear contributions by subtracting a weighted nuclear spectrum (taken at the central position), relying on the spectral signature of the broad nuclear Balmer lines. Dynamics, BPT diagrams, and more are thus derived from the host-alone spectra. The method is fully described and applied to HE 0450−2958 by Letawe et al. (2008b). Up-todate synthesis on this object is described by Elbaz et al. (2009).Imaging: A large sample of bright low-redshift quasars, observed with NTT/SUSI2 through two optical filters, has been deconvolved, separating quasar and hosts (Letawe et al. 2009). A detailed analysis of morphologies, asymmetries, and gas content of the hosts shows that (i) host galaxies have on average more ionized gas than quiescent galaxies, with the discrepancy being more pronounced for ellipticals, (ii) asymmetries in ellipticals are mainly due to a shift between the position of the active nuclei and the center of the galaxy, possibly suggestive of a BH recoil after a binary merger, and (iii) 60% of the hosts show signs of interaction, both ellipticals (50% of the sample) and spirals (25% of the sample).

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The Role of Quasars in Galaxy Formation

Elbaz¹

2009

Proc. IAU

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Abstract. We discuss evidence that quasars, and more generally radio jets, may have played an active role in the formation stage of galaxies by inducing star formation, i.e., through positive feedback. This mechanism first proposed in the 1970s has been considered as anecdotal until now, contrary to the opposite effect that is generally put forward, i.e., the quenching of star formation in massive galaxies to explain the galaxy bimodality, downsizing, and the universal black hole mass over bulge stellar mass ratio. This suggestion is based on the recent discovery of an ultra-luminous infrared galaxy, i.e., an extreme starburst, that appears to be triggered by a radio jet from the QSO HE 0450−2958 at z = 0.2863, together with the finding in several systems of a positional offset between molecular gas and quasars, which may be explained by the positive feedback effect of radio jets on their local environment.

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Slit and integral-field optical spectroscopy of the enigmatic quasar HE 0450–2958

Cited by 11 publications

References 20 publications

Further evidence for a quasar-driven jet impacting its neighbour galaxy: The saga of HE0450-2958 continues

Further evidence for a quasar-driven jet impacting its neighbour galaxy: The saga of HE0450-2958 continues

The Power of Deconvolution for Study of QSO Host Galaxies

The Role of Quasars in Galaxy Formation

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