An optical spectroscopic survey of the 3CR sample of radio galaxies with z  &lt;  0.3

Capetti, A.; Buttiglione, S.; Axon, D. J.; Robinson, Andrew; Celotti, A.; Baldi, Ranieri D.; Chiaberge, M.; Macchetto, F.; Sparks, W. B.

doi:10.1051/0004-6361/201016026

Cited by 12 publications

(11 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Moreover, further evidence for intermittency of the fuel supply is provided by mid‐IR spectroscopic observations of ULIRGs which, despite generally being considered to represent the final stages of gas‐rich mergers (within ∼100 Myr of coalescence of the nuclei; Rodríguez‐Zaurín et al ), show a considerable range in the level of nuclear AGN activity, with the AGN energetically dominant in <50 per cent of cases (Veilleux et al ). We also note that, based on the detailed analysis of their optical emission‐line spectra, it has been suggested that the AGN in some other WLRG have only recently switched off (Capetti et al ).…”

Section: Discussionmentioning

confidence: 73%

“…However, if the AGN has switched off completely over this period, and the AGN is the only source of ionization for the [O iii ] emission, then we would expect to observe negligible [O iii ] flux in most WLRGs. This is because the e‐folding time of the intensity decline in the [O iii ] emission is only ∼20 yr for a typical NLR electron density of n e = 100 cm −3 (Binette & Robinson ; Capetti et al ). In contrast, we do detect weak but significant [O iii ] emission from all three WLRGs in the high‐power radio galaxy sample described above.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

PKS 0347+05: a radio-loud/radio-quiet double active galactic nucleus system triggered in a major galaxy merger

Tadhunter

Almeida

Morganti

et al. 2012

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We present optical, infrared (IR) and radio observations of the powerful Fanaroff–Riley type II (FR II) radio source PKS 0347+05 (z = 0.3390), and demonstrate that it is a rare example of a radio‐loud/radio‐quiet double active galactic nucleus (AGN) system, comprising a weak‐line radio galaxy (WLRG) separated by 25 kpc (in projection) from a Seyfert 1 nucleus at the same redshift. Our deep Gemini optical images show a highly disturbed morphology, with a warped dust lane crossing through the halo and nuclear regions of the radio galaxy host, tidal tails and a bridge connecting the radio galaxy to the Seyfert 1 nucleus. Spectral synthesis modelling of our Gemini optical spectrum of the radio galaxy shows evidence for a reddened young stellar population of age ≤100 Myr. Further evidence for recent star formation activity in this source is provided by the detection of strong polycyclic aromatic hydrocarbon features in mid‐IR Spitzer/IRS spectra. Together, these observations support a model in which both AGN have been triggered simultaneously in a major galaxy merger. However, despite the presence of a powerful FR II radio source, and the apparently plentiful supply of fuel provided by the merger, the nucleus of the radio galaxy shows only weak, low‐ionization emission‐line activity. We speculate that the fuel supply to nuclear regions of the radio galaxy has recently switched off (within the last ∼106 yr), but the information about the resulting decrease in nuclear AGN activity has yet to reach the extended lobes and hotspots of the FR II radio source. Based on this scenario, we derive a lower limit on the typical lifetimes of powerful, intermediate‐redshift FR II radio sources of τ FR II ≳5×106 yr. Overall, our observations emphasize that the fuelling of AGN activity in major galaxy mergers is likely to be highly intermittent.

show abstract

Section: Discussionmentioning

confidence: 73%

Section: Discussionmentioning

confidence: 99%

PKS 0347+05: a radio-loud/radio-quiet double active galactic nucleus system triggered in a major galaxy merger

Tadhunter

Almeida

Morganti

et al. 2012

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…It is well known that high-luminosity radio sources have optical spectra that usually exhibit strong emission lines like Hα, [NII]λλ6548, 6584, [OIII]λλ4959, 5007, and Hβ (see e.g. Buttiglione et al 2009aButtiglione et al , 2009bHardcastle, Evans & Croston 2009;Capetti et al 2011).…”

Section: Distribution Of Xuvmentioning

confidence: 99%

Far-UV to mid-IR properties of nearby radio galaxies

Ruiter

Parma

Fanti

et al. 2015

A&A

View full text Add to dashboard Cite

Aims. We investigate whether the far-UV continuum of nearby radio galaxies is due solely to the parent galaxy that passively evolves, or if it reveals evidence for the presence of other star-forming or non-stellar components. If the UV excess is due to an additional radiation component, we compare this with other properties such as radio power, optical spectral type (e.g. high-and low-excitation galaxies), and the strength of the emission lines. We also discuss the possible correlation between the ultraviolet flux, IR properties, and the central black hole mass. Methods. We used a sample of low-luminosity B2 radio galaxies and a small sample of higher luminosity 3C radio galaxies at comparable redshift (z < 0.2). Spectral energy distributions (SEDs) were constructed using a number of on-line databases that are freely available now: GALEX, SDSS, 2MASS, and WISE. These were compared with model SEDs of early-type galaxies with passively evolving stellar populations at various ages (typically 0.5−1.3×10 9 years). We established whether a second component was needed to obtain a satisfactory fit with the observed overall SED. We introduce the parameter XUV , which measures the excess slope of the UV continuum between 4500 and 2000 Å with respect to the UV radiation produced by the underlying old galaxy component. Results. We find that the UV excess as measured by XUV is usually small or absent in low-luminosity (FR I) sources, but sets in abruptly at the transition radio power, above which we find mostly FRII sources. XUV behaves very similarly to the strength of the optical emission lines (in particular Hα). Below P 1.4 GHz < 10 24 WHz −1 XUV is close to zero. XUV correlates strongly with the Hα line strength, but only in sources with strong Hα emission. We discuss whether the line emission might be due to photoionization by radiation from the parent galaxy, possibly with additional star formation, or if it requires the presence of a non-stellar active galactic nucleus component. XUV and the slope of the mid-IR are strongly correlated, as measured by the WISE bands in the interval 3.4 to 22 μm, in the sense that sources with a strong UV excess also have stronger IR emission. There is an inverse correlation between XUV and central black hole mass: the M BH of objects with strong UV excess is on average two to three times less massive than that of objects without UV excess. Low-luminosity radio galaxies tend to be more massive and contain more massive black holes.

show abstract

“…We classify those remaining two as extremely low excitation radio galaxies (ELERGs) based on their unusually low [OIII]/Hβ of 0.57 and 0.67, respectively, which is consistent with the [OIII]/Hβ ∼ 0.5 indicative of extremely lowexcitation sources. Capetti et al (2011) describe extremely low-excitation galaxies as "radio relics" i.e., sources which recently experienced a drop in nuclear activity -perhaps this is the case in NGC 315 and NGC 541. We see no issues with this interpretation for NGC 541 but NGC 315 shows a warm thermal MIR component.…”

Section: Discussionmentioning

confidence: 99%

Searching for Nuclear Obscuration in the Infrared Spectra of Nearby FR I Radio Galaxies

Gleisinger,

O'Dea,

Gallimore

et al. 2021

Preprint

View full text Add to dashboard Cite

How do active galactic nuclei with low optical luminosities produce powerful radio emission? Recent studies of active galactic nuclei with moderate radio and low optical luminosities (Fanaroff & Riley 1974 class I, FR-I) searching for broad nuclear emission lines in polarized light, as predicted by some active galactic nucleus unification models, have found heterogeneous results. These models typically consist of a central engine surrounded by a torus of discrete dusty clouds. These clouds would absorb and scatter optical emission, blocking broad nuclear emission lines, and re-radiate in mid-infrared. Some scattered broad line emission may be observable, depending on geometry, which would be polarized. We present a wide-band infrared spectroscopic analysis of ten nearby FR-I radio galaxies to determine whether there is significant emission from a dusty obscuring structure. We used Markov-chain Monte Carlo algorithms to decompose Spitzer /IRS spectra of our sample. We constrained the wide-band behavior of our models with photometry from 2MASS, Spitzer /IRAC, Spitzer /MIPS, and Herschel /SPIRE. We find one galaxy is best fit by a clumpy torus and three others show

show abstract

An optical spectroscopic survey of the 3CR sample of radio galaxies with z < 0.3

Cited by 12 publications

References 23 publications

PKS 0347+05: a radio-loud/radio-quiet double active galactic nucleus system triggered in a major galaxy merger

PKS 0347+05: a radio-loud/radio-quiet double active galactic nucleus system triggered in a major galaxy merger

Far-UV to mid-IR properties of nearby radio galaxies

Searching for Nuclear Obscuration in the Infrared Spectra of Nearby FR I Radio Galaxies

Contact Info

Product

Resources

About