Radio and spectroscopic properties of miniature
 radio galaxies: revealing the bulk of the radio-loud AGN population

Baldi, Ranieri D.; Capetti, A.

doi:10.1051/0004-6361/200913021

Cited by 74 publications

(99 citation statements)

References 67 publications

(84 reference statements)

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“…They find a lower limit of 0.86 for unresolved sources. Column (14): FR is the Fanaroff-Riley type at low frequency (1.4 GHz) (Fanaroff & Riley 1974;Baldi & Capetti 2009;Ghisellini 2011). …”

Section: Columns (2) and (3)mentioning

confidence: 99%

Hi absorption in nearby compact radio galaxies

Glowacki

Allison

Sadler

et al. 2017

Mon. Not. R. Astron. Soc.

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Hi absorption studies yield information on both AGN feeding and feedback processes. This AGN activity interacts with the neutral gas in compact radio sources, which are believed to represent the young or recently re-triggered AGN population. We present the results of a survey for Hi absorption in a sample of 66 compact radio sources at 0.040 < z < 0.096 with the Australia Telescope Compact Array. In total, we obtained seven detections, five of which are new, with a large range of peak optical depths (3% to 87%). Of the detections, 71% exhibit asymmetric, broad (∆v FWHM > 100 km s −1 ) features, indicative of disturbed gas kinematics. Such broad, shallow and offset features are also found within low-excitation radio galaxies which is attributed to disturbed circumnuclear gas, consistent with early-type galaxies typically devoid of a gas-rich disk. Comparing mid-infrared colours of our galaxies with Hi detections indicates that narrow and deep absorption features are preferentially found in late-type and high-excitation radio galaxies in our sample. These features are attributed to gas in galactic disks. By combining XMM-Newton archival data with 21-cm data, we find support that absorbed X-ray sources may be good tracers of HI content within the host galaxy. This sample extends previous Hi surveys in compact radio galaxies to lower radio luminosities and provides a basis for future work exploring the higher redshift universe.

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Section: Columns (2) and (3)mentioning

confidence: 99%

Hi absorption in nearby compact radio galaxies

Glowacki

Allison

Sadler

et al. 2017

Mon. Not. R. Astron. Soc.

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“…The lack of clear starburst regions in the optical HST images (Capetti & Balmaverde 2005) and no evidence of young stellar populations in their optical spectra (Baldi & Capetti 2009) rule out a star formation origin for these trends. A reasonable, but not obvious, explanation of the trends might be the most basic mechanism of heating of the molecular clouds by high-energy photons (e.g., UV and X-ray photons) from the AGN, as suggested by Braine & Combes (1992).…”

Section: Molecular Gas and Nuclear Propertiesmentioning

confidence: 98%

“…These studies show that the two optical classes of objects correspond to different AGN properties. On one hand, the CoreG represent "miniature radio galaxies", i.e., a scaled-down version of FR Is (Baldi & Capetti 2009). They invariably host RL nuclei, spectroscopically classified as low-excitation galaxies, with an average radio-loudness parameter of R = L 5 GHz /L B ∼ 4000, similarly to FR Is.…”

Section: Sample Observations and Datamentioning

confidence: 99%

Molecular gas and nuclear activity in early-type galaxies: any link with radio loudness?

Baldi

Giroletti

Capetti

et al. 2015

A&A

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Aims. We want to study the amount of molecular gas in a sample of nearby early-type galaxies (ETGs) that host low-luminosity active galactic nuclei (AGN). We look for possible differences between the radio-loud (RL) and radio-quiet (RQ) AGN. Methods. We observed the CO(1-0) and CO(2-1) spectral lines with the IRAM 30 m and NRO 45 m telescopes for eight galaxies. They belong to a large sample of 37 local ETGs that host both RQ and RL AGN. We gather data from the literature for the entire sample. Results. We report the new detection of CO(1-0) emission in four galaxies (UGC 0968, UGC 5617, UGC 6946, and UGC 8355) and CO(2-1) emission in two of them (UGC 0968 and UGC 5617). The CO(2-1)/CO(1-0) ratio in these sources is ∼0.7 ± 0.2. Considering both the new observations and the literature, the detection rate of CO in our sample is 55± 9%, with no statistically significant difference between the hosts of RL and RQ AGNs. For all the detected galaxies we converted the CO luminosities into the molecular masses, M H 2 , which range from 10 6.5 to 10 8.5 M , without any statistically significant differences between RL and RQ galaxies. This suggests that the amount of molecular gas does not likely set the radio loudness of the AGN. Furthermore, despite the low statistical significance, the presence of a weak trend between the H 2 mass with various tracers of nuclear activity (mainly [O III] emission line nuclear power) cannot be excluded.

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“…the 2 Jy (Morganti et al 1997;Tadhunter et al 1998) follow relations between radio and line emission similar to the 3CR. Baldi & Capetti (2009) showed that a large ratio of line emission to the radio power with respect to 3CR sources is characteristic of the radio-loud AGN selected by Best et al (2005). The latter authors cross-matched the ∼212 000 galaxies drawn from the SDSS-DR2 with the NVSS and FIRST 7 radio surveys, selecting a sample of 2215 radio-loud AGN (with a radio flux threshold of 5 mJy) to which we refer hereafter as the SDSS/NVSS sample.…”

Section: The Parent Populationmentioning

confidence: 99%

“…Moreover, they saw that HEG are associated with very powerful FR II only, while LEG are spread on a wide range of radio powers, and can be of both FR II and FR I type. Actually, the situation is even more complex, as the existence of miniature radio galaxies, characterized by extremely low radio power, relatively luminous narrow emission lines, and no BLR, demonstrates (Baldi & Capetti 2009). …”

Section: Introductionmentioning

confidence: 99%

Is BL Lacertae an “orphan” AGN?

Capetti¹,

Raiteri²,

Buttiglione

2010

A&A

Self Cite

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Aims. We have analysed optical spectra of BL Lacertae, the prototype of its blazar subclass, to verify the broad Hα emission line detected more than a decade ago and its possible flux variation. We used the spectroscopic information to investigate the question of the BL Lacertae parent population. Methods. Low-and high-resolution optical spectra of BL Lacertae were acquired with the DOLORES spectrograph at the 3.58 m telescopio nazionale Galileo (TNG) during four nights in [2007][2008], when the source was in a relatively faint state. In three cases we were able to fit the complex Hα spectral range with multiple line components and to measure both the broad Hα and several narrow emission line fluxes. Results. A critical comparison with previous results suggests that the broad Hα flux has increased by about 50% in ten years. This might be due to an addition of gas in the broad line region (BLR), or to a strengthening of the disc luminosity, but such flux changes are not unusual in Broad Lined active nuclei. We estimated the BL Lacertae black hole mass by means of its relation with the bulge luminosity, finding 4−6 × 10 8 M . The virial mass estimated from the spectroscopic data gives instead a value 20-30 times lower. An analysis of the disc and BLR properties in different AGNs suggests that this discrepancy is due to an underluminosity of the BL Lacertae BLR. Finally, we addressed the problem of the BL Lacertae parent population, comparing its isotropic quantities with those of other AGN classes. From the point of view of the narrow emission line spectrum, the source is located close to low-excitation radio galaxies. When one also considers its diffuse radio power, an association with FR I radio galaxies is severely questioned due to the lower radio luminosity (at a given line luminosity) of BL Lacertae. The narrow line and radio luminosities of BL Lacertae instead match those of a sample of miniature radio galaxies, which however do not show a BLR. Yet, if existing, "misaligned BL Lacertae" objects should have entered that sample. We also rule out the possibility that they were excluded because of a QSO optical appearance. Conclusions. The observational constraints suggest that BL Lacertae is caught in a short term transient stage, which does not leave a detectable evolutionary "trace" in the AGN population. We present a scenario that can account for the observed properties.

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Radio and spectroscopic properties of miniature radio galaxies: revealing the bulk of the radio-loud AGN population

Cited by 74 publications

References 67 publications

Hi absorption in nearby compact radio galaxies

Hi absorption in nearby compact radio galaxies

Molecular gas and nuclear activity in early-type galaxies: any link with radio loudness?

Is BL Lacertae an “orphan” AGN?

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