Feedback from low-luminosity radio galaxies: B2 0258+35

Low-luminosity radio-loud active galactic nuclei (AGN) are of importance in studies concerning feedback from radio AGN since a dominant fraction of AGN belong to this class. We report high-resolution Very Large Array (VLA) and European VLBI Network (EVN) observations of H I 21 cm absorption from a young, compact steep-spectrum radio source, B2 0258+35, nested in the early-type galaxy NGC 1167, which contains a 160 kpc H I disc. Our VLA and EVN H I absorption observations, modelling, and comparison with molecular gas data suggest that the cold gas in the centre of NGC 1167 is very turbulent (with a velocity dispersion of ∼90 km s−1) and that this turbulence is induced by the interaction of the jets with the interstellar medium (ISM). Furthermore, the ionised gas in the galaxy shows evidence of shock heating at a few kpc from the radio source. These findings support the results from numerical simulations of radio jets expanding into a clumpy gas disc, which predict that the radio jets in this case percolate through the gas disc and drive shocks into the ISM at distances much larger than their physical extent. These results expand the number of low-luminosity radio sources found to impact the surrounding medium, thereby highlighting the possible relevance of these AGN for feedback.

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A multiwavelength study of the dual nuclei in Mrk 212

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3375 ◽

2020 ◽

Vol 500 (3) ◽

pp. 3908-3919

Author(s):

K Rubinur ◽

P Kharb ◽

M Das ◽

P T Rahna ◽

M Honey ◽

...

Keyword(s):

Radio Source ◽

Galactic Nuclei ◽

Optical Emission ◽

Radio Observations ◽

Radio Structure ◽

Very Large Array ◽

Extended Radio ◽

The Galaxy ◽

Double Radio Source ◽

Tidal Tails

ABSTRACT We present radio observations of the galaxy merger remnant Mrk 212 with the Karl G. Jansky Very Large Array (VLA) and the upgraded Giant Meter Radio Telescope (uGMRT). Mrk 212 has two previously known radio sources associated with the two optical nuclei, S1 and S2, with a projected separation of ∼6 kpc, making it a dual active galactic nuclei (AGN) candidate. Our new 15-GHz VLA observations reveal that S1 is a double radio source centred around the optical nucleus; its total extent is ∼750 pc its average 1.4−8.5 GHz spectral index is −0.81 ± 0.06. S1 therefore resembles a compact symmetric object. The 15-GHz VLA image identifies the radio source at S2 to be a compact core. Our radio observations therefore strongly support the presence of a dual AGN in Mrk 212. The optical emission line flux ratios obtained from the Himalayan Chandra Telescope (HCT) observations however, show that S1 and S2 both fall in the AGN + star formation (SF) region of the Baldwin, Philips and Terlevich (BPT) diagram. Weak AGN lying in the SF or AGN + SF intermediate regions in the BPT diagram have indeed been reported in the literature; our sources clearly fall in the same category. We find an extended radio structure in our newly reduced 8.5-GHz-VLA data, that is offset by ∼1 arcsec from the optical nucleus S2. New deep FUV and NUV observations with the Ultraviolet Imaging Telescope aboard AstroSat reveal SF knots around S2 as well as kpc-scale tidal tails; the SF knots around S2 coincide with the extended radio structure detected at 8.5 GHz. The radio spectral indices are consistent with SF. Any possible association with the AGN in S2 is unclear at this stage.

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Probing the cool ISM in galaxies via 21 cm H i absorption

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313001014 ◽

2012 ◽

Vol 8 (S292) ◽

pp. 188-188

Author(s):

J. R. Allison ◽

E. M. Sadler ◽

S. J. Curran ◽

S. N. Reeves

Keyword(s):

Spectral Line ◽

Active Galactic Nuclei ◽

Large Scale ◽

Galactic Nuclei ◽

Host Galaxies ◽

The Galaxy ◽

Early Type Galaxy ◽

Finding Method ◽

Compact Array ◽

Cold Gas

AbstractRecent targeted studies of associated H i absorption in radio galaxies are starting to map out the location, and potential cosmological evolution, of the cold gas in the host galaxies of Active Galactic Nuclei (AGN). The observed 21 cm absorption profiles often show two distinct spectral-line components: narrow, deep lines arising from cold gas in the extended disc of the galaxy, and broad, shallow lines from cold gas close to the AGN (e.g. Morganti et al. 2011). Here, we present results from a targeted search for associated H i absorption in the youngest and most recently-triggered radio AGN in the local universe (Allison et al. 2012b). So far, by using the recently commissioned Australia Telescope Compact Array Broadband Backend (CABB; Wilson et al. 2011), we have detected two new absorbers and one previously-known system. While two of these show both a broad, shallow component and a narrow, deep component (see Fig. 1), one of the new detections has only a single broad, shallow component. Interestingly, the host galaxies of the first two detections are classified as gas-rich spirals, while the latter is an early-type galaxy. These detections were obtained using a spectral-line finding method, based on Bayesian inference, developed for future large-scale absorption surveys (Allison et al. 2012a).

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Radio Continuum Emission from the Nuclei of Normal Galaxies

Highlights of Astronomy ◽

10.1017/s1539299600003877 ◽

1980 ◽

Vol 5 ◽

pp. 177-184 ◽

Cited By ~ 2

Author(s):

J. M. van der Hulst

Keyword(s):

Radio Emission ◽

Galactic Center ◽

Galactic Nuclei ◽

Radio Continuum ◽

Continuum Emission ◽

Thermal Source ◽

Very Large Array ◽

Normal Galaxies ◽

The Galaxy ◽

Sgr A

During the last few years detailed and sensitive observations of the radio emission from the nuclei of many normal spiral galaxies has become available. Observations from the Very Large Array (VLA) of the National Radio Astronomy Observatory (NRAO1), in particular, enable us to distinguish details on a scale of ≤100 pc for galaxies at distances less than 21 Mpc. The best studied nucleus, however, still is the center of our own Galaxy (see Oort 1977 and references therein). Its radio structure is complex. It consists of an extended non-thermal component 200 × 70 pc in size, with embedded therein several giant HII regions and the central source Sgr A (˜9 pc in size). Sgr A itself consists of a thermal source, Sgr A West, located at the center of the Galaxy, and a weaker, non-thermal source, Sgr A East. Sgr A West moreover contains a weak, extremely compact (≤10 AU) source. The radio morphology of several other galactic nuclei is quite similar to that of the Galactic Center, as will be discussed in section 2. Recent reviews of the radio properties of the nuclei of normal galaxies have been given by Ekers (1978a,b) and De Bruyn (1978). The latter author, however, concentrates on galaxies with either active nuclei or an unusual radio morphology. In this paper I will describe recent results from the Westerbork Synthesis Radio Telescope (WSRT, Hummel 1979), the NRAO 3-element interferometer (Carlson, 1977; Condon and Dressel 1978), and the VLA (Heckman et al., 1979; Van der Hulst et al., 1979). I will discuss the nuclear radio morphology in section 2, the luminosities in section 3, and the spectra in section 4. In section 5 I will briefly comment upon the possible implications for the physical processes in the nuclei that are responsible for the radio emission.

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High-Resolution Radio Observations of Five Optically Selected Type 2 Quasars

Symmetry ◽

10.3390/sym12040527 ◽

2020 ◽

Vol 12 (4) ◽

pp. 527

Author(s):

Máté Krezinger ◽

Sándor Frey ◽

Zsolt Paragi ◽

Roger Deane

Keyword(s):

Structural Information ◽

Galactic Nuclei ◽

High Angular Resolution ◽

Very Large Array ◽

Long Baseline ◽

Spectrum Radio ◽

Sky Survey ◽

5 Ghz ◽

Symmetric Structures

Many low-luminosity active galactic nuclei (AGNs) contain a compact radio core which can be observed with high angular resolution using very long baseline interferometry (VLBI). Combining arcsec-scale structural information with milliarcsec-resolution VLBI imaging is a useful way to characterise the objects and to find compact cores on parsec scales. VLBI imaging could also be employed to look for dual AGNs when the sources show kpc-scale double symmetric structure with flat or inverted radio spectra. We observed five such sources at redshifts 0.36 < z < 0.58 taken from an optically selected sample of Type 2 quasars with the European VLBI Network (EVN) at 1.7 and 5 GHz. Out of the five sources, only one (SDSS J1026–0042) shows a confidently detected compact VLBI core at both frequencies. The other four sources are marginally detected at 1.7 GHz only, indicating resolved-out radio structure and steep spectra. Using first-epoch data from the ongoing Karl G. Jansky Very Large Array Sky Survey, we confirm that indeed all four of these sources have steep radio spectra on arcsec scale, contrary to the inverted spectra reported earlier in the literature. However, the VLBI-detected source, SDSS J1026−0042, has a flat integrated spectrum. Radio AGNs that show kpc-scale symmetric structures with truly flat or inverted spectra could still be promising candidates of dual AGNs, to be targeted with VLBI observations in the future.

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The duty cycle of radio galaxies revealed by LOFAR: remnant and restarted radio source populations in the Lockman Hole

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1172 ◽

2020 ◽

Vol 496 (2) ◽

pp. 1706-1717 ◽

Cited By ~ 2

Author(s):

Stanislav S Shabala ◽

Nika Jurlin ◽

Raffaella Morganti ◽

Marisa Brienza ◽

Martin J Hardcastle ◽

...

Keyword(s):

Active Galactic Nuclei ◽

Radio Source ◽

Low Frequency ◽

Galactic Nuclei ◽

Radio Jets ◽

Modelling Analysis ◽

Self Consistent ◽

Large Populations ◽

Source Populations ◽

Lockman Hole

ABSTRACT Feedback from radio jets associated with active galactic nuclei (AGNs) plays a profound role in the evolution of galaxies. Kinetic power of these radio jets appears to show temporal variation, but the mechanism(s) responsible for this process are not yet clear. Recently, the LOw Frequency ARray (LOFAR) has uncovered large populations of active, remnant, and restarted radio jet populations. By focusing on LOFAR data in the Lockman Hole, in this work we use the Radio AGNs in Semi-Analytic Environments (RAiSE) dynamical model to present the first self-consistent modelling analysis of active, remnant, and restarted radio source populations. Consistent with other recent work, our models predict that remnant radio lobes fade quickly. Any high (>10 per cent) observed fraction of remnant and restarted sources therefore requires a dominant population of short-lived jets. We speculate that this could plausibly be provided by feedback-regulated accretion.

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PKS 2005-489: A very bright BL Lac object in a nearby galaxy

Symposium - International Astronomical Union ◽

10.1017/s0074180900152271 ◽

1986 ◽

Vol 119 ◽

pp. 59-60

Author(s):

J V Wall ◽

I J Danziger ◽

M Pettini ◽

R S Warwick ◽

W Wamsteker

Keyword(s):

Radio Source ◽

Power Law ◽

Nearby Galaxy ◽

Bl Lac Objects ◽

X Ray ◽

Spectrum Radio ◽

Bl Lac ◽

The Galaxy

The galaxy identified with the flat-spectrum radio source PKS 2005-489 has a bright stellar nucleus with V ⋍ 13 mag. Optical, UV and X-ray observations indicate variability and power-law continua in each of these wavebands, leading to the conclusion that PKS 2005-489 is one of the brightest BL Lac objects known.

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Feeding and feedback in nuclei of galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320002239 ◽

2020 ◽

Vol 15 (S359) ◽

pp. 307-311

Author(s):

Anelise Audibert ◽

Françoise Combes ◽

Santiago García-Burillo ◽

Kalliopi Dasyra

Keyword(s):

High Resolution ◽

Active Galactic Nuclei ◽

Galaxy Evolution ◽

Galactic Nuclei ◽

Radio Galaxies ◽

Host Galaxy ◽

Molecular Gas ◽

Molecular Outflows ◽

Radio Jets ◽

The Impact

AbstractOur aim is to explore the close environment of Active Galactic Nuclei (AGN) and its connection to the host galaxy through the morphology and dynamics of the cold gas inside the central kpc in nearby AGN. We report Atacama Large Millimeter/submillimeter Array (ALMA) observations of AGN feeding and feedback caught in action in NGC613 and NGC1808 at high resolution (few pc), part of the NUclei of GAlaxies (NUGA) project. We detected trailing spirals inside the central 100 pc, efficiently driving the molecular gas into the SMBH, and molecular outflows driven by the AGN. We present preliminary results of the impact of massive winds induced by radio jets on galaxy evolution, based on observations of radio galaxies from the ALMA Radio-source Catalogue.

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5.1. Molecular gas in luminous galactic nuclei

Symposium - International Astronomical Union ◽

10.1017/s0074180900084631 ◽

1998 ◽

Vol 184 ◽

pp. 205-212

Author(s):

N. Z. Scoville ◽

A. J. Baker

Keyword(s):

Near Infrared ◽

Galactic Nuclei ◽

Infrared Emission ◽

Molecular Gas ◽

Luminous Infrared Galaxies ◽

Radio Jets ◽

Mass Fractions ◽

Ngc 1068 ◽

Nuclear Regions ◽

Lower Luminosity

In the last five years, millimeter-wave interferometry has clearly shown the existence of enormous masses (109–1010 M⊙) of molecular gas concentrated in the nuclear regions (R < 500 pc) of many luminous and ultra-luminous infrared galaxies. In these systems, molecular gas is an obvious source of fuel for nuclear starbursts and active galactic nuclei (AGN). For nearer, lower-luminosity systems there exists less systematic characterization of either the properties or the structure of the nuclear gas. Here we review recent results on the molecular gas in the nuclei of two near, lower-luminosity systems (M51 and NGC 1068) and contrast these results with those for the best studied ultra-luminous IRAS galaxy, Arp 220. For all three galaxies, there now exists CO(2–1) interferometry at high resolution which reveals, for the first time, disks of extremely dense, highly excited gas on scales of 50-300 pc. These structures vary in their levels of axisymmetry, thickness, and clumpiness. However, they share the ability to extinguish optical and near-infrared emission from active or stellar nuclei and perhaps to collimate radio jets and ionized outflows. Within the nuclear regions of these three galaxies, the molecular gas constitutes 10-50% of the total mass, with the most luminous systems having the highest gas mass-fractions.

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The Role of Quasars in Galaxy Formation

Proceedings of the International Astronomical Union ◽

10.1017/s174392131000551x ◽

2009 ◽

Vol 5 (S267) ◽

pp. 17-25 ◽

Cited By ~ 1

Author(s):

D. Elbaz

Keyword(s):

Star Formation ◽

Galaxy Formation ◽

Positive Feedback ◽

Local Environment ◽

Active Role ◽

Molecular Gas ◽

Massive Galaxies ◽

Radio Jets ◽

The Galaxy

AbstractWe 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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Powerful AGN jets and unbalanced cooling in the hot atmosphere of IC 4296

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz1728 ◽

2019 ◽

Vol 488 (2) ◽

pp. 1917-1925 ◽

Cited By ~ 6

Author(s):

R Grossová ◽

N Werner ◽

K Rajpurohit ◽

F Mernier ◽

K Lakhchaura ◽

...

Keyword(s):

Elliptical Galaxy ◽

Very Large Array ◽

X Ray ◽

Total Enthalpy ◽

Radio Jets ◽

Mechanical Power Output ◽

The Galaxy ◽

Bow Shocks ◽

Sharp Edges ◽

Projected Distance

Abstract We present new Karl G. Jansky Very Large Array (VLA, 1.5 GHz) radio data for the giant elliptical galaxy IC 4296, supported by archival radio, X-ray (Chandra, and XMM–Newton) and optical (SOAR, and HST) observations. The galaxy hosts powerful radio jets piercing through the inner hot X-ray emitting atmosphere, depositing most of the energy into the ambient intracluster medium (ICM). Whereas the radio surface brightness of the A configuration image is consistent with a Fanaroff–Riley Class I system, the D configuration image shows two bright, relative to the central region, large (${\sim } 160\, \rm {kpc}$ diameter), well-defined lobes, previously reported by Killeen et al., at a projected distance $r\gtrsim 230\, \rm {kpc}$. The XMM–Newton image reveals an X-ray cavity associated with one of the radio lobes. The total enthalpy of the radio lobes is ${\sim }7\times 10^{59}\, \rm {erg}$ and the mechanical power output of the jets is ${\sim } 10^{44}\, \rm {erg\, s}^{-1}$. The jets are mildly curved and possibly rebrightened by the relative motion of the galaxy and the ICM. The lobes display sharp edges, suggesting the presence of bow shocks, which would indicate that they are expanding supersonically. The central entropy and cooling time of the X-ray gas are unusually low and the nucleus hosts a warm Hα + [$\rm{N\,{\small II}}$] nebula and a cold molecular CO disc. Because most of the energy of the jets is deposited far from the nucleus, the atmosphere of the galaxy continues to cool, apparently feeding the central supermassive black hole and powering the jet activity.

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