The AGN fuelling/feedback cycle in nearby radio galaxies I. ALMA observations and early results

Ruffa, Ilaria; Prandoni, I.; Laing, R. A.; Paladino, R.; Parma, P.; Ruiter, H. de; Mignano, A.; Davis, Timothy A.; Bureau, Martin; Warren, Joshua

doi:10.1093/mnras/stz255

Cited by 63 publications

(71 citation statements)

References 111 publications

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“…Our indexes are consistent (1-1.5σ) with those from Best et al (1999) (also shown in Table 1). The lobes present a steep SED, consistent with the optically thin synchrotron emission of the jets (Best et al 1999;Laing & Bridle 2013;Nyland et al 2017;Ruffa et al 2019;Grossová et al 2019), while the AGN core SED is flatter, which is consistent with optically thicker (self-absorbed) synchrotron emission (Best et al 1999;Ruffa et al 2019;Grossová et al 2019).…”

Section: Active Galactic Nucleus Continuum Emissionsupporting

confidence: 70%

“…This is consistent with the same or a connected physical origin of the two emissions. In fact, the AGN synchrotron emission dominates at both our NOEMA observed frequency (rest-frame ν ∼ 230 GHz/λ ∼ 1.3 mm), and in the radio observation frequency range (Bregman 1990;Haas et al 1998;Hönig et al 2008;Nyland et al 2017;Ruffa et al 2019). At both frequency ranges, the signal corresponds to the non-thermal synchrotron radiation emitted by the relativistic charged particles from the AGN jets (Gómez et al 1995(Gómez et al , 1997Mioduszewski et al 1997;Aloy et al 2000;Porth et al 2011;Fuentes et al 2018).…”

Section: Active Galactic Nucleus Continuum Emissionmentioning

confidence: 74%

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Massive molecular gas reservoir around the central AGN in the CARLA J1103 + 3449 cluster at z = 1.44

Markov

Mei

Salomé

et al. 2020

A&A

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Passive early-type galaxies dominate cluster cores at z ≲ 1.5. At higher redshift, cluster core galaxies are observed to have on-going star-formation, which is fueled by cold molecular gas. We measured the molecular gas reservoir of the central region around the radio-loud active galactic nucleus (AGN) in the cluster CARLA J1103 + 3449 at z = 1.44 using NOEMA. The AGN synchrotron emission dominates the continuum emission at 94.48 GHz, and we measured its flux at the AGN position and at the position of two radio jets. Combining our measurements with published results over the range 4.71–94.5 GHz, and assuming Ssynch ∝ ν−α, we obtain a flat spectral index of α = 0.14 ± 0.03 for the AGN core emission, and a steeper index of α = 1.43 ± 0.04 and α = 1.15 ± 0.04 at positions close to the western and eastern lobes, respectively. The total spectral index is α = 0.92 ± 0.02 over the range 73.8 MHz–94.5 GHz. We detect two CO(2–1) emission lines, both blueshifted with respect to the AGN. Their emission corresponds to two regions, ~17 kpc southeast and ~14 kpc southwest of the AGN, not associated with galaxies. In these two regions, we find a total massive molecular gas reservoir of Mgastot = 3.9 ± 0.4 × 1010 M⊙, which dominates (≳60%) the central total molecular gas reservoir. These results can be explained by massive cool gas flows in the center of the cluster. The AGN early-type host is not yet quenched; its star formation rate is consistent with being on the main sequence of star-forming galaxies in the field (star formation rate ~30–140 M⊙ yr−1), and the cluster core molecular gas reservoir is expected to feed the AGN and the host star formation before quiescence. The other confirmed cluster members show star formation rates at ~2σ below the field main sequence at similar redshifts and do not have molecular gas masses larger than galaxies of similar stellar mass in the field.

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Section: Active Galactic Nucleus Continuum Emissionsupporting

confidence: 70%

Section: Active Galactic Nucleus Continuum Emissionmentioning

confidence: 74%

Massive molecular gas reservoir around the central AGN in the CARLA J1103 + 3449 cluster at z = 1.44

Markov

Mei

Salomé

et al. 2020

A&A

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“…Following the works of David et al (2014); Tremblay et al (2016); Ruffa et al (2019); Rose et al (2019), the eight detections of molecular absorption we present significantly increases the number of brightest cluster galaxies in which cold, molecular gas has been observed in absorption against the host galaxy's bright radio core. These detections are made through CO absorption and emission lines, as well as previously undetected CN lines.…”

Section: Discussionsupporting

confidence: 53%

“…Despite these advantages, molecular absorption studies remain rare, with only a handful of absorbing systems having been found in this way. In terms of brightest cluster galaxies, five associated absorbers have been detected, where the absorption is observed in the spectrum of the bright radio source spatially coincident with the galaxy's supermassive black hole (David et al 2014;Tremblay et al 2016;Ruffa et al 2019;Rose et al 2019;Nagai et al 2019). A small selection of intervening absorbers have also been detected in gravitational lens systems, where absorption is observed in a galaxy separate from, but along the same line of sight as a distant and bright radio continuum source such as a quasi-stellar object (Combes 2008;Wiklind et al 2018;Combes et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Constraining cold accretion on to supermassive black holes: molecular gas in the cores of eight brightest cluster galaxies revealed by joint CO and CN absorption

Rose

Edge

Combes

et al. 2019

Monthly Notices of the Royal Astronomical Society

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To advance our understanding of the fuelling and feedback processes which power the Universe's most massive black holes, we require a significant increase in our knowledge of the molecular gas which exists in their immediate surroundings. However, the behaviour of this gas is poorly understood due to the difficulties associated with observing it directly. We report on a survey of 18 brightest cluster galaxies lying in cool cores, from which we detect molecular gas in the core regions of eight via carbon monoxide (CO), cyanide (CN) and silicon monoxide (SiO) absorption lines. These absorption lines are produced by cold molecular gas clouds which lie along the line of sight to the bright continuum sources at the galaxy centres. As such, they can be used to determine many properties of the molecular gas which may go on to fuel supermassive black hole accretion and AGN feedback mechanisms. The absorption regions detected have velocities ranging from -45 to 283 km s −1 relative to the systemic velocity of the galaxy, and have a bias for motion towards the host supermassive black hole. We find that the CN N = 0 -1 absorption lines are typically 10 times stronger than those of CO J = 0 -1. This is due to the higher electric dipole moment of the CN molecule, which enhances its absorption strength. In terms of molecular number density CO remains the more prevalent molecule with a ratio of CO/CN ∼ 10, similar to that of nearby galaxies. Comparison of CO, CN and H I observations for these systems shows many different combinations of these absorption lines being detected.the behaviour of this molecular gas across a wide range of spatial scales, observational studies typically focus on emission, which probes gas within relatively large collections of molecular clouds and struggles to reveal how it behaves in more compact regions. This includes areas of particular interest, such as the surroundings of the most massive supermassive black holes. As a result of this observational shortfall, there exists a significant gap in our knowledge concerning the behaviour and properties of the molecular gas surrounding active galactic nuclei (AGN). While observations have been absent at this level, simulations such as chaotic cold accretion have predicted that the large reservoirs of molecular gas we see observationally (e.g. Edge 2001), exist 1 Assuming a carbon abundance equal to that of the Milky Way gas phase, and that all gas phase carbon exists in CO molecules, the ratio of carbon monoxide to molecular hydrogen is CO/H 2 = 3.2 × 10 −4 (Sofia et al. 2004).

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“…This system may be a combination of a (nearly edge-on) rotating disk/ring and components with disturbed kinematics. The relative amount of the disturbed gas to the rotating gas is large, which is contrary to the other radio galaxies with dust or molecular gas (Kotanyi & Ekers 1979;de Koff et al 2000;de Ruiter et al 2002;Ruffa et al 2019).…”

Section: Co Velocity Fieldmentioning

confidence: 78%

Complex distribution and velocity field of molecular gas in NGC 1316 as revealed by the Morita Array of ALMA

Morokuma-Matsui

Serra

Maccagni

et al. 2019

Publications of the Astronomical Society of Japan

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We present the results of 12 CO(J=1-0) mosaicing observations of the cD galaxy NGC 1316 at kpc-resolution performed with the Morita Array of the Atacama Large Millimeter/submillimeter Array (ALMA). We reveal the detailed distribution of the molecular gas in the central region for the first time: a shell structure in the northwest, a barely resolved blob in the southeast of the center and some clumps between them. The total molecular gas mass obtained with a standard Milky-Way CO-to-H 2 conversion factor is (5.62 ± 0.53) × 10 8 M , which is consistent with previous studies. The disturbed velocity field of the molecular gas suggests that the molecular gas is injected very recently (< 1 Gyr) if it has an external origin and is in the process of settling into a rotating disk. Assuming that a low-mass gas-rich galaxy has accreted, the gas-to-dust ratio and H 2 -to-H i ratio are unusually low (∼ 28) and high (∼ 5.6), respectively. To explain these ratios, additional processes should be taken into accounts such as an effective dust formation and conversion from atomic to molecular gas during the interaction. We also discuss the interaction between the nuclear jet and the molecular gas.

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The AGN fuelling/feedback cycle in nearby radio galaxies I. ALMA observations and early results

Cited by 63 publications

References 111 publications

Massive molecular gas reservoir around the central AGN in the CARLA J1103 + 3449 cluster at z = 1.44

Massive molecular gas reservoir around the central AGN in the CARLA J1103 + 3449 cluster at z = 1.44

Constraining cold accretion on to supermassive black holes: molecular gas in the cores of eight brightest cluster galaxies revealed by joint CO and CN absorption

Complex distribution and velocity field of molecular gas in NGC 1316 as revealed by the Morita Array of ALMA

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