M87, in the Virgo cluster, allows us to study the interaction of a supermassive black hole (SMBH) with its hot gaseous atmosphere. Deep Chandra observations reveal a nearly circular shock front with a Mach number of 1.2 and a radius of 13 kpc which is driven by a central cavity inflated by an SMBH outburst began 12 million years ago. An outburst with an energy of a ~5×57 ergs and a duration of ~2 Myrs provides a good match to all the constraints. For an outburst repetition rate of about 12 Myrs (the outburst age), the outburst energy is sufficient to balance the radiative cooling of the gas. The outburst duration in M87 argues for a “gentle” (long duration) outburst that does not generate strong shocks and where much of the outburst energy is deposited in the cavities that then transfer energy to the surrounding gas as they buoyantly rise.

We present a method that uses photoionization codes (CLOUDY) to estimate the supermassive black hole masses (MBH) for quasars at low and high redshift. This method is based on the determination of the physical conditions of the broad line region (BLR) using observational diagnostic diagrams from line ratios in the UV. We also considered that the density and metallicity of the BLR in quasars at high z could be different from those at the nearby Universe. The computed black hole masses obtained using this method are in agreement with those derived from the method of reverberation mapping.

Recent molecular line observations with ALMA and NOEMA in several Brightest Cluster Galaxies (BCG) have revealed the large-scale filamentary structure at the center of cool core clusters. These filaments extend over 20-100kpc, they are tightly correlated with ionized gas (Hα, [NII]) emission, and have characteristic shapes: either radial and straight, or also showing a U-turn, like a horse-shoe structure. The kinematics is quite regular and laminar, and the derived infall time is much longer than the free-fall time. The filaments extend up to the radius where the cooling time becomes larger than the infall time. Filaments can be perturbed by the sloshing of the BCG in its cluster, and spectacular cooling wakes have been observed. Filaments tend to occur at the border of cavities driven in the X-ray gas by the AGN radio jets. Observations of cool core clusters support the thermal instability scenario, which accounts for the multiphase medium in the upper atmospheres of BCG, where the right balance between heating and cooling is reached, and a chaotic cold gas accretion occurs. Molecular filaments are also seen associated to ram-pressure stripped spiral galaxies in rich galaxy clusters, and in jet-induced star formation, suggesting a very efficient molecular cloud formation even in hostile cluster environments.

The international collaboration of VLBI in East Asia (EA) is rapidly growing. Besides the recent successful operation of the KVN and VERA Array (KaVA), the effort of joint VLBI operation in EA is being expanded into China. This forms the East Asian VLBI Network (EAVN), which offers detailed imaging and monitoring of the innermost regions of relativistic jets at cm wavelengths and thus complementary to the Event Horizon Telescope operated at mm wavelengths. In this contribution we present some of the ongoing KaVA/EAVN studies for the inner jets of the two important nearby radio galaxies 3C84 and M87. The observations have revealed detailed kinematics for the parsec-to-subparsec-scale structures of these jets. Future regular observations with the East-Asia-To-Italy-Nearly-Global (EATING) VLBI, a joint effort between EAVN and the Italian VLBI Network, will enable us to resolve and regularly monitor the innermost regions of nearby AGN jets at tens of micro-arcsecond scales.

We present the analysis of the 93 ksec Chandra ACIS–S data for the galaxy CGCG 292–057 (z = 0.054), with complex radio structure indicative of the intermittent jet activity. In order to characterize precisely the spectrum of the unresolved low-luminosity active nucleus in the source, we performed detailed MARX/PSF simulations and studied the radial profile of the source region surface brightness. In this way, we have detected an additional X-ray component extending from a few up to ∼10 kpc from the unresolved core, which could be associated with the hot gaseous medium compressed and heated (up to 0.9 keV) by the expanding inner lobes of the radio galaxy. We modeled the X-ray spectrum of the unresolved nucleus assuming various emission models, including an absorbed power-law, a power-law plus thermal emission component, and a two-temperature thermal plasma. The best fit was however obtained assuming a power-law emission scattered by a hot ionized gas, giving rise to the 6.7 keV iron line.

Our view of the central regions of AGN has been enriched by the discovery of fast and massive outflows of H I and molecular gas. Here we present a brief summary of results obtained for young (and restarted) radio AGN. We find that H I outflows tend to be particularly common in this group of objects. This supports the idea that the jet, expanding in a clumpy medium, plays a major role in driving these outflows. The clumpiness of the medium is confirmed by VLBI and ALMA observations. The H I observations reveal that, at least part of the gas, is distributed in clouds with sizes up to a few tens of pc and mass ~104Mȯ. A change of the conditions in the outflow, with an increasing fraction of diffuse components, as the radio jets grow, is suggested by the high resolution H I observations. The molecular gas completes the picture, showing that the radio plasma jet can couple well with the ISM, strongly affecting the kinematics, but also the physical conditions of the molecular gas. This is confirmed by numerical simulations reproducing, to first order, the kinematics of the gas.

This paper summarizes our recent works of studying AGN feedback in an isolated elliptical galaxy by performing high-resolution hydrodynamical numerical simulations. Bondi radius is resolved and the mass accretion rate of the black hole is calculated. The most updated AGN physics, namely the discrimination of cold and hot accretion modes and the exact descriptions of the AGN radiation and wind for a given accretion rate are adopted and their interaction with the gas in the host galaxy is calculated. Physical processes such as star formation and SNe feedback are taken into account. Consistent with observation, we find the AGN spends most of the time in the low-luminosity regime. AGN feedback overall suppresses the star formation; but depending on location in the galaxy and time, it can also enhance it. The light curve of specific star formation rate is not synchronous with the AGN light curve. These results put a serious challenge to the observational test of the relation between AGN activity and star formation. We find that wind usually plays a dominant role in controlling the AGN luminosity and star formation, but radiation also cannot be neglected.

We constrained the jet proper motion of PMN J2134–0419 at z = 4.33 to μ = 0.035±0.023mas yr−1 using very long baseline interferometry (VLBI). This is the second most distant source where such a measurement could be made. Another distant blazar SDSS J1026+2542 (z = 5.27) shows jet component proper motions up to μ = 0.112 ± 0.031 mas yr−1. In both cases, the measured values are consistent with the expectations of current ΛCDM cosmological models.

We propose that two emission regions are present in the decelerating jet of radio galaxy at this same moment. Isotropic electrons, in the farther blob as counted along the jet, up-scatter mono-directional soft radiation, from the closer blob, at a relatively large angles to the jet axis. Such model can naturally explain the large angle gamma-ray emission observed from radio galaxies.

Observations at high-energies are important to define the first stages of the evolution of extragalactic radio sources and to characterize the interstellar medium of their host galaxies. In some of the X-ray-observed Compact Symmetric Objects (CSOs, among the youngest and most compact radio galaxies), we measured values of the total hydrogen column densities large enough to slow or prevent the radio source growth. The γ-ray window has the potential to constrain the non-thermal contribution of jets and lobes to the total high-energy emission. However, so far, young radio sources remain elusive in γ-rays, with only a handful of detections (or candidates) reported by Fermi. I present our γ-ray study of the CSO PKS 1718–649, and draw comparison with the restarted, γ-ray detected, radio galaxy 3C 84.

By performing the multi-epoch monitoring observation with KaVA at 43 GHz, we investigate the kinematics of the notable newborn bright component C3 located at the tip of the recurrent jet of 3C 84. During 2015 August-September,we discover the positional flip of the C3 component about 0.4 milli-arcsecond in angular scale. The flux density of the C3 component coherently showed the monotonic increase after the flip during our monitoring period. These phenomena are in good agreement with characteristic behaviors of a jet propagation in clumpy ambient medium predicted in hydrodynamical simulations.

X-ray spectroscopy is key to address the theme of “The Hot Universe”, the still poorly understood astrophysical processes driving the cosmological evolution of the baryonic hot gas traceable through its electromagnetic radiation. Two future X-ray observatories: the JAXA-led XRISM (due to launch in the early 2020s), and the ESA Cosmic Vision L-class mission Athena (early 2030s) will provide breakthroughs in our understanding of how and when large-scale hot gas structures formed in the Universe, and in tracking their evolution from the formation epoch to the present day.

In galactic nuclei (AGN), the kinetic energy flux of the jet may exceed the bolometric luminosity of the disk a few orders of magnitude. At the “cold” accretion the radiation from the disk is suppressed because the wind from the disk carries out almost all the angular momentum and the gravitational energy of the accreted material. We calculate an unavoidable radiation from such a disk and the ratio of the kinetic-to-bolometric luminosity from a super massive black hole in framework of the paradigm of the optically thick α-disk of Shakura & Sunyaev. The results confirm that the gravitational energy of the accreted material can be the only source of energy in AGNs.

We present the results of two-dimensional, grid-type hydrodynamical simulations, with parsec-scale central resolution, for the evolution of the hot gas in isolated early-type galaxies (ETGs). The simulations include a physically self-consistent treatment of the mechanical (from winds) and radiative AGN feedback, and were run for a large set of realistic galaxy models. AGN feedback proves to be very important to maintain massive ETGs in a time-averaged quasi-steady state, keeping the star formation at a low level, and the central black hole mass on observed scaling relations. A comparison with recent determinations of the X-ray properties of ETGs in the local universe shows that, at later epochs, AGN feedback does not dramatically alter the gas content originating in stellar recycled material. Thus, the present-day X-ray luminosity is not a robust diagnostic of the impact of AGN activity, within a scenario where the hot gas mostly originates from the stellar population.

Thanks to the Fermi λ-ray satellite and the current Imaging Atmospheric Cherenkov Telescopes, radio galaxies have arisen as a new class of high- and very-high energy emitters. The favourable orientation of their jets makes radio galaxies extremely relevant in addressing important issues such as: (i) revealing the jet structure complexity; (ii) localising the emitting region(s) of high- and very-high energy radiation; (iii) understanding the physical processes producing these photons. In this review the main results on the λ-ray emission studies of radio galaxies from the MeV to TeV regimes will be presented, and the impact of future Cherenkov Telescope Array observations will be discussed.

We report preliminary results of long-term multi-frequency monitoring observations of S5 0716+714. We conducted observations at 22 and 43 GHz using Korean VLBI Network (KVN) radio telescopes and combined 8 (UMRAO), 15 (OVRO), 95 (CARMA), and 230 GHz (SMA) data to investigate characteristics of radio flares. We identified six flares (P1-P6) from 2010 November to 2014 June. The magnetic field strengths by assuming a synchrotron self-absorption model are in the range of 9 mG - 11 G in P2, 26 mG - 3G in P3, 3 mG - 38 G in P4, and 1 mG - 8 G in P6.

Here we present some preliminary results of our analysis of the combined Chandra observations of the Pictor A radio galaxy. All the available Chandra data for the target, consisting of multiple pointings spanning over 15 years and amounting to the total exposure time of 464 ks, have been included in the analysis. We studied in detail the PSFs of the core region in the individual pointings, as well as the radial profile of the X-ray surface brightness of the source in the combined dataset, in order to discriminate between the radiative output of the unresolved core and the host galaxy. Based on these, we have performed spectral modeling of the active nucleus, constraining its variability.

It is still a mystery why only a small fraction of quasars contain relativistic jets. A strong magnetic field is a necessary ingredient for jet formation. Gas falls from the Bondi radius RB nearly freely to the circularization radius Rc, and a thin accretion disk is formed within Rc We suggest that the external weak magnetic field threading interstellar medium is substantially enhanced in this region, and the magnetic field at Rc can be sufficiently strong to drive outflows from the disk if the angular velocity of the gas is low at RB. In this case, the magnetic field is efficiently dragged in the disk, because most angular momentum of the disk is removed by the outflows that lead to a significantly high radial velocity. The strong magnetic field formed in this way may accelerate jets in the region near the black hole, either by the Blandford-Payne or/and Blandford-Znajek mechanisms. If the angular velocity of the circumnuclear gas is low, the field advection in the thin disk is inefficient, and it will appear as a radio-quiet (RQ) quasar.

The Medicina and Noto radiotelescopes have been employed for over 14 years to monitor the flux density variations of a vast sample of blazars at different radio frequencies. Radio data are essential components of blazar spectral energy distribution (SED, spanning from radio waves to gamma rays), whose trend with luminosity and shape changes provide decisive information on the physics of extra-galactic jets and, eventually, on the mechanism extracting energy from the central black hole in radio-loud AGN. Observations presently carried out at 5, 8 and 24 GHz have taken advantage of the continually evolving control system installed at the antennas. A new, batch-wise analysis tool was also produced, in order to easily handle and reduce the datasets acquired in monthly sessions. We here describe the latest developments and achievements.

It has been controversial for years that the accretion mode is different for bright active galactic nuclei (AGNs) and low-luminosity AGNs (LLAGNs). In this work, we compile from literature a sample of 32 LLAGNs, consisting 18 LINERs and 14 low Eddington ratio (λ) Seyfert galaxies. A strong negative correlation between the radio loudness RUV and the optical to X-ray spectral index αox is reported for the first time. We further demonstrate that this negative correlation can be understood consistently and comprehensively under the truncated accretion — jet model, a model that has been applied successfully to LLAGNs. We argue that the scatter in the observations is mainly due to the spread in the viscosity parameter α of a hot accretion flow, a parameter that can potentially serve as a diagnosis of the strength and/or configuration of magnetic fields in accretion flows.