Browsing by Author "Speranza, G."

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    The MURALES survey IV. Searching for nuclear outflows in 3C radio galaxies at z < 0.3 with MUSE observations
    (2021) Speranza, G.; Balmaverde, B.; Capetti, A.; Massaro, F.; Tremblay, G.; Marconi, A.; Venturi, G.; Chiaberge, M.; Baldi, R. D.; Baum, S.; Grandi, P.; Meyer, E. T.; O'Dea, C.; Sparks, W.; Terrazas, B. A.; Torresi, E.
    We analyze VLT/MUSE observations of 37 radio galaxies from the Third Cambridge catalogue (3C) with redshift < 0.3 searching for nuclear outflows of ionized gas. These observations are part of the MURALES project (a MUse RAdio Loud Emission line Snapshot survey), whose main goal is to explore the feedback process in the most powerful radio-loud AGN. We applied a nonparametric analysis to the [O III] lambda 5007 emission line, whose asymmetries and high-velocity wings reveal signatures of outflows. We find evidence of nuclear outflows in 21 sources, with velocities between similar to 400 and 1000 km s(-1), outflowing masses of similar to 10(5) - 10(7) M-circle dot, and a kinetic energy in the range similar to 10(53) - 10(56) erg. In addition, evidence for extended outflows is found in the 2D gas velocity maps of 13 sources of the subclasses of high-excitation (HEG) and broad-line (BLO) radio galaxies, with sizes between 0.4 and 20 kpc. We estimate a mass outflow rate in the range 0.4-30 M-circle dot yr(-1) and an energy deposition rate of (E)over dot(kin) similar to 10(42) - 10(45) erg s(-1). Comparing the jet power, the nuclear luminosity of the active galactic nucleus, and the outflow kinetic energy rate, we find that outflows of HEGs and BLOs are likely radiatively powered, while jets likely only play a dominant role in galaxies with low excitation. The low loading factors we measured suggest that these outflows are driven by momentum and not by energy. Based on the gas masses, velocities, and energetics involved, we conclude that the observed ionized outflows have a limited effect on the gas content or the star formation in the host. In order to obtain a complete view of the feedback process, observations exploring the complex multiphase structure of outflows are required.
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    The MURALES survey VI. Properties and origin of the extended line emission structures in radio galaxies
    (2022) Balmaverde, B.; Capetti, A.; Baldi, R. D.; Baum, S.; Chiaberge, M.; Gilli, R.; Jimenez-Gallardo, A.; Marconi, A.; Massaro, F.; Meyer, E.; O'Dea, C.; Speranza, G.; Torresi, E.; Venturi, G.
    This is the sixth paper presenting the results of the MUse RAdio Loud Emission line Snapshot survey. We observed 37 radio sources from the 3C sample with z < 0.3 and a declination <20 degrees with the Multi Unit Spectroscopic Explorer optical integral field spectrograph at the Very Large Telescope. Here, we focus on the properties of the extended emission line regions (EELRs) that can be studied with unprecedented detail thanks to the depth of these observations. Line emission in the ten FR Is is, in most cases, confined to within less than or similar to 4kpc, while large-scale (greater than or similar to 4 kpc) ionized gas is seen in all but two of the 26 FR Its. It usually takes the form of elongated or filamentary structures, typically extending between 10 and 30 kpc, but also reaching distances of similar to 80 kpc. We find that the large-scale ionized gas structures show a tendency to be oriented at large angles from the radio axis, and that the gas on a scale of a few kiloparsecs from the nucleus often shows ordered rotation with a kinematical axis forming a median angle of 65 degrees with the radio axis. We also discuss the velocity field and ionization properties of the EELRs. The observed emission line structures appear to be associated with gaseous "superdisks" that formed after a gas-rich merger. The different properties of the EELR can be explained with a combination of the source evolutionary state and the orientation of the superdisk with respect to the radio axis. The general alignment between the superdisks and radio axis might be produced by stable and coherent accretion maintained over long timescales.