Browsing by Author "Venturi, Giacomo"
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- ItemFeedback and ionized gas outflows in four low-radio power AGN at z ∼ 0.15(EDP Sciences, 2024) Ulivi L.; Venturi, Giacomo; Cresci G.; Marconi A.; Marconcini C.; Amiri A.; Belfiore F.; Bertola E.; Carniani S.; D' Amato Q.; Di Teodoro E.; Ginolfi M.; Girdhar A.; Harrison C.; Maiolino R.; Mannucci F.; Mingozzi M.; Perna M.; Scialpi M.; Tomicic N.; Tozzi G.; Treister E.© 2024 EDP Sciences. All rights reserved.An increasing number of observations and simulations suggests that low-power (< 1044 erg s1) jets may be a significant channel of feedback produced by active galactic nuclei (AGN), but little is known about their actual effect on their host galaxies from the observational point of view. We targeted four luminous type 2 AGN hosting moderately powerful radio emission (∼1044 erg s1), two of which and possibly a third are associated with jets, with optical integral field spectroscopy observations from the Multi Unit Spectroscopic Explorer (MUSE) at the Very Large Telescope (VLT) to analyze the properties of their ionized gas as well as the properties and effects of ionized outflows. We combined these observations with Very Large Array (VLA) and e-MERLIN data to investigate the relations and interactions between the radio jets and host galaxies. We detected ionized outflows as traced by the fast bulk motion of the gas. The outflows extended over kiloparsec scales in the direction of the jet, when present. In the two sources with resolved radio jets, we detected a strong enhancement in the emission-line velocity dispersion (up to 1000 km s1) perpendicular to the direction of the radio jets. We also found a correlation between the mass and the energetics of this high-velocity dispersion gas and the radio power, which supports the idea that the radio emission may cause the enhanced turbulence. This phenomenon, which is now being observed in an increasing number of objects, might represent an important channel for AGN feedback on galaxies
- ItemGaseous nebulae and massive stars in the giant HI ring in Leo(2021) Corbelli, Edvige; Mannucci, Filippo; Thilker, David; Cresci, Giovanni; Venturi, GiacomoContext. Chemical abundances in the Leo ring, the largest HI cloud in the local Universe, have recently been determined to be close to or above Solar values. This is a finding that is incompatible with prior claims that the ring was primordial in origin. The gas, pre-enriched in a galactic disk and tidally stripped, did not manage to efficiently form stars in the intergalactic space.Aims. Using H alpha emission and a multi-wavelengths analysis of its extremely faint optical counterpart, we investigate the process of star formation and the slow build-up of a stellar population that could form diffuse and metal-rich dwarf galaxies in the Leo ring.Methods. We mapped nebular lines in three dense HI clumps and complemented the data with archival stellar continuum observations from the Galaxy Evolution Explorer and the Hubble Space Telescope, as well as with population synthesis models.Results. We detect a sparse population of stars in the main body of the ring, with individual young stars as massive as O7-types powering some HII regions. The average star-formation rate density in the ring is on order of 10(-5)M(circle dot) yr(-1) kpc(-2) and proceeds with local bursts a few hundred parsecs in size, where loose stellar associations of 500-1000 M-circle dot occasionally host massive outliers. The far ultraviolet-to-H alpha emission ratio in nebular regions implies recent stellar bursts, from 2 to 7 Myr ago. The relation between the local HI gas density and the star-formation rate in the ring is similar to what is found in dwarfs and outer disks with gas depletion times as long as 100 Gyr. We find a candidate planetary nebula in a compact and faint H alpha region with [OIII]/H alpha line enhancement, which is consistent with the estimated mean stellar surface brightness of the ring. The presence of a 1 kpc partial ring that is emitting weak H alpha lines around the brightest and youngest HII region suggests that local shocks might triggers future star-forming sites.
- ItemHeavy Elements Unveil the Non-primordial Origin of the Giant H I Ring in Leo(2021) Corbelli, Edvige; Cresci, Giovanni; Mannucci, Filippo; Thilker, David; Venturi, GiacomoThe origin and fate of the most extended extragalactic neutral cloud known in the local universe, the Leo ring, is still debated 38 yr after its discovery. Its existence is alternatively attributed to leftover primordial gas with some low level of metal pollution versus enriched gas stripped during a galaxy-galaxy encounter. Taking advantage of Multi Unit Spectroscopic Explorer operating at the Very Large Telescope, we performed optical integral field spectroscopy of three H I clumps in the Leo ring where ultraviolet continuum emission has been found. We detected, for the first time, ionized hydrogen in the ring and identify four nebular regions powered by massive stars. These nebulae show several metal lines ([O III], [N II], [S II]) that allowed reliable measures of metallicities, found to be close to or above the solar value (0.8 <= Z/Z <= 1.4). Given the faintness of the diffuse stellar counterparts, less than 3% of the observed heavy elements could have been produced locally in the main body of the ring and not much more than 15% in the H I clump toward M96. This inference, and the chemical homogeneity among the regions, convincingly demonstrates that the gas in the ring is not primordial, but has been pre-enriched in a galaxy disk, then later removed and shaped by tidal forces and it is forming a sparse population of stars.
- ItemPre-supernova stellar feedback in nearby starburst dwarf galaxies(2024) Rowland, Lucie E.; Mcleod, Anna F.; Fattahi, Azadeh; Belfiore, Francesco; Cresci, Giovanni; Hunt, Leslie; Krumholz, Mark; Kumari, Nimisha; Marasco, Antonino; Venturi, GiacomoContext. Stellar feedback in dwarf galaxies remains, to date, poorly explored, yet is crucial to understanding galaxy evolution in the early Universe. In particular, pre-supernova feedback has recently been found to play a significant role in regulating and disrupting star formation in larger spiral galaxies, but it remains uncertain if it also plays this role in dwarfs. Aims. We study the ionised gas properties and stellar content of individual star-forming regions across three nearby, low-metallicity (12 + log(O/H)similar to 7.5), dwarf (M* similar to 40 x 106 M circle dot), starburst (log(SFR)similar to - 2.8) galaxies (J0921, KKH046, and Leo P) to investigate how massive stars influence their surroundings and how this influence changes as a function of environment. Methods. We extracted integrated spectra of 30 HII regions from archival VLT/MUSE integral field spectroscopic observations of these three dwarf starburst galaxies. We fitted the HII regions' main emission lines with Gaussian profiles to derive their oxygen abundances, electron densities, and luminosities, and we used the Stochastically Ligthing Up Galaxies (SLUG) code to derive the stellar mass, age, and bolometric luminosity of the stellar populations driving the HII regions. We quantified two pre-supernova stellar feedback mechanisms, namely the direct radiation pressure and photoionisation feedback, and explored how feedback strength varies with HII region properties. Results. Our findings suggest that stellar feedback has less of an impact on evolved regions, with both the pressure of the ionised gas and the direct radiation pressure decreasing as a function of HII region size (i.e. the evolutionary stage). We find that these stellar feedback mechanisms are also dependent on the metallicity of the HII regions. These findings extend results from stellar feedback studies of more massive star-forming galaxies to the low-mass, low-metallicity regime. In addition, we conclude that the use of stochastic stellar population models significantly affects the relationships found between feedback-related pressure terms and HII region properties, and in particular that non-stochastic models can severely underestimate the bolometric luminosity of low-mass stellar populations.
- ItemThe Complex Gaseous and Stellar Environments of the Nearby Dual Active Galactic Nucleus Mrk 739(2021) Tubín, Dusán ; Treister, Ezequiel ; D’Ago, Giuseppe ; Venturi, Giacomo ; Bauer, Franz E. ; Privon, George C. ; Koss, Michael J. ; Ricci, Federica ; Comerford, Julia M. ; Müller-Sánchez, FranciscoWe present integral field spectroscopic observations of the nearby (z similar to 0.03) dual active galactic nuclei (AGNs) Mrk 739, whose projected nuclear separation is similar to 3.4 kpc, obtained with the Multi Unit Spectroscopic Explorer at the Very Large Telescope. We find that the galaxy has an extended AGN-ionized emission-line region extending up to similar to 20 kpc away from the nuclei, while star-forming regions are more centrally concentrated within 2-3 kpc. We model the kinematics of the ionized gas surrounding the eastern nucleus using a circular disk profile, resulting in a peak velocity of 237(28)(+26) km s(-1) at a distance of similar to 1.2 kpc. The enclosed dynamical mass within 1.2 kpc is logM(M-circle dot) = 10.20 +/- 0.06, similar to 1000 times larger than the estimated supermassive black hole (SMBH) mass of Mrk 739E. The morphology and dynamics of the system are consistent with an early stage of the collision, where the foreground galaxy (Mrk 739W) is a young star-forming galaxy in an ongoing first passage with its background companion (Mrk 739E). Since the SMBH in Mrk 739W does not show evidence of being rapidly accreting, we claim that the northern spiral arms of Mrk 739W are ionized by the nuclear activity of Mrk 739E.
- ItemThe Molecular Gas in the NGC 6240 Merging Galaxy System at the Highest Spatial Resolution(2020) Treister, Ezequiel; Messias, Hugo; Privon, George C.; Nagar, Neil; Medling, Anne M.; U, Vivian; Bauer, Franz Erik; Cicone, Claudia; Barcos Muñoz, Loreto; Venturi, Giacomo
- ItemThe MURALES survey : III. Completing the MUSE observations of 37 3C low- z radio galaxies(2021) Balmaverde, B.; Capetti, A.; Marconi, A.; Venturi, Giacomo; Chiaberge, M.; Baldi, R. D.; Baum, S.; Gilli, R.; Grandi, P.; Meyer, E. T.; Miley, G.; O'Dea, C.; Sparks, W.; Torresi, E.; Tremblay, G.
- ItemThe MURALES survey II. Presentation of MUSE observations of 20 3C low-z radio galaxies and first results(2019) Balmaverde, B.; Capetti, A.; Marconi, A.; Venturi, Giacomo; Chiaberge, M.; Baldi, R.; Baum, S.; Gilli, R.; Grandi, P.; Meyer, E.; Miley, G.; O'Dea, C.; Sparks, W.; Torresi, E.; Tremblay, G.
- ItemThe WISSH quasars project : IX. Cold gas content and environment of luminous QSOs at z ∼2.4-4.7(2021) Bischetti, M.; Feruglio, C.; Piconcelli, E.; Duras, F.; Perez-Torres, M.; Herrero, R.; Venturi, Giacomo; Carniani, S.; Bruni, G.; Gavignaud, I.; Testa, V.; Bongiorno, A.; Brusa, M.; Circosta, C.; Cresci, G.; D'Odorico, V.; Maiolino, R.; Marconi, A.; Mingozzi, M.; Pappalardo, C.; Perna, M.; Traianou, E.; Travascio, A.; Vietri, G.; Zappacosta, L.; Fiore, F.