Found 11 talks width keyword supermassive black hole, SMBH

Tuesday October 1, 2019
Dr. Omaira González Martín
Instituto de Radioastronomía y Astrofísica, México


The dust component of active galactic nuclei (AGN) produces a broad infrared spectral energy distribution (SED), whose power and shape depends on the fraction of the source absorbed, and the geometry of the absorber respectively. This emitting region is expected to be concentrated within the inner ∼5 pc of the AGN which makes almost impossible to image it with the current instruments. The study of the infrared SED by comparison between infrared AGN spectra and predicted models is one of the few ways to infer the properties of the AGN dust. We explore a set of six dusty models of AGN with available SEDs, namely Fritz et al. (2006), Nenkova et al. (2008B), Hoenig & Kishimoto (2010), Siebenmorgen et al. (2015), Stalevski et al. (2016), and Hoenig & Kishimoto (2017). They cover a wide range of morphologies, dust distributions, and compositions.

We explore the discrimination among models and parameter restriction using synthetic spectra (Gonzalez-Martin et al. 2019A), and perform spectral fitting of a sample of 110 AGN with Spitzer/IRS drawn from the Swift/BAT survey (Gonzalez-Martin et al. 2019B). Our conclusion is that most of these models can be discriminated using only mid-infrared spectroscopy as long as the host galaxy contribution is less than 50%. The best model describing the sample is the clumpy disk-wind model by Hoenig & Kishimoto (2017). However, large residuals are shown irrespective of the model used, indicating that AGN dust is more complex than models. We found that the parameter space covered by models is not completely adequate. This talk will give tips for observers and modelers to actually answer the question: how is the dust arrange in AGN? This question will be one of the main subjects of future research using JWST in the AGN field.

Tuesday January 8, 2019
Dr. Johan Knapen


We present the discovery of a small 0.2'' (60 pc) radius kinematically decoupled core, as well as an outflow jet, in the archetypical AGN-starburst "composite" galaxy NGC 7130 from integral field data obtained with the adaptive optics-assisted MUSE-NFM instrument on the VLT. Correcting the already good natural seeing at the time of our science verification observations with the four-laser GALACSI AO system we reach an unprecedented spatial resolution of around 0.15''. We confirm the existence of star-forming knots arranged in an 0.58'' (185 pc) radius ring around the nucleus, previously observed from UV and optical  Hubble Space Telescope and CO(6-5) ALMA imaging. We determine the position of the nucleus as the location of a peak in gas velocity dispersion. A plume of material extends towards the NE from the nucleus until at least the edge of our FOV at 2'' (640 pc) radius which we interpret as an outflow jet originating in the AGN. The plume is not visible morphologically, but is clearly characterised in our data by emission lines ratios characteristic of AGN emission, enhanced gas velocity dispersion, and distinct non-circular gas velocities. Its orientation is roughly perpendicular to line of nodes of the rotating host galaxy disk. An 0.2''-radius circumnuclear area of positive and negative velocities indicates a tiny inner disk, which can only be seen after combining the integral field spectroscopic capabilities of MUSE with adaptive optics.

Tuesday December 4, 2018
Dr. Chiara Feruglio
INAF Observatory of Trieste


Why did galaxies stop forming stars? Why do black holes in galactic nuclei have masses proportional to bulge masses? What are the physical mechanisms leading the transition from gas-rich, star-forming galaxies, to red gas-deprived passive galaxies? Theoretical models predict that AGN should play a major role in this co-evolution, by driving super winds that are eventually able to remove gas from galaxies, thus quenching star-formation and preventing them from over growing.  
Today’s flagship Instruments - like ALMA and MUSE/VLT - allow to routinely detect AGN-driven massive winds, and to spatially resolve and measure their main parameters. AGN driven galactic winds seem a widespread feature in AGN host galaxies in the local universe, with mounting numbers also in the distant universe.  
But questions arise about their net impact on the surrounding ISM, on the relative importance of quenching versus stimulating star-formation, on the removal of the gas reservoirs from the disks of the host galaxies. 
Do we really understand the interplay of these AGN super-winds with the ISM of the host galaxy, and -perhaps more importantly- with the entire AGN/host galaxy/circum-galactic medium (CGM) ecosystem? I will discuss both observational and theoretical recent results on this topic - and highlight possible strategies to progress. 

Tuesday July 30, 2013
Dr. Ezequiel Treister
Universidad de Concepción


It is now clear that supermassive black holes (M>1e6 Msun) live in the center of most (all) galaxies, including our own Milky Way. Furthermore, the energy released during the growth of this black hole is a critical ingredient in understanding galaxy formation and evolution. In this talk, I will show what we know about how, when and where these supermassive black holes are acquiring their masses. In particular, I will focus on the effects of obscuration, as it is now clear that the majority of this black hole growth is hidden from our view by large amounts of gas and dust. I will present statistical evidence suggesting that while most nuclear activity is triggered by internal secular processes, the most violent episodes are linked to major galaxy mergers. Finally, I will show how future data obtained combining observations with the ALMA radio telescope and the NuSTAR X-ray observatory will allow us to understand the physical details of the connection between black hole growth and galaxy evolution.

Thursday April 26, 2012
Prof. Luis C. Ho
The Observatories of the Carnegie Institution for Science, USA


Supermassive black holes are ubiquitous in galaxies and play a fundamental role in their life cycle. I will review observational progress in defining and refining the various empirical scaling relations between black hole masses and host galaxy properties. I will emphasize ways in which the intrinsic scatter of the scaling relations can be quantified, and present evidence that the scatter correlates with physical properties. I will describe how the scaling relations can be extended to active galaxies and summarize preliminary efforts to probe the evolution of these scaling relations with redshift. I will present new measurements of the cold ISM content in AGN host galaxies and constraints they place on currently popular models of AGN feedback. Lastly, I will discuss a new class of low-mass black holes in bulgeless and dwarf galaxies that serve as local analogs of seed supermassive black holes.

Friday May 20, 2011
Prof. Ramesh Narayan
Harvard-Smithsonian Center, USA.


In his public talk, Prof. Narayan will summarize our knowledge of Black Holes in the universe. He will describe how Black Holes are discovered, how their properties are measured, and what the results mean. He will also discuss the many ways in which Black Holes influence their surroundings and the profound effect they have had on the evolution of the universe.

Thursday March 3, 2011
Miss Mar Mezcua
Max Planck Institute for Radio Astronomy, Germany


The detection and number estimates of supermassive binary black holes (SMBBHs) provide important constraints on the hierarchical models for galaxy formation and evolution. I will present two different approaches for the possible identification of SMBBHs. 1.Radio-optical studies of X-shaped radio sources:X-shaped radio galaxies are extragalactic radio sources that present two pairs of radio lobes passing symmetrically through the center of the host galaxy, giving the galaxy the X-shaped morphology seen on radio maps.This morphology can reflect either a recent merger of two supermassive black holes or the presence of a second active black hole in the galactic nucleus. This scenario is studied by determining the mass, luminosity, jet dynamic age and starburst of a sample of X-shaped sources and comparing the results to a sample of radio-loud active nuclei with similar redshift and luminosities. 2.Compact radio emission in ULX objects: Ultraluminous X-ray sources (ULXs) have luminosities exceeding 10E39 erg/s, suggesting either the presence of black holes larger than stellar mass black holes or sources apparently radiating above the Eddington limit. I will present milliarcsecond-scale radio observations of some ULXs located within optical bright galaxies, resolving their compact radio emission, and measuring its brightness temperature and spectral properties. This allows us to uncover the nature of these sources and investigate whether they are intermediate mass black holes or supermassive black holes stripped of their accretion disks in post-merger systems.

Thursday February 11, 2010
Dr. Marina Vika
University of St Andrews, UK


We present our latest measurement of the SMBH mass function at redshift zero based on detailed structural studies of 1743 galaxies extracted from the B-band Millennium Galaxy Catalogue. Using the empirical correlations between the mass of the black hole and the photometric properties of the spheroid, MBH-L and MBH-n we estimated the SMBH mass of each galaxy and from this construct empirically derived SMBH mass functions. In addition, using a sample of 30 nearby elliptical and spiral galaxies, we will present new results showing the near-IR correlation between bulge properties and SMBH mass.

Thursday July 2, 2009
Miss Javiera Guedes
University of California Santa Cruz, USA


The coalescence of a massive black hole (MBH) binary leads to the gravitational-wave recoil of the system and its ejection from the galaxy core. We have carried out N-body simulations of the motion of a M=3.7 M⊙ MBH remnant in the “Via Lactea I” Milky Way-sized halo. The hole receives a kick velocity of Vkick = 80, 120, 200, 300, and 400 km/s at redshift 1.5, and its orbit is followed for over 1 Gyr within a “live” host halo, subject only to gravity and dynamical friction against the dark matter background. We show that, owing to asphericities in the dark matter potential, the orbit of the MBH is highly non-radial, resulting in a significantly increased decay timescale compared to a spherical halo. The simulations are used to construct a semi-analytic model of the motion of the MBH in a time-varying triaxial Navarro-Frenk-White dark matter halo plus a spherical stellar bulge, where the dynamical friction force is calculated directly from the velocity dispersion tensor. Such a model should offer a realistic picture of the dynamics of kicked MBHs in situations where gas drag, friction by disk stars, and the flattening of the central cusp by the returning hole are all negligible effects. We find that, in a Milky Way-sized galaxy, a recoiling hole carrying a gaseous disk of initial mass ~2 MBH may shine as a quasar for a substantial fraction of its “wandering” phase. The long decay timescales of recoiling MBHs predicted by this study may thus be favorable to the detection of off-nuclear quasar activity.

Wednesday January 21, 2009
Dr. Nadine Neumayer
European Southern Observatory, Garching, Germany


The centers of massive galaxies are special in many ways, not least because all of them are believed to host supermassive black holes. Since the discovery of a number of relations linking the mass of this central black hole to the large scale properties of the dynamically hot component of its host galaxy (bulge) it has become clear that the growth of the central black hole is intimately connected to the evolution of its host galaxy. However, for bulge-less galaxies, the situation is much less clear. Interestingly, these galaxy often host star clusters in their nuclei, and unlike black holes, these nuclear star clusters provide a visible record of the accretion of stars and gas into the nucleus. I will present my ongoing projects on nuclear star clusters that aim to understand their formation process and might give a hint on how black holes get to the centers of galaxies.

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