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26 September 2017

PhD graduate at the Institute of Astrophysics UC publishes article on the evolution of binary black holes

Felipe Garrido Goicovic, who recently defended his doctoral thesis, wrote an interesting paper that presents a new mechanism for the evolution of binary systems of super-massive black holes.

icsSuper-massive black holes, as their name suggests, are black holes that have a mass greater than a million suns, found in the centers of galaxies. In fact, they are fundamental for galaxy evolution because they emit large amounts of energy when they feed on material. Felipe Garrido Goicovic, recently graduated from the UC Institute of Astrophysics, has studied the evolution of binary systems of super-massive black holes for several years. "During their life, galaxies merge with each other to form new ones. Therefore, it is inevitable that their black holes meet and orbit each other, forming a binary system."

At the present time, he says, there is little observational evidence of these systems and the mechanisms that lead the binary system to its fusion. "I investigate the evolution of molecular gas clouds as they approach and are captured by binary super-massive black holes. This new paper presents the results of thirteen simulations developed to study the evolution of the binary's orbit as a function of the trajectory of the clouds. With the results of the simulations, we build a simple model to 'evolve' a binary and find the time scale on which the black holes would merge".

The results of his research show that the binary would merge within a few hundred million years only, "suggesting that cloud infall to the centers of galaxies could be an important mechanism in the evolution of these binaries".

The next step, he says, is to develop simulations where we model the interaction of a binary with a sequence of clouds (unlike the study to be published, where it was simulated with individual clouds), "that will allow us to compare directly with the simplified model and thus to separate the effect that the cloud has when impacts directly on the binary from the effect of the material that accumulates around it."

The research will be published on the Monthly Notices of the Royal Astronomical Society, and was part of Felipe's PhD thesis that started in 2013 and was successfully defended in August this year. Felipe is now working as a postdoctoral researcher at the Institute for Theoretical Studies in Heidelberg (HITS), Germany.

You can view the paper here.

14 June 2017

Possible Sponsors

Felipe Barrientos

Research lines: Galaxy clusters and their evolution through imaging, strong lensing and SZ signatures. Machine learning techniques to exploit large imaging surveys.

Current projects: Imaging surveys like VST-ATLAS and the Chilean U-band extension (UVAS). Follow up of SZ galaxy clusters. Quasars behind Clusters (QbC). Red-Sequence Cluster Surveys. MOONS Extragalactic Survey.

Franz Bauer

Research lines: Multi-wavelength studies of AGN structure, distant star-forming galaxies, and extragalactic transients

Looking to sponsor postdocs who can be incorporated into the following projects:
VLT/MOONS Extragalactic Survey - PUC is a member of the instrument team and PUC-MOONS team members (incl. Bauer, Treister, Barrientos, Padilla, Vanzi) are taking part in an SDSS-like guaranteed-time sky survey to acquire 0.6-1.8um spectra for >200,000 galaxies at z~1.5. PUC will be involved in the planning, observing, reduction and analysis of the spectra, and lead AGN and z>6 galaxy characterization programs. Sponsored postdocs would take part in the assembly of these samples (including new observations with Chilean facilities) and early commissioning campaigns.
LSST AGN and transients - PUC faculty Bauer and Treister are members of the LSST AGN working group and are involved in much of the preparatory work required to identify and study the AGNs that will be probed by LSST. At the moment the AGN working group is focusing on the Deep Drilling fields to generate effective truth tables to use with the fully sky survey. More generally, Bauer is involved in the development of the ALERCE broker for ZTF, HAT-PI, LSST, etc. Sponsored postdocs would take part in preparatory work (optimization of search algorithms, assembly of these samples, optimization of follow-up, etc), as well as help with the commissioning data and follow-up campaigns.
ALMA studies of AGNs and SMGs - Bauer is PI of ongoing programs to observe dusty star forming galaxies in the Frontier Fields and CDF-S survey regions, as well as co-I in several other surveys and individual studies. Sponsor postdocs with interferometry expertise would work on proprietary and archival data to place useful constraints on distant obscured star formation and black hole accretion.
X-ray studies of AGNs and extragalactic transients - Sponsored postdocs would exploit archive and new X-ray observations to test and probe AGN, TDEs, SNe, ULXs, and other objects.

Márcio Catelan

Research lines: stellar structure and evolution; pulsating stars; variable stars and their use as tracers of Galactic structure, formation and evolution; extraction and classification of variable stars in large surveys; globular star clusters. A list of publications can be found at https://tinyurl.com/y5fccxdo. Currently involved in a variety of large-scale surveys, such as Catalina, VVV(X), and LSST. Postdoctoral candidates with an interest in exploring the synergies among these and other ongoing surveys, such as Gaia and TESS, are especially encouraged to apply. E-mail address for questions: mcatelan@astro.puc.cl or marcatelan@gmail.com.

Julio Chanamé

Research lines: stellar dynamics of galaxies and star clusters; stellar structure and evolution; stellar rotation; Milky Way and Local Group stellar populations; wide binaries

Looking for postdocs who could join and take the lead on any of the following projects:
Dynamical modeling (Jeans and discrete Schwarzchild) of the resolved stellar populations of nearby galaxies and star clusters (luminous and dark mass content and distribution, central black holes). Projects within the HSTPROMO collaboration.
Search and characterization of debris from the Magellanic Clouds using deep optical and near-infrared data wide field data.
Based on products of surveys such as APOGEE (as member of SDSS-IV), RAVE, K2, Gaia, TESS, etc., my team works on problems such as: the census of 2nd generation stars in the Galactic field, the rotational evolution of low-mass stars, rotation and lithium in red giants, gyrochronology, age determination of field stars, and others.
Gaia wide binaries and applications: wide binary formation channels, chemical tagging, the initial-to-final mass relation for white dwarfs, rotational evolution of low-mass stars, gyrochronology, halo dark matter constraints, testing gravity at the low acceleration regime, statistics of hierarchical triples, double white dwarfs with distant tertiaries as progenitors of type Ia supernovae, moving groups, wide binaries in other galaxies, etc.

Alejandro Clocchiatti

Research lines: Observational studies of bright SN based on spectrophotometric evolution and polarization spectra, with special interest on luminous or subluminous Type Ia SNe. Theoretical studies of these events in collaboration with long term visiting professor Stephane Blondin. Empirical methods of distance estimation using SNe, with emphasis on Type II events. Intensive follow up of transients at early time using a dedicated, automated, 0.5m telescope.

Jorge Cuadra

Research lines: Galactic centre astrophysics; protoplanetary discs and planet–disc interactions; supermassive black hole binaries; star formation and dynamics in galactic nuclei.

Current projects:
Max Planck Partner Group on Galactic Centre Astrophysics: JC leads this group, established in collaboration with MPE in Garching. We are interested in gas dynamics, stellar winds, black hole accretion, stellar dynamics and star formation in the region around Sgr A*.
We are part of the Millennium Nucleus on Planet Formation (NPF), together with astronomers in nearby Valparaíso. At PUC we're mostly interested in modelling dust and gas dynamics, circumbinary and perturbed discs, and the effects of accretion feedback from growing planets.
We are also interested in massive black hole binaries, their interaction with accretion discs and background stars, and their decay due to gravitational wave emission.
For more details, please check our group website.

Rolando Dünner

Research lines: CMB observations and instrumentation, CMB science, mm-wave extragalactic sources, SZ galaxy clusters.

Current projects:
Simons Observatory: participate in the design, field setup and first observations using the new generation of CMB experiments.
Atacama Cosmology Telescope: the new AdvACT dataset will cover 40% of the sky with unprecedented sensitivity and resolution, allowing for state of the are studies of CMB physics, galaxy clusters through tSZ and kSZ, CMB lensing, and B-mode search for primordial GW.
CLASS experiment: new W-band receivers have been installed, entering its scientific CMB observation phase. We participate from several aspects of the experiment, which will provide an independent measurement of primordial B-modes at large angular scales.
Drone-based antenna calibrators: we are developing mm-wave sources that can be flown on drones to measure the antenna response of CMB telescopes, including beam shape, polarization, sidelobes and bandpass calibration.

Gaspar Galaz

Research lines: Extragalactic Astronomy. Low surface brightness galaxies - Ultra diffuse galaxies. Properties of the galaxy distribution. Infrared extragalactic astronomy.

Current and potential projects:
A detailed study of the giant low surface brightness galaxy Malin 1.
Diffuse galaxies in Fornax and intracluster light (in collaboration with Thomas Puzia and team).
Formation and evolution of low surface brightness galaxies in the cosmic web, using simulations (in collaboration with Nelson Padilla).
Galaxy populations in the UVAS survey (in collaboration with Leopoldo Infante and Felipe Barrientos).
Formation of gigantic spiral arms in low surface brightness galaxies (in collaboration with Chanda Jog, India).
A detailed study of low surface brightness galaxies in the SDSS, in particular those edge-on spirals.

Viviana Guzmán

Research lines: Astrochemistry, prestellar cores, photo-dominated regions and protoplanetary disks.

Current projects:
- Chemistry in protoplanetary disks
- Complex organic molecules in PDRs
- Wide-field spectral-imaging of giant molecular clouds (ORION-B IRAM-30m Large Program http://iram.fr/~pety/ORION-B/)

Andrés Jordán

Research lines: Discovery and characterization of extrasolar planets.

Current projects: HATSouth (http://hatsouth.org), CHAT (http://chat.hatsurveys.org), HATPI (http://hatpi.org), ACCESS (survey of transmission spectra with IMACS/Magellan)

Nelson Padilla

Research lines: galaxy formation, structure formation, cosmology

Current projects:
Understanding the relation between dark matter haloes and galaxies via HOD and SHAM phenomenological models of clustering, and semi-analytic and hydro simulations.
Members of the GALFORM collaboration, studying effects of different merger tree codes, improving the treatment of angular momentum of galaxies.
SDSS-IV surveys eBOSS (cosmology via clustering measurements, bivariate functions for galaxy formation), MANGA (inhomogeneities in SF in galaxies)
Preparations for LSST with the Dark Energy Science Collaboration (DESC) constructing mock catalogues for survey design.

Thomas Puzia

Research lines: formation and evolution of galaxies, galaxy scaling relations and morphologies, star cluster systems and stellar populations, population synthesis models, stellar content of the Milky Way (see also https://goo.gl/gajsd).

Current projects: Our group is leading the following large surveys:

Coma Cluster Core Project (C3PO)
Next Generation Fornax Survey (NGFS)
Survey of Centaurus A's Baryonic Structures (SCABS)
Next Generation Virgo Survey - Infrared (NGVS-IR)
GeMS/GSAOI Galactic Globular Cluster Survey (G4CS)
Panchromatic High-Resolution Spectroscopic Survey of LG Star Clusters
VIMOS Virgo Cluster Survey - The Baryonic Angular Momentum Content of Galaxy Halos

We have numerous projects related to the exploitation of these datasets as well as their follow-up projects that the candidate postdoctoral fellows could lead and/or fuse with their expertise. Our group has also recently commissioned a new H-alpha filter on DECam at CTIO, which opens various interesting follow-up opportunities for postdoctoral projects.

Andreas Reisenegger

Research lines: High-energy astrophysics, neutron stars, stellar magnetic fields, high-energy gamma-ray emission, large-scale structure (group web site: http://www2.astro.puc.cl/answers/)

Current projects:
Very high energy gamma ray emission from dark matter decay/annihilation, pulsars, and other sources, prospects for the Cherenkov Telescope Array (CTA)
Neutron stars with stable magnetic field configurations or crust "mountains" as sources of continuous gravitational waves
Magnetic field evolution in neutron stars
Neutron star reheating processes: modeling of thermal evolution and spectral energy distribution, observational constraints from HST UV/optical observations of old pulsars
Pulsar and magnetar glitches & starquakes: phenomenology and modeling
Physical models of fast radio bursts
Gravitational collapse of superclusters of galaxies: constraints from the Shapley Supercluster

Ezequiel Treister

Research lines: Supermassive black hole growth, multiwavelength extragalactic surveys, galaxy mergers

Current projects:
Multiwavelength (ALMA, optical and near-IR IFUs, mid-IR imaging, X-rays) observations of AGN in major galaxy mergers. Member of the MODA (Multiwavelength Observations of Dual AGN) collaboration.
High redshift, z>5, AGN surveys. Formation of the first supermassive black hole seeds. Gas contents of high redshift AGN with ALMA.
High energy census of supermassive black holes. Member of the BASS collaboration.
AGN population synthesis models and studies of AGN structure.

Manuela Zoccali

Research lines: Old stellar populations in the Milky Way, with special emphasis in the Galactic bulge.

Current projects:

  • High spatial resolution study of the Nuclear Bulge
  • Chemical abundances and kinematics in the Galactic bulge with APOGEE, and in preparation for MOONS.
  • Proper motions in the Galactic bulge and disk, from VVV and VVVX data. 3D kinematics + metallicity for bulge field stars.
  • Search and confirmation of new star clusters.
12 April 2017

UC astronomers perform simulation that allows the search for super massive binary black holes

Three researchers from the Institute of Astrophysics at the Universidad Católica de Chile made an important discovery which establishes that the light signatures of the binary black hole merger are different from what was previously predicted.

circumbinaryJust over a year ago the LIGO collaboration reported the first detection of gravitational waves produced during the merger of two black holes of approximately thirty times the mass of the sun. However, there are vastly larger black holes called "super-massive", with masses millions of times larger and whose waves could be detected by new instruments.

Much information can be obtained from gravitational waves, the difficulty is to identify exactly where they are coming from, that is, where the black hole merger is occurring. To achieve this a light signal must be identified, for example: X-rays, radio waves, or simply visible photons, indicating their location. In the case of super-massive black holes, it is the expected gas around them that produces radiation by being "squeezed" or consumed. Professor Jorge Cuadra, from the UC Institute of Astrophysics (IA), and Xian Chen, now at Peking University, but until recently a postdoctoral researcher at IA, as well as dozens of astrophysicists around the world, have been studying what type of signals the black hole binaries can produce in the different phases of their evolution until they reach fusion.

Camilo Fontecilla, PhD student, has joined the group at UC to develop a project that specifically seeks to study how the thickness of the gas disk that forms around the primary black hole (the more massive) influences the light signal. The IA team discovered that the disk, as it becomes thicker, "will be less susceptible to the gravitational effect of the secondary black hole, producing what we call a 'second decoupling' and allowing a significant amount of material to survive the fusion process without being 'squeezed' or consumed. This will allow the luminosity of the system to gradually decrease, unlike the model considered so far that, assuming the disk disappeared completely, considered a sharp cut", says Camilo Fontecilla.

The discovery took place using one-dimensional simulations of a gas disk, developed by Fontecilla since 2014, that allows to study the long-term evolution of these systems. "The most remarkable thing is that with the changes that we propose to the current model, we can consider new alternatives for the temporal evolution of luminosity. According to our work there will still be material around the system when the black holes are very close together, and even after they merge. Therefore, it would be possible to obtain a counterpart of electromagnetic luminosity to the emission of gravitational waves that will be emitted in these stages of the process", explains Camilo Fontecilla, lead author of the study.

The results of the research were published in the Monthly Notices of the Royal Astronomical Society (MNRAS) at the beginning of 2017.

13 March 2017

Research

The faculty staff of the Institute of Astrophysics conduct multiple investigations that are detailed below:

Barrientos, Felipe: Evolution of Galaxies and Clusters of Galaxies; Gravitational Lensing.
Bauer, Franz: AGN (and Galaxy) Demographics, Growth, and Evolution; Radio to X-ray Extragalactic and Galactic Surveys; Nearby SNe and XRBs.
Catelan, Márcio: Stellar Evolution; Globular Clusters; Variable Stars.
Chanamé, Julio: Wide Binaries; Stellar Evolution.
Clocchiatti, Alejandro: Supernovae; Cosmological Distance Relations.
Cuadra, Jorge: Gas Dynamics in the Galactic Centre; Proto-Planetary Discs; Massive Black Hole Binaries; Star Formation and Dynamics in Galactic Nuclei.
Dünner, Rolando: Experimental Astronomy and Instrumentation; Large Scale Structure and Cosmology.
Galaz, Gaspar: Stellar Content in Galaxies; Low Surface Brightness Galaxies; Statistical Properties of the Galaxy Distribution; Galaxy Evolution; Morphological and Spectral Classification of Distant Galaxies Observational Cosmology.
Infante, Leopoldo: Large Scale Structure, Galaxy Formation and Evolution; Large Surveys.
Jordán, Andrés: Discovery and Characterization of Transiting Exoplanets; Instrumentation.
Padilla, Nelson: Large Scale Structure Simulations and Observational Surveys.
Puzia, Thomas H.: Galaxy Formation and Evolution; Star Cluster Systems and Stellar Populations in Galaxies.
Reisenegger, Andreas: Neutron Stars; Magnetohydrodynamics; Stellar Magnetic Fields; Dynamics of Clusters and Superclusters of Galaxies; Statistical Mechanics, Phase Transitions / Astrophysical Tests of Fundamental Physics.
Treister, Ezequiel: Formation and Evolution of Supermassive Black Holes.
Zoccali, Manuela: The Galactic Bulge; Stellar Populations; Chemical Abundances; Galactic Globular Clusters; The Initial Mass Function.

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