2,853 research outputs found
Black hole primer for undergraduate students of physics and astronomy
No full textLecture about black holes and their importance in astrophysics for undergraduate students and first year grad students in physics and astronomy. Prepared and taught by Prof. Rodrigo Nemmen at IAG USP. Gravitational waves are discussed in a separate set of slides.Credit for the slides/figures belongs to Rodrigo Nemmen, unless otherwise stated.</p
Lecture Slides: Graduate Course on Active Galactic Nuclei
No full textActive Galactic Nuclei (AGN): Graduate Course Slides by Prof. Rodrigo Nemmen, August 2020Slides from the graduate course “Active galactic nuclei”, prepared and taught by Prof. Rodrigo Nemmen at IAG, Universidade de Sao Paulo. The course gives a broad overview of observations and theory of active galactic nuclei (AGN). The slides reflect the material of the August 2020 course offering.The following topics are covered in the slides:1. IntroductionOverview of course. Historical perspective. Basic concepts of black hole physics. Main parameters of the problem.2. AGN zooObservational properties of AGNs. Type I/II. Obscuring torus. Relevant spatial scales. Radio-loudness. Spectral energy distributions. Grand unification.3. Supermassive black hole detectionsEvidence for supermassive black holes (SMBHs). Methods for measuring SMBH masses: BH shadow, stellar proper motion, Maser NGC 4258, Stellar dynamics, Gas dynamics, Reverberation mapping, Indirect methods (scalings).4. Accretion physicsDissipation. Basic equations of accretion flows. Accretion states. Thin disk (Shakura & Sunyaev). Radiatively inefficient accretion flow (RIAF). Emission lines. GRMHD.5. Jets: theoryBasic facts. Jet formation. Blandford-Znajek model. Jet-disk connection. Unification.6. AGN FeedbackMotivation. Order-of-magnitude estimates. SMBH outflows. Modes and effects. Quasar mode. Radio mode. Cosmological simulations.7. Open questionsAGN unification. Accretion physics. Jets. Feedback.-------------------------------------------------------------------------------The lectures had a total duration of about 15 hours.Credit for the slides and figures belongs to Rodrigo Nemmen, unless otherwise stated. Some of the figures were adapted from other sources; due credit is given when it is the case. </p
Active galactic nuclei and blazars, lecture
No full textSlides from a set of lectures about active galactic nuclei (AGNs) and blazars for advanced undergraduate and graduate students in physics and astronomy. Prepared and taught by Prof. Rodrigo Nemmen. The slides give a broad overview of observations and theory of AGN, with some emphasis on jetted AGNs (blazars) and high-energy electromagnetic radiation The following topics are covered:1. Historical perspective2. Black hole physics3. Observed AGN zoo4. The ins of BHs: accretion5. The outs: jets6. BlazarsThis was presented in two lectures with a total duration of 3 hours. I was not able to cover all material available in the slides. Credit for the slides and figures belongs to Rodrigo Nemmen, unless otherwise stated.https://rodrigonemmen.com</div
Sci-fi na perspectiva de um astrofísico. Slides de apresentação (PDF)
No full textApresentação dada pelo Professor Rodrigo Nemmen no evento Encontro de Universos, que aconteceu no IAG USP no dia 24 de Abril de 2019. Encontro de universos: uma conversa sobre ficção científicaEm que pontos a ciência e a arte literária tangenciam? Esta atividade reunirá um astrofísico e um escritor para dialogar e oferecer diferentes pontos de vista sobre o gênero da ficção científica, no qual a criação artística e a reflexão filosófica tem como ponto de partida descobertas da ciência e as especulações que podem ser elaboradas tendo em mente as revoluções tecnológicas de nosso tempo. A conversa contará com o astrofísico Rodrigo Nemmen, professor no IAG USP, e o escritor Antônio Xerxenesky, doutor em literatura pela FFLCH-USP e autor de vários livros de ficção. Mediação de Eduardo Cypriano.SOBRE OS PARTICIPANTESAntônio Xerxenesky é escritor, tradutor e doutorando em Teoria Literária pela FFLCH-USP. É autor de As perguntas e F.Rodrigo Nemmen é astrofísico, professor do IAG-USP e membro afiliado da Academia Brasileira de Ciências. Sua pesquisa envolve buracos negros e astrofísica de altas energias.Eduardo Cypriano é astrofísico, professor do IAG-USP. Sua pesquisa envolve astrofísica extragaláctica e cosmologia observacional.</div
A Nonthermal Bomb Explains the Near-infrared Superflare of Sgr A&z.ast
No full textThe Galactic center supermassive black hole, Sgr A, has experienced a strong, unprecedented flare in 2019 May when its near-infrared luminosity reached much brighter levels than ever measured. We argue that an explosive event of particle acceleration to nonthermal energies in the innermost parts of the accretion flow- A nonthermal bomb-explains the near-infrared light curve. We discuss potential mechanisms that could explain this event such as magnetic reconnection and relativistic turbulence acceleration. Multiwavelength monitoring of such superflares in radio, infrared, and X-rays should allow a concrete test of the nonthermal bomb model and put better constraints on the mechanism that triggered the bomb.Fil: Gutiérrez, Eduardo Mario. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Nemmen, Rodrigo. Universidade de Sao Paulo; BrasilFil: Cafardo, Fabio. Universidade de Sao Paulo; Brasi
Simulation data, model 5, mdot=0.02
No full textSimulation data files in the binary format used by Pluto. For the notebooks that process these data, see the Notebooks child projects associated with the main one.Reference: Nemmen et al., Emergence of hot corona and truncated disk in simulations of accreting stellar mass black holes. MNRAS, submittedDescription of filesarchive.?.tarBinary files packed with tar, without compression. Use the unpack.py code to unpack all files.misc.tar.bz2Miscellaneous files generated by Pluto during the run, compressed with the bzip2 protocol.unpack.pyPython code to unpack all tar files in the current directory.</p
Simulation data, model 4, mdot=0.06
No full textSimulation data files in the binary format used by Pluto. For the notebooks that process these data, see the Notebooks child projects associated with the main one.Reference: Nemmen et al., Emergence of hot corona and truncated disk in simulations of accreting stellar mass black holes. MNRAS, submittedDescription of filesarchive.?.tarBinary files packed with tar, without compression. Use the unpack.py code to unpack all files.misc.tar.bz2Miscellaneous files generated by Pluto during the run, compressed with the bzip2 protocol.unpack.pyPython code to unpack all tar files in the current directory.</p
Simulation data, model 3, mdot=0.11
No full textSimulation data files in the binary format used by Pluto. For the notebooks that process these data, see the Notebooks child projects associated with the main one.Reference: Nemmen et al., Emergence of hot corona and truncated disk in simulations of accreting stellar mass black holes. MNRAS, submittedDescription of filesarchive.?.tarBinary files packed with tar, without compression. Use the unpack.py code to unpack all files.misc.tar.bz2Miscellaneous files generated by Pluto during the run, compressed with the bzip2 protocol.unpack.pyPython code to unpack all tar files in the current directory.</p
Black Hole Weather Forecasting with Deep Learning: A Pilot Study
No full textThis repository contains the data files containing the convolutional neural network weights resulting from our multi GPU training using Tensorflow v1.8.0. Both files are in the HDF5 binary format. The results from this architecture was published in Black Hole Weather Forecasting with Deep Learning: A Pilot Study (Duarte, Nemmen & Navarro, MNRAS, in press). • dl_fluids.h5: one-sim model• dl_fluids-1.h5: multi-sim modelPlease refer to the source fileinference.py available in the github repository (https://github.com/black-hole-group/DL_BH_fluids), which demonstrates how to create predictions using these data files. In particular, you can load the weights using model.load("/path/to/.h5/dl_fluids.h5").</p
Spectral models for low-luminosity active galactic nuclei in LINERs
No full textSpectral energy distribution data from the paper Nemmen et al. 2014, "Spectral models for low-luminosity active galactic nuclei in LINERs: the role of advection-dominated accretion and jets", published in MNRAS. This dataset includes the observational data and model SEDs published in the paper. For more info about the data, please open the README.md file included.DOI for paper: 10.1093/mnras/stt2388This notation applies to all files:- Each filename begins with the name of the galaxy- `ad` in the filename refers to an ADAF-dominated model- `jd` in the filename refers to a jet-dominated model- Extensions `.adaf`, `.ssd`, `.jet` or `.sum` refer to model SEDs- Extension `.dat` refer to observational data- Extension `.popstar` refer to the stellar population spectrum# PDF filesThe spectral energy distribution (SED) plots published in the paper, in the PDF format.# Spectral models: accretion flow and jetASCII files with the models for each galactic nucleus, with two columns: 1. log10(nu / Hz)2. log10(nu * L_nu / erg/s)The spectral model files end with one of the following extensions: `.adaf`, `.ssd`, `.jet` or `.sum`. Each extension refers to the physical component of the flow which is considered: ADAF (`adaf`), thin accretion disk (`ssd`), relativistic jet (`jet`) or the sum of all components (`sum`).`ad` refers to an ADAF-dominated model, `jd` refers to a jet-dominated model.# Spectral model: stellar populationThe file `Sed_Mar05_Z_0.02_Age_10.00000000.popstar` corresponds to a stellar population spectrum based on the Bruzual & Charlot models which we plotted with every SED. We fit this spectrum to the optical-UV data for each galaxy, hence deriving the stellar mass.# ObservationsASCII files containing the observed SED data points for each galaxy. These files end with extensions `.dat`.Each column in he data files is the following:1. Frequency (Hz) 2. Observed nu*L_nu (erg/s) 3. nu*L_nu (erg/s) 4. Fractional Uncertainty (Variability) 5. Upper limit? (1-yes, 0-no)`NGC3998 old.dat` includes a high-frequency UV data point which as suggested by Mike Eracleous I ended up discarding. Please read the paper for more info.</div
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