Download or read book Star Formation in Low Radio Luminosity AGN from the Sloan Digital Sky Survey written by and published by . This book was released on 2007 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: We investigate faint radio emission from low- to high-luminosity Active Galactic Nuclei (AGN) selected from the Sloan Digital Sky Survey (SDSS). Their radio properties are inferred by coadding large ensembles of radio image cut-outs from the FIRST survey, as almost all of the sources are individually undetected. We correlate the median radio flux densities against a range of other sample properties, including median values for redshift, [O III] luminosity, emission line ratios, and the strength of the 4000Å break. We detect a strong trend for sources that are actively undergoing star-formation to have excess radio emission beyond the ≈ 1028 ergs s−1 Hz−1 level found for sources without any discernible star-formation. Furthermore, this additional radio emission correlates well with the strength of the 4000Å break in the optical spectrum, and may be used to assess the age of the star-forming component. We examine two subsamples, one containing the systems with emission line ratios most like star-forming systems, and one with the sources that have characteristic AGN ratios. This division also separates the mechanism responsible for the radio emission (star-formation vs. AGN). For both cases we find a strong, almost identical, correlation between [O III] and radio luminosity, with the AGN sample extending toward lower, and the star-formation sample toward higher luminosities. A clearer separation between the two subsamples is seen as function of the central velocity dispersion [sigma] of the host galaxy. For systems at similar redshifts and values of [sigma], the star-formation subsample is brighter than the AGN in the radio by an order of magnitude. This underlines the notion that the radio emission in star-forming systems can dominate the emission associated with the AGN.
Download or read book Using Wide area Surveys to Study the Faint Radio Sky written by Jacqueline Alleen Hodge and published by . This book was released on 2010 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Quenching Star Formation in Low mass Galaxies Hosting Active Galactic Nuclei written by Catherine Witherspoon (Ph.D.) and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis aims to better understand the role active galactic nuclei (AGN) play in shutting down - quenching - star formation in low-mass galaxies. Using the Sloan Digital Sky Survey IV (SDSS-IV) Mapping Nearby Galaxies at Apache Point Observatory (MaNGA), we select a sample of low-mass galaxies with signatures of accretion onto a massive black hole. In order to disentangle the effects of environmental quenching mechanisms and AGN feedback, we investigate the group richness for active and inactive low-mass galaxies and their quiescent and star-forming sub-samples. We find that the quiescent low-mass galaxies hosting AGN prefer isolation or small groups suggesting that environmental process are not the primary quenching mechanisms. We also observed HI and CO gas in low-mass galaxies with AGN, and we find that the active galaxies are gas-depleted in both their atomic and molecular gas reservoirs, which indicates that these galaxies are in the process of quenching. Finally, we show that the mass-weighted stellar ages of low-mass galaxies hosting AGN have significantly younger stellar populations in their centers than their outskirts while the inactive galaxies have relatively flat radial stellar age gradients. These radial age gradients may be dependent on the strength of the AGN such that strong-AGN efficiently clear out the gas in the galaxy centers and prevent further star formation. Because weak-AGN cannot completely remove the centrally-located gas, the remaining gas in the galaxy is used for fueling the AGN and forming the last stars before the galaxy quenches. The combination of these works suggest that AGN could influence the star formation in low-mass galaxies and potentially be a dominant quenching mechanism.
Download or read book Volume 16 How to Detect and Handle Outliers written by Boris Iglewicz and published by Quality Press. This book was released on 1993-01-08 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: Outliers are the key focus of this book. The authors concentrate on the practical aspects of dealing with outliers in the forms of data that arise most often in applications: single and multiple samples, linear regression, and factorial experiments. Available only as an E-Book.
Download or read book The Physics and Evolution of Active Galactic Nuclei written by Hagai Netzer and published by Cambridge University Press. This book was released on 2013-09-16 with total page 369 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive introduction to the theory underpinning our study of active galactic nuclei and the ways we observe them.
Download or read book Astronomical Data Analysis Software and Systems X written by Frank Roderic Harnden and published by . This book was released on 2001 with total page 616 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Big Data in Astronomy written by Linghe Kong and published by Elsevier. This book was released on 2020-06-13 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: Big Data in Radio Astronomy: Scientific Data Processing for Advanced Radio Telescopes provides the latest research developments in big data methods and techniques for radio astronomy. Providing examples from such projects as the Square Kilometer Array (SKA), the world's largest radio telescope that generates over an Exabyte of data every day, the book offers solutions for coping with the challenges and opportunities presented by the exponential growth of astronomical data. Presenting state-of-the-art results and research, this book is a timely reference for both practitioners and researchers working in radio astronomy, as well as students looking for a basic understanding of big data in astronomy. - Bridges the gap between radio astronomy and computer science - Includes coverage of the observation lifecycle as well as data collection, processing and analysis - Presents state-of-the-art research and techniques in big data related to radio astronomy - Utilizes real-world examples, such as Square Kilometer Array (SKA) and Five-hundred-meter Aperture Spherical radio Telescope (FAST)
Download or read book Supermassive Black Holes in the Distant Universe written by A.J. Barger and published by Springer Science & Business Media. This book was released on 2004-08-03 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quasars, and the menagerie of other galaxies with "unusual nuclei", now collectively known as Active Galactic Nuclei or AGN, have, in one form or another, sparked the interest of astronomers for over 60 years. The only known mechanism that can explain the staggering amounts of energy emitted by the innermost regions of these systems is gravitational energy release by matter falling towards a supermassive black hole --- a black hole whose mass is millions to billions of times the mass of our Sun. AGN emit radiation at all wavelengths. X-rays originating at a distance of a few times the event horizon of the black hole are the emissions closest to the black hole that we can detect; thus, X-rays directly reveal the presence of active supermassive black holes. Oftentimes, however, the supermassive black holes that lie at the centers of AGN are cocooned in gas and dust that absorb the emitted low energy X-rays and the optical and ultraviolet light, hiding the black hole from view at these wavelengths. Until recently, this low-energy absorption presented a major obstacle in observational efforts to map the accretion history of the universe. In 1999 and 2000, the launches of the Chandra and XMM-Newton X-ray Observatories finally broke the impasse. The impact of these observatories on X-ray astronomy is similar to the impact that the Hubble Space Telescope had on optical astronomy. The astounding new data from these observatories have enabled astronomers to make enormous advances in their understanding of when accretion occurs.
Download or read book AGN Physics with the Sloan Digital Sky Survey written by Gordon T. Richards and published by . This book was released on 2004 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Astronomical Data Analysis Software and Systems XIV written by Patrick L. Shopbell and published by . This book was released on 2005 with total page 776 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamentals of Galaxy Dynamics Formation and Evolution written by Ignacio Ferreras and published by UCL Press. This book was released on 2019-04-02 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: Galaxies, along with their underlying dark matter halos, constitute the building blocks of structure in the Universe. Of all fundamental forces, gravity is the dominant one that drives the evolution of structures from small density seeds at early times to the galaxies we see today. The interactions among myriads of stars, or dark matter particles, in a gravitating structure produce a system with fascinating connotations to thermodynamics, with some analogies and some fundamental differences. Ignacio Ferreras presents a concise introduction to extragalactic astrophysics, with emphasis on stellar dynamics, and the growth of density fluctuations in an expanding Universe. Additional chapters are devoted to smaller systems (stellar clusters) and larger ones (galaxy clusters). Fundamentals of Galaxy Dynamics, Formation and Evolution is written for advanced undergraduates and beginning postgraduate students, providing a useful tool to get up to speed in a starting research career. Some of the derivations for the most important results are presented in detail to enable students appreciate the beauty of maths as a tool to understand the workings of galaxies. Each chapter includes a set of problems to help the student advance with the material.
Download or read book Active Galactic Nuclei from He Ii a More Complete Census of AGN in SDSS Galaxies Yields a New Population of Low luminosity AGN in Highly Star forming Galaxies written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Interplay Among Black Holes Stars and ISM in Galactic Nuclei IAU S222 written by International Astronomical Union. Symposium and published by Cambridge University Press. This book was released on 2004 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt: How massive are the largest and smallest nuclear black holes in galaxies? Why are the masses of nuclear black holes proportional to those of their host galaxy bulges? How is nuclear activity triggered? What are the observational signatures of such processes? What are the connections between the active nucleus, stars and interstellar medium in galaxies? Answers to these questions are addressed in this book, which presents a compilation of 191 works covering recent observations from X-rays to radio wavelengths, as well as theoretical modeling of accretion disks, stellar populations and galaxy and black hole evolution. This volume presents the nuclear activity as a phase in the life of a galaxy, which is intimately connected to the evolution of its stars and interstellar medium. It brings together recent developments in topics covering most aspects of galaxy evolution, and is a valuable resource for astronomers and graduate students working in extragalactic astronomy.
Download or read book Astrophysics in a Nutshell written by Dan Maoz and published by Princeton University Press. This book was released on 2016-02-23 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ideal one-semester astrophysics introduction for science undergraduates—now expanded and fully updated Winner of the American Astronomical Society's Chambliss Award, Astrophysics in a Nutshell has become the text of choice in astrophysics courses for science majors at top universities in North America and beyond. In this expanded and fully updated second edition, the book gets even better, with a new chapter on extrasolar planets; a greatly expanded chapter on the interstellar medium; fully updated facts and figures on all subjects, from the observed properties of white dwarfs to the latest results from precision cosmology; and additional instructive problem sets. Throughout, the text features the same focused, concise style and emphasis on physics intuition that have made the book a favorite of students and teachers. Written by Dan Maoz, a leading active researcher, and designed for advanced undergraduate science majors, Astrophysics in a Nutshell is a brief but thorough introduction to the observational data and theoretical concepts underlying modern astronomy. Generously illustrated, it covers the essentials of modern astrophysics, emphasizing the common physical principles that govern astronomical phenomena, and the interplay between theory and observation, while also introducing subjects at the forefront of modern research, including black holes, dark matter, dark energy, and gravitational lensing. In addition to serving as a course textbook, Astrophysics in a Nutshell is an ideal review for a qualifying exam and a handy reference for teachers and researchers. The most concise and current astrophysics textbook for science majors—now expanded and fully updated with the latest research results Contains a broad and well-balanced selection of traditional and current topics Uses simple, short, and clear derivations of physical results Trains students in the essential skills of order-of-magnitude analysis Features a new chapter on extrasolar planets, including discovery techniques Includes new and expanded sections and problems on the physics of shocks, supernova remnants, cosmic-ray acceleration, white dwarf properties, baryon acoustic oscillations, and more Contains instructive problem sets at the end of each chapter Solutions manual (available only to professors)
Download or read book Issues in Astronomy and Astrophysics 2013 Edition written by and published by ScholarlyEditions. This book was released on 2013-05-01 with total page 1145 pages. Available in PDF, EPUB and Kindle. Book excerpt: Issues in Astronomy and Astrophysics / 2013 Edition is a ScholarlyEditions™ book that delivers timely, authoritative, and comprehensive information about Planetary Science. The editors have built Issues in Astronomy and Astrophysics: 2013 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Planetary Science in this book to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Astronomy and Astrophysics: 2013 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.
Download or read book Secular Evolution of Galaxies written by Jesús Falcón-Barroso and published by Cambridge University Press. This book was released on 2012 with total page 657 pages. Available in PDF, EPUB and Kindle. Book excerpt: The formation and evolution of galaxies is one of the most important topics in modern astrophysics. Secular evolution refers to the relatively slow dynamical evolution due to internal processes induced by a galaxy's spiral arms, bars, galactic winds, black holes and dark matter haloes. It plays an important role in the evolution of spiral galaxies with major consequences for galactic bulges, the transfer of angular momentum, and the distribution of a galaxy's constituent stars, gas and dust. This internal evolution is in turn the key to understanding and testing cosmological models of galaxy formation and evolution. Based on the twenty-third Winter School of the Canary Islands Institute of Astrophysics, this volume presents reviews from nine world-renowned experts on the observational and theoretical research into secular processes, and what these processes can tell us about the structure and formation of galaxies. The volume provides a firm grounding for graduate students and early career researchers working on galactic dynamics and galaxy evolution.
Download or read book Starbursts and Galaxy Evolution written by Xuan Thuan Trinh and published by Atlantica Séguier Frontières. This book was released on 1987 with total page 626 pages. Available in PDF, EPUB and Kindle. Book excerpt:
