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Author : Pece Podigachoski
Publisher :
ISBN 13 : 9789036791830
Total Pages : 174 pages
Book Rating : 4.7/5 (918 download)
Download or read book Star Formation and AGN Activity in Distant Massive Galaxies written by Pece Podigachoski and published by . This book was released on 2016 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Corentin Schreiber
Publisher : Springer
ISBN 13 : 3319442937
Total Pages : 234 pages
Book Rating : 4.3/5 (194 download)
Download or read book A Statistical and Multi-wavelength Study of Star Formation in Galaxies written by Corentin Schreiber and published by Springer. This book was released on 2016-09-12 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a pioneering method for gleaning the maximum information from the deepest images of the far-infrared universe obtained with the Herschel satellite, reaching galaxies fainter by an order of magnitude than in previous studies. Using these high-quality measurements, the author first demonstrates that the vast majority of galaxy star formation did not take place in merger-driven starbursts over 90% of the history of the universe, which suggests that galaxy growth is instead dominated by a steady infall of matter. The author further demonstrates that massive galaxies suffer a gradual decline in their star formation activity, providing an alternative path for galaxies to stop star formation. One of the key unsolved questions in astrophysics is how galaxies acquired their mass in the course of cosmic time. In the standard theory, the merging of galaxies plays a major role in forming new stars. Then, old galaxies abruptly stop forming stars through an unknown process. Investigating this theory requires an unbiased measure of the star formation intensity of galaxies, which has been unavailable due to the dust obscuration of stellar light.
Author : Vincenzo Antonuccio-Delogu
Publisher : Cambridge University Press
ISBN 13 : 1139492152
Total Pages : 219 pages
Book Rating : 4.1/5 (394 download)
Download or read book AGN Feedback in Galaxy Formation written by Vincenzo Antonuccio-Delogu and published by Cambridge University Press. This book was released on 2010-10-28 with total page 219 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the past decade, convincing evidence has been accumulated concerning the effect of active galactic nuclei (AGN) activity on the internal and external environment of their host galaxies. Featuring contributions from well-respected researchers in the field, and bringing together work by specialists in both galaxy formation and AGN, this volume addresses a number of key questions about AGN feedback in the context of galaxy formation. The topics covered include downsizing and star-formation time scales in massive elliptical galaxies, the connection between the epochs of supermassive black hole growth and galaxy formation and the question of whether AGN and star formation coexist. Authors also discuss key challenging computational problems, including jet-interstellar/intergalactic medium interactions, and both jet- and merging-induced star formation. Suitable for researchers and graduate students in astrophysics, this volume reflects the engaging and lively discussions taking place in this emerging field of research.
Author : Jonathan Florez
Publisher :
ISBN 13 :
Total Pages : 432 pages
Book Rating : 4.:/5 (126 download)
Download or read book Exploring the Interplay Between Star Formation and Active Galactic Nuclei and the Role of Environment in Galaxy Evolution written by Jonathan Florez and published by . This book was released on 2021 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the central goals of extragalactic astronomy is to understand how galaxies grow their stellar mass and central black holes, the connection between star formation and active galactic nuclei (AGN), and the impact of environment on this growth. In this thesis, I utilize multiwavelength surveys that are both deep and wide, advanced computational codes that model the spectral energy distributions of galaxies with and without AGN, as well as state-of-the-art simulations of galaxy evolution in order to explore how galaxy properties are impacted by their surrounding environment and AGN activity. These studies explore galaxies over a redshift range of 0.015 z 0.023 (lookback time of ~ 0.2 to ~ 0.3 Gyr), and over a redshift range of 0.5 z 3.0 (lookback time of ~ 5 to ~ 12 Gyr). The large-area surveys used here provide some of the largest and most statistically robust samples to-date of rare massive galaxies (with stellar mass M [subscript *] 1011 M☉) and extremely luminous AGN (with X-ray luminosity L [subscript X] 1044 erg s−1) out to z ~ 3, thereby limiting the effects of cosmic variance and Poisson statistics. I analyze the observed stellar masses and star formation rates of galaxies as a function of environment and AGN activity, compare the empirical results to theoretical models of galaxy evolution, and discuss the implications of such comparisons. This work will provide significant guidance and constraints to the future development of theoretical models of galaxy growth. In Chapter 2 (Florez et al. 2021, ApJ, 906, 97) I measure the environmental dependence, where environment is defined by the distance to the third nearest neighbor, of multiple galaxy properties inside the Environmental COntext (ECO) catalog. I focus primarily on void galaxies at redshifts z = 0.015 - 0.023, which I define as the 10% of galaxies having the lowest local density. I compare the properties of void and non-void galaxies: baryonic mass, color, fractional stellar mass growth rate (FSMGR), morphology, and gas-to-stellar-mass ratio. The void galaxies typically have lower baryonic masses than galaxies in denser environments, and they display the properties expected of a lower mass population: they have more late-types, are bluer, have higher FSMGR, and are more gas rich. I also control for baryonic mass and investigate the extent to which void galaxies are different at fixed mass. I find that void galaxies are bluer, more gas-rich, and more star forming at fixed mass than non-void galaxies, which is a possible signature of galaxy assembly bias and other environmental processes. Furthermore, I show that these trends persist even at fixed mass and morphology, and I find that voids host a distinct population of early-types that are bluer and more star-forming than the typical red and quenched early-types. In addition to these empirical observational results, I also present theoretical results from mock catalogs with built-in galaxy assembly bias. I show that a simple matching of galaxy properties to (sub)halo properties, such as mass and age, can recover the observed environmental trends in the local galaxy population. In Chapter 3 (Florez et al. 2020, MNRAS, 497, 3273) I investigate the relation between AGN and star formation activity at 0.5 z 3 by analyzing 898 galaxies with high X-ray luminosity AGN (L [subscript X] 1044 erg s−1) and a large comparison sample of ~ 320,000 galaxies without such AGN. My samples are selected from a large (11.8 deg2) area in Stripe 82 that has multi-wavelength (X-ray to far-IR) data. The enormous comoving volume (~ 0.3 Gpc3) at 0.5
Author : Andreas Zezas
Publisher : Cambridge University Press
ISBN 13 : 1316877523
Total Pages : 318 pages
Book Rating : 4.3/5 (168 download)
Download or read book Star-Formation Rates of Galaxies written by Andreas Zezas and published by Cambridge University Press. This book was released on 2021-04-29 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt: Star-formation is one of the key processes that shape the current state and evolution of galaxies. This volume provides a comprehensive presentation of the different methods used to measure the intensity of recent or on-going star-forming activity in galaxies, discussing their advantages and complications in detail. It includes a thorough overview of the theoretical underpinnings of star-formation rate indicators, including topics such as stellar evolution and stellar spectra, the stellar initial mass function, and the physical conditions in the interstellar medium. The authors bring together in one place detailed and comparative discussions of traditional and new star-formation rate indicators, star-formation rate measurements in different spatial scales, and comparisons of star-formation rate indicators probing different stellar populations, along with the corresponding theoretical background. This is a useful reference for students and researchers working in the field of extragalactic astrophysics and studying star-formation in local and higher-redshift galaxies.
Author : Ekta Arjunkumar Shah
Publisher :
ISBN 13 :
Total Pages : 180 pages
Book Rating : 4.:/5 (129 download)
Download or read book The Effect of Galaxy Interactions on Star Formation and AGN Activity at 0:5 written by Ekta Arjunkumar Shah and published by . This book was released on 2021 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Galaxy interactions and mergers play an important role in the hierarchical formation and evolution of galaxies. Studies in the nearby universe show a higher star formation rate (SFR) and active galactic nuclei (AGN) fraction in interacting and merging galaxies than in their isolated counterparts, indicating that such interactions are important contributors to star formation and black hole growth. A large fraction of massive galaxies is thought to be affected by galaxy mergers at high redshifts because the galaxy merger rate increases with redshift. We use deep observations and cosmological simulations to study the role of galaxy mergers and interactions in enhancing SFR and AGN activity in galaxies at $0.5 z 3.0$, covering the peak of cosmic star formation and AGN activity ($z\sim2$). For the observational study, we use deep CANDELS and COSMOS observations to compile the largest known sample of major spectroscopic galaxy pairs (2381 with $V
Author : Christopher Mark Harrison
Publisher : Springer
ISBN 13 : 3319284541
Total Pages : 208 pages
Book Rating : 4.3/5 (192 download)
Download or read book Observational Constraints on the Influence of Active Galactic Nuclei on the Evolution of Galaxies written by Christopher Mark Harrison and published by Springer. This book was released on 2016-01-20 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: This prize-winning Ph.D. thesis by Chris Harrison adopts a multi-faceted approach to address the lack of decisive observational evidence, utilising large observational data sets from several world-leading telescopes. Developing several novel observational techniques, Harrison demonstrated that energetic winds driven by Active Galactic Nuclei (AGN) are found in a large number of galaxies, with properties in agreement with model predictions. One of the key unsolved problems in astrophysics is understanding the influence of AGN, the sites of growing supermassive black holes, on the evolution of galaxies. Leading theoretical models predict that AGN drive energetic winds into galaxies, regulating the formation of stars. However, until now, we have lacked the decisive observational evidence to confirm or refute these key predictions. Careful selection of targets allowed Harrison, to reliably place these detailed observations into the context of the overall galaxy population. However, in disagreement with the model predictions, Harrison showed that AGN have little global effect on star formation in galaxies. Theoretical models are now left with the challenge of explaining these results.
Author : Jonathan Florez
Publisher :
ISBN 13 :
Total Pages : 124 pages
Book Rating : 4.:/5 (124 download)
Download or read book Exploring AGN and Star Formation Activity of Massive Galaxies at Cosmic Noon written by Jonathan Florez and published by . This book was released on 2020 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: We investigate the relation between AGN and star formation (SF) activity at 0.5 z 3 by analyzing 898 galaxies with X-ray luminous AGN (L [subscript x] 1044 erg s−1) and a large comparison sample of ~ 320,000 galaxies without X-ray luminous AGN. Our samples are selected from a large (11.8 deg2) area in Stripe 82 that has multi-wavelength (X-ray to far-IR) data. The enormous comoving volume (~ 0.3 Gpc3) at 0.5 z
Author : I. Pérez-Fournon
Publisher : Cambridge University Press
ISBN 13 : 9780521825917
Total Pages : 302 pages
Book Rating : 4.8/5 (259 download)
Download or read book Galaxies at High Redshift written by I. Pérez-Fournon and published by Cambridge University Press. This book was released on 2003-03-20 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents lectures of the XI Canary Islands Winter School of Astrophysics written by experts in the field.
Author : Weimin Wang
Publisher :
ISBN 13 :
Total Pages : 536 pages
Book Rating : 4.8/5 (46 download)
Download or read book The Starburst-AGN Connection written by Weimin Wang and published by . This book was released on 2009 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt: Starburst and AGN, which are among the most active extragalactic phenomena, have been studied independently for many years. Recent observations reveal that many galaxies exhibit both AGN and starburst features, which naturally invites an investigation of their physical connection. Considerable new multi-wavelength observations during the last decade together with the results of many theoretical studies are enabling the physics and connectedness of these two phenomena to be understood more deeply. These proceedings are of a conference held at Shanghai Normal University, on a very pleasant campus southwest of the city. More than 120 participants from over 20 different countries were in attendance. The goals of the conference were to review past progress, present new results, plan future work, and establish observational and theoretical collaborations. We were treated to the first in-depth presentation of Spitzer Space Telescope mid- IR spectroscopy and imaging/photometry as well as new detailed theoretical modeling of the relationship and interaction between starbursts and AGN. Also presented were major new studies of the local universe from SDSS and other ground-based radio, IR/optical, and space-based x-ray observatories. The importance of the intense starburst and AGN activity in the early universe only 1 billion years after the Big Bang is becoming evident from the very early formation of extremely massive galaxies and black holes. The coming together and cross-fertilization of these studies at the conference was most productive.
Author : Bomee Lee
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (983 download)
Download or read book Intrinsic Characteristics of Galaxies in the Distant Universe written by Bomee Lee and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the major questions in observational cosmology is how galaxies formed and how they evolved. In particular, understanding the assembly history of galaxies at the peak epoch of the star formation activity, z=1-3, is a key to understanding the whole picture of the Universe, but remains uncertain. Galaxies with various physical properties and morphologies have different formation and evolution histories. As such, we seek insight into galaxy formation and evolution at z=1-3 using galaxies selected from Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) in this dissertation. First, we investigate the relationship between spectral types and morphologies using various parametric diagnostics and visual inspections. Our sample clearly separates into massive, red, and passive galaxies versus less massive, blue, and star forming ones, and this dichotomy correlates very well with the galaxies' morphological properties. From this study, we suggest that the backbone of the Hubble sequence was already in place at z~2. Second, we explore how the choice of star formation histories affects estimating galaxy properties by adopting flexible star formation history models to the fitting of galaxy's spectrum. The estimation of galaxy properties is improved using CANDELS observations providing unprecedented coverage and depths, and using an advanced fitting technique. We find that galaxy properties, particularly age and star formation rate, are sensitive to the choice of star formation histories. We also find that using different best-fit star formation histories leads to significantly different results on the main sequence of star formation. Our results demonstrate that using the best-fit star formation history for each galaxy is more appropriate way than using one analytic model for all galaxy types. Third, with accurately measured stellar mass and star formation rate, we study characteristics of galaxies on, above, and below the main sequence. We find that distinct morphological differences are shown among different galaxy populations using various diagnostics. On average, as star formation activities decrease, galaxies become denser having smaller sizes and steeper light profiles at all explored redshifts. We also show that the compact morphology is not necessary to precede a passivity of star formation. Our results do not support that gas-rich merging is the key driver to assemble very compact, massive early-type galaxies observed at z~2. Instead, we suggest that compact galaxies simply assemble at very early times and evolve through in situ star formation to form compact massive, quiescent galaxies without significant merging events.
Author : Isaac Shlosman
Publisher : Cambridge University Press
ISBN 13 : 9780521543309
Total Pages : 534 pages
Book Rating : 4.5/5 (433 download)
Download or read book Mass-Transfer Induced Activity in Galaxies written by Isaac Shlosman and published by Cambridge University Press. This book was released on 2003-10-30 with total page 534 pages. Available in PDF, EPUB and Kindle. Book excerpt: How gas flows and starbursts light up active galaxies.
Author : Jose Franco
Publisher : Cambridge University Press
ISBN 13 : 9780521444125
Total Pages : 418 pages
Book Rating : 4.4/5 (441 download)
Download or read book Star Formation, Galaxies and the Interstellar Medium written by Jose Franco and published by Cambridge University Press. This book was released on 1993-06-10 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt: The enormously powerful phenomena of starbursts are examined in this book. These spectacular star-forming events are seen on large scales in some galaxies, often triggered by galactic interactions. An intriguing implication of starburst research is that active galactic nuclei (AGN) may not be powered by accreting black holes. Instead theories are presented where compact powerhouses of dust-enshrouded star formation lie at the core of AGN, with supernovae exploding roughly once per year within massive nuclear concentrations of gas. This book collects articles from a timely international conference in Elba, Italy, in 1992; these comprise a thorough review of the most important developments in galactic-scale star formation since the starburst revolution of the late 1980s. This text will introduce graduate students to this exciting area and keep experts apace with rapid developments in it.
Author : Veronique Cayatte
Publisher : World Scientific
ISBN 13 : 9814542776
Total Pages : 494 pages
Book Rating : 4.8/5 (145 download)
Download or read book Building Galaxies: From The Primordial Universe To The Present, Procs Of The Xixth Rencontres De Moriond written by Veronique Cayatte and published by World Scientific. This book was released on 2000-07-17 with total page 494 pages. Available in PDF, EPUB and Kindle. Book excerpt: These proceedings provide a summary of the state-of-the-art in the understanding of physical processes which control galaxy formation. Many topics are discussed which present the latest observational results: dust extinction, the role of AGNs in the formation of massive galaxies, etc. How future instruments such as NGST, ALMA, FIRST, KMT and SKAI can help to resolve these questions is also addressed. The book will serve as a useful reference in the field for many years to come.
Author : Matthew Louis Stevans (Jr.)
Publisher :
ISBN 13 :
Total Pages : 256 pages
Book Rating : 4.:/5 (112 download)
Download or read book Investigating the Stellar Mass Growth and Quiescence of Massive Galaxies In the Early Universe Using Wide-field Imaging written by Matthew Louis Stevans (Jr.) and published by . This book was released on 2019 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: While galaxies formed stars most actively around z=2, or ~3 Gyr after the Big Bang, when the universal star formation density in the universe peaked. By this time a population of massive galaxies had already formed 1011 - 1012 [solar mass] of stars and some had their star-formation shut off in a process known as quenching. Understanding how these massive galaxies build up their stellar mass and then quench so early in the universe is a fundamental observational test of galaxy evolution. If not obscured by dust, massive galaxies are very bright, and can be observed in the optical and infrared (IR) to probe their redshifted ultraviolet (UV) and optical emission, respectively. The UV emission is produced by newly formed O and B type stars within 100 Myrs of forming, while the rest-frame optical light is produced by stars of all type and traces the stellar mass in the galaxy. By measuring the UV and optical output of galaxies, astronomers can derive star-formation rates and stellar masses. Measuring these properties for large samples of galaxies across a wide dynamic range provides benchmarks for simulations of galaxy formation and evolution physics. The work in this dissertation focuses on completing a wide field imaging survey of galaxies with high UV star-formation rates and high stellar masses at high redshift to perform the most statistically robust census to date. In Chapter 1 we motivate measuring the UV output and the quiescent fraction of high-redshift galaxies. To measure the UV output of massive star-forming galaxies at high redshift we utilize an extensive multi-wavelength dataset assembled in the Spitzer HETDEX Exploratory Large Area Survey (SHELA) Field. The data set includes five bands of deep optical imaging from the Dark Energy Camera (DECam), deep 3.6 micron and 4.5 micron imaging for Spitzer, and J and K [subscript s] imaging for the VISTA-CFHT Stripe 82 (VICS82) Near-infrared Survey. Our extensive dataset compiled from both ground and space-based observatories is uniquely capable of studying the most actively star-forming galaxies which are often very massive galaxies residing in the rarest high-sigma density peaks of the cosmic web. In Chapter 2 we study the bright end of the z=4 galaxy UV luminosity distribution or luminosity function by fitting the spectral energy distributions (SEDs) of the galaxies in our photometric data with Stellar Population Synthesis (SPS) models to measure the galaxies' redshifts and UV luminosity. In addition to measuring the bright end of the galaxy luminosity function, we had the unanticipated result of measuring the faint end of the z=4 active galactic nuclei (AGN) UV luminosity function, which has implications on the contribution of AGNs during the end of the reionization era. We compare our observed galaxy luminosity function to luminosity functions predicted by semi-analytical models (SAMs) with different prescriptions for star formation physics, such as the density of neutral hydrogen. We find our observations are consistent with predictions that galaxies at z=3-4 form stars more efficiently than at lower redshifts due to shorter neutral hydrogen depletion times. In Chapter 3, we measure the fraction of massive (M [subscript *] > 1011 [solar mass] galaxies at z=3-5 in the largest volume to date. To do this we produce a K [subscript s] -selected catalog by combining deep K [subscript s] -band imaging from the NEWFIRM HETDEX survey (NHS), which we obtain, reduce, and catalog. We select quiescent galaxies by performing SED-fitting with SPS models to measure their redshifts, SFRs, and stellar masses. We define quiescent galaxies as having a specific SFR (sSFR; sSFR = SFR / stellar mass)
Author : Jingwen Wu
Publisher :
ISBN 13 :
Total Pages : 226 pages
Book Rating : 4.:/5 (75 download)
Download or read book Massive Star Formation, from the Milky Way to Distant Galaxies written by Jingwen Wu and published by . This book was released on 2006 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: Studying massive star formation is hard, both observationally and theoretically. Many basic questions concerning the formation and early evolution of massive stars remain unclear. Based on a series of spectral lines and mapping surveys on a large sample of massive star-forming cores, we have been able to study the dynamics and physical properties of massive star-forming regions. The HCN 3-2 survey has revealed a large fraction of line asymmetry that indicates the global existence of infall in massive cores. Using the spectra and maps of multiple HCN and CS transitions, as well as of their isotopes, we have started to model the massive star-forming cores with a 1D Monte Carlo simulation. The surveys of dense gas tracers in Galactic cores revealed a linear correlation between the star formation rate, as indicated by the infrared luminosity, and the amount of the dense gas, as traced by the line luminosity of dense gas tracer like HCN 1-0. The linear LIR-L' HCN1-0 correlation was found to extend over 8 orders of magnitude, from distant starburst and normal galaxies to Galactic massive cores, with a lower cutoff in luminosity. It suggests that star formation may follow a simple relationship when the appropriate tracers are used, and we may understand distant star formation in terms of the known properties of local star-forming regions. To explain this linear correlation, we propose the existence of a basic unit for the clustered star formation in galaxies, with the basic units similar to the massive dense cores studied in the Galaxy.
Author : Chi-hun Kim
Publisher : Stanford University
ISBN 13 :
Total Pages : 189 pages
Book Rating : 4.F/5 ( download)
Download or read book Galaxy Formation and Mergers with Stars and Massive Black Holes written by Chi-hun Kim and published by Stanford University. This book was released on 2011 with total page 189 pages. Available in PDF, EPUB and Kindle. Book excerpt: While mounting observational evidence suggests the coevolution of galaxies and their embedded massive black holes (MBHs), a comprehensive astrophysical understanding which incorporates both galaxies and MBHs has been missing. To tackle the nonlinear processes of galaxy formation, we develop a state-of-the-art numerical framework which self-consistently models the interplay between galactic components: dark matter, gas, stars, and MBHs. Utilizing this physically motivated tool, we present an investigation of a massive star-forming galaxy hosting a slowly growing MBH in a cosmological LCDM simulation. The MBH feedback heats the surrounding gas and locally suppresses star formation in the galactic inner core. In simulations of merging galaxies, the high-resolution adaptive mesh allows us to observe widespread starbursts via shock-induced star formation, and the interplay between the galaxies and their embedding medium. Fast growing MBHs in merging galaxies drive more frequent and powerful jets creating sizable bubbles at the galactic centers. We conclude that the interaction between the interstellar gas, stars and MBHs is critical in understanding the star formation history, black hole accretion history, and cosmological evolution of galaxies. Expanding upon our extensive experience in galactic simulations, we are well poised to apply this tool to other challenging, yet highly rewarding tasks in contemporary astrophysics, such as high-redshift quasar formation.
