Download or read book Exploring the History of Star Formation in Galaxies and Its Environmental Dependence at High Redshift written by Christopher C. Lovell and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
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
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.
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.
Download or read book Exploring the Limits of Star Formation from the Extreme Environment of Galaxy Interactions to the Milky Way written by Amanda Lea Heiderman and published by . This book was released on 2012 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, I explore the rate at which molecular gas is converted to stars through detailed studies of a sample of molecular clouds in the Milky Way, IFU spatially resolved observations of gas-rich nearby interacting galaxies, as well as the environmental dependence of star formation and galaxy morphology in a galaxy supercluster. This thesis is composed of three individual projects that investigate nearby star formation within the local 500 pc of our Sun, to neighboring extreme star forming environments of interacting starburst galaxies, and finally studying how star formation varies with galaxy morphology in a galaxy supercluster a z~0.165. I discuss the relation between the star formation rate (SFR) and molecular gas surface densities (e.g., Schmidt-Kennicutt relation) in Galactic star forming regions and find there is a discrepancy between my study and extragalactic relations. The discrepancy is attributed to extragalactic measurements that are averaged over large>kpc scales and include star forming molecular gas (above some threshold) and molecular gas the is not dense enough to form stars. I find a steep increase in the Galactic SFR-gas surface density relation indicative of a threshold for efficient star formation that is best fit to a broken power law with a linear slope above 129 Msun pc−2. I introduce the VIRUS-P Investigation of the eXtreme ENviroments of Starbursts (VIXENS) project which is a survey of interacting is a large integral field unit survey of nearby infrared bright (L_IR>3x1010 Lsun) interacting/starburst galaxies. The main goal of VIXENS is to investigate the relation between star formation and gas content on spatially resolved scales of ~0.1-1 kpc in the extreme star forming environments of interacting/starburst galaxies. The VIXENS sample is composed of systems in a range interaction stages with morphological signatures from early phase (close pairs) to late stage mergers (single system with multiple nuclei), SFRs, and gas surface densities. I highlight the first results from the VIXENS survey in the late interaction phase galaxy merger Arp 299. I find 1.3 kpc regions in Arp 299 to lie along the SFR-gas surface density relation found for mergers at high redshift, but this relation is highly dependent on the CO to molecular hydrogen (H2) conversion factor. I find evidence for a Galactic CO-to-H2 conversion factor using metallicity and dust temperature measurements, which would place 1.3 kpc regions in the Arp 299 merger in between the high redshift and Kennicutt-Schmidt relations. Comparing the SFR to dense gas surface densities as traced by HCN and HCO, I find an agreement between the spatially resolved measurements and that found on global scales in spirals and (ultra)luminous infrared galaxies. Finally, I present an investigation of the influence of environment on frequency, distribution, color, and star formation properties of galaxy mergers and non-interacting galaxies in the Abell 901/902 supercluster at z~0.165. I find galaxy mergers be preferentially blue in color and have an enhanced SFR by a factor of ~2 compared to non-interacting galaxies. This result may be due to a decrease in galaxy velocity dispersion in the cluster outskirt, favoring galaxy-galaxy interactions, or to interacting galaxies that are part of groups or field galaxies being accreted along cosmological filaments by the clusters. I compare to N-body simulations of groups and field galaxies accreting onto the clusters and find the fraction of mergers are similar to that predicated at group overdensities. I find the SFR of galaxies in the supercluster to be depressed compared to field galaxies in both the core and cluster outskirts, suggesting that an environmental process such as ram pressure stripping is effective throughout the cluster. The results of a modest SFR enhancement and a low merger fraction culminate in my finding that mergers contribute only a small fraction (between 10% and 15%) of the total SFR density of the Abell 901/902 clusters.
Download or read book The Dependence of Galaxy Star Formation Histories on Environment at 0 6 written by Shannon G. Patel and published by . This book was released on 2010 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High Redshift Galaxies written by Immo Appenzeller and published by Springer Science & Business Media. This book was released on 2009-06-17 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: The high-redshift galaxies became a distinct research ?eld during the ?nal decade of the20thcentury. AtthattimetheLyman-breaktechniquemadeitpossibletoidentify signi?cant samples of such objects, and the new generation of 8 to 10-m telescopes resulted in ?rst good spectroscopic data. Today the high-redshift galaxies have developed into one of the important topics of astrophysics, accounting for about 5–10% of the publications in the major scienti?c journals devoted to astronomy. Because high-redshift galaxies is a rapidly developing ?eld and since new results are published constantly, writing a book on this topic is challenging. On the other hand, in view of the large amount of individual results now in the literature, and in view of the still growing interest in this topic, it appears worthwhile to summarize and evaluate the available data and to provide an introduction for those who wish to enter this ?eld, or who, for various reasons, might be interested in its results. The end of the ?rst decade of the 21st century appears to be a good point in time to attempt such a summary. The current generation of ground-based 8 to 10-m - optical telescopes, the Hubble Space Telescope, and the most important large radio telescopes have by now been in operation since about one or two decades. Although these instruments will continue to produce important scienti?c results for some time to come, many of the initial programs exploiting their unique new possibilities have been completed.
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 Environmental Dependence of Star Formation in Field and Cluster Galaxies written by Claire F. Thomas and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Star Formation Efficiency in Extended UV Disks and at High Redshift written by Isadora Chaves Bicalho and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Perhaps one of the most enigmatic domains of astrophysics is that of galaxy formation and evolution.A galaxy is defined by its stellar and gas contents. Hence, any theory of galaxy formation has to address the question of the formation of stars.Observations show that star formation takes place in dense molecular clouds.Therefore, the efficiency of star formation of a galaxy is determined by its ability to form molecular clouds.The determination of these processes and their efficiency is among the most important issues in our understanding of star formation.The present work studies the star formation laws in a wide range of physical and dynamical conditions, even in low density environmentsand down to molecular cloud scales, as well as high redshift galaxies, to explore the cosmic star formation history.Low density environments, like the outermost disk of galaxies mimic the physical conditions of dwarf galaxies and also that of galaxiesin the early Universe. Across the Hubble time, there was a peak in the star formation rate, at z ~1-2, about ten billions years ago. Then the average star formation rate dropped by a factor 20 down to the present rate. This Ph.D focuses on the star formation efficiency in two contexts: in low environments, like outer galaxy disks and at the epoch the near the peak of star formation.
Download or read book Galaxy Formation and Evolution written by Houjun Mo and published by Cambridge University Press. This book was released on 2010-05-20 with total page 841 pages. Available in PDF, EPUB and Kindle. Book excerpt: A coherent introduction for researchers in astronomy, particle physics, and cosmology on the formation and evolution of galaxies.
Download or read book Environment and the Formation of Galaxies 30 years later written by Ignacio Ferreras and published by Springer. This book was released on 2011-07-06 with total page 253 pages. Available in PDF, EPUB and Kindle. Book excerpt: The publication of the morphology - density relation by Alan Dressler in 1980 brought into the limelight the role played by environment in the formation and evolution of galaxies. The symposium Environment and the Formation of Galaxies: 30 years later, was organised with the purpose of establishing the environmental impact on the evolution of galaxies and its dependence on look-back time. Special emphasis was placed on the physical mechanisms that are responsible for transforming galaxies once they are accreted by a group or a cluster, including the observable imprint left in the galaxy HI distribution. Other major topics of the symposium were the environmental dependence of galaxy properties at z ≥ 1 and the implementation of environmental effects in cosmological models of galaxy formation and evolution. This book presents the edited proceedings of this stimulating meeting.
Download or read book Evolution of early type galaxies at z 1 written by Raphaël Gobat and published by Sudwestdeutscher Verlag Fur Hochschulschriften AG. This book was released on 2009 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of the spectroscopic, photometric and morphological properties of early-type galaxies, especially at high redshift and over a range of environmental densities, allows to put constraints on galaxy formation and evolution models. In particular, the presence of old passive stellar populations up to z 1.5 pushes further back the epoch of the last significant star formation episode in massive early-type galaxies. This book presents a study of the star formation history in these high redshift early-type galaxies, in both cluster and field environments, and the novel method used to reconstruct it.
Download or read book Structure Star Formation History and Environment of Galaxies written by K. Kelkar and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Star formation History of Massive Galaxies written by Anita M. Schael and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents multi-frequency data, galaxy identifications, estimated redshifts, and derived physical properties for the sub-millimetre source sample produced by the SCUBA HAlf Degree Extragalactic Survey (SHADES). SHADES is the largest, complete, sub-millimetre survey undertaken to date, and the aim of this work is to exploit this survey to study the evolution of sub-mm selected galaxies at high redshift, explore their possible connectionwith localmassive ellipticals, and to test current models of galaxy formation. The SHADES sample was selected from 850 micron images made with the submillimetre camera SCUBA at the James Clerk Maxwell Telescope. These submillimetre maps cover a total area of 720 arcmin2 split between two well-studied extra-galactic survey fields, the Lockman Hole East and the Subaru/XMMNewton Deep Field (SXDF). The resulting sample of 120 sub-millimetre sources is the focus of this thesis. Here the wealth of information provided by deep radio, optical, near-infrared and mid-infrared imaging of the two SHADES fields is exploited to complete the identification of the SHADES sample, and then to derive a robust redshift estimate for every sub-millimetre source. Where possible this is achieved from the optical+ infrared photometry using a new two-component redshift estimation code developed specifically to deal with starbursting galaxies with potentially highly stochastic star-formation histories. The effectiveness of this code is demonstrated via comparison with the small subset of SHADES source which possess robust spectroscopic redshifts. For those galaxies which are too faint for effective redshift constraints to be provided by the existing optical+infrared photometry, the information on the long-wavelength spectral energy distribution provided by the radio+submm photometry is utilised to provide cruder constraints or limits on redshift. The result is the first complete and unbiased estimate of the redshift distribution of the bright extragalactic sub-millimetre galaxy population. It is found that the brightest sub-mm sources are confined to the redshift range 2
Download or read book Star Formation in Merging Clusters of Galaxies written by Alison Seiler Mansheim and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis straddles two areas of cosmology, each of which are active, rich and plagued by controversy in their own right: merging clusters and the environmental dependence of galaxy evolution. While the greater context of this thesis is major cluster mergers, our individual subjects are galaxies, and we apply techniques traditionally used to study the differential evolution of galaxies with environment. Our first system (Chapter 2) is a cluster merger known as Musket Ball that is in a post-merging state. Our second system (Chapter 3), referred to as Cl J0910, is comprised of two clusters that have not yet merged. The order in which they are presented is intentional because, while it would have made more sense to study the pre-merger system first, our approach in Chapter 3 was shaped by what we learned by handling the significantly more difficult post-merger system. The body of this thesis is drawn from two papers: Mansheim et al. 2016a and Mansheim et al. 2016b, one on each system. Both projects benefited from exquisite data sets assembled as part of the Merging Cluster Collaboration (MC2), and Observations of Redshift Evolution in Large Scale Environments (ORELSE) survey, allowing us to scrutinize the evolutionary states of galaxy populations in multiple lights. Multi-band optical and near-infrared imaging was available for both systems, allowing us to calculate photometric redshifts for completeness corrections, colors (red vs. blue) and stellar masses to view the ensemble properties of the populations in and around each merger. High-resolution spectroscopy was also available for both systems, allowing us to confirm cluster members by measuring spectroscopic redshifts, which are unparalleled in accuracy, and gauge star formation rates and histories by measuring the strengths of certain spectral features. We had the luxury of HST imaging for Musket Ball, allowing us to use galaxy morphology (late-type vs. early-type) as an additional diagnostic. For Cl J0910, 24 [mu]m imaging allowed us to defeat a most pernicious source of uncertainty (dusty starburst vs. quiescent). Details on the acquisition and reduction of multi-wavelength data for each system are found within each respective chapter. It is important to note that the research presented in Chapter 3 is based on a letter which had significant space restrictions, so much of the observational details are outsourced to papers written by ORELSE collaboration members. Below is a free-standing summary of each project, drawn from the abstracts of each paper. The Chapter 1 contains an introduction to the topic and motivation to fill a vacuum in knowledge using our hypothesis. Chapter 4, following the meat of the thesis in Chapters 2 and 3, gives closure and looks to the future. In Chapter 2, we investigate star formation in DLSCL J0916.2+2953, a dissociative merger of two clusters at z=0.53 that has progressed 1.1[superscript +1.3][subscript-0.4] Gyr since first pass-through. We attempt to reveal the effects a collision may have had on the evolution of the cluster galaxies by tracing their star formation history. We probe current and recent activity to identify a possible star formation event at the time of the merger using EW(H[delta]), EW[(OII)], and D[subscript n](4000) measured from the composite spectra of 64 cluster and 153 coeval field galaxies. We supplement Keck DEIMOS spectra with DLS and HST imaging to determine the color, stellar mass, and morphology of each galaxy and conduct a comprehensive study of the populations in this complex structure. Spectral results indicate the average cluster and cluster red sequence galaxies experienced no enhanced star formation relative to the surrounding field during the merger, ruling out a predominantly merger-quenched population. We find that the average blue galaxy in the North cluster is currently active and in the South cluster is currently post-starburst having undergone a recent star formation event. While the North activity could be latent or long-term merger effects, a young blue stellar population and irregular geometry suggest the cluster was still forming prior the collision. While the South activity coincides with the time of the merger, the blue early-type population could be a result of secular cluster processes. The evidence suggests that the dearth or surfeit of activity is indiscernible from normal cluster galaxy evolution. In Chapter 3, we examine the effects of an impending cluster merger on galaxies in the large scale structure (LSS) RX Cl J0910 at z =1.105. Using multi-wavelength data, including 102 spectral members drawn from the ORELSE survey and precise photometric redshifts, we calculate extinction-corrected star formation rates and map the specific star formation rate density of the LSS galaxies. These analyses along with an investigation of the color-magnitude properties of LSS galaxies indicate lower levels of star formation activity in the region between the merging clusters relative to the outskirts of the system. We suggest gravitational tidal forces due to the potential of merging halos may be the physical mechanisms responsible for the observed suppression of star formation in galaxies caught between the merging clusters.
Download or read book The Environment and Evolution of Galaxies written by J. Michael Shull and published by Springer Science & Business Media. This book was released on 1993 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt: In July 1992, over 300 astronomers attended the Third Tetons Summer School on the subject of 'The Environment and Evolution of Galaxies'. This book presents 28 papers based on invited review talks and a panel discussion on 'The Nature of High Redshift Objects'. The major themes include: the Interstellar and Intergalactic Medium, Galaxy Formation and Evolution, Cooling Flows, Quasars and Radiation Backgrounds, and Interactions between Galaxies/AGNs and their Environment. Recent advances with the ROSAT, COBE and Hubble Space Telescope are discussed, together with current theoretical developments. The tutorial nature of the papers make this book a valuable supplement for professional astonomers, graduate students, and senior undergraduates. As with previous Tetons conferences, this book provides both the current state of observational and theoretical research and material complementary to courses in extragalactic and interstellar astrophysics.
