Download or read book A Magnified View of High Redshift Star Formation written by Eva Wuyts and published by . This book was released on 2012 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work takes advantage of the magnified view of the z = 1−3 Universe provided by cluster-scale strong gravitational lensing to advance our understanding of the physical mechanisms driving the assembly of galaxies at this epoch of peak star formation. In the first chapter, high signal-to-noise multi-wavelength photometry and long-slit rest-frame optical spectroscopy for four of the brightest lensed galaxies known at z = 1−3 is combined for a detailed study of their stellar populations and the physical conditions of their ionized gas. I find these systems to be young starbursts without much dust content which have only recently started the build-up of their stellar mass. A comparison of SFR indicators from the dust-corrected UV light, the Hα and [O II] 3727 nebular emission lines, and the dust-reprocessed 24 μm emission suggests that the Calzetti dust extinction law is too flat to accurately correct dust extinction in young star-forming galaxies at z ∼ 2. In a second chapter, the observed relation between stellar mass and gas-phase metallicity for star-forming galaxies at z ∼ 2 is extended to lower stellar masses than previously studied, with a sample of 10 lensed galaxies. I find less redshift evolution of the mass-metallicity relation in this mass range. There is a general agreement with the local fundamental relation between metallicity, stellar mass and SFR from Mannucci et al., though the scatter becomes large for specific star formation rates > 10−9 yr−1 . Using the Kennicutt-Schmidt law to infer gas fractions, I investigate the importance of gas inflows and outflows on the shape of the mass-metallicity relation with simple analytical models. The last chapter presents a combined analysis of HST/WFC3 optical/near-IR imaging and Keck/OSIRIS near-IR IFU spectroscopy aided by laser-guide star adaptive optics for RCSGA0327, the brightest distant lensed galaxy currently known in the Universe. Due to the high lensing magnification of the system, these observations reach spatial scales of

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.

Download or read book The Effect of Star Formation on Observed Properties of High Redshift Absorption Systems written by and published by . This book was released on 2006 with total page 59 pages. Available in PDF, EPUB and Kindle. Book excerpt: Damped Lyman-alpha absorber systems (DLAs) are thought to be one of the best probes to understand structure formation in the early universe. DLAs are defined as such systems with neutral hydrogen column density N(HI)> 2x1020 cm−2. They have also been considered to be the most important neutral-gas reservoir for star formation at high redshift, and the key to uncovering the mystery of the progenitors of present-day galaxies. For many years, there has been a debate on the nature of the galaxies causing these absorptions at high redshift. One idea is that DLAs are small proto-galaxy clumps formed in the process of hierarchical structure formation. Another idea is that DLAs can be best explained with rapidly rotating, large, cold disks of galaxies. It is believed that through full understanding of the mechanism that control the processes, we are able to construct the history of galaxy evolution. In order to test on these ideas, we used highresolution AMR (adaptive mesh refinement) hydrodynamics simulations to study kinematics properties and abundances of DLAs at redshift z = 3. Our simulations are based on standard cold dark matter cosmology ([Lambda]CDM), and include full radiative transfer and star formation/feedback recipes, which are considered to be the two key ingredients to solve the low velocity-widths problem found in previous numerical simulations. Our results show that although we are able to reproduce the observed column density distribution, our velocity widths are still much lower than the observations. Further more, we plot line profiles through the points with highest radial velocities, which we believe are in the violent star or galaxy forming regions. From the single line profile, we can see some star formation/feedback effects by comparing the simulation runs with and without star formation/feedback. However, in a larger picture, these effects are not very obvious. This is probably due to the small volume size and insufficient grid-resolution. We conclude that it is essential to include full radiative transfer in order to reproduce reasonable HI column density distribution, and for further simulations, we should have larger volume size, and much higher resolution in order to resolve substructures such as star forming regions or supernova explosions.

Download or read book From Dusty to Dust free written by Logan Houston Jones and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The creation of new stars from cold gas is one of the most fundamental astrophysical processes that can be observed in our own galaxy and in others. At a broad level, the modern phenomenological picture of how stars form is consistent with observations of systems ranging from nearby molecular clouds to the most distant galaxies. Many gaps and limitations in the details of such a picture, however, remain unfilled and unanswered. For example, questions remain about the interplay between star formation and chemical enrichment in blue, metal-poor galaxies and the impact of that relationship in cosmic reionization -- one of the final frontiers of observational extragalactic astrophysics. Meanwhile, on the other end of the electromagnetic and metallicity spectrum, there exists a population of high-redshift, far-infrared-bright, and heavily dust-obscured starbursting galaxies that represent a fleeting but possibly integral stage in the growth of massive galaxies and of dense, large-scale structures like (proto)clusters of galaxies. However, the mechanism(s) that trigger such starbursts, especially in dense environments, remains ambiguous. The research that comprises this dissertation aims to answer two questions that, while both relevant to astronomers' understanding of the birth and evolution of galaxies in the broadest sense, are largely disjoint from one another. These questions are: 1) What are the intermediate- to high-redshift analogs to the sources that reionized the universe at very early times?; and 2) As a function of redshift and/or environment, how common are massively star-forming, dust-obscured galaxies? Because these questions are so different from one another, this dissertation will be split into two major parts. In the first, I present a search in two legacy fields (the GOODS-North and the GOODS-South) for galaxies at high redshift that may be sources of ionizing ultraviolet photons. Such objects are expected to be analogs, in various ways, to the first generation of galaxies, and thus provide clues to the nature of very-high-redshift galaxies that will be discovered en masse by future ground- and space-based observatories. In the second part, I present the spectroscopic confirmation of an overdensity of dusty starbursting galaxies at $z \approx 3.14$, signposting a protocluster of galaxies near the peak of star formation activity in the universe. Compared to similar recent discoveries in the literature, this new protocluster is relatively late-forming and includes several of the most infrared-luminous starbursts currently known. This makes it an excellent laboratory for testing theories of starburst triggering and the subsequent buildup of stellar mass in dense environments. In the final chapter of this dissertation, I reiterate the key results of the research presented in chapters 2, 3, and 5.

Download or read book Extragalactic Astronomy and Cosmology written by Peter Schneider and published by Springer. This book was released on 2014-10-08 with total page 637 pages. Available in PDF, EPUB and Kindle. Book excerpt: This second edition has been updated and substantially expanded. Starting with the description of our home galaxy, the Milky Way, this cogently written textbook introduces the reader to the astronomy of galaxies, their structure, active galactic nuclei, evolution and large scale distribution in the Universe. After an extensive and thorough introduction to modern observational and theoretical cosmology, the focus turns to the formation of structures and astronomical objects in the early Universe. The basics of classical astronomy and stellar astrophysics needed for extragalactic astronomy are provided in the appendix. While this book has grown out of introductory university courses on astronomy and astrophysics and includes a set of problems and solutions, it will not only benefit undergraduate students and lecturers; thanks to the comprehensive coverage of the field, even graduate students and researchers specializing in related fields will appreciate it as a valuable reference work.

Download or read book Stellar Populations Outflows and Morphologies of High redshift Galaxies written by Katherine Anne Kornei and published by . This book was released on 2012 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the regulation and environment of star formation across cosmic time is critical to tracing the build-up of mass in the Universe and the interplay between the stars and gas that are the constituents of galaxies. Three studies are presented in this thesis, each examining a different aspect of star formation at a specific epoch. The first study presents the results of a photometric and spectroscopic survey of 321 Lyman break galaxies (LBGs) at z = 3 to investigate systematically the relationship between Ly & alpha; emission and stellar populations. Ly & alpha; equivalent widths were calculated from rest-frame UV spectroscopy and optical/near-infrared/Spitzer photometry was used in population synthesis modeling to derive the key properties of age, dust extinction, star formation rate (SFR), and stellar mass. We directly compare the stellar populations of LBGs with and without strong Ly & alpha; emission, where we designate the former group (Ly & alpha; equivalent widths greater than 20 & Aring;) as Ly & alpha;-emitters (LAEs) and the latter group (Ly & alpha; equivalent widths fewer than 20 & Aring;) as non-LAEs. This controlled method of comparing objects from the same UV luminosity distribution represents an improvement over previous studies in which the stellar populations of LBGs and narrowband-selected LAEs were contrasted, where the latter were often intrinsically fainter in broadband filters by an order of magnitude simply due to different selection criteria. Using a variety of statistical tests, we find that Ly & alpha; equivalent width and age, SFR, and dust extinction, respectively, are significantly correlated in the sense that objects with strong Ly & alpha; emission also tend to be older, lower in star formation rate, and less dusty than objects with weak Ly & alpha; emission, or the line in absorption. We accordingly conclude that, within the LBG sample, objects with strong Ly & alpha; emission represent a later stage of galaxy evolution in which supernovae-induced outflows have reduced the dust covering fraction. We also examined the hypothesis that the attenuation of Ly & alpha; photons is lower than that of the continuum, as proposed by some, but found no evidence to support this picture. The second study focuses specifically on galactic-scale outflowing winds in 72 star-forming galaxies at z = 1 in the Extended Groth Strip. Galaxies were selected from the DEEP2 survey and follow-up LRIS spectroscopy was obtained covering SiII, CIV, FeII, MgII, and MgI lines in the rest-frame ultraviolet. Using GALEX, HST, and Spitzer imaging available for the Extended Groth Strip, we examine galaxies on a per-object basis in order to better understand both the prevalence of galactic outflows at z = 1 and the star-forming and structural properties of objects experiencing outflows. Gas velocities, measured from the centroids of FeII interstellar absorption lines, are found to span the interval -217, +155 km s-1. We find that approximately 40% (10%) of the sample exhibits blueshifted FeII lines at the 1 & sigma; (3 & sigma;) level. We also measure maximal outflow velocities using the profiles of the FeII and MgII lines; we find that MgII frequently traces higher velocity gas than FeII. Using quantitative morphological parameters derived from the HST imaging, we find that mergers are not a prerequisite for driving outflows. More face-on galaxies also show stronger winds than highly inclined systems, consistent with the canonical picture of winds emanating perpendicular to galactic disks. In light of clumpy galaxy morphologies, we develop a new physically-motivated technique for estimating areas corresponding to star formation. We use these area measurements in tandem with GALEX-derived star-formation rates to calculate star-formation rate surface densities. At least 70% of the sample exceeds a star-formation rate surface density of 0.1 solar masses yr-1 kpc-2, the threshold necessary for driving an outflow in local starbursts. At the same time, the outflow detection fraction of only 40% in FeII absorption provides further evidence for an outflow geometry that is not spherically symmetric. We see a 3 & sigma; trend between outflow velocity and star-formation rate surface density, but no significant trend between outflow velocity and star-formation rate. Higher resolution data are needed in order to test the scaling relations between outflow velocity and both star-formation rate and star-formation rate surface density predicted by theory. Galactic winds are further explored in the third study of this thesis, where we present a study at z = 1 of the prevalence and kinematics of ultraviolet emission lines from fine-structure FeII* transitions and resonance MgII transitions. Utilizing a multiwavelength dataset of 212 star-forming galaxies, we investigate how the strength and kinematics of FeII* and MgII emission lines vary as a function of galaxy properties. We find that FeII* emission is prevalent in the sample; composite spectra assembled on the basis of a variety of galaxy properties all show FeII* emission, particularly in the stronger 2396 and 2626 & Aring; lines. This prevalence of emission is in contrast to observations of local galaxies; the lack of FeII* emission in the small star-forming regions targeted by spectroscopic observations at z = 0 may imply that FeII* emission arises in more extended galaxy halos. The strength of FeII* emission is most strongly modulated by star-formation rate, dust attenuation, and [OII] equivalent width, such that systems with lower star-formation rates, lower dust levels, and larger [OII] equivalent widths show stronger FeII* emission. MgII emission, while not observed in a spectral stack of all the data in our sample, is seen in 30% of individual objects. We find that objects showing MgII emission have preferentially larger [OII] equivalent widths, bluer U-B colors, and lower stellar masses than the sample as a whole. Active galactic nuclei are not likely responsible for the MgII emission in our sample, since we have excluded active galaxies from our dataset. We also do not observe the NeV emission line at 3425 & Aring; characteristic of active galaxies in our co-added spectra. We find that the kinematics of FeII* emission lines are consistent with the systemic velocity. This result does not necessarily imply that these lines arise from star-forming regions, however, as an optically thin galactic wind could show blueshifted and redshifted FeII* emission lines centered around 0 km s-1. We note that FeII* emission arising from extended gas is consistent with the hypothesis that slit losses are responsible for the lack of FeII* emission in local samples. We propose that dust is primarily responsible for the correlations between FeII* strength and galaxy properties, as objects with lower star-formation rates and larger [OII] equivalent widths also exhibit lower dust attenuations, on average. The strong MgII emission seen in systems with larger [OII] equivalent widths, bluer U-B colors, and lower stellar masses may also be the result of low dust attenuation in these objects. Larger studies composed of high signal-to-noise observations will be critical for testing the hypothesis that dust is the primary modulator of fine-structure and resonance emission.

Download or read book The Interstellar Medium Properties of High Redshift Galaxies written by Tsz Kuk Daisy Leung and published by . This book was released on 2020 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a dissertation in six chapters, where we aim to obtain a better understanding of the most luminous source populations at the peak epoch of cosmic star formation rate density using observational data collected with state-of-the-art facilities. Previous studies report star formation rates (SFR) comparable to and even exceeding the local ultra-luminous IR galaxy (ULIRG) for a population of dust-obscured (IR)-luminous starbursting galaxies discovered at z>2 (dubbed dusty star-forming galaxies, DSFG), but the ULIRGs and DSFGs have different global star formation and interstellar medium (ISM) properties. Meanwhile, a picture connecting the evolution of dust-obscured starburst galaxies and the growth of supermassive black holes (SMBHs) has emerged under the "quasar-starburst co-evolutionary link" paradigm. This body of work examines the nature and origin of the most extreme DSFGs and the postulated quasar-starburst co-evolution picture by examining the ISM conditions, gas kinematics and morphologies of these high-z galaxy populations using a suite of radio/sub-millimeter interferometers (e.g., ALMA, the VLA, NOEMA), complemented by data taken with space-based facilities such as SOFIA and the HST. Leveraging multi-wavelength photometry and (sub-)kpc resolution imaging of CO and far-infrared (FIR)-bright lines (e.g.,[CII]) enabled by the latest instrument and facilities, we examine how the morphology of DSFG varies with molecular gas fractions and IR luminosities, and how the molecular gas fraction, IR luminosity, and active galactic nucleus (AGN) luminosity are related, as postulated in the quasar-starburst evolutionary picture; and study properties of the gas, stellar, and dust components of high-z DSFG and quasar host galaxies. In the detailed case studies of high-z quasars, we find that the decreased in molecular gas fraction at intermediate redshift (0z

Download or read book Hubble Space Telescope And The High Redshift Universe The Proceedings Of The 37th Herstmonceux Conference written by Nial R. Tanvir and published by World Scientific. This book was released on 1997 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Since the successful refurbishment mission, the Hubble Space Telescope has made dramatic and exciting progress in unravelling the nature of sources at high redshift. The upcoming installation of the next generation of instruments will give further impetus to the field, particularly in the infrared spectral region. The proceedings of this landmark meeting review the results of the first three years of post-repair data, including the deepest astronomical images ever obtained: the Hubble Deep Field. This was the first presentation of these exciting results at a major international conference. The interface between HST and ground-based facilities and planned programmes with forthcoming HST instruments are also extensively discussed."--Publisher's website.

Download or read book The First Galaxies in the Universe written by Abraham Loeb and published by Princeton University Press. This book was released on 2013-01-15 with total page 572 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive, self-contained introduction to one of the most exciting frontiers in astrophysics today: the quest to understand how the oldest and most distant galaxies in our universe first formed. Until now, most research on this question has been theoretical, but the next few years will bring about a new generation of large telescopes that promise to supply a flood of data about the infant universe during its first billion years after the big bang. This book bridges the gap between theory and observation. It is an invaluable reference for students and researchers on early galaxies. The First Galaxies in the Universe starts from basic physical principles before moving on to more advanced material. Topics include the gravitational growth of structure, the intergalactic medium, the formation and evolution of the first stars and black holes, feedback and galaxy evolution, reionization, 21-cm cosmology, and more. Provides a comprehensive introduction to this exciting frontier in astrophysics Begins from first principles Covers advanced topics such as the first stars and 21-cm cosmology Prepares students for research using the next generation of large telescopes Discusses many open questions to be explored in the coming decade

Download or read book High Redshift and Primeval Galaxies written by Jacqueline Bergeron and published by Atlantica Séguier Frontières. This book was released on 1987 with total page 548 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Kiloparsec Scale Structure and Kinematics of High Redshift Star Forming Galaxies written by David R. Law and published by Universal-Publishers. This book was released on 2008-09 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: We study the spatially resolved properties of star-forming galaxies at redshift z 2 - 3 on scales 1 kpc using a combination of morphological and kinematic analyses in an effort to characterize the major mechanisms of galaxy formation in the young universe. Using a sample of 216 galaxies which have been spectroscopically confirmed to lie between redshifts z = 1.8 - 3.4 in the GOODS-N field we demonstrate that rest-UV morphology (as seen by the Hubble Space Telescope) is statistically uncorrelated with physical properties such as star formation rate and is therefore unable to support the hypothesis that the prevalence of irregular morphologies indicates a high major merger fraction. Further, we present a sample of 13 galaxies observed with the OSIRIS integral field spectrograph and the Keck laser-guide star adaptive optics system which demonstrate the prevalence of high velocity dispersions 80 km/s and generally little in the way of spatially resolved velocity gradients, inconsistent with favored rotating disk models. We discuss the implications of these results for galaxy formation models, including gas accretion via cold flows and gravitational instability of early gas-rich galactic disks. There is some evidence for a trend towards stronger rotational signatures in galaxies with more massive stellar populations.

Download or read book The Hubble Deep Field written by Space Telescope Science Institute (U.S.). Symposium and published by Cambridge University Press. This book was released on 1998-10-13 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Hubble Deep Field (HDF) is the deepest optical image of the Universe ever obtained. It is the result of a 150-orbit observing programme with the Hubble Space Telescope. It provides a unique resource for researchers studying the formation and evolution of stars and galaxies. This timely volume provides the first comprehensive overview of the HDF and its scientific impact on our understanding in cosmology. It presents articles by a host of world experts who gathered together at an international conference at the Space Telescope Science Institute. The contributions combine observations of the HDF at a variety of wavelengths with the latest theoretical progress in our understanding of the cosmic history of star and galaxy formation. The HDF is set to revolutionize our understanding in cosmology. This book therefore provides an indispensable reference for all graduate students and researchers in observational or theoretical cosmology.

Download or read book Cold Gas at High Redshift written by M.N. Bremer and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent years have seen increasing evidence that the main epoch of galaxy formation in the universe may be directly accessible to observation. An gular fluctuations in the background relict radiation have been detected by various ground-based instruments as well as by the COBE satellite, and suggest that the epoch of galaxy formation was not so very early. Combined optical and radio studies have found galaxies at redshifts above 2. 0, systems that at least superficially show the characteristics expected of large galaxies seen only shortly after their formation. And absorption lines in the spectra of quasars seem to be telling us that most cold gas at early to intermediate cosmological epochs was in clouds having roughly galaxy sized masses. What kinds of new observations will best help us study this high redshift universe in future? What new instruments will be needed? These are questions that loom large in the minds of the Dutch astronom ical community as we celebrate 25 years of operation of the Westerbork Synthesis Radio Telescope. Celebration of this Silver Jubilee has included a birthday party (on 23 June, 1995), a commemorative volume looking at both the history and the future of the facility ("The Westerbork Observa tory, Continuing Adventure in Radio Astronomy," Kluwer 1996), and an international workshop, held in the village of Hoogeveen on 28-30 August, 1995.

Download or read book Principles of Gravitational Lensing written by Arthur B. Congdon and published by Springer. This book was released on 2018-12-01 with total page 287 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook provides an introduction to gravitational lensing, which has become an invaluable tool in modern astrophysics, with applications that range from finding planets orbiting distant stars to understanding how dark matter and dark energy conspired to form the cosmic structures we see today. Principles of Gravitational Lensing begins with Einstein’s prediction that gravity bends light, and shows how that fundamental idea has spawned a rich field of study over the past century. The gravitational deflection of light was first detected by Eddington during a solar eclipse in May 1919, launching Einstein and his theory of relativity into public view. Yet the possibility of using the phenomenon to unlock mysteries of the Universe seemed remote, given the technology of the day. Theoretical work was carried out sporadically over the next six decades, but only with the discovery of the system Q0957+561 in 1979 was gravitational lensing transformed from a curiosity of general relativity into a practical observational tool. This book describes how the three subfields known as strong lensing, weak lensing, and microlensing have grown independently but become increasingly intertwined. Drawing on their research experience, Congdon and Keeton begin with the basic physics of light bending, then present the mathematical foundations of gravitational lensing, building up to current research topics in a clear and systematic way. Relevant background material from physics and mathematics is included, making the book self-contained. The derivations and explanations are supplemented by exercises designed to help students master the theoretical concepts as well as the methods that drive current research. An extensive bibliography guides those wishing to delve more deeply into particular areas of interest. Principles of Gravitational Lensing is ideal for advanced students and seasoned researchers looking to penetrate this thriving subject and even contribute research of their own.

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 Star Formation and Galaxy Evolution Since Z 2 written by Drew Grinnell Brisbin and published by . This book was released on 2014 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our recent studies in galaxy evolution have revealed a surprising new paradigm of star formation. Contrary to the notion that major mergers play an increasingly dominant role going backwards in cosmic history, we find that over the last ~10 Gyr, much of star formation has been fueled by accreting cold gas from the cosmic web. Accretion rates were presumably larger in the past, so star forming systems may have very different properties in the early Universe and today. Large scale astronomical surveys, such as the Herschel Multi-Tiered Extragalactic Survey (HerMES), and the Sloan Digital Sky Survey (SDSS) have provided a wealth of extragalactic data covering a statistically large number of sources. Targeted, niche surveys, like our fine structure line survey of star forming galaxies in the early Universe observed with the redshift (z) Early Universe Spectrometer (ZEUS) have provided detailed observations of high interest sources. We have made use of this diverse set of data to study galaxy evolution from the epoch of peak star formation at z=1-2 up to the present. Data from HerMES is a reliable probe of infrared emission, particularly useful for characterizing the far infrared dust peak, and therefore determining star formation rates out to redshifts of a few. Deep integrations with the Herschel SPIRE photometer rapidly reach the confusion limit, tempering its utility in studying faint high redshift galaxies. With appropriate care taken to identify blended sources, however, HerMES data is useful in identifying bright, red- shifted, star forming sources. We have compiled spectral energy distributions from HerMES and ancillary data and found that, even sources at high redshift are well fit by local star forming galaxy templates. In the local Universe, spectroscopic SDSS data has allowed us to estimate crucial galaxy properties on ~105 sources, providing an opportunity to observe general statistical trends, and constrain theories of galaxy evolution. A toy model of cold flow accretion powered star formation reproduces the observed fundamental plane of galaxy stellar mass, metallicity, and star formation for small and medium mass galaxies. Our fine structure line survey with ZEUS detected the [CII] 157.7 [MICRO SIGN]m line in eight galaxies from the epoch of peak star formation at z=1-2. We augmented this survey with observations of the [OI] 63 [MICRO SIGN]m line and far infrared photometry from Herschel, as well as Spitzer IRS spectra from the literature. Most of our sources have higher than average gas heating efficiency with L[CII] /LF IR 10[-]2 . We interpret the majority of them as being dominated by star formation powered PDRs, extending to kpc scales. In two sources there is evidence for enhanced [CII] emission due to heating by low velocity shocks. These findings are consistent with a picture of gas accretion fueling star formation on a near galaxy-wide scale. In synthesizing this data we find a remarkable consistency in the nature of star formation over the last 10 Gyr. In contrast with the model of sustained hierarchical merging, we find that star formation since z~2 is fueled largely by cold flow accretion of gas from the cosmic web, which presents itself as moderate density star formation with correspondingly moderate UV fields.

Download or read book The Evolution of Star Formation Rates in High redshift Galaxies written by Andrew H. Marquis and published by . This book was released on 2010 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: