A Statistical and Multi-wavelength Study of Star Formation in Galaxies PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download A Statistical and Multi-wavelength Study of Star Formation in Galaxies PDF full book. Access full book title A Statistical and Multi-wavelength Study of Star Formation in Galaxies by Corentin Schreiber. Download full books in PDF and EPUB format.
Author: Corentin Schreiber
Publisher: Springer
ISBN: 3319442937
Category : Science
Languages : en
Pages : 234
Get Book Here
Book Description
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: Corentin Schreiber
Publisher: Springer
ISBN: 3319442937
Category : Science
Languages : en
Pages : 234
Get Book Here
Book Description
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: Madison V. Smith
Publisher:
ISBN:
Category : Astrophysics
Languages : en
Pages : 0
Get Book Here
Book Description
I present the results of a multi-wavelength study of global, radial and local star formation histories (SFHs) in a statistical sample of 34 nearby galaxies. The SFHs are estimated using spectral energy distribution (SED) fitting, and are presented alongside classic indicators of changes in stellar population ages (optical colors, specific star formation rates, and H-alpha equivalent widths). I interpret the results of this methodology in the context of the literature for each galaxy. In addition to the global and radial measurements, ultraviolet-selected sources in each galaxy are detected and cataloged. I use two different methods (k-means clustering and two-point angular correlation functions) to describe the spatial distributions of these UV sources. I find that there is a connection between the clustering of UV sources in M63 and the presence of spiral arms. The less-clustered distributions of UV sources seen in galaxies without spiral arms suggests that the spiral arms help to cluster star formation in the stellar disk. Finally, I find that there is a detectable radial gradient in the age of the younger stellar population when looking at the full catalog of all UV sources. This result agrees with the leading theory for structure formation in the universe, the Lambda-CDM model, which theorizes that galaxies form and evolve "inside-out".
Author: Naveen Reddy
Publisher: Universal-Publishers
ISBN: 1581123310
Category : Science
Languages : en
Pages : 208
Get Book Here
Book Description
We examine the census of star-forming galaxies and their extinction properties at redshift z 2, when a large fraction of the stellar mass in the universe formed. We find a good agreement between the X-ray, radio, and de-reddened UV estimates of the average star formation rate (SFR) for our sample of z 2 galaxies of 50 Msun/yr, indicating that the locally calibrated SFR relations appear to be statistically valid from redshifts 1.5
Author: Alvio Renzini
Publisher: Springer Science & Business Media
ISBN: 9783540256656
Category : Science
Languages : en
Pages : 520
Get Book Here
Book Description
The possibilities of astronomical observation have dramatically increased over the last decade. Major satellites, like the Hubble Space Telescope, Chandra and XMM Newton, are complemented by numerous large ground-based observatories, from 8m-10m optical telescopes to sub-mm and radio facilities. As a result, observational astronomy has access to virtually the whole electromagnetic spectrum of galaxies, even at high redshifts. Theoretical models of galaxy formation and cosmological evolution now face a serious challenge to match the plethora of observational data. In October 2003, over 170 astronomers from 15 countries met for a 4-day workshop to extensively illustrate and discuss all major observational projects and ongoing theoretical efforts to model galaxy formation and evolution. This volume contains the complete proceedings of this meeting and is therefore a unique and timely overview of the current state of research in this rapidly evolving field.
Author: Drew Grinnell Brisbin
Publisher:
ISBN:
Category :
Languages : en
Pages : 167
Get Book Here
Book Description
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.
Author: Javier Álvarez Márquez
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Get Book Here
Book Description
Since the mid-1990s, the sample of galaxies in the early universe has been growing thanks to the increasing sensitivities in the Optical/NIR telescopes. However, their dust properties are poorly known due to the lack of deep far-infrared or sub-mm observations. This thesis explores the multi-wavelength properties of a population of galaxies observed ~2Gyr after the Big Bang. Our sample includes 22000 galaxies, and it has been selected by the classical U-dropout or Lyman Break technique. We use a statistical technique, called stacking analysis, that combines the signal from a large number of sources to lower the detection limits on the current long wavelengths observations. It allows us to obtain data over the full FUV-to-FIR spectral domain, and study the star formation and dust attenuation of these galaxies.
Author: Andreas Zezas
Publisher: Cambridge University Press
ISBN: 1316877523
Category : Science
Languages : en
Pages : 318
Get Book Here
Book Description
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: Irene Shivaei
Publisher:
ISBN: 9780355472042
Category : Cosmic dust
Languages : en
Pages : 20
Get Book Here
Book Description
Redshift of z
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 230
Get Book Here
Book Description
Author: Tsutomu Takeuchi
Publisher: Springer
ISBN: 9789811950926
Category : Science
Languages : en
Pages :
Get Book Here
Book Description
This book introduces various physical processes related to the formation and evolution of galaxies, such as gravitation, electromagnetism, statistical physics, condensed matter, non-equilibrium processes, and relativity. Real data are analyzed using statistical methods and theoretical understanding. These topics give students and researchers in other fields a cross-sectional, interdisciplinary review. In particular, the author puts a great emphasis on multi-wavelength observations and surveys, which are now fundamental to understand the physics of any kind of cosmological and galactic comprehensive study. This is the first book to look at multi-wavelength surveys from the view of both observation and theory. This book is intended to be a standard guide to the physics of galaxy formation and evolution, which is popular in astrophysics but is not dealt with in detail in other books for young graduate students and non-experts in physics. Physical processes related to the formation and evolution of stars in galaxies are particularly mentioned from the view of multi-wavelength observations, which leads to an understanding of how the current universe has developed.
