[PDF] Dusty Star Formation In Extreme Environments eBook

Author : Stacey L. Alberts
Publisher :
Page : 204 pages
File Size : 40,74 MB
Release : 2014
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In this thesis, we present a comprehensive study of the dust-obscured star formation (SF) activity in galaxy clusters out to high redshift using infrared (IR) imaging. Using hundreds of galaxy clusters and wide-field far-IR imaging across nine square degrees, we quantify the average star formation rates (SFRs) out to the distant Universe for mass-limited cluster galaxy samples using stacking. We compare the evolution of this SF activity to field galaxies, finding that the evolution in clusters occurs more rapidly than in the field and clusters have field-like SF approximately nine billion years ago, during an epoch before SF quenching becomes effective in massive clusters. Building on this result, we present new, deep far-IR imaging of 11 spectroscopically-confirmed clusters at high redshift, which allows us to examine the SFRs of individual IR-luminous cluster galaxies as a function of environment. We find a transition from field-like SF to quenching of IR-luminous galaxies in the cluster cores over the redshift range probed. We present the first UV-to-far-IR spectral energy distributions (SEDs) of high redshift cluster galaxies, quantify the cluster-to-cluster variations in SF properties, and compare cluster galaxies to star forming galaxies in the field. In addition, we examine the SEDs of cluster galaxies with measurable emission from black hole accretion and quantify the fraction of these galaxies as a function of environment and redshift, finding an excess at high redshift in the cluster cores. Lastly, we compare dust-obscured SFRs from far-IR to unobscured SFRs from optical emission lines. In the last section, we present new submillimeter imaging of a massive cluster in the distant Universe. We characterize the FIR/submillimeter SED of IR-luminous cluster galaxies, finding dust temperatures similar to that in field galaxies in the same epoch. We use imaging of dust emission in the optically thin regime to derive the interstellar medium (ISM) masses of cluster galaxies. Through this analysis, we determine that IR-luminous cluster galaxies at high redshift have comparable ISM masses, gas fractions, and gas depletion timescales as field galaxies.

Author : Logan Houston Jones
Publisher :
Page : 0 pages
File Size : 12,47 MB
Release : 2021
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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.

Author : Diego F. Torres
Publisher : Springer Science & Business Media
Page : 500 pages
File Size : 45,12 MB
Release : 2013-04-19
Category : Science
ISBN : 3642354106

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These are the proceedings of the Sant Cugat Forum 2nd Workshop on Cosmic-ray Induced Phenomenology in Stellar Environments, held April 16-19, 2012. The aim of this Workshop was to address the current knowledge and challenges of high-energy emission from stellar environments at all scales and provide a comprehensive review of the state of the field from the observational to the theoretical perspectives. In the meeting, the prospects for possible observations with planned instruments across the multi-wavelength spectrum were analyzed and also how they impact on our understanding of these systems.

Author : Duncan MacKay
Publisher : Cambridge University Press
Page : 339 pages
File Size : 32,95 MB
Release : 2023-03-31
Category : Science
ISBN : 1009277448

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A succinct overview of our current understanding in the molecular astronomy of star formation for graduate students and early researchers.

Author : Marco Bocchio
Publisher :
Page : 0 pages
File Size : 29,92 MB
Release : 2014
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The main goal of my PhD study is to understand the dust processing that occurs during the mixing between the galactic interstellar medium and the intracluster medium. This process is of particular interest in violent phenomena such as galaxy-galaxy interactions or the "Ram Pressure Stripping'' due to the infalling of a galaxy towards the cluster centre.Initially, I focus my attention to the problem of dust destruction and heating processes, re-visiting the available models in literature. I particularly stress on the cases of extreme environments such as a hot coronal-type gas (e.g., IGM, ICM, HIM) and supernova-generated interstellar shocks. Under these conditions small grains are destroyed on short timescales and large grains are heated by the collisions with fast electrons making the dust spectral energy distribution very different from what observed in the diffuse ISM.In order to test our models I apply them to the case of an interacting galaxy, NGC 4438. Herschel data of this galaxy indicates the presence of dust with a higher-than-expected temperature.With a multi-wavelength analysis on a pixel-by-pixel basis we show that this hot dust seems to be embedded in a hot ionised gas therefore undergoing both collisional heating and small grain destruction.Furthermore, I focus on the long-standing conundrum about the dust destruction and dust formation timescales in the Milky Way. Based on the destruction efficiency in interstellar shocks, previous estimates led to a dust lifetime shorter than the typical timescale for dust formation in AGB stars. Using a recent dust model and an updated dust processing model we re-evaluate the dust lifetime in our Galaxy. Finally, I turn my attention to the phenomenon of "Ram Pressure Stripping''. The galaxy ESO 137-001 represents one of the best cases to study this effect. Its long H2 tail embedded in a hot and ionised tail raises questions about its possible stripping from the galaxy or formation downstream in the tail. Based on recent hydrodynamical numerical simulations, I show that the formation of H2 molecules on the surface of dust grains in the tail is a viable scenario.