Galactic Bulges

Abstract

978-3-319-19377-9 ISBN 978-3-319-19378-6 (eBook) DOI 10.1007/978-3-319-19378-6 Library of Congress Control Number: 2015949217 Springer Cham Heidelberg New York Dordrecht London © Springer International Publishing Switzerland 2016 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made.Cover Illustration: In the cover the 3.6 images of one nearby galaxy, NGC 4565, is shown. The images are from the Spitzer Survey of Stellar Structure in Galaxies (PI Kartik Sheth).Printed on acid-free paper Springer International Publishing AG Switzerland is part of Springer Science+Business Media (www.springer.com) PrefaceThe main motivation for this book was our impression that when observers talk about bulges in galaxies, they do not necessarily mean the same thing as people making theoretical models. Even among the observers, it is not always clear what they mean by classical and pseudobulges. According to most researchers, classical bulges are highly relaxed systems typically formed in galaxy mergers or by coalescence of massive gas clumps at high redshifts, whereas pseudobulges have more disc-like properties. Some people divide pseudobulges further into discy pseudobulges, defined as small central discs in the plane of the galactic disc, and boxy/peanut bulges which are actually dynamically heated, vertically thick inner parts of bars. Galaxies can also have central star clusters, usually called nuclear clusters, which structures are not called bulges in this book (see the review by Cole and Debattista). In recent years significant progress has been made both on the theoretical and observational sides, including galactic and extragalactic research. In this book we try to bring all these communities closer to each other.Most probably many of us share the Copernican approach trying to understand the universe with some simple beautiful theory. Such an attempt is the current paradigm of structure formation, i.e., the hierarchical growth of dark matter halos ( CDM), and the subsequent formatio...

The clustering of galaxies with pseudo-bulge and classical bulge in the local Universe

“…Nevertheless, the current picture can not fully explain the observational properties of bulges. In particular, many giant galaxies have been observed to have no sign of a classical bulge, a result that is inconsistent with the hierarchical clustering cosmology which predicts the opposite, indicating that bulge formation may be somehow suppressed in mergers (Laurikainen et al 2016). This problem is a strong function of environment: while most of the giant galaxies in the Local Group are bulgeless or with pseudo bulges, galaxies in Virgo cluster are mostly ellipticals or with classical bulges.…”

“…In general, the current theoretical picture is that classical bulges are produced during rapid processes like merger and clumpy disc instabilities which happen more often at high redshifts. On the other hand, secular evolution affects in a long term the appearance and growth of pseudo bulges, and is still shaping morphologies of galaxies at the present day (Obreja et al 2013;Laurikainen et al 2016). Detailed studies of the formation of bulges also indicate possibilities beyond this general picture.…”

The Correlations of Stellar Tidal Disruption Rates with Properties of Massive Black Holes and Their Host Galaxies

“…A tidal disruption event (TDE) happens when a star travels too close to a massive black hole (MBH) so that the tidal force exerted on the star by the MBH surpasses the star's selfgravity, causing the star to be ripped apart and disrupted, accompanied by luminous flares due to the subsequent accretion of the stripped stellar material (e.g., Hills 1975;Rees 1988). TDEs may frequently occur at the centers of galaxies, as observations have shown the ubiquitous existence of MBHs (with mass ∼10 6 -10 10 M e ) at galactic nuclei (e.g., Ferrarese & Merritt 2000;Gebhardt et al 2000;Tremaine et al 2002;Kormendy & Ho 2013;Graham 2016). These TDEs provide rich electromagnetic signals, which help us study the relativistic effects, accretion physics, formation of radio jets and the interior structure of torn stars, etc.…”

The complex inner Milky Way disentangled with chemistry-kinematics

“…1 Centre for Computational Astrophysics, Flatiron Institute. 2 Institute for Astronomy, University of Edinburgh.…”

“…The inner regions of galaxies are key to understand the formation and evolution of galaxies [1,2]. For the case of disc galaxies like our Milky Way (MW), these central regions are commonly referred to as bulges, and are the regions of highest stellar density.…”