The Velocity Dispersion Profile of NGC 6388 From Resolved-Star Spectroscopy: No Evidence of a Central Cusp and New Constraints on the Black Hole Mass

Lanzoni, B.; Mucciarelli, A.; Origlia, L.; Bellazzini, M.; Ferraro, F. R.; Valenti, E.; Miocchi, P.; Dalessandro, E.; Pallanca, Cristina; Massari, D.

doi:10.1088/0004-637x/769/2/107

Cited by 117 publications

(143 citation statements)

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“…mass segregation) of the discrepancies reported in the literature (e.g. those relative to NGC 6388, Lützgendorf et al 2011;Lanzoni et al 2013).…”

Section: Introductionmentioning

confidence: 85%

“…In the following analysis, when referring to the model velocity dispersion profile we will consider only the profiles 6 Note that an additional dependence can be introduced by the wavelength range and the specific spectroscopic features that are used to measure the kinematics; for example, spectral features like CO bands will be preferentially sensitive to giant stars (Lanzoni et al 2013). Figure 5).…”

Section: The True Kinematic Tracermentioning

confidence: 99%

“…These putative intermediate mass black holes (IMBHs) have proven elusive, with disputed evidence for their presence in Galactic globular clusters (GCs, Gebhardt et al 2000;van den Bosch et al 2006;Noyola et al 2010;van der Marel & Anderson 2010;Lützgendorf et al 2013;Lanzoni et al 2013;den Brok et al 2014) and extra-galactic ultra-luminous X-ray sources (e.g., Matsumoto et al 2001;Fabbiano et al 2001). The search for the existence of IMBHs within GCs has partially been motivated by the observation that the extrapolation of the M• − σ relation for galaxies, linking the mass of the central back hole to the velocity dispersion of the host stellar system (Ferrarese & Merritt 2000;Magorrian et al 1998), suggests that GCs are ideal environments to find central IMBHs with masses of 10 3 − 10 4 M .…”

Section: Introductionmentioning

confidence: 99%

“…In particular, integrated light spectroscopy seems to measure rising central velocity dispersions, favouring the presence of IMBHs (see e.g., Noyola et al 2010 for ω Cen; Lützgendorf et al 2011Lützgendorf et al , 2015 for NGC 6388), while resolved stellar kinematics do not confirm the presence of this signature (see van der Marel & Anderson 2010 for proper motion measurements of ω Cen; Lanzoni et al 2013 for individual line-of-sight measurements in NGC 6388).…”

Section: Introductionmentioning

confidence: 99%

“…Progress in understanding how this difference could influence the measurements has been made, for example, in understanding that unresolved kinematics can be strongly biased by the presence of a few bright stars dominating the integrated spectra, increasing the shot noise of the velocity dispersion (e.g. see Dubath et al 1997;Noyola et al 2010;Lanzoni et al 2013). Moreover, Lützgendorf et al (2015) recently showed that measurements of velocity dispersions from discrete velocities of individual stars can also be biased towards lower values of velocity dispersions.…”

Section: Introductionmentioning

confidence: 99%

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Understanding the central kinematics of globular clusters with simulated integrated-light IFU observations

Bianchini

Norris

Ven

et al. 2015

Mon. Not. R. Astron. Soc.

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The detection of intermediate mass black holes in the centres of globular clusters is highly controversial, as complementary observational methods often deliver significantly different results. In order to understand these discrepancies, we develop a procedure to simulate integral field unit (IFU) observations of globular clusters: Simulating IFU Star Cluster Observations (SISCO). The input of our software are realistic dynamical models of globular clusters that are then converted in a spectral data cube. We apply SISCO to Monte Carlo cluster simulations from Downing et al. (2010), with a realistic number of stars and concentrations. Using independent realisations of a given simulation we are able to quantify the stochasticity intrinsic to the problem of observing a partially resolved stellar population with integrated-light spectroscopy. We show that the luminosity-weighted IFU observations can be strongly biased by the presence of a few bright stars that introduce a scatter in the velocity dispersion measurements up to 40% around the expected value, preventing any sound assessment of the central kinematic and a sensible interpretation of the presence/absence of an intermediate mass black hole. Moreover, we illustrate that, in our mock IFU observations, the average kinematic tracer has a mass of 0.75 M , only slightly lower than the mass of the typical stars examined in studies of resolved line-of-sight velocities of giant stars. Finally, in order to recover unbiased kinematic measurements we test different masking techniques that allow us to remove the spaxels dominated by bright stars, bringing the scatter down to a level of only a few percent. The application of SISCO will allow to investigate state-of-the-art simulations as realistic observations.

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“…mass segregation) of the discrepancies reported in the literature (e.g. those relative to NGC 6388, Lützgendorf et al 2011;Lanzoni et al 2013).…”

Section: Introductionmentioning

confidence: 85%

Section: The True Kinematic Tracermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Understanding the central kinematics of globular clusters with simulated integrated-light IFU observations

Bianchini

Norris

Ven

et al. 2015

Mon. Not. R. Astron. Soc.

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Observational dynamics of low‐mass stellar systems

Frank

2014

Astron Nachr

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The last fifteen years have seen the discovery of new types of low-mass stellar systems that bridge the gap between the once well-separated regimes of galaxies and of star clusters. Whether such objects are considered galaxies depends also on the definition of the term "galaxy", and several possible criteria are based on their internal dynamics (e.g. the common concept that galaxies contain dark matter). Moreover, studying the internal dynamics of low-mass stellar systems may also help understand their origin and evolutionary history. The focus of this paper is on two classes of stellar systems at the interface between star clusters and dwarf galaxies: ultra-compact dwarf galaxies (UCDs) and diffuse Galactic globular clusters (GCs). A review of our current knowledge on the properties of UCDs is provided and dynamical considerations applying to diffuse GCs are introduced. In the following, recent observational results on the internal dynamics of individual UCDs and diffuse Galactic globular clusters are presented.

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Galactic Bulges

2016

Astrophysics and Space Science Library

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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...

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The Velocity Dispersion Profile of NGC 6388 From Resolved-Star Spectroscopy: No Evidence of a Central Cusp and New Constraints on the Black Hole Mass

Cited by 117 publications

References 55 publications

Understanding the central kinematics of globular clusters with simulated integrated-light IFU observations

Understanding the central kinematics of globular clusters with simulated integrated-light IFU observations

Observational dynamics of low‐mass stellar systems

Galactic Bulges

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