Garching bei München, Germany
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De Gasperin F.,Max Planck Institute for Astrophysics | De Gasperin F.,Exzellenzcluster Universe | Orru E.,Radboud University Nijmegen | Murgia M.,National institute for astrophysics | And 106 more authors.
Astronomy and Astrophysics | Year: 2012

Context.M 87 is a giant elliptical galaxy located in the centre of the Virgo cluster, which harbours a supermassive black hole of mass 6.4 × 109 M·, whose activity is responsible for the extended (80 kpc) radio lobes that surround the galaxy. The energy generated by matter falling onto the central black hole is ejected and transferred to the intra-cluster medium via a relativistic jet and morphologically complex systems of buoyant bubbles, which rise towards the edges of the extended halo. Aims. To place constraints on past activity cycles of the active nucleus, images of M 87 were produced at low radio frequencies never explored before at these high spatial resolution and dynamic range. To disentangle different synchrotron models and place constraints on source magnetic field, age and energetics, we also performed a detailed spectral analysis of M 87 extended radio-halo. Methods. We present the first observations made with the new Low-Frequency Array (LOFAR) of M 87 at frequencies down to 20 MHz. Three observations were conducted, at 15-30 MHz, 30-77 MHz and 116-162 MHz. We used these observations together with archival data to produce a low-frequency spectral index map and to perform a spectral analysis in the wide frequency range 30 MHz-10 GHz. Results. We do not find any sign of new extended emissions; on the contrary the source appears well confined by the high pressure of the intra-cluster medium. A continuous injection of relativistic electrons is the model that best fits our data, and provides a scenario in which the lobes are still supplied by fresh relativistic particles from the active galactic nuclei. We suggest that the discrepancy between the low-frequency radio-spectral slope in the core and in the halo implies a strong adiabatic expansion of the plasma as soon as it leaves the core area. The extended halo has an equipartition magnetic field strength of ≲ 10 μG, which increases to ≲ 13 μG in the zones where the particle flows are more active. The continuous injection model for synchrotron ageing provides an age for the halo of ≲ 40 Myr, which in turn provides a jet kinetic power of 6-10 × 1044 erg s-1. © ESO, 2012.


Applegate D.E.,Argelander Institute For Astronomie | Mantz A.,University of Chicago | Mantz A.,Kavli Institute for Particle Astrophysics and Cosmology | Mantz A.,Stanford University | And 17 more authors.
Monthly Notices of the Royal Astronomical Society | Year: 2016

This is the fourth in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. Here, we use measurements of weak gravitational lensing from the Weighing the Giants project to calibrate Chandra X-ray measurements of total mass that rely on the assumption of hydrostatic equilibrium. This comparison of X-ray and lensing masses measures the combined bias of X-ray hydrostatic masses from both astrophysical and instrumental sources. While we cannot disentangle the two sources of bias, only the combined bias is relevant for calibrating cosmological measurements using relaxed clusters. Assuming a fixed cosmology, and within a characteristic radius (r2500) determined from the X-ray data, we measure a lensing to X-ray mass ratio of 0.96 ± 9 per cent (stat) ± 9 per cent (sys). We find no significant trends of this ratio with mass, redshift or the morphological indicators used to select the sample. Our results imply that any departures from hydrostatic equilibrium at these radii are offset by calibration errors of comparable magnitude, with large departures of tensof- percent unlikely. In addition, we find a mean concentration of the sample measured from lensing data of c200 = 3.0-1.8. +4.4 Anticipated short-term improvements in lensing systematics, and a modest expansion of the relaxed lensing sample, can easily increase the measurement precision by 30-50 per cent, leading to similar improvements in cosmological constraints that employ X-ray hydrostatic mass estimates, such as on Ωm from the cluster gas mass fraction. © 2016 The Authors.


Koepferl C.M.,Ludwig Maximilians University of Munich | Ercolano B.,Ludwig Maximilians University of Munich | Ercolano B.,Exzellenzcluster Universe | Dale J.,Ludwig Maximilians University of Munich | And 5 more authors.
Monthly Notices of the Royal Astronomical Society | Year: 2013

The time-scale over which and the modality by which young stellar objects (YSOs) disperse their circumstellar discs dramatically influence the eventual formation and evolution of planetary systems. By means of extensive radiative transfer modelling, we have developed a new set of diagnostic diagrams in the infrared colour-colour plane (K - [24] versus K - [8]), to aid with the classification of the evolutionary stage of YSOs from photometric observations. Our diagrams allow the differentiation of sources with unevolved (primordial) discs from those evolving according to different clearing scenarios (e.g. homologous depletion versus inside-out dispersal), as well as from sources that have already lost their disc. Classification of over 1500 sources in 15 nearby star-forming regions reveals that approximately 39 per cent of the sources lie in the primordial disc region, whereas between 31 and 32 per cent disperse from the inside-out and up to 22 per cent of the sources have already lost their disc. Less than 2 per cent of the objects in our sample lie in the homogeneous draining regime. Time-scales for the transition phase are estimated to be typically a few 105 yr independent of stellar mass. Therefore, regardless of spectral type, we conclude that currently available infrared photometric surveys point to fast (of the order of 10 per cent of the global disc lifetime) inside-out clearing as the preferred mode of disc dispersal. © 2012 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.


Saglia R.P.,Max Planck Institute for Extraterrestrial Physics | Saglia R.P.,Universitats Sternwarte Munich | Opitsch M.,Max Planck Institute for Extraterrestrial Physics | Opitsch M.,Universitats Sternwarte Munich | And 16 more authors.
Astrophysical Journal | Year: 2016

We investigate the correlations between the black hole (BH) mass MBH, the velocity dispersion σ, the bulge mass MBu, the bulge average spherical density , and its spherical half-mass radius rh, constructing a database of 97 galaxies (31 core ellipticals, 17 power-law ellipticals, 30 classical bulges, and 19 pseudobulges) by joining 72 galaxies from the literature to 25 galaxies observed during our recent SINFONI BH survey. For the first time we discuss the full error covariance matrix. We analyze the well-known MBH-σ and MBH-MBu relations and establish the existence of statistically significant correlations between MBu and rh and anticorrelations between MBu and . We establish five significant bivariate correlations (MBH-σ-ρh, MBH-σ-rh, MBH-MBu-σ, MBH-MBu-ρh, MBH-MBu-rh) that predict MBH of 77 core and power-law ellipticals and classical bulges with measured and intrinsic scatter as small as dex and dex, respectively, or 0.26 dex when the subsample of 45 galaxies defined by Kormendy & Ho is considered. In contrast, pseudobulges have systematically lower MBH but approach the predictions of all of the above relations at spherical densities or scale lengths . These findings fit in a scenario of coevolution of BH and classical-bulge masses, where core ellipticals are the product of dry mergers of power-law bulges and power-law ellipticals and bulges the result of (early) gas-rich mergers and of disk galaxies. In contrast, the (secular) growth of BHs is decoupled from the growth of their pseudobulge hosts, except when (gas) densities are high enough to trigger the feedback mechanism responsible for the existence of the correlations between MBH and galaxy structural parameters. © 2016. The American Astronomical Society. All rights reserved.


Hanggi P.,University of Augsburg | Hilbert S.,Exzellenzcluster Universe | Dunkel J.,Massachusetts Institute of Technology
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences | Year: 2016

Depending on the exact experimental conditions, the thermodynamic properties of physical systems can be related to one or more thermostatistical ensembles. Here, we survey the notion of thermodynamic temperature in different statistical ensembles, focusing in particular on subtleties that arise when ensembles become non-equivalent. The 'mother' of all ensembles, the microcanonical ensemble, uses entropy and internal energy (the most fundamental, dynamically conserved quantity) to derive temperature as a secondary thermodynamic variable. Over the past century, some confusion has been caused by the fact that several competing microcanonical entropy definitions are used in the literature, most commonly the volume and surface entropies introduced by Gibbs. It can be proved, however, that only the volume entropy satisfies exactly the traditional form of the laws of thermodynamics for a broad class of physical systems, including all standard classical Hamiltonian systems, regardless of their size. This mathematically rigorous fact implies that negative 'absolute' temperatures and Carnot efficiencies more than 1 are not achievable within a standard thermodynamical framework. As an important offspring of microcanonical thermostatistics, we shall briefly consider the canonical ensemble and comment on the validity of the Boltzmann weight factor.We conclude by addressing open mathematical problems that arise for systems with discrete energy spectra. © 2016 The Author(s).


Hilbert S.,Exzellenzcluster Universe | Hanggi P.,University of Augsburg | Dunkel J.,Massachusetts Institute of Technology
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2014

The recent experimental realization of exotic matter states in isolated quantum systems and the ensuing controversy about the existence of negative absolute temperatures demand a careful analysis of the conceptual foundations underlying microcanonical thermostatistics. Here we provide a detailed comparison of the most commonly considered microcanonical entropy definitions, focusing specifically on whether they satisfy or violate the zeroth, first, and second laws of thermodynamics. Our analysis shows that, for a broad class of systems that includes all standard classical Hamiltonian systems, only the Gibbs volume entropy fulfills all three laws simultaneously. To avoid ambiguities, the discussion is restricted to exact results and analytically tractable examples. © 2014 American Physical Society.


PubMed | University of Augsburg, Massachusetts Institute of Technology and Exzellenzcluster Universe
Type: Journal Article | Journal: Philosophical transactions. Series A, Mathematical, physical, and engineering sciences | Year: 2016

Depending on the exact experimental conditions, the thermodynamic properties of physical systems can be related to one or more thermostatistical ensembles. Here, we survey the notion of thermodynamic temperature in different statistical ensembles, focusing in particular on subtleties that arise when ensembles become non-equivalent. The mother of all ensembles, the microcanonical ensemble, uses entropy and internal energy (the most fundamental, dynamically conserved quantity) to derive temperature as a secondary thermodynamic variable. Over the past century, some confusion has been caused by the fact that several competing microcanonical entropy definitions are used in the literature, most commonly the volume and surface entropies introduced by Gibbs. It can be proved, however, that only the volume entropy satisfies exactly the traditional form of the laws of thermodynamics for a broad class of physical systems, including all standard classical Hamiltonian systems, regardless of their size. This mathematically rigorous fact implies that negative absolute temperatures and Carnot efficiencies more than 1 are not achievable within a standard thermodynamical framework. As an important offspring of microcanonical thermostatistics, we shall briefly consider the canonical ensemble and comment on the validity of the Boltzmann weight factor. We conclude by addressing open mathematical problems that arise for systems with discrete energy spectra.


Moll A.,Max Planck Institute for Physics | Moll A.,Exzellenzcluster Universe
Journal of Physics: Conference Series | Year: 2011

The future of CP-Violation experiments is to begin in 2014 with the launch of the SuperKEKB collider in Tsukuba, Japan. As a part of this process the BELLE experiment will undergo an upgrade, giving rise to the BELLE II experiment. The BELLE II detector will include improvements and redesigns of various subdetectors, as well as the addition of an entire new subdetector for precise vertexing. In order to reflect these changes in the existing BELLE software framework, major modifications of nearly all parts of the software would have been necessary. As a result the decision was made to completely rewrite the software framework. In this article the main concepts of the new framework and the applied technologies are presented.


De Gasperin F.,Max Planck Institute for Astrophysics | De Gasperin F.,Exzellenzcluster Universe | Merloni A.,Exzellenzcluster Universe | Merloni A.,Max Planck Institute for Extraterrestrial Physics | And 4 more authors.
Monthly Notices of the Royal Astronomical Society | Year: 2011

We present the results of the analysis of a sample of 17 low-luminosity (LX≲ 1042ergs-1), radio-loud active galactic nuclei in massive galaxies. The sample is extracted from the Sloan Digital Sky Survey data base and it spans uniformly a wide range in optical [Oiii] emission line and radio luminosity, but within a narrow redshift range (0.05 < z < 0.11) and a narrow supermassive black hole mass range (∼108M⊙). For these sources we measured core X-ray emission with the Chandra X-ray Telescope and radio emission with the Very Large Array. Our main goal is to establish which emission component, if any, can be regarded as the most reliable accretion/jet-power estimator at these regimes. In order to do so, we studied the correlation between emission-line properties, radio luminosity, radio spectral slopes and X-ray luminosity, as well as more complex multivariate relations involving black hole mass, such as the Fundamental Plane of black hole activity. We find that 15 out of 17 sources of our sample can be classified as low-excitation galaxies (LEGs), and their observed properties suggest X-ray and radio emission to originate from the jet basis. We also find that X-ray emission does not appear to be affected by nuclear obscuration and can be used as a reliable jet-power estimator. More generally, X-ray, radio and optical emission appear to be related, although no tight correlation is found. In accordance with a number of recent studies of this class of objects, these findings may be explained by a lack of cold (molecular) gaseous structures in the innermost region of these massive galaxies. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.

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