bluuebunny/crossref_metadata_2025 huggingface dataset:
Density profile and line-of-sight mass contamination of SLACS gravitational lenses
Authors: Guimarães C. C. , Sodré Laerte
Published: October 2010

We use data from 58 strong lensing events surveyed by the Sloan Lens ACS Survey to estimate the projected galaxy mass inside their Einstein radii by two independent methods: stellar dynamics and strong gravitational lensing. We perform a joint analysis of both estimates examining the galaxy-lens density profile (that we approximate by a power law), the anisotropy of the velocity distribution (represented by an effective constant parameter), and a possible line-of-sigh (l.o.s.) mass contamination (which is suggested by various independent works in the literature). For each model, a likelihood analysis is performed to find the parameters that produce the best agreement between the dynamical and lensing masses, and the parameter confidence levels. The Bayesian evidence is calculated to allow a comparison among the models. We find a degeneracy among the slope of the density profile, the anisotropy parameter and the l.o.s. mass contamination. For a density profile close to isothermal, a l.o.s. mass contamination of the order of a few percent is possible, being less probable with larger anisotropy.
Dark Matter Determinations from Chandra Observations of Quadruply Lensed Quasars
Authors: Pooley David , Blackburne Jeffrey A. , Rappaport Saul , Schechter Paul L.
Published: October 2010

We present Chandra X-ray observations of 14 quadruply lensed quasars. The X-ray data reveal flux ratio anomalies which are more extreme than those seen at optical wavelengths, confirming the microlensing origin of the anomalies originally seen in the optical data. The reduction of the anomalies in the optical, as compared to X-ray, indicates that the sizes of the optical emitting regions of the quasars must be about 1/3 the size of the projected Einstein radii of the microlensing stars. The X-ray emitting regions are essentially point sources and therefore give a microlensing signal unencumbered by source size considerations. For each lensing galaxy, we determine the most likely ratio of smooth material (dark matter) to clumpy material (stars) to explain the X-ray flux ratios. The ensemble of Chandra-observed quads indicates that the amount of matter projected along the lines of sight to the images (at radial distances of several kpc from the centers of the lensing galaxies) is ~90% smooth dark matter and ~10% stars.
Chemo-dynamical evolution of dwarf galaxies: from flat to cuspy dark matter density profiles
Authors: Pasetto S. , Grebel E. K. , Berczik P. , Spurzem R.
Published: October 2010

A model of an isolated dwarf spherical galaxy (dSph) is considered in its chemo-dynamical evolution with time. The system is composed by 3 γ-model density profiles: gas, stellar and dark matter, and it is realized in a spherical symmetric equilibrium configuration. The total masses used in our simulations are covering the dwarf galaxies mass range. The stability of this configuration is first tested for the system evolving under the gravity effect alone and then evolved taking into account for the most relevant stellar astrophysical processes implemented with a Smooth Particle Hydrodynamic approach. The two different kinds of evolution are compared. The dark matter evolves naturally from a centrally cuspy density profile into a flatter one within a timescale of several Gyr. The effect manifests itself naturally, without any tuned initial conditions, as soon as few standard criteria on star formation are assumedand the SN feedback on the ISM has been adopted the prescription in (Cioffi & Shull 1991) and (Bradamante et al. 1998). This result is expected to be a possible natural explanation for the discrepancy between observations that want flatter dark matter profiles (e.g. de Block 2005), and N-body simulations that predict cuspy dark matter profiles (Navarro et al. 1997). Chemical considerations are presented as a tool to follow with observational parameters the theory predictions.
Scaling relations in early-type galaxies from integral-field stellar kinematics
Authors: Cappellari M. , Scott N. , Alatalo K. , Blitz L. , Bois M. , Bournaud F. , Bureau M. , Davies R. L. , Davis T. A. , de Zeeuw P. T. , Emsellem E. , Falcon-Barroso J. , Khochfar S. , Krajnovic D. , Kuntschner H. , Lablanche P.-Y. , McDermid R. M. , Morganti R. , Naab T. , Sarzi M. , Serra P. , van den Bosch R. C. E. , van de Ven G. , Weijmans A. , Young L. M.
Published: October 2010

Early-type galaxies (ETGs) satisfy a now classic scaling relation Re ∝ σ1.2eI−0.8e, the Fundamental Plane (FP; Djorgovski & Davis 1987; Dressler et al. 1987), between their size, stellar velocity dispersion and mean surface brightness. A significant effort has been devoted in the past twenty years to try to understand why the coefficients of the relation are not the ones predicted by the virial theorem Re ∝ σ2eI−1e.
Lenticular vs spiral galaxies: dark matter content and the Tully-Fisher relation
Authors: Bureau M. , Williams M. J. , Cappellari M.
Published: October 2010

We provide observational constraints on disk galaxy evolution for a sample of 28 local edge-on early-type (S0–Sb) disk galaxies. We do this in two ways: (i) we use simple dynamical modelling techniques to constrain their stellar and dark matter content (Williams et al. 2009) and (ii) we compare the zero points of the Tully-Fisher relations (TFRs; Tully & Fisher 1977) of the spirals and S0s.
Scaling relations of early-type galaxies in the 6dF Galaxy Survey
Authors: Magoulas C. , Colless M. , Jones H. , Mould J. , Springob C.
Published: October 2010

Over 10,000 early-type galaxies from the 6dF Galaxy Survey (6dFGS) (Jones, D. H. et al. (2009), Jones et al. (2004)) have been used to determine the Fundamental Plane at optical and near-infrared wavelengths. We find that a maximum likelihood fit to an explicit three-dimensional Gaussian model for the distribution of galaxies in size, surface brightness and velocity dispersion can precisely account for selection effects, censoring and observational errors, leading to precise and unbiased parameters for the Fundamental Plane and its intrinsic scatter.
Galaxy formation from dry and hydro simulations
Authors: Ciotti Luca
Published: October 2010

The effects of dry and wet merging on the Scaling Laws (SLs) of elliptical galaxies (Es) are discussed. It is found that the SLs, possibly established at high redshift by the fast collapse of gas-rich and clumpy stellar distributions in preexisting dark matter halos following the cosmological SLs, are compatible with a (small) number of galaxy mergers at lower redshift.
The growth of the red-sequence in clusters since ≃1
Authors: Muñoz Roberto P. , Barrientos L. F. , Koester B. P. , Gilbank D. G. , Gladders M. D. , Yee H. K. C.
Published: October 2010

We use deep nIR imaging of 15 galaxy clusters at z ≃ 1 to study the build-up of the red-sequence in rich clusters since the Universe was half its present age. We measured, for the first time, the luminous-to-faint ratio of red-sequence galaxies at z=1 from a large ensemble of clusters, and found an increase of 100% in the ratio of luminous-to-faint red-sequence galaxies from z=0.45 to 1.0. The measured change in this ratio as function of redshift is well-reproduced by a simple evolutionary model developed in this work, that consists in an early truncation of the star formation for bright cluster galaxies and a delayed truncation for faint cluster galaxies.
The outer haloes of massive, elliptical galaxies
Authors: Das Payel , Gerhard Ortwin , de Lorenzi Flavio , McNeil Emily , Churazov Eugene , Coccato Lodovico
Published: October 2010

The outer haloes of massive elliptical galaxies are dark-matter dominated regions where stellar orbits have longer dynamical timescales than the central regions and therefore better preserve their formation history. Dynamical models out to large radii suffer from a degeneracy between mass and orbital structure, as the outer kinematics are unable to resolve higher moments of the line-of-sight velocity distribution. We mitigate this degeneracy for a sample of quiescent, massive, nearby ellipticals by determining their mass distributions independently using a non-parametric method on X-ray observations of the surrounding hot interstellar medium. We then create dynamical models using photometric and kinematic constraints consisting of integral-eld, long-slit and planetary nebulae (PNe) data extending to ~50 kpc. The rst two galaxies of our sample, NGC 5846 and NGC 1399, were found to have very shallow pro jected light distributions with a power law index of ~1.5 and a dark matter content of 70–80% at 50 kpc. Spherical Jeans models of the data show that, in the outer haloes of both galaxies, the pro jected velocity dispersions are almost inde- pendent of the anisotropy and that the PNe prefer the lower end of the range of mass distributions consistent with the X-ray data. Using the N-body code NMAGIC, we cre- ated axisymmetric models of NGC 5846 using the individual PNe radial velocities in a likelihood method and found them to be more constraining than the binned velocity dispersions. Characterising the orbital structure in terms of spherically averaged proles of the velocity dispersions we nd σψ > σr > σθ.
JD2 - Diffuse Light in Galaxy Clusters
Authors: Arnaboldi Magda , Gerhard Ortwin
Published: October 2010

Diffuse intracluster light (ICL) has now been observed in nearby and in intermediate redshift clusters. Individual intracluster stars have been detected in the Virgo and Coma clusters and the first color-magnitude diagram and velocity measurements have been obtained. Recent studies show that the ICL contains of the order of 10% and perhaps up to 30% of the stellar mass in the cluster, but in the cores of some dense and rich clusters like Coma, the local ICL fraction can be high as 40%-50%. What can we learn from the ICL about the formation of galaxy clusters and the evolution of cluster galaxies? How and when did the ICL form? What is the connection to the central brightest cluster galaxy? Cosmological N-body and hydrodynamical simulations are beginning to make predictions for the kinematics and origin of the ICL. The ICL traces the evolution of baryonic substructures in dense environments and can thus be used to constrain some aspects of cosmological simulations that are most uncertain, such as the modeling of star formation and the mass distribution of the baryonic component in galaxies.
Gamma-ray emission from pulsar/massive-star binaries
Authors: Romero Gustavo E.
Published: October 2010

I present a review of the main phenomenological properties at high energies related to massive gamma-ray binaries and I discuss some aspects of pulsar models for these objects.
Probing fundamental physics with pulsars
Authors: Lorimer Duncan R. , McLaughlin Maura A.
Published: October 2010

Pulsars provide a wealth of information about General Relativity, the equation of state of superdense matter, relativistic particle acceleration in high magnetic fields, the Galaxy's interstellar medium and magnetic field, stellar and binary evolution, celestial mechanics, planetary physics and even cosmology. The wide variety of physical applications currently being investigated through studies of radio pulsars rely on: (i) finding interesting objects to study via large-scale and targeted surveys; (ii) high-precision timing measurements which exploit their remarkable clock-like stability. We review current surveys and the principles of pulsar timing and highlight progress made in the rotating radio transients, intermittent pulsars, tests of relativity, understanding pulsar evolution, measuring neutron star masses and the pulsar timing array
Gravitational waves from neutron stars
Authors: Andersson Nils
Published: October 2010

In this presentation, I will outline some of the different ways that neutron stars can generate gravitational waves, discuss recent improvements in modeling the relevant scenarios in the context of improving detector sensitivity, and show how observations are beginning to put interesting “constraints” on our theoretical models.
Pushing the limit of instrument capabilities
Authors: Shulyak Denis V. , Weiss Werner W. , Mathys Gautier , Eyer Laurent , Kholtygin Alexander F. , Kochukhov Oleg , North Pierre , Fabrika Sergey N. , Burlakova Tatyana E.
Published: October 2010

Chemically Peculiar (CP) stars have been the subject of systematic research for more than 50 years. With the discovery of pulsation of some of the cool CP stars, and the availability of advanced spectropolarimetric instrumentation and high signal-to-noise, high resolution spectroscopy, a new era of CP star research emerged about 20 years ago. Together with the success in ground-based observations, new space projects are developed that will greatly benefit future investigations of these unique objects. In this contribution we will give an overview of some interesting results obtained recently from ground-based observations and discuss the future outstanding Gaia space mission and its impact on CP star research.
The challenge raised by Gaia
Authors: Robin Annie C.
Published: October 2010

Gaia will perform an unprecedented high quality survey of the Milky Way. Distances, 3D kinematics, ages and abundances will be obtained, giving access to the overall mass distribution and to the Galactic potential. Gaia data analysis will involve a high level of complexity requiring new and efficient multivariate data analysis methods, improved modelling of the stellar populations and dynamical approaches to the interpretation of the data in terms of the chemical and dynamical evolution of the Galaxy.
Dynamics and history of the Milky Way
Authors: Helmi Amina
Published: October 2010

The structure and dynamics of the Galaxy contain information about both its current workings and its assembly history. I review our understanding of the dynamics of the disk and stellar halo, and sketch how these may be used to unravel how our Galaxy formed.
Star-formation histories, metallicity distributions and luminosity functions
Authors: Wyse Rosemary F. G.
Published: October 2010

A selection of topics was discussed, but given the limits of space, I discuss here only the IMF in any depth, with only a brief supplementary comment on the bulge.
Connecting Moving Groups to the Bar and Spiral Arms of the Milky Way
Authors: Antoja T. , Valenzuela O. , Figueras F. , Pichardo B. , Moreno E.
Published: October 2010

We use test-particle orbit integration with a realistic Milky Way (MW) potential to study the effect of the resonances of the Galactic bar and spiral arms on the velocity distribution of the Solar Neighbourhood and other positions of the disk. Our results show that spiral arms create abundant kinematic substructure and crowd stars into the region of the Hercules moving group in the velocity plane. Bar resonances can contribute to the origin of low-angular momentum moving groups like Arcturus. Particles in the predicted dark disk of the MW should be affected by the same resonances as stars, triggering dark-matter moving groups in the disk. Finally, we evaluate how this study will be advanced by upcoming Gaia data.
Cosmological simulations of the Milky Way
Authors: Mayer Lucio
Published: October 2010

Recent simulations of forming low-mass galaxies suggests a strategy for obtaining realistic models of galaxies like the Milky-Way.
Modelling the Galaxy with orbital tori
Authors: Binney James
Published: October 2010

The principles and advantages of torus modelling are explained.
In What Detail Can We Represent the Milky Way in a Conventional N-Body Model?
Authors: Debattista Victor P.
Published: October 2010

After a brief review of past N-body models of the Milky Way, I consider some of the difficulties that are inherent in the N-body approach to modelling any disk galaxy.
Made-to-Measure N-body Modeling of the Milky Way Galaxy
Authors: Gerhard Ortwin
Published: October 2010

In this talk a brief introduction is given to made-to-measure particle methods and their potential use for modeling the Milky Way Galaxy.
A New Approach to the Construction of Dynamical Structure of our Galaxy
Authors: Ueda H. , Gouda N. , Yano T. , Koyama H. , Sakagami M.
Published: October 2010

Information about positions and velocities of stars that will be gained in the era of GAIA is crucial for determining dynamical structure in our Galaxy. The distribution function of all component objects in our Galaxy is fundamental for describing its dynamics. However, only the distribution function of observable stars is obtained from space astrometry observations, and it is therefore necessary to develop theoretical studies of how to construct the distribution function of all matter including dark matter and unobservable stars using astrometric data of observable stars. This procedure falls into three categories.
Monitoring UT1 from astro-geodetic techniques at the EOP Center of the IERS
Authors: Gambis D. , Bizouard C.
Published: October 2010

Monitoring the Earth rotation is essential in various domains linked to reference frames firstly with applications in orbit determination, space geodesy or Astronomy. Secondly for geophysical studies where are involved mass motions within the different external fluid layers, atmosphere, hydrosphere, core and mantle of the earth, this on time scales ranging from a few hours to decades. The Earth Orientation Centre of the IERS is continuously monitoring the earth orientation variations from results derived from the various astro-geodetic techniques. It has in particular the task of deriving an optimal combined series of UT1 which is now based mainly on Very Long Baseline Interferometry (VLBI) with some contribution of LOD derived from GPS. We give here a brief summary concerning the contribution of the various techniques to UT1 and in aprticular how the use of LOD derived from GPS can improve the combination. More details are available in Gambis (2004) and Bizouard and Gambis (2009) and the website http://hpiers.obspm.fr/eop-pc/
Instability of the celestial reference frame and effect on UT1
Authors: Zharov Vladimir E.
Published: October 2010

It was shown that the ICRF radio sources including the defining sources have significant apparent motion that leads to rotation of the ICRF. This rotation is transformed to secular variations of EOP that is decreased or removed if motion of sources is took into account.
Determination of UT1 by VLBI
Authors: Schuh Harald , Boehm Johannes , Englich Sigrid , Nothnagel Axel
Published: October 2010

Very Long Baseline Interferometry (VLBI) is the only space geodetic technique which is capable of estimating the Earth's phase of rotation, expressed as Universal Time UT1, over time scales of a few days or longer. Satellite-observing techniques like the Global Navigation Satellite Systems (GNSS) are suffering from the fact that Earth rotation is indistinguishable from a rotation of the satellite orbit nodes, which requires the imposition of special procedures to extract UT1 or length of day information. Whereas 24 hour VLBI network sessions are carried out at about three days per week, the hour-long one-baseline intensive sessions (‘Intensives’) are observed from Monday to Friday (INT1) on the baseline Wettzell (Germany) to Kokee Park (Hawaii, U.S.A.), and from Saturday to Sunday on the baseline Tsukuba (Japan) to Wettzell (INT2). Additionally, INT3 sessions are carried out on Mondays between Wettzell, Tsukuba, and Ny-Alesund (Norway), and ultra-rapid e-Intensives between E! urope and Japan also include the baseline Metsähovi (Finland) to Kashima (Japan). The Intensives have been set up to determine daily estimates of UT1 and to be used for UT1 predictions. Because of the short duration and the limited number of stations the observations can nowadays be e-transferred to the correlators, or to a node close to the correlator, and the estimates of UT1 are available shortly after the last observation thus allowing the results to be used for prediction purposes.
Semidiurnal signal in UT1 due to the influence of tidal gravitation on the triaxial structure of the Earth
Authors: Brzeziński Aleksander , Capitaine Nicole
Published: October 2010

The axial component of Earth rotation, which is conventionally expressed by Universal Time (UT1), contains small physical signals with diurnal and subdiurnal periods. This part of the spectrum is dominated by the tidal effects which are regular and predictable. The largest components express the influence of the gravitationally forced ocean tides with diurnal and semidiurnal periods and amplitudes up to 0.02 milliseconds (ms) in UT1 corresponding to an angular displacement of 0.30 milliarcseconds (mas); see Table 8.3 of the IERS Conventions (IERS, 2003). There are also smaller subdiurnal components (amplitudes up to 0.03 mas), designated as “spin libration” by Chao et al. (1991), due to direct influence of the tidal gravitation on those features of the Earth's density distribution which are expressed by the non-zonal terms of the geopotential. These components are not included in the models recommended by the IERS Conventions, in contrast to the corresponding effect in polar motion (ibid., Table 5.1).

Here we consider in detail the subdiurnal libration in UT1. We derive an analytical solution for the structural model of the Earth consisting of an elastic mantle and a liquid core which are not coupled to each other. The reference solution for the rigid Earth is computed by using the satellite-determined coefficients of geopotential and the recent developments of the tide generating potential (TGP). We arrived to the conclusion that the set of terms with amplitudes exceeding the truncation level of 0.005 mas consists of 11 semidiurnal harmonics due to the influence of the TGP term u22 on the equatorial flattening of the Earth expressed by the Stokes coefficients C22, S22. There is an excellent agreement between our estimates for the rigid Earth and the amplitudes derived by Wünsch (1991). The only important difference is the term with the tidal code ν2, which seems to be overlooked in the development of Wünsch. Our amplitudes computed for an elastic Earth with liquid core appear to be in reasonable agreement with those derived by Chao et al. (1991), but the latter model was not complete. The estimated effect is superimposed on the ocean tide influences having the same frequencies but 9 to 11 times larger amplitudes. Nevertheless, its maximum peak-to-peak size is about 0.105 mas, hence definitely above the current uncertainty of UT1 determinations. Comparison with the corresponding model of prograde diurnal polar motion associated with the Earth's triaxiality (IERS Conventions, Table 5.1) shows that: 1) the two effects are of similar size, 2) there is consistency between the underlying dynamical models, parameters employed, etc. In conclusion, we recommend adding the model developed here to the set of procedures provided by the IERS Conventions.
Pulsar timing array
Authors: Rodin Alexander E.
Published: October 2010

Simultaneous timing of several pulsars distributed over the sky, so called Pulsar Timing Array (PTA), is used for a variety of metrological and astronomical applications. Three examples of PTA application are presented: link between celestial reference frames, ensemble pulsar time scale and detection of gravitational waves.
Impact of Pulsar Giant Pulses on Distant Clocks Comparison
Authors: Ilyasov Yury P. , Zharov Vladimir E. , Sekido M.
Published: October 2010

New method of precise clocks comparison based on observation and registration of giant pulses of the millisecond pulsars is discussed. It was shown that expected accuracy of comparison is about 0.2–2 ns and depends on uncertainty of delay in the Earth ionosphere and troposphere.
Timing of binary pulsars and the search for the low-frequency gravitational waves
Authors: Potapov Vladimir A. , Kopeikin Sergei M.
Published: October 2010

Millisecond and binary pulsars are the most stable natural standards of astronomical time giving us a unique opportunity to search for gravitational waves (GW) and to test General Relativity. GWs from violent events in early Universe and from the ensemble of galactic and extragalactic objects perturb propagation of radio pulses from a pulsar to observer bringing about stochastic fluctuations in the times of arrival of the pulses (TOA). If one observes the pulsar over a sufficiently long time span, the fluctuations will be registered as a low-frequency, correlated noise affecting the timing residuals in the frequency range 10−12 ÷ 10−7 Hz. This work demonstrates how the standard procedure of processing of the pulsar timing data can bias the estimate of the upper limit on the density of the GW background (GWB).
Accretion Disks around low-mass Stars unveiled by the new Generation of cm to submm Arrays
Authors: Dutrey Anne
Published: October 2010

In the context of accretion disks, I briefly discuss the impact of three major forthcoming radio facilities: e-VLA, ALMA and SKA. These arrays are complementary by their frequency range and angular resolution. Around nearby low-mass stars, they will likely provide the first insights in the inner gas and dust disks (radius < 10-30 AU) in the area where planet formation should occur but would also allow the first investigations of the star, jet and disk connections.
Outflows in nearby AGNs
Authors: Storchi-Bergmann Thaisa
Published: October 2010

I report results of kinematic studies of the Narrow-Line Region (NLR) of nearby Active Galactic Nuclei (AGN) from integral field spectroscopy (IFS) obtained with the Gemini Telescopes, including mass outflow rates and corresponding kinetic power. The IFS has allowed the construction of velocity channel maps which provide a better coverage of the gas kinematics and do not support the presence of acceleration up to hundred parsec scales in the NLR as found in previous studies based solely on centroid velocity maps.
On the role of magnetic reconnection in jet/accretion disk systems
Authors: de Gouveia Dal Pino Elisabete M. , Piovezan Pamela , Kadowaki Luis , Kowal Grzegorz , Lazarian Alex
Published: October 2010

The most accepted model for jet production is based on the magneto-centrifugal acceleration out off an accretion disk that surrounds the central source (Blandford & Payne, 1982). This scenario, however, does not explain, e.g., the quasi-periodic ejection phenomena often observed in different astrophysical jet classes. de Gouveia Dal Pino & Lazarian (2005) (hereafter GDPL) have proposed that the large scale superluminal ejections observed in microquasars during radio flare events could be produced by violent magnetic reconnection (MR) episodes. Here, we extend this model to other accretion disk systems, namely: active galactic nuclei (AGNs) and young stellar objects (YSOs), and also discuss its hole on jet heating and particle acceleration.
The ejection-accretion connection in young stars: Testing MHD disk winds
Authors: Cabrit S. , Ferreira J. , Dougados C. , Garcia P.
Published: October 2010

Jets are ubiquitous in young accreting stars at all evolutionary stages, from deeply embedded protostars aged less than 0.1Myr to optically revealed 10Myr old T Tauri stars. The similar jet collimation at all ages is shown to require an effective magnetic collimation within the inner disk regions (inside 20 AU). This fact, and the high ejection to accretion ratio ≃10%, appear to favor the presence of MHD disk winds. Ejection out to > 0.1 AU could explain the velocity drop and rotation signatures across the jets, and their dust and molecular content.
A New Look at Optical and X-ray Emission in SDSS/XMM-Newton Quasars
Authors: Young Monica C. B.
Published: October 2010

We develop a new approach to the well-studied anti-correlation between the optical-to-X-ray spectral index, αox, and the monochromatic optical luminosity, lopt. By cross-correlating the SDSS DR5 quasar catalog with the XMM-Newton archive, we create a sample of 327 quasars with both optical and X-ray spectra, allowing αox to be defined at arbitrary frequencies, rather than the standard 2500 Å and 2 keV. We find that while the choice of optical wavelength does not strongly influence the αox−lopt relation, the slope of the relation flattens significantly with X-ray energy. This result suggests a change in the efficiency of X-ray photon production, where the efficiency of low energy X-ray production depends more strongly on the seed (optical/UV) photon supply. We discuss implications for line-driven wind models.
Jets from Compact X-ray Sources
Authors: Kylafis Nick D.
Published: October 2010

Jets have been observed from both neutron stars and black holes in binary X-ray sources. The neutron star jets are typically 30 times weaker than the black-hole ones. Thus, the second have been studied more extensively. Contrary to common belief, jets from compact X-ray sources are not simply “fireworks” that emit radio waves. I will demonstrate that they play a central role in the observed phenomena in both neutron star and black-hole systems. In particular, for black-hole jets, a simple jet model can explain the very stringent correlations that have been found between the power-law X-ray spectrum and a) the time lag between hard and soft X-rays and b) the characteristic frequencies observed in the power spectra. Up to now, no other model has even attempted to explain these correlations. I will present the weaknesses of the model and the improvements that need to be done to it.
JD8 - Hot Interstellar Matter in Elliptical Galaxies
Authors: Kim Dong-Woo , Pellegrini Silvia
Published: October 2010

The physical properties of the hot interstellar matter in elliptical galaxies are directly related with the formation and evolution of elliptical galaxies via star formation episodes, environmental effects such as stripping, infall, and mergers, and growth of super-massive black holes. The recent successful Chandra and XMM-Newton X-ray space missions have provided a large amount of high spatial/spectral resolution observational data on the hot ISM in elliptical galaxies. At the same time, theoretical studies with numerical simulations and analytical modeling of the dynamical and chemical evolution of elliptical galaxies have made a significant progress and start to predict various observable quantities.
The hot ISM of early-type galaxies
Authors: Fabbiano G.
Published: October 2010

This talks reviews the history of the discovery of the hot ISM in elliptical galaxies, and the ensuing debate on the suitability of X-ray observations of these galaxies for mass measurements. How much of the X-ray emission is truly from a hot ISM, and is this ISM in hydrostatic equilibrium? While the debate went on, a deeper understanding on the evolution of the halos was generated. High resolution Chandra observations are providing an answer.
Hot gas morpoloy, thermal structure, and the AGN connection in elliptical galaxies
Authors: Statler Thomas S. , Diehl Steven
Published: October 2010

Recent studies of the hot interstellar medium in normal elliptical galaxies have shown that (1) the gas is only approximately hydrostatic; (2) morphological disturbances are corrleated with radio and X-ray signatures of AGN; and (3) temperature gradients in the main bodies of the galaxies are correlated with nuclear activity but not with environment. An X-ray Gas Fundamental Plane (XGFP), unrelated to the stellar fundamental plane, links the global gas properties in a relation whose origin is not yet understood.
Hot gas flows on global and nuclear galactic scales
Authors: Pellegrini Silvia
Published: October 2010

One of the most significant observational improvements allowed by the high quality Chandra data of galaxies is the measurement of the nuclear luminosities down to low values, and of the hot ISM properties down to very low gas contents. I present here some recent developements concerning the possibility of accreting and outflowing gas, based on modeling results that take into account the role of a central supermassive black hole (MBH).
Confronting feedback simulations with observations of hot gas in elliptical galaxies
Authors: Wang Q. Daniel
Published: October 2010

Elliptical galaxies comprise primarily old stars, which collectively generate a long-lasting feedback via stellar mass-loss and Type Ia SNe. This feedback can be traced by X-ray-emitting hot gas in and around such galaxies, in which little cool gas is typically present. However, the X-ray-inferred mass, energy, and metal abundance of the hot gas are often found to be far less than what are expected from the feedback, particularly in so-called low LX/LB ellipticals. This “missing” stellar feedback is presumably lost in galaxy-wide outflows, which can play an essential role in galaxy evolution (e.g., explaining the observed color bi-modality of galaxies). We are developing a model that can be used to properly interpret the X-ray data and to extract key information about the dynamics of the feedback and its interplay with galactic environment.
Suzaku observation of the metallicity in the interstellar medium of NGC 1316
Authors: Konami S. , Matsushita K. , Sato K. , Nagino R. , Isobe N. , Tashiro M. S. , Seta H. , Matsuta K. , Tamagawa T. , Makishima K.
Published: October 2010

Metal abundances of the hot X-ray emitting interstellar medium (ISM) include important information to understand the history of star formation and evolution of galaxies. The metals are mainly synthesized by Type Ia (SNe Ia) and stellar mass loss in elliptical galaxies. The productions of stellar mass loss reflect stellar metallicity. SNe Ia mainly product Fe. Therefore, the abundance pattern of ISM can play key role to investigate the metal enrichment history.
Feedback and environmental effects in elliptical galaxies
Authors: Sarazin Craig L.
Published: October 2010

The role of the environment of an elliptical galaxy on its hot interstellar gas is discussed. In general, the X-ray halos of early-type galaxies tend to be smaller and fainter in denser environments, with the exception of group-central galaxies. X-ray observations show many examples of nearby galaxies which are undergoing gas stripping. On the other hand, most bright galaxies in clusters do manage to retain small coronae of X-ray emission. Recent theoretical and observational results on the role of feedback from AGN at the centers of elliptical galaxies on their interstellar gas are reviewed. X-ray observations show many examples of X-ray holes in the central regions of brightest-cluster galaxies; in many cases, the X-ray holes are filled with radio lobes. Similar radio bubbles are seen in groups and individual early-type galaxies. “Ghost bubbles” are often seen at larger radii in clusters and galaxies; these bubbles are faint in high radio frequencies, and are believed to be old radio bubbles which have risen buoyantly in the hot gas. Low frequency radio observations show that many of the ghost bubbles have radio emission; in general, these long wavelength observations show that radio sources are much larger and involve greater energies than had been previously thought. The radio bubbles can be used to estimate the total energy output of the radio jets. The total energies deposited by radio jets exceed the losses from the gas due to radiative cooling, indicating that radio sources are energetically capable of heating the cooling core gas and preventing rapid cooling.
Scaling properties of the hot gas in early-type galaxies
Authors: Ponman Trevor J. , O'Sullivan J.
Published: October 2010

We examine the processes responsible for the large scatter in the X-ray/optical luminosity scaling relation of early-type galaxies.
Effects of environment on the properties of cluster galaxies via ram pressure stripping
Authors: Tecce T. E. , Cora S. A. , Tissera P. B. , Abadi M. G.
Published: October 2010

We study the effect of ram pressure stripping (RPS) on the colours, cold gas content and star formation of galaxies in clusters, using a combination of N-Body/SPH simulations of galaxy clusters and a semi-analytic model of galaxy formation that includes the effect of RPS.
AGN feedback in details and in surveys
Authors: Finoguenov Alexis
Published: October 2010

I will review the new details on AGN feedback revealed by recent Chandra observations of M84 and present its theoretical modeling. Using the results of COSMOS survey I will present the direct measurement of halo occupation statistics for radio galaxies.
Warm ionized ISM in the bulge of Andromeda galaxy
Authors: Gilfanov Marat , Bogdan Akos
Published: October 2010

We demonstrate that unresolved X-ray emission from the bulge of M31 is composed of at least three different components: (i) Broad-band emission from a large number of faint sources – mainly accreting white dwarfs and active binaries, associated with the old stellar population, similar to the Galactic Ridge X-ray emission of the Milky Way. (ii) Soft emission from ionized gas with temperature of about ~ 300 eV and mass of ~ 4 × 106 M⊙. The gas distribution is significantly elongated along the minor axis of the galaxy suggesting that it may be outflowing in the direction perpendicular to the galactic disk. The shadows cast on the gas by spiral arms and the 10-kpc star-forming ring confirm large off-plane extent of the gas. (iii) Hard unresolved emission from spiral arms, most likely associated with protostars and young stellar objects located in the star-forming regions.
IAU Joint Discussion 9: Are the Fundamental Constants Varying in Space-time?
Authors: Molaro Paolo , Vangioni Elisabeth
Published: October 2010

The Joint Discussion on the variability of fundamental constants within the IAU GA 2009 was organized with the coordination of the IAU Division VIII Galaxies & the Universe and the support of IAU Commissions N. 47 Cosmology, N. 52 Relativity in Fundamental Astronomy, N.40 Radio Astronomy and N. 30 Radial velocities. The JD provided a timely opportunity to confront different points of view on this rather exciting subject.
Variable Constants - A Theoretical Overview
Authors: Olive Keith A.
Published: October 2010

In many theories of unified interactions, there are additional degrees of freedom which may allow for the variation of the fundamental constants of nature. I will review the motivation for such variations, and describe the theoretical relations between variations of gauge and Yukawa couplings.
Reconstructing the evolution of dark energy with variations of fundamental parameters
Authors: Nunes N. J. , Dent T. , Martins C. J. A. P. , Robbers G.
Published: October 2010

A popular candidate of dark energy, currently driving an accelerated expansion of the universe, is a slowly rolling scalar field or quintessence. A scalar field, however, must couple with other sources of matter. Consequently, its dynamical evolution can result in extra interactions between standard particles, which are mediated by the field, and to a variation in the fundamental parameters. Curiously, it has been reported that observations of a number of quasar absorption lines suggest that the fine structure constant was smaller in the past, at redshifts in the range z=1-3 (Murphy et al. (2003), Murphy et al. (2004), but see also Srianand et al. (2007)). Could this indeed be the signature of a slowly evolving scalar field?
SNIa, white dwarfs and the variation of the gravitational constant
Authors: Isern J. , Garcia–Berro E. , Lorén–Aguilar P.
Published: October 2010

The critical role that the gravitational constant, G, plays in the Theory of General Relativity and the possibility, introduced by theories that unify gravity with other interactions, that G could vary in time and space have bursted the interest in detecting such variations or, at least, to bound them as tightly as possible.

White dwarfs represent the last evolutionary stage of stars with masses smaller than 10 ± 2 M⊙. Since their mechanical structure is sustained by the pressure of degenerate electrons, they do not radiate nuclear energy and their evolution is just a simple gravothermal cooling process. On the other hand, white dwarfs in close binary systems can accrete matter from the companion, experiencing nova outbursts, or in some cases they can also reach Chandrasekhar's mass and explode as a Type Ia supernova (SNIa). Since the cooling of single white dwarfs and the properties of SNIa strongly depend on the precise value of G and on its possible secular variation, white dwarfs can be used to constrain such hypothetical variations.

When white dwarfs are cool enough, their luminosity is entirely of gravothermal origin. Any variation of G modifies the energy balance of their interiors and, consequently, also modifies their luminosity. Formally, the influence of a secular variation of G can be expressed as L=-Ḃ+Ω(Ġ/G) where B=U+Ω is the total binding energy, U is the total internal energy and Ω is the gravitational energy. Thus, if Ġ ≠ 0 the luminosity is modified and the characteristic cooling time is different from that obtained in the case in which Ġ = 0. Detecting such variations can be done using the luminosity function of white dwarfs, which is defined as the number of white dwarfs of a given luminosity per unit of magnitude interval. It increases monotonically with the magnitude and displays a sharp cut-off due to the finite age of the Galaxy. The position of this cut-off is sensitive to the age of the Galaxy and to the value of Ġ and, thus, it can be used to obtain a bound. White dwarfs also display g-mode pulsations driven by the κ-mechanism and the period of pulsation experiences a secular drift of Ṗ/P ≃ -aṪ/T + bṘ/R, where a and b are model-dependent constants of the order of unity. Since both Ṫ and Ṙ depend on Ġ, the measure of Ṗ can also provide useful constraints.

Type Ia supernovae are thought to be the result of the thermonuclear explosion of a carbon-oxygen white dwarf with a mass near Chandrasekhar's limit in a close binary system. The peak luminosity of SNIa is proportional to the mass of nickel synthesized which can be considered as a fixed fraction of the mass of the exploding star, MNi ∝ MCh = (ħc)3/2/mpG3/2. Therefore the properties of this peak with redshift can be used to test the variation of G with cosmic ages.

Although the bounds obtained in these ways have been currently superseeded by other more accurate methods, when the ongoing surveys searching for SNIa and white dwarfs will be completed, the expected bounds will be as tight as ~ 10−13 yr−1.
21 cm radiation: A new probe of fundamental physics
Authors: Khatri Rishi , Wandelt Benjamin D.
Published: October 2010

New low frequency radio telescopes currently being built open up the possibility of observing the 21 cm radiation from redshifts 200 > z > 30, also known as the dark ages, see Furlanetto, Oh, & Briggs(2006) for a review. At these high redshifts, Cosmic Microwave Background (CMB) radiation is absorbed by neutral hydrogen at its 21 cm hyperfine transition. This redshifted 21 cm signal thus carries information about the state of the early Universe and can be used to test fundamental physics. The 21 cm radiation probes a volume of the early Universe on kpc scales in contrast with CMB which probes a surface (of some finite thickness) on Mpc scales. Thus there is many orders of more information available, in principle, from the 21 cm observations of dark ages. We have studied the constraints these observations can put on the variation of fundamental constants (Khatri & Wandelt(2007)). Since the 21 cm signal depends on atomic physics it is very sensitive to the variations in the fine structure constant and can place constraints comparable to or better than the other astrophysical experiments (Δα/α= < 10−5) as shown in Figure 1. Making such observations will require radio telescopes of collecting area 10 - 106 km2 compared to ~ 1 km2 of current telescopes, for example LOFAR. We should also expect similar sensitivity to the electron to proton mass ratio. One of the challenges in observing this 21 cm cosmological signal is the presence of the synchrotron foregrounds which is many orders of magnitude larger than the cosmological signal but the two can be separated because of their different statistical nature (Zaldarriaga, Furlanetto, & Hernquist(2004)). Terrestrial EM interference from radio/TV etc. and Earth&s ionosphere poses problems for telescopes on ground which may be solved by going to the Moon and there are proposals for doing so, one of which is the Dark Ages Lunar Interferometer (DALI). In conclusion 21 cm cosmology promises a large wealth of data and provides the only way to observe the redshift range between recombination and reionization.
Constraining a possible time-variation of the gravitational constant through “gravitochemical heating” of neutron stars
Authors: Reisenegger Andreas , Jofré Paula , Fernández Rodrigo
Published: October 2010

A hypothetical time-variation of the gravitational constant G would produce gravitochemical heating of old (≳ 107−8 yr) neutron stars. It could produce detectable thermal ultraviolet emission from such stars for changes as small as |Ġ/G|~ 10−12 yr−1, comparable to the best existing upper limits from other methods.
Markov Chain Monte Carlo methods applied to measuring the fine structure constant from quasar spectroscopy
Authors: King Julian , Mortlock Daniel , Webb John , Murphy Michael
Published: October 2010

Recent attempts to constrain cosmological variation in the fine structure constant, α, using quasar absorption lines have yielded two statistical samples which initially appear to be inconsistent. One of these samples was subsequently demonstrated to not pass consistency tests; it appears that the optimisation algorithm used to fit the model to the spectra failed. Nevertheless, the results of the other hinge on the robustness of the spectral fitting program VPFIT, which has been tested through simulation but not through direct exploration of the likelihood function. We present the application of Markov Chain Monte Carlo (MCMC) methods to this problem, and demonstrate that VPFIT produces similar values and uncertainties for Δα/α, the fractional change in the fine structure constant, as our MCMC algorithm, and thus that VPFIT is reliable.
Observational Determinations of the Proton to Electron Mass Ratio in the Early Universe
Authors: Thompson Rodger I.
Published: October 2010

The values of the fundamental physical constants determine the nature of our universe from the height of mountains on earth to the evolution of the universe over its history. One of these constants is μ = MP/Me the ratio of the proton to electron mass. Astronomical observations provide a determination of this ratio in the early universe through observations of molecular absorption and emission lines in distant objects. Observations of molecular hydrogen in distant damped Lyman Alpha clouds provide a measurement of μ at a time when the universe was only 20% of its present age. To date there is no evidence for a change in μ at the level of 1 part in 105. This limit produces an observational constraint on quintessence theories for the evolution of the universe and Super Symmetric theories of elementary particles.
Probing fundamental constant evolution with redshifted radio lines
Authors: Kanekar Nissim
Published: October 2010

I report new results from radio studies of fundamental constant evolution, using comparisons between (1) conjugate satellite OH lines, and (2) inversion and rotational lines.
Sensitivity of microwave and FIR spectra to variation of fundamental constants
Authors: Kozlov M. G. , Lapinov A. V. , Levshakov S. A.
Published: October 2010

Microwave and far infrared (FIR) spectra of atoms and molecules are in general more sensitive to the variation of the fundamental constants than optical spectra. For example, FIR transitions between levels of the ground state multiplet 3PJ of Carbon-like ions are sensitive to α-variation, (Levshakov et al. (2008)). Moreover, sensitivities of the transitions (1-0) and (2-1) are different, (Kozlov et al. (2008)). This allows to study α-variation by comparing apparent redshifts for these two transitions of the same ion and significantly reduce systematic errors from the Doppler noise.