1207.1432
Fermi-LAT Observations and a broadband study of Supernova remnant CTB 109
Castro, SLane, Ellison, Patnaude
A Galactic SNR model: hydrodynamics, CR acceleration, non-thermal emission, and self-consistent X-ray thermal emission; study broadband characteristics of the remnant. Two models fit well: (i) gamma-ray emission produced primarily by lepton accelerated at SNR forward shock, (ii) gamma-rays produced by forward shock accelerated CR ions dominate the high-energy emission.
1207.1436
The X-ray light curve of Sgr A* over the past 150 years inferred from Fe-Ka line reverberation in Galactic Centre molecular clouds
Capelli et al
The inferred Sgr A* lightcurve over the past 150 years show a long-term downwards trend punctuated by occasional brightening episodes of at least 5 years duration.
1207.1439
An improved model for the nonlinear velocity power spectrum
Jennings
Velocity divergence power spectrum is a key ingredient in modeling redshift space distortion effects on quasi-linear and nonlinear scales. Improve model for z=0 velocity divergence auto and cross power spectrum. Using numerical simulations and tessellation; obtain accurate prediction of velocity divergence power spectra on scales k< 1h/Mpc, now accurate to 2%. Velocity field shows larger differences between modified gravity cosmologies and LCDM, compared to matter field.
1207.1448
The snapshot Hubble U-band cluster survey; a cluster complex in NGC 2146
Adamo, Smith
SHUCS: U-band imaging survey of nearby SF galaxies, constrain reliable ages, masses, and extinctions of the cluster populations of these galaxies. Found ring-like cluster complex (tidal streams), dubbed Ruby Ring. A clear ring-like distribution of star clusters around a central object, a product of an intense and localized burst of SF. A case of triggered SF.
1206.1465
MPTbreeze: a fast renormalized perturbative scheme
Crocce, Scoccimarro, Bernardeau
Calculate NL matter power spectra with multi-point propagators (MPs). On large scales, these propagators reduce to the well-known kernels in standard perturbation theory, while at smaller scales, they are suppressed due to NL couplings. Test with numerical simulations; this decay is characterized by the same damping scale for both 2- and 3-pt propagators. The transition can be well modeled with resummation results that exponentiate one-loop computations. Measure the 4 components of the NL (2-pt) propagator using dedicated sims from 2 independent Gaussian fields for positions and velocities, verify the fundamentals of propagator resummation. use these results to develop MP-expansion for NL power spectrum that only requires seconds to evaluate at BAO scales. Construct 6 suites of large sims with different cosmologies. The NL power spectrum can be described at the ~2% level at BAO scales for redshifts in the range 0-2.5. Public release of the MPTbreeze code.
1207.1492
Interacting dark matter and modified holographic Ricci dark energy plus a noninteracting cosmic component
Chimento, Richarte
Constrain cosmo parameters and analyze the amount of DE in the radiation era for both MHRDE and holografic Ricci DE models. Former consistent with the bount Omega_x(z~1100)<0.1 reported for the behavior of DE at early times, while the latter does not fulfill it.
1207.1503
Energy conditions bounds on f(T) gravity
Liu, Reboucas
In GR, energy conditions important in understanding several properties of the Universe, including: singularity theorems, accelerating expansion phase, possible phantom fields. If f(T) gravity is true, then some issues need to be reexamined in the framework of f(T) theories. Current investigation on the limits and potentialities of f(T) gravity theories. The null and strong energy conditons in the framework of f(T) gravity derived from first principles. In the limit f(T) = T, the standard GR are recovered.
1207.1515
Constraints on the faint end of the quasar luminosity function at z~5 in the COSMOS field
Ikeda, Nagao, ... Capak, .. Koekemoer, ... Scoville et al
Constraint the faint end of the quasar luminosity function at z~5, 14/15 candidates got spectra, one low-luminosity type-2 quasar at z~5.07 found, but no type-1s found (set upper limits). Result consistent with so-called downsizing evolution of quasars seen at lower redshifts.
1207.1528
VAST: an ASKAP survey for variables and low transients
Murphy et al
* scintillation:
- astronomical scintillation = "twinkling"
- scintillation in physics, "a flash of light produced in certain materials when they absorb ionizing radiation."
- Interplanetary scintillation = "fluctuations of radio waves caused by the solar wind."
Australian Square Kilometre Array Pathfinder (ASKAP): opportunity to investigate the transient sky at radio wavelengths. Flare stars, intermittent pulsars, X-ray binaries, magnetars, extreme scattering events [?], interstellar scintillation, radio supernovae and orphan afterglows of GRBs.
1207.1530
Cl 1103.7-1245 at z=0.96: the highest redshift galaxy cluster in the EDisCS survey
Vulcani, ... von der Linden, .. Zaritsky, et al
Spectro observations in a field containing highest-z cluster of EDisCS. Measure galaxy redshifts and determine the velocity dispersions of the galaxy structures located in this field. Two clusters found at z=0.9580 and z=0.9830, with very different galaxy populations. The first has a mixture of passive elliptical galaxies and SF spirals and irregulars. In the second one, all galaxies are lower-mass SF irregulars are pecliars. Compare other low-z clusters with similar dispersions (522 pm 111 km/s), find: the first follow the evolutionary trends found at lower redshifts (number of galaxies increase as the expected mass increase of clusters, and the fraction of passive early-type galaxies increases with time while SF late types become less dominant. Mean stellar masses are similar in all clusters; suggests that massive cluster galaxies were already present at z~1.
1207.1544
Models for the lithium abundances of multiple populations in globular clusters and the possible role of the big bang lithium
D'Antona, D'Ercole, Carini, Vesperini, Ventura
Li abundance in unprocessed gas affects the Li chemical patterns among cluster stars. Scenario in which processed gas from AGB (which is Li rich) mixes with unprocessed, pristine gas to create the 2nd generation stars. Once a chemical model is well constrained, the O-Li distribution could perhaps be used to shed light on the primordial Li abundance.
1207.1560
Quasi-star jets as unidentified gamma-ray sources
Czerny Janiuk, Sikora, Lasota
Many unidentified gamma-ray sources, many out of Galactic plane (probably extragalactic in origin). Assume that formation of SMBH in galactic nuclei proceeds through a quasi-star stage, consider the possibility of jet production by such objects. Those jets would be the sources of collimated synchrotron and Compton emission, extending from radio to gamma rays. Expected lifetimes of quasi-stars are of the order of million of years, while the jet luminosities (somewhat smaller than quasar jets) are sufficient to account for the unidentified gamma-ray sources. Jet emission dominates over the thermal emission of quasi-star in all energy bands when jet is pointed towards an observer [unobservable otherwise?]. Synchrotron predicted to peak in the IR band, close to the limits of IR all-sky surveys. Gamma-ray to IR flux is very large (~60), much larger than Bl Lac objects, but similar to some radio-loud quasars (but radio-loud quasars show broad emission lines, which are not expected from quasi-stars). So should be able to check an IR counter part, with spectroscopy.
1207.1566
A study of the environments of large radio galaxies using SDSS
Pirya, Saikia, Singh, Chandola
Distribution of galaxies in 16 large radio source environments studied using SDSS. Although most large sources occur in regions of low galaxy density, the shorter arm is brighter in most cases, suggesting asymmetries in the IGM which may not be apparent in the distribution of galaxies.
1207.1569
The stellar scintillation on large and extremely large telescopes
Kornilov
Accuracy of ground-based photometry limited by: (i) photon statistics and (ii) stellar scintillation arising when star light passes through Earth's atmosphere. Examine theoretical role of the outer scale L_0 of the optical turbulence (OT) which suppresses the low-frequency component of the scintillation. For typical values of L_0~25-30m, effect becomes noticeable for telescopes of diameter around 4m. On extremely large (30-40m) telescopes with exposures longer than a few seconds, the inclusion of the outer scale in the calculation reduces the scintillation power by more than a factor of 10 relative to conventional estimates. Details discussed for non-Kolmogorov turbulence models. Quantitative description of the influence of the telescope central obscuration on the measured scintillation noise introduced and combined with the effect of the outer scale. Evaluation of the scintillation noise on the future TMT and E-ELT predicts an amplitude of approximately 10 umag for 60s exposures.
1207.1573
Detections of diffuse interstellar bands in the SDSS Low-resolution spectra
Yuan, Liu
* diffuse interstellar bands (DIBs): absorption features seen in local MW object spectra, caused by absorption of light by the interstellar medium. Their central wavelengths do not correspond with any known spectral lines of any ion or molecule. Determining the nature of the absorbing material ('carrier') is a crucial problem in astrophysics. Strengths of most DIBs are not correlated with each other == there must be many carriers. Strength of DIBs broadly correlated with extinction (caused by dust in ISM) == likely due to dust or related. Existence of substructures in DIBs == caused by molecules. Carrier most likely large carbon-bearing molecules.
Carries of DIBs are ubiquitous in the diffuse ISM. DIB fieatures also been detected in LAMOST. Made huge database.
1207.1588
Testing for a large local void by investigating the near-infrared galaxy luminosity function
Kenan, Barger, Cowie, Wang, Wold, Trouille
Local underdensity on scales of few hundred Mpc (out to z~0.1) could produce apparent acceleration seen in SNIa measurements. Some galaxy count studies in NIR found local universe apears to be under-dense by ~25-50 compared with regions a few hundred Mpc distant. If local universe is under-dense, the normalization of the NIR galaxy LF at z>0.1 should be higher than z<0.1. Present a highly complete (>90%) spectroscopic sample of 1436 galaxies to study the normalization at 0.1<z<0.3, and address the question of whether or not we reside in a large local underdensity. Find: in the 6 fields, phi*L* is ~30 higher at 0.1<z<0.3 than z=0 (although statistical errors on the ~10 level, with higher cosmic variance systematics). Observations cannot yet rule out the possibility that the local universe is under-dense at z<0.1.
1207.1616
The flux calibration of Gaia
Pancino
Although Gaia is described as a self-calibrated mission, it still needs to tie part of its measurements to external scales. The model requires a grid of ~200 stars, calibrated to a few percenet wrt Vega, and covering different spectral types.
1207.1621
Statistical interpretation of the spatial distribution of current 130 GeV gamma-ray line signal within the dark matter annihilation scenario
Yang, Yuan, Feng, Fan, Chang
Morphology study show gamma-ray signal consistent with DM annihilation, but with an offset ~220 pc (1.5 deg) of the center from Sgr A*. 130 GeV signal consists of ~14 photons. Need more signal.
1207.1634
High zenith angle observations of PKS 2155-304 with the MAGIC-I telescope
The MAGIC collaboration, et al
VHE, E>100 GeV, gamma-rays detected from z=0.116, about 20% of Carb Nebula flux, detected by HESS with high S/N; HESS VHE gamma-ray emission variable on scales of minutes and mean of 7x Crab Nebula. Flare has similar spectral index as another flare; nigh-by-night variability of maximal amplidue of x3 to x4, an intranight variability similar to another.
1207.1647
Physical properties underlying observed kinematics of satellite galaxies
Wojtak, Mamon
Kinematics of satellite around isolated galaxies from SDSS spectra catalog. Determine properties of halo mass distribution and the orbital anisotropy of the satellites as a function of the colour-based morphological type and the stellar mass of the central. Place constraints on halo mass and the concentration parameter of DM and the satellite number density profiles. Obtain concentration mass relation for galactic DM halo consistent with predictions of a standard LCDM. Number density profile of satellites appears to be shallower than of DM, with scale radius typically 1.6 times larger than of DM. Orbital anisotropy around red hosts exhibits a mild excess of radial motions, in agreement with the typical anisotropy profiles found in cosmological simulations, whereas blue galaxies are found to be consistent with an isotropic velocity distribution. New constraints on the halo masses of galaxies are used to provide analytic approximations of the halo-to-stellar mass relation for red and blue galaxies.
1207.1654
A method for constraining cosmic magnetic field models using ultra-high energy cosmic rays: the field scan method
Sutherland, Baughman, Beatty
The Galactic B-field (few uG) sufficiently strong to induce deflections in the arrival directions of UHE CRs. Establishes measure of self-consistency for hypothesis sets comprised of cosmic B-field models and UHE CR composition and source distributions. The method uses two independent procedures to compare the backtracked velocity directions of many isotropic observations with the same primary energies. This allows for an estimate of the statistical consistence between the observed data and simulated isotropic observations. ...
1207.1664
Formalism for inclusion of measured reaction cross sections in stellar rates including uncertainties and its application to neutron capture in the s-process
Rauscher
As the title says. Asses maximally possible reduction of uncertainties in stellar rates by experiments. Revise stellar neutron capture reactivities from KADoNiS v0.3, show remaining uncertainties. Allows larger range of some reaction rates than previously assumed.
1207.1684
Tidal interaction vs. ram pressure stripping effects as seen in X-rays. Hot gas in group and cluster galaxies
Wezgoweic, Bomans, Ehle, Chyzy, Urbanik, Braine, Soida
Try to distinguish between tidal and ram pressure interactions, both of which show similar radio polarimetry observations, by spatial and spectral analysis of x-ray data. Look at gas temperatures and thus shock signatures (ram pressure resulting from supersonic velocities). Weak tidal interactions not expected to influence the temperature of ionized gas.
1207.1694
Model-independent constraints on the cosmic opacity
Holanda, Carvalho, Alcaniz
Use current measurements of the expansion rate H(z) and cosmic background radiation bounds on the spatial curvature of the Universe to impose cosmological model-independent constraints on cosmic opacity. Two light-curve fitters (SALT2 and MLCS2K2) present a significant conflict (MLCS2K2 incompatible with flat and transparent universe).
1207.1709
Analytical solutions to the mass-anisotropy degeneracy with higher order jeans analysis: a general method
Richardson, Fairbairn
* Jeans instability: collapse of interstellar gas clouds and subsequent star formation; occurs when the internal gas pressure is not strong enough to prevent gravitational collapse of a region filled with matter. In general, the cloud is unstable if it is very massive at a given temperature, or very cool at a given mass for gravity to overcome the gas pressure.
The Jeans analysis is often used to infer the total density of a system by relating the velocity moments of an observable tracer population to the underlying gravitational potential. Presence of DM inferred via stellar velocities; precise account of the density is needed to constrain the expected gamma ray flux from DM self-annihilation and to distinguish between cold and warm dark matter models. [I guess they're talking about Jeans mass collapse of DM? But DM doesn't have pressure. ??]
[Mon **/45] Jul 9
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