Day 524

Tuesday.

1310.0828
Dark Matter constraints from observations of 25 Milky Way satellite galaxies with the Fermi Large area telescope
The Fermi-LAT collaboration

dSphs are the most DM-dominated objects known; considered to be promising targets for indirect detection of DM via gamma rays (proximity, high DM content, lack of astrophysical BG).  Report on gamma-ray observations of 25 MW dwarf spheroidal satellite galaxies based on 4 years of Fermi LAT data.  None of the dwarf galaxies are significantly detected in gamma rays, and present gamma-ray flux upper limits between 500 MeV and 500 GeV.  Determine the DM content of 18 dSphs from stellar kinematic data, and combine LAT observations of 15 dwarf galaxies to constrain the DM annihilation cross section.  Set some of the tightest constraints to date on the annihilation of DM particles with masses between 2 GeV and 10 TeV into prototypical Standard Model channels.  Find these results to be robust against systematic uncertainties in the LAT instrument performance, diffuse gamma-ray BG modeling, and assumed DM density profile.

1310.1396
Characterizing diffused stellar light in simulated galaxy clusters
Cui, Monaco, Borgani, ... et al

An analysis of the performance of two different methods to identify the diffuse stellar light in cosmological hydrodynamical simulations of galaxy clusters.  First method: based on dynamical analysis of the stellar component [DSC?].  Second method: closer to techniques commonly employed in observational studies [surface brightness limit, SBL].  Both the dynamical method and the method based on the surface brightness limit criterion are applied  to the same set of hydro sims for a large sample about 80 galaxy clusters.  Find significant differences between the ICL and DSC [?] fractions computed with the two corresponding methods, which amounts to about a factor of two for the AGN simulations, and a factor of four for the CSF [?] set.  Also find that the inclusion of AGN feedback boosts the DSC and ICL fractions by 1.5-2x, respectively, while leaving the BCG+ICL and BCG+DSC mass fraction almost unchanged.  The sum of the BCG and DSC mass stellar mass fraction is found to decrease from ~80% in galaxy groups to ~60 % in rich clusters, thus in excess of what found from observational analysis.  Identify the average surface brightness limits that yields the ICL fraction from the SBL method close to the DSC fraction from the dynamical method.  These surface brightness limits turn out to be brighter in the CSF [??] than in the AGN simulations.  This is consistent with the finding the AGN feedback makes BCGs to be less massive and with shallower density profiles tan in the CSF simulations.  The BCG stellar component, as identified by both methods, are slightly older and more metal-rich than the stars in the diffuse component.

1310.1398
Reversal or no reversal: the evolution of the star formation rate-density relation up to z~1.6?
Ziparo et al

SFR in ECDFS and GOODS to z~1.6; use "traditional" and "dynamical" approach, where galaxies are classified by local density and environmental regimes (group, "filament", field), respectively.  Both methods show no evidence of a SFR-density reversal [SFR peaks at around z~2?].  Moreover, group galaxies show a mean SFR lower than other environments up to z~1, while at earlier epochs group and field galaxies exhibit consistent levels of SF activity.  Find that processes related to a massive DM halo must be dominant in the suppression of the SF below z~1, with respect to purely density-related processes.  Confirm this finding by studying the distribution of galaxies in different environments with respect to purely density-related processes.  Confirm this finding by studying the distribution of galaxies in different environments with respect to the so-called MS (main sequence) of SF galaxies.  Galaxies in both group and "filament" environments preferentially lie below the MS up to z~1, with group galaxies exhibiting lower levels of SF activity at a given mass.  At z>1, the SF galaxies in groups reside on the MS.  Groups exhibit the highest fraction of quiescent galaxies up to z~1, after which group, filament, and field environments have a similar mix of galaxy types.  Conclude that groups are the most efficient locus for SF quenching.  Thus, a fundamental difference exists between bound and unbound objects, or between DM haloes of different masses.

1310.1476
The nature of the ISM in galaxies during the star-formation activity peak of the Universe
Popping, et al

Use SAM (tracks atomic and molecular phases of cold gas) with 3d radiative transfer and line tracing code to study the sub-mm emission from several atomic and molecular species (CO, HCN, C, C+, [OI]) in galaxies.  Aim to understand the physics that drives the formation of stars at the epoch of peak SF in the universe; find that normal SF galaxies at high z have much higher CO excitation peaks than their local counterparts, higher HCN/CO ratios and that CO cooling predominantly takes place through molecules with higher excitation levels.  Find an increase in the ratio between [OI] and [CII] in typical SF galaxies at z=1.2 and 2.0 wrt counterparts at z=0.  All the model results suggest that typical SF galaxies at high z consist of different ISM conditions.  Galaxies belonging to the tail of the SF activity peak of the universe (z=1.2) are already less dense and cooler than counterparts during the actual peak of SF activity (z=2.0).  Use results to discuss how future ALMA surveys can best confront predictions and constrain models of galaxy formation.

1310.1554
The Polarized Radiation Imaging and Spectroscopy Mission
Many from Europe

PRISM proposed to ESA as a large-class mission for investigating within the framework of ESA cosmic vision program a set of important scientific questions that require high-res, high sensitivity, full-sky observations of the sky emission at wavelengths from mm to FIR.  PRISM's main objective is to explore the distant universe, probing cosmic history from very early times until now, as well as the structures, distribution of matter, and velocity flows throughout the Hubble volume.  PRISM will survey the full sky in a large number of frequency bands in both intensity and polarization and will measure the absolute spectrum of sky emission more than three orders of magnitude better than COBE FIRAS.  

1310.1559
Multi-wavelenth study of 14000 star-forming galaxies from the Sloan Digital sky survey
Izotov et al

Large sample of 14000 dwarf SF galaxies with strong emission lines from SDSS; distributed in over 0<z<0.6.  Modeled SED of all galaxies based on SDSS spectra in the visible (0.38-0.92 micron) and included both the stellar and ionised gas emission.  These SEDs were extrapolated to the UV and MIR to cover 0.1-22 micron; supplemented by photometric data from the GALEX, SDSS, 2MASS, WISE, IRAS and NVSS all-sky surveys.  Derived global characteristics of the galaxies, such as their element abundances, luminosities, and stellar masses.  THe luminosities and stellar masses range within the sample over ~5 orders of magnitude, thereby linking low-mass and low-luminosity BCD (blue compact dwarf) galaxies to luminous galaxies, which are similar to high-z LBGs.  The luminosity L(Hbeta), a characteristic of the youngest stellar population with an age of a few Myr, is correlated with luminosities in other wavelength ranges.  This implies that the most recent burst of SF makes a significant contribution to the emission in the visible range and dominates in other wavelength ranges.  Found 20 galaxies with very red WISE MIR color (3.4-4.6 um) color (>2 mag), which suggests the important contribution of the hot (with a temperature of several hundred degree) dust emission in these galaxies.  Analysis of the balance between the luminosity in the WISE bounds that covered a wavelength range of 3.4-22 um and the luminosity of the emission absorbed at shorter wavelengths showed that the luminosity of the hot dust emission is increased with increasing L(Hbeta) and EW(Hbeta).

1310.1422
Degree-scale CMB polarization measurements from three years of BICEP1 data
BICEP1 collaboration

EE spectrum (21<=l<=335) consistent with LDCM, BB spectrum consistent with zero.  From B-modes only, constrain the tensor-to-scalar ratio to r=0.03pm0.25, or r<0.70 at 95% CL.

1310.1665
Greenland telescope (GLT) project: "A direct confirmation of black hole with submillimeter VLBI"
Nakamura, et al

Primary goal: image a shadow of the SMBH of 6e9 Msun in M87 at the center of Virgo cluster.  The expected SMBH shadow size of 40-50 micro-arcsec requires superbly high angular resolution, suggesting that the submm VLBI would be the only way to obtain the shadow image.  Expected first light on 2015-2016.

1310.1731
On the cross-section of dark matter using substructure infall into galaxy clusters
Harvey, Tittley, Massey, Kitching, Taylor, Pike, Kay, Lau, Nagai

Develop a statistical method to measure the interaction cross-section of DM, exploiting the continuous minor merger events in which small substructures fall into galaxy clusters.  Take ratio of the distances between the galaxies and DM, and galaxies and gas in accreting sub-haloes, find that it is possible to calibrate and measure the DM self-interaction cross-setion, remove any inherent LoS projects.  In order to interpret this ratio as a cross-section of DM, derive an analytical description of sub-halo infall which encompasses: the force of the main cluster potential, the drag on a gas sub-halo, a model for DM self-interactions and the resulting sub-halo drag, the force on the gas and galaxies due to the DM sub-halo potential, and the buoyancy on the gas and DM.  Create mock observations from cosmo sims of structure formation and find that collisionless DM becomes physically separated from X-ray gas by up to 20 kpc/h.  Adding realistic levels of noise, able to predict achievable constraints from observational data.  Current archival data should be able to detect a difference in the dynamical behavior of DM and standard model particles at 6 sigma, and measure the total interaction cross-section sigma/m with 68% CL of pm 1cm^2/g.  Better by 2x of Bullet Cluster.  Not restricted by the number of major merging events and is easily extended to large samples of clusters from future surveys which could potentially push statistical errors to 0.1 cm^2/g.

1310.1107
Recent progress in cosmology and particle astrophysics
Chen

As the title says.