Day 497

Saturday, catching up.

1308.4979
Bounds on dark matter properties from radio observations of Ursa Major II using the Green Bank telescope
Natarajan, Peterson, Voytek, Spekkens, Mason, Aguirre, Willman

Radio observations of Ursa Major II dSph galaxy are used to place bounds on WIMP DM properties.  DM annihilation releases energy in the form of charged particles [always?] which emit synchrotron radiation in the B-field of the dwarf galaxy.  Compute the expected synchrotron radiation intensity from WIMP annihilation to various primary channels.  The predicted synchrotron radiation is sensitive to the distribution of DM in the halo, the diffusion coefficient D_0, the B-field strength B, the particle mass m_chi, the annihilation rate <sigma_v>, and the annihilation channel.  Limits on <sigma_v>, m_chi, B and D_0 are obtained fro the e+, e-, mu+, mu-, tau+, tau- and b bar{b} channels.  For the best fit halo parameters derived from stellar kinematics, exclude 10 GeV WIMPs annihilating directly to e+e- at the thermal rate <sigma v>=2.18e-26 cm^3/s at the 2 sigma level, for B>0.6 uGauss (1.6 uGauss) and D_0=0.1 (1.0) x the MW diffusion value.

1308.4982
The third gravitational lensing accuracy testing (GREAT3) challenge handbook
Mandelbaum, Rowe, Bosch, Chang, Courbin, Gill, Jarvis, Kannawadi, Kacprzak, Lackner, Leauthaud, Miyatake, Nakajima, Rhodes, Simet, Zuntz, Armstrong, Bridle, Coupon, Dietrich... et al

GREAT3: has goal of testing and facilitating the development of methods for analyzing astronomical images that will be used to measure weak gravitational lensing.  This measurement requires extremely precise estimation of very small galaxy shape distortions, in the presence of far larger intrinsic galaxy shapes and distortions due to the blurring kernel caused by the atmosphere, telescope optics, and instrumental effects.  The GREAT3 challenge is posted to the astronomy, machine learning, and statistic communities, and includes tests of 3 specific effects that are of immediate relevance to upcoming weak lensing surveys, two of which have never been tested in a community challenge before.  These effects include realistically complex galaxy models based on high-resolution imaging from space; spatially varying blurring kernel; and combination of multiple different exposures.  To facilitate entry by people new to the field, and for use as a diagnostic tool, the simulation software for the challenge is publicly available, though the exact parameters used for the challenge are blinded.  Sample scripts to analyze the challenge data using existing methods will also be provided.  See http://great3challenge.info and http://great3.projects.phys.ucl.ac.uk/leaderboard/ for more information.

1308.4989
THELI -- convenient reduction of optical, near- and mid-infrared imaging data
Schirmer

Surge of new multi-chip optical and NIR imagers cropped up in the past 15 years, but user-friendly and generic reduction tools are uncommon.  Introduce the numerous advantages of THELI, an end-to-end pipeline for the reduction of any optical, NIR and MIR imaging data.  Combining a multitude of processing algorithms and third party SW, THELI provides researchers with a single, homogeneous tool.  A steep learning curve ensures quick success for new and more experienced observers alike.  All tasks are largely automated, while at the same time a high level of flexibility and alternative reduction schemes ensure that widely different scientific requirements can be met.  Over 90 optical and IR instruments at observatories world-wide are pre-configured, while more can be added by the user.  The online Appendix contains 3 walk-through examples using public data (optical, NIR and MIR).  Additional extensive online documentation is available for training and troubleshooting.

1308.5109
Final model independent result of DAMA/LIBRA-phase1
Bernabei et al


Results from 1.04 ton-yr by DAMA/LIBRA-phase1 deep underground at Gran Sasso (LNGS) of the I.N.F.N. during 7 annual cycles (i.e. adding a further 0.17 ton-yr exposure) are presented.  The DAMA/LIBRA-phase1 data give evidence for the presence of DM particles in the galactic halo, on the basis of the exploited model independent DM annual modulation signature by using highly radio-pure NaI (Tl) target, at 7.5 sigma C.L..  Including also the first generation DAMA/NaI experiment (cumulative exposure 1.33 ton-yr, corresponding to 14 anjual cycles), the C.L. is 9.3 sigma and the modulation ampliltude of the single-hit events in the (2-6) keV energy interval is : (0.0112 pm 0.0012) cpd/kg/keV; the measured phase is (144 pm 7) days and the measured period is (0.998 pm 0.002) yr, values well in agreement with those expected for DM particles.  No systematic or side reaction able to mimic the explited DM signature has been found or suggested by anyone over more than a decade [wait---how about seasonal effects?].

1308.5224
A link between star formation quenching and inner stellar mass density in SDSS central galaxies
Fang, Faber, Koo, Dekel

Study the correlation between galaxy structure and the quenching of SF using a sample of SDSS central galaxies with stellar masses 9.75 < log M*/Msun < 11.25 and z<0.075.  GALEX UV data used to cleanly divide the sample in to SF and quenched galaxies, and to identify galaxies in transition (the green valley).  Despite a stark difference in visual appearance between blue and red galaxies, their average radial stellar mass density profiles are remarkably similar (especially in the outer regions) at fixed mass.  The inner stellar mass surface density within a radius of 1 kpc, Sigma_1, is used to quantify the growth of the bulge as galaxies evolve.  When galaxies are divided into narrow mass bins, their distribution in the color-Sigma_1 plane at fixed mass forms plausible evolutionary tracks.  Sigma_1 seems to grow as galaxies evolve through the blue cloud, and once it crosses a threshold value, galaxies are seen to quench at fixed Sigma_1.  The Sigma_1 threshold for quenching grows with stellar mass, Sigma_1 ~ M*^0.64.  However, the existence of some SF galaxies above the threshold Sigma_1 implies that a dense bulge is necessary but not sufficient to quench a galaxy fully.  This would be consistent with a 2-step quenching process in which gas within a galaxy is removed or stabilized against SF by bulge-driven processes (such as a starburst, AGN feedback, or morphological quenching), whereas external gas accretion is suppressed by separate halo-driven processes (such as halo gas shock heating).  Quenching thus depends on an interplay between the inner structure of a galaxy and its surrounding DM halo, and lack of perfect synchrony between the two could produce the observed scatter in color vs. Sigma_1.