Tuesday. Busy week already.
Monday. Got Euclid testing done last week, but no reading. It's September now, I'm coming back to business.
1208.6304
Hot disks and delayed bar formation
Sheth, et al
Find bars are preferentially found in galaxies that are massive and dynamically cold (rotation-dominated), and on the stellar Tully-Fisher relationship, for 257 galaxies between 0.1<z<0.84 (same as local barred spiral galaxies). Explains steep decline in overall bar fraction from z=0 to z=0.84 in L* and brighter disks seen in previous studies. Decline in the bar fraction at high z is almost exclusively in the lower mass (log(M*/Msun)=10-11), later type and bluer galaxies: "downsizing" of the bar formation/stellar structure formation. Reason: lower mass galaxies may not form bars because they could be dynamically hotter than more massive systems from increased turbulence of accreting gas, elevated star formation, and/or increased interaction/merger rates at higher z. But data also show that not every disk galaxy that is massive and cold has a stellar bar, suggesting that mass and dynamic coldness of a disk are necessary but not sufficient conditions for bar formation. Interaction history between DM halo and baryonic matter may play a role in bar formation too.
1208.6311
Lithium generated by cosmic rays: an estimator of the time that Mars had a thicker atmosphere and liquid water
Durand-Manterola
With proton CRs bombarding carbon and oxygen atmosphere, nuclear fission generates Lithium. At >2atm of pure CO2 atmosphere in Mars, calculate Li of 162-642 million metric tons (Earth lithium estimated reserves are 30 million metric tons). Amount of Li serves to estimate the time that mars had a thick atmosphere.
1208.6334
"Invisible AGN" I: Sample Selection and optical/near-IR spectral energy distributions
Yan, et al
Purpose: to find high-z molecular absorbers. Look for highly obscured, radio-loud "invisible AGN" using the VLA faint images of the Radio Sky at Twenty centimeters (FIRST) radio survey in conjunction with SDSS, identify 82 strong radio sources coincident with late-type, gas-rich galaxies. This paper describes the selection process. Among 70 sources, 33 show galaxy-type SEDs, 17 have galaxy components to their SEDs, and 20 have quasar power-law continua. At least 9 with galaxy SEDs have K-band flux densities too faint to be giant ellipticals. Photo-z too inaccurate for an efficient radio-frequency absorption line search; spec-z required. Subsequent papers describe radio continuum properties of the sample.
1208.6419
Age and mass studies for young star clusters in M31 from SEDs-fit
Wang et al
Photometry for young star clusters in M31, 15 intermediate-band filters covering 3000-10000A. Derive star clusters' ages and masses from SEDs and SPS models. Results in good agreement with past studies. Data suggest a recent passage of a satellite galaxy (M32) through the M31 disk.
1208.6512
A unified empirical model for infrared galaxy counts based on observed physical evolution of distant galaxies
Bethermin et al
Reproduce MIR to radio galaxy counts with an empirical model based on evolution of MS and SB galaxies. Rely on SED library based on Herschel observations. Able to reproduce galaxy counts from Herschel, including counts per z slice. The agreement demonstrates the power of 2 SF modes (2SFM) contribution of MS and SB galaxies to the number counts at various wavelengths and flux densities. MS galaxies responsible for a bump in the 1.4 Radio counts at 50 micro-Jy.
1208.6522
Gamma ray bursts
Gehrels, Meszaros
GRB review.
1208.6547
Cosmological Ohm's law and dynamics of non-minimal electromagnetism
Hollenstein Jain Urban
Origin of large-scale B-field in cosmic structures and IGM is poorly understood. The effects of non-minimal couplings of EM on the cosmo evolution of currents and B-fields explored. NL plasma dynamics around recombination that generate weak B-fields revisited. Full equation for plasma currents and derive generalized Ohm's law valid on large scales, as well as with non-minimal couplings. Conclude that modifications of the standard (adiabatic) evolution of B-fields are severely limited.
1208.5054
The luminosity of supernovae of type Ia from TRGB distances and the value of H_0
Tammann, Reindl
Distances from the tip of the red-giant branch (TRGB) in the halo population of galaxies (calibrated through RR Lyr stars, and tied to Hipparcos paralaxes) used to determine luminosity of six nearby SNIa. The correction is M_V^corr = -19.41; the large-scale Hubble constant follows H_0 = 64 pm 3 km/s/Mpc from SNIa; SN HST project gave H+0 = 62.3 pm 6. Results can be reconciled with WMAP5 data (Reid+ 2010).
1208.5356
Dark matter and fundamental physics with the Cherenkov Telescope Array
Doro et al
CTA: project for next-generation observatory for very high energy (GeV-TeV) ground-based gamma-ray astronomy, currently in design. 10x better sensitivity than HESS, MAGIC and VERITAS; energy coverage of few tens of GeV to several tens of TeV; FoV of up to 10 deg. Cold DM searches with dwarf galaxies of MW; galactic center; clusters of galaxies.
1208.5482
Hunting for dark halo substructure using submilliarcsecond-scale observations of macrolensed radio jets
Zackrisson, et al
Dark halo substructure observed thorugh small-scale gravitational lensing effects; use multiply-imaged quasar jets, probe 1e3-1e8 Msun mass range substructures. By mapping ~5 strongly lensed systems, possible to detect or robustly rule out primordial BHs in this mass range if they constitute >1% of the DM in these lenses. Ultracompact minihalos are hardter to detect using this tecnique, but 1e6-1e8 Msun could in principle be detected if they constitute >10% of the DM.
1208.5598
COSMOGRAIL XI: Techniques for time delay measurement in presence of microlensing
Tewes, Courbin, Meylan
Requires long and well sampled optical light curves of the numerous lensed quasars (e.g., as in COSMOGRAIL). Need novel numerical techniques to measure the delays, even in the presence of microlensing variations. Propose 3 different point estimators to measure time delays, explicitly designed to handle light curves with extrinsic variability. The different methods must be sensitive to different bias sources; test self-consistency of the approach.
1208.5682
Domain of validity for pseudo-elliptical NFW lens models
Damet-Montoya, Caminha, Makler
Elliptical potentials used in GL, but generally lead to nonphysical mass distributions in some regions. Revisit physical limitations of the pseudo-elliptical NFW (PNFW) model, for a broad range of the potential ellipticity parameter epsilon and characteristic convergence kappa_s focusing on the behavior of the mass distribution close to the tangential critical curve. Look at shape of the mass distribution in the region. Check out which regions are valid.
1208.5712
Stellar mass map and dark matter distribution in M31
Tamm et al
Use optical and IR imaging to obtain stellar mass map; combine stellar mass model with kinematical data, and constrain the properties of DM halo of the galaxy. SED sampled at each imaging pixel; dust extinction taken into account with FIR. Fit SPS models, provide stellar surface mass density. Model 3d with bulge, nucleus, disk, young disc, and halo, each following Einasto profile. Compare stellar mass distribution to the observed rotation curve and kinematics of outer globular clusters, the DM halo parameters estimated. SPS suggest M31 domianted by old stars throughout the galaxy. Total stellar mass is 1-1.5e11 Msun. 30% in bulge, 56% in disc. No DM distribution models can be falsified on the basis of stellar matter distribution and the rotation curve of the galaxy. Virial mass of the DM halo is 0.8-1.1e12 Msun, and virial radius is ~200 kpc. Central density of DM halo comparable to that of nearby dwarf galaxies, low-surface-birghtness galaxies and distant massive disc galgaxies, thus the evolution of central DM halo properties seems to be regulated by similar processes for a broad range of halo masses, environments and cosmological epochs.
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