Day 24

I think it's day 24.  It's Thursday, I read a lot yesterday.  I'll read more today.


LBL RPM
Testing strong-field classical and quantum electrodynamics with intense field lasers
Antonio Di Piazza


Areas of investigation of classical ED (CED) and QED.  Test extreme conditions with ultra-intense laser fields.  Landau-Lifshitz (LL) has not been tested yet: the fact that e.g., an e-, when radiating, changes its direction of travel ("radiation reaction").  Explore the regime in which radiation reaction is large, where quantum recoil and radiation reaction effects both dominate.  QED also predicts that EM fields can also interact with charged virtual particles.  


* I didn't understand the last part about using virtual particle, matterless double-slit scenario (the two laser beams) that are probed by a third laser beam to "generate interference patter entirely from light."  What's so special about light-only diffraction pattern?  We did it in high school.


LBL INPA
GRB 090429B: enlightening the dark ages of the universe
Antonio Chucchiara


GRB explosions releases energy x1000 that of SNe, and can be visible from z>10.  Key elements of GRB, and GRB as a factory of high-energy gamma rays; SF tracers, role as diagnostics for the chemical evolution of the interstellar and intergalactic medium.  
Recent discovery of GRB at z=9.4 (~500Myr after BB).  Future GRB science-driven missions.


* GRB: flashes of gamma rays associated with extremely energetic explosions, observed in distant galaxies, lasting 20-40 seconds.  Usually followed by a longer-lived afterglow.  Believed to consist of a narrow beam of intense radiation released during a SNe event ("long duration"), or a merger of binary neutron stars ("short duration").


1105.4876
Filamentary infall of cold gas and escape of lyman alpha and hydrogen ionizing radiation from an interacting high-redshift galaxy
Rauch et al.


* This is my second reading of the abstract.  I understand it better.


Interacting (dwarf) galaxies cause leaking of ionizing and Lya photos outside of the galaxy.  This may be a contributing factor to the reionization of the universe.


1105.5381
Evidence for cold accretion: discovery of primitive gas flowing onto a galaxy at z~0.274
Ribaudo, ...Prochaska, et al.


UV and optical observations from COS HST of a z~0.2 Lyman Limit system (LLS).  The LLS traces infalling gas, and the O VI arises due to its interaction with the galaxy halo.  Gas cannot trace an outflow due to its very low metallicity (???).  Ionization conditions of such accreting gas favor intermediate ions such as CIII and Si III as observational tracers of "cold" (1e4K) streams which are metal-poor and predominantly ionized.


1106.4312
An examination of possible gravitational perturbations in the transit timing variations of exoplanet WASP-3b
Littlefield


Claim of sinusoidal variation in the transit timing detected.  Signal might be the consequence of gravitational perturbations caused by a hypothetical second exoplanet in the WASP-3 system.  5 transit timing measurements made.


1106.4313
An improved forecast of patchy reionization reconstruction with CMB
Su, Yadav, McQuinn, Yoo, Zaldarriaga


Angular fluctuation in the CMB optical depth tau due to inhomogeneous reionization.  This can correlate different spherical harmonic modes, and imprint non-Gaussianity on CMB maps.  Recent derivation of minimum variance estimator found tau fluctuations can be detected with S/N of 10 in e.g., CMBPol.  Non-G signal from gravitational lensing of CMB is the dominant source of contamination, even after delensing of 98%.  Construct unbiased estimators the simultaneously reconstruct inhomogeneous reionization signals and gravitational lensing signals.  Apply new unbiased estimators to future CMB experiment, show that (S/N)^2 ~ O(1) to ~O(10).


1106.4410
One micron excess sources in the UKIDSS- I. Three T dwarfs in the SDSS southern equatorial stripe
Matsuoka, et al.


Discovery of two field brown dwarfs, and a rediscovery of another.  From 1um excess in UKIDSS.  Classification supported by optical to near IR colors as well.  One of the faintest T-dwarfs known.  Distances are 50-110pc, most distant T-dwarfs known.  Significant propermotions of 150-290 mas/yr, or 40-100 km/s transverse motion.  No detectable brightness variations.


1106.4526
A very high proper motion star and the first L dwarf in the Kepler field
Gizis, Troup, Burgasser


* OBAFGKM-LT(Y) is the Harvard spectral classification system for the stars.
* RNS are mixed in with the M giants.  Other classifications available.


Wide-field Infrared Survey Explorer (WISE) and 2MASS: report two nearby high proper motion dwarfs.  2.1"/yr and 0.48"/yr, estimated distance @ 17 pc.  Lie at low galactic latitudes.


1107.4984
Radiative events as a probe of dark forces at GeV-Scale e+e- colliders
Barze', et al.


Ideal environment to search for a light weakly coupled vector boson U (dark photon), emerging in new physics models, with GeV scale, high luminosity e+e- colliders ("flavor factories").  U boson production in association with a photon, then decay of U boson into lepton pairs.  Some details that escapes me.


1006.3359
Modeling dielectric half-wave plates for CMB polarimetry using a Mueller matrix formalism
Bryan, Montroy, Ruhl


* dielectric: electrical insulator that can be polarized by an applied electric field.
* half-wave plate: retards one polarization by half a wavelength (180 degrees).  
* Mueller calculus: matrix method for manipulating Stokes vectors, represent the polarization of incoherent light.  Light wich is unpolarized or partially polarized must be treated using Mueller calculus, while fully polarized light can be treated with either Mueller calculus or the simpler Jones calculus.  A 4x4 matrix, generalization of the Jones matrix.
* Jones calculus: in optics, polarized light can be described using the Jones calculus (Jones vectors have 2 elements for each of the polarization components).  A 2x2 matrix.  
* birefringent: double refraction.  Used to make wave plates, polarizing prisms, and Lyot (narrow passband, used in solar astronomy) filters.


Derive analytic formula using the Mueller matrix formalism--parameterizes nonidealities of the half-wave plate (HWP) made from dielectric antireflection-coated birefringent slabs.  Model accounts for frequency-dependent effects at normal incidence, including those driven by the reflections at dielectric boundaries.  Model also used to guide the characterization of an instrument that uses a HWP.  Coupling of HWP to different source spectra, and impact on foreground removal for the SPIDER CMB experiment.  Used in a mapmaking algorithm that fully corrects for HWP nonidealities.


1104.0672
ARKCoS: Artifact-Suppressed Accelerated radial kernel convolution on the sphere
Elsner, Wandelt


Hybrid Fourier/direct space convolution algorithm for compact radial (azimuthally symmetric) kernels on the sphere.


Takes advantage of the inexpensive massive parallelism afforded by GPUs.  Applications: modeling of instrumental beam shapes in compact kernels, fine-scale wavelet transformations, optimal filtering for the detection of point sources.  Works for any pixelization where pixels are grouped into isolatitude rings.  Ringing  features completely absent on ECP grid.  Highly suppressed on HEALPix pixelization.  Example: running on GPU speeds up beam convolution for simulations on Planck by two orders of magnitude, while maintaining a fractional RMS accuracy of 1e-5.


1104.3987
On the dynamics of planetesimals embedded in turbulent protoplanetary discs with dead zones
Gressel, Nelson, Turner


* magnetorotational instability (MRI): fluid instability that arises when the angular velocity of a magnetized fluid decreases as the distance from the center increases.  Relevance in astrophysics where it is an important part of the dynamics in accretion discs.  (Violates Rayleigh stability criterion.)


Accretion in protoplanetry discs is thought to be driven by turbulence via the magnetorotational instability (MRI).  Fully turbulent disk leads to collisional destruction of bodies with radii R_p < 100 km.  Diffusion of semimajor axes also arises, leading to large-scale spreading of the planetesimal population throughout the inner regions of the protoplanetary disc.  Examine turbulent excitation of the velocity dispersion and radial diffusion of planetesimals in these discs.  Employ 3D simulation.  Planetesimals develop large random velocities leading to collisional destruction/erosion for bodies with sizes < 100km.   Diffusion (radial) < 0.25 AU, consistent with solar system constraints.  A dead zone may provide a safe haven in which km-sized planetesimals an avoid mutual destruction through collisions.


1106.0040
Enhanced CMB non-Gaussianities from Lorentz violation
Chialva


Lorentz symmetry violation effects on the scalar CMB byspectrum.  THer ecan be enhancements, when symmetry breaking violate adiabatic condition temporarily in the early universe.  Depend on the form of the modified dispersion relation (pattern of Lorentz violation). Study Lorentz violation through these phenomena.