Day 27

Skipped Sunday afterall, then also skipped Monday.  Tuesday at KIAS.


1106.3366
The 6dF Galaxy Survey: BAO and the local hubble constant
Beutler, Blake, et al.


* Let's see if I can remember this abstract from before...


Measured BAO at z=0.106, as well as local H_0 measured with 6dF.  Use H_0 to break degeneracy between w and H_0 in the CMB data.  Comments on future surveys.


* it was a number-heavy abstract


1106.2815
Purely kinetic coupled gravity
Gubitosi, Linder


* another abstract read before...


Cosmic acceleration through kinetic terms coupled to gravity (instead of flat scalar field potential).  Some procedure on deriving the proper equations.  Couple Einstein tensor with the kinetic term (of what?), and that can be interpreted as adding a new term to Galileon gravity in curved spacetime.  Examine cosmological implications.  Find late time cosmological constant.


* what is "naturalness?"


1106.1469
Low-Resolution sodium D absorption is a bad proxy for extinction
Poznanski, Ganeshaligam, Silverman, Filippenko


* is it that bad?


Based on 443 low-resolution spectra of 172 Type Ia SNe for which both the dust extinction and Na I D equivalent width measured, the two BARELY CORRELATE.  Examine causes for this large scatter.


* it's BAD.  (actually, I have no idea how bad, having not read the paper)


1106.3328
Cluster Lensing and supernova survey with Hubble (CLASH): an overview
Postman et al.


* I read this one too.


It's a proposal paper.


1106.4016
Complete WMAP constraints on bandlimited inflationary features
Dvorkin, Hu


* What is bandlimited inflationary features?  I read this one too.


Test slow roll and single field inflation with the WMAP7 data.  Couldn't find any deviation, except one anomaly out of the 20 components.  See if the anomaly has a correspondence in the polarization spectrum, that would test their inflationary origin.  Complete analysis for bandlimited features (l<60?) in the source function of generalized slow roll--can be used to constrain parameters of specific models of the inflaton potential.


* I think I understand bandlimited, but I still don't quite understand what happened in this abstract.




KIAS Preprint
Relaxation limited evaporation of globular clusters
Maurice van Putten


* evaporation of stellar objects in globular clusters
* Kelvin-Helmholtz time scale: Astronomical process of cooling of the surface of a star or planet after gravitational contraction.  Cooling causes pressure to drop, and the star/planet shrinks as a result (Jupiter/Saturn/Brown dwarfs).  
* Globular clusters: spherical collection of stars that orbits a galactic core as a satellite out to 40 kpc.  Found in haloes of galaxies, contain considerably more stars, and are much older than the galactic open clusters found in disk.  150-158 currently known, perhaps 10 or 20 more.  Andromeda has ~500.  Some ellipticals can have as many as 13,000 globular clusters. Formation currently poorly understood.  Composed of low-metal, old stars.  
* Fokker-Planck equation: time evolution of the PDF of the velocity of a particle (can be generalized to other observables).  


When N_c >~1600, evaporative evolution of stellar clusters is shown to be relaxation limited.  The total energy loss per relaxation time is larger than total particle loss per, so it's an energy-loss process.  Evaporation time is found to be 20 x t_relax (where t_relax is the time it takes for a particle in a system to change its direction by pi/2); this result agrees with N-body simulations and Fokker-Planck calculations.  t_relax is expressed in terms of the half-mass radius.  Calculates grey-body factor, derive the tidal sensitivity d ln t_ev / dy ~ -1.9 to -0.7, as a function of the virial-to-tidal radius ratio.  Evaporation drives streams of stars into the tidal field with a mean KE or 0.71 relative to the temperature of cluster.  Tidal disruption stream S-shaped.  Can/should be tested.


1106.4052
Implicit priors in galaxy cluster mass and scaling relation determinations
Mantz, Allen


Cluster mass from ICM observation requires prior information, such as parameterized functions of gas density and gas profiles.  Investigate implicit priors on hydrostatic masses (fully parametric) --- naturally imposes a prior on the slopes of the derived scaling relations, favors self-similar model.  Bias does not exist for techniques which adopt an explicit prior on the form of the mass profile but describe the ICM non-parametrically.  Constraints on M-T_X relation in literature show a separation based on the approach employed, with the results from ully parametric ICM modeling clustering nearer the self-similar value.  Shouldn't be using parametric relations, if one wants to test self-similar relations.  Alternative methods discussed.


* Assuming the gas/density profile to have a certain form results in a prior where it biases the form to have a certain slope, favoring scaling relations.  
* what does it mean to have : explicit prior on the form of mass profile?


1106.4116
Probing cosmic acceleration by using the SNLS3 SNIa dataset
Li, et al.


472 SNIa, measure acceleration.  Combine with WMAP7, SDSS DR7 BAO, and H_0 from HST WFPC3.  Find w~-1 to 1 sigma.  LCDM compatible with current observations.


1106.4264
Enhancements to velocity-dependent Dm interactions from tidal streams nad the shells in the Andromeda galaxy
Sanderson, Mohayaee, Silk


* I've read this one


Cross-section enhancement due to velocity; this can be detected in tidal streams.


1106.4294
Hubble parameter data constraints on DE
Chen, Ratra


Measure H(z) to place constraints on model parameters