Wednesday. Yesterday I got notice that my computer is at customs. I hope I get my computer soon.
1106.1938
From deSitter to deSitter: A new cosmic scenario without dark energy
Lima, Basilakos
* Apparently about cosmology with particle creation.
Inflation, radiation-dominated, matter-dominated, DE-dominated. What is the connection between the two accelerating stages, inflation and DE domination? Propose an alternative cosmic scenario: gravitationally-induced particle production: non-singular IC, spacetime emerging from a pure initial deSitter stage. Production of massless particles causes evolution to the standard radiation dominated era. Then CDM, then negative pressure associated with creation of CDM particles accelerates the expansion to the final deSitter stage; no dark energy. The energy density of the two deSitter spaces are connected by 122 orders of magnitude [!].
* deSitter: spatially flat universe neglecting ordinary matter: dynamics dominated by the cosmological constant (DE or inflaton field). This Universe was deSitter at t=10e-33 sec after BB, and far into the future. The expansion accelerates in this universe: a(t) = exp(Ht).
* Good thing I looked this up, because I had the wrong idea about deSitter space.
1106.2046
Mock weak lensing analysis of simulated galaxy clusters: bias and scatter in mass and concentration
Bahe, McCarthy, King
* Apparently this talks about M-c relations.
M & c bias and scatter derived from a mock WL survey, and their effect on M-c relation investigated [as the title says]. Use Millenium, take 3000 galaxy cluster halos at z=0.2, simulate WL distortion on bg gals. M-c normalization ok, but the slope a bit steep. Small bias in derived mass. Both mass and concentration derived from WL show considerable scatter, decreasing slightly at higher mass range (down to ~30% scatter in c and ~20% in mass) [good news for us]. Scatter due to inaccurate modeling of the matter distribution outside the virial radius (departure from NFW). Propose a simple modification to the standard modelling method which reduce the bias to +/- 3%. Source gal shot noise is a minor contributor to the scatter for M>10e14.1 M_sun. Orientation of the triaxial cluster halos dominate the concentration scatter, while the bias in c and its mass dependence is due to substructure within the virial radius.
* "departure from NFW at outer radii--isn't that different from what Umetsu+2011 said? But I guess Umetsu+2011 describes a very massive cluster! Then this is consistent with what they're saying.
* concentration scatter due to triaxiality!, bias due to substructure.
1005.2158
SPIDER: a bolloon-born CMB polarimeter for large angular scales
Filippini et al.
* 8% of sky, degree-scale resolution of polarization. read this before.
1106.2000
General second order scalar-tensor theory, self tuning, and the Fab Four
Charmousis, Copeland, Padilla, Saffin
* What the f?
Action that would allow for the existence of a consistent self-tuning mechanism on FLRW backgrounds [self tuning of what?], starting from the most general scalar-tensor theory with second order field equations in 4D. Combination of 4 base Lagrangians with a geometric structure dependent on Einstein tensor with Gauss-Bonnet combination [?]. Scalar field breaks Poincare invariance on the self-tuning vacua, evading the Weinberg no-go theorem. Four arbitrary functions of the scalar field combine to possibly obtain non-trivial cosmological solutions [to what???].
* Weinberg-Witten theorem (no-go theorem): no massless particles with spin j greater than 1 are consistent with any renormalizable Lorenz-invariant quantum field theory excluding only theories of gravity and super gravity.
* Coleman-Mandula theorem (no-go theorem): space-time and internal symmetries cannot be combined in any but a trivial way.
* Gauss-Bonnet theorem: connects geometry (curvature) to topology (Euler characteristic).
1106.2161
Oscillating nonlinear large scale structure in growing neutrino quintessence
Baldi, Pettorino, Amendola, Wetterich
* what is quintessence again? the 5th force?
* Quintessence: a scalar field which is a hypothetical form of dark energy; a dynamic equation that changes over time. Can be either attractive or repulsive depending on the ratio of kinetic to potential energy in the universe.
The "growing neutrino quintessence" scenario predicts the formation of large scale neutrino lumps which could be observed. Ran simulations (N-body). Pulsation shown, lead to enhanced bulk flow, but density contrast differs little from std LCDM scenario. Determine statistical distribution of neutrino lumps (mass functions). Results limited to z>1.
1006.2185
The SZ signal of the maxBCG SDSS galaxy clusters in WMAP
Draper, Dodelson, Hao, Rozo
* Planck SZ signal is weak, compared to estimates from maxBCG [mass?].
Planck measures SZ signal from SDSS clusters (optically selected),, finding that it falls significantly below expectations based on existing mass calibraiton of the maxBCG galaxy clusters [oooh]. Either [Planck] data must go up, or theoretical [SZ] expectations must come down. Use WMAP to perform independent estimate of the SZ decrement; find consistent with Planck but with larger error bars. Observed discrepancy must be theoretical [baryonic phycis] in origin.
1106.2205
The gravitational lens equation for embedded lenses: magnification and ellipticity
Chen, Kantowski, Dai
* what does "embedded lenses" mean?
Lens equation for light deflections caused by point mass condensations in an otherwise homogeneous and flat universe. Assume signal from distance source is deflected by a single condensation before it reaches the observer. This is called an embedded lens because the deflecting mass is part of the mean density; conventional lens eqn differs from embedded because the deflector mass is not simply and addition to the cosmic mean. Prescribe an interation scheme to solve this new lens equation, use it to compare results with std linear lensing theory. Also compute analytic expressions for the lowest order corrections to image amplifications and distortions.
* are there any differences between embedded and std lens? they don't state their results. Apparently there is some difference, but the magnitude is not given.
* It's a <1% effect (haha!)
1106.2476
Modified gravity and cosmology
Clifton, Ferreira, Padilla, Skordis
Thoroughly comprehensive survey on modified theories of gravity and their cosmological consequences. GR, Scalar-Tensor, Einstein-aether, Bimetric, TeVeS, f(R), higher-order theories, Horava-Lifschitz, Galileons, Ghost condensates. Models of extra dimensions including Kaluza-Klein, Randall-SUndrum, DGP, higher codimension braneworlds. Parameterised post-Friedmannian formalism; constrain deviations from GR in large scales (cosmologically). Recent observations allow for precision tests of fundamental physics on the scale of the observable Universe. Purpose of this paper: reference tool for researchers and students in cosmology and gravitational physics. A self-contained, comprehensive and up-to-date introduction to the subject as a whole.
* sounds interesting. I wish someone would read it for me.
1106.2529
Supersymmetry and dark matter in ligt of LHC 2010 and Xenon100 data
Buchmueller, Cavanaugh, Colling, De Roeck, Dolan, et al.
* Yeech, HEP experiments with jargons.
* what is "frequentist"? Frequentist inference: one of a number of possible ways of formulating schemes for making statistical inferences (drawing conclusions from statistical samples). Alternatives: Bayesian inference, fiducial inference. Frequency interpretation of probability; "correct conclusion should be drawn with a given (high) probability. In frequentist approach, cannot assign probabilities with unknown parameters (they are unknown and fixed).
From some parameter spaces of acronym-laden theories, search for SUSY from 2010 LHC run and Xenon100 direct DM scattering search. LHC: ATLAS and CMS searches for jet + ETslach events (w/ or w/o leptons) and the heavier MSSM Higgs bosons. Other acronyms I don't understand. Absence of signals in LHC favour heavier mass spectra, and somewhat smaller dark amtter scattering cross section, close to or within pre-LHC 68% CL range. Some predictions.
1106.2547
Estimating parameters of coalescing compact binaries with a detector network including LIGO Australia
Aylott, Farr, Kalogera, Mandel, Raymond, Rodriguez, van der Sluys, Vecchio, Veitch
Next goal of grav-wave astronomy: Simultaneous detection of grav-wave and EM transients: next gen ground-based grav-wave detectors. Examine a proposed extension of the network in Australia as a 4th site, in addition to Hanford, Livingston and Cascina. Study improvement in parameter estimation; the Australian site can break degeneracies in several parameters, in particular the localization of the source on the sky is improved by a factor of 4. Modest improvements in distance and binary inclination.
1106.2548
Two upper limits on the Rossiter-McLaughlin effect with different implications: WASP-1 has high obliquity and WASP-2 is Indeterminate
Albrecht, et al.
* what is the Rossiter-McLaughlin effect?
* spectroscopic phenomenon observed when an eclipsing binary's second star or planet is seen to transit across the face of the primary or parent star. Hiding of the blue- or red-shifted side appears to make the spectral peak shift. Has shown that up to 25% of hot Jupiters are orbiting in retrograde.
RM effect can also be used to study he obliquity of the planet orbit. WASP-1 is a F7V star, which are typically rapidly rotating, so the weak signal of a prograde orbit indicates that the star is viewed nearly pole-on---implies high obliquity. WASP-2 is a K1V star, expected to be a slow rotator, no firm conclusions can be drawn (and no RM signal detected anyhow). Contradicts earlier claim that WASP-2b has a retrograde orbit.
1106.2607
Efficient computation of the non-linear matter power spectrum of LCDM
Audren, Lesgourgues
* how do they compute NL P(k) efficiently?
With efficient semi-analytic methods; Time Renormalization Group (TRG) and Dynamical 1-Loop limit implemented in Boltzmann code CLASS. Runs in 1 min for D1L, or 1 hr for TRG. careful comparison reveals precise computation of mildly NL corrections at high z >= 2. Percent precision achieved until k=0.35 h/Mpc at z=2 or k=0.18 h/Mpc at z=1.
1106.2702
Probing the role of magnetic-field variations in NOAA LAR 8038 in producing solar flare and CME on 12-May-1997
Jain, Awasthi, Chandel, Bharti, Hanaoka, Kiplinger
* What the f is a CME? -- coronal mass ejection, probably.
I'm not going to read this abstract.
1106.2757
Bayesian inference from photometric redshift surveys
Jasche, Wandelt
* inferring what?
Enhance redshift accuracy of surveys consisting of tracers with highly uncertain positions along the line of sight [positions of what kind of tracer?]. Achieved by imposing an isotropy and 2pt corerlation prior in a Bayesian analysis, and is completely independent of the process that estimates the photoz. This method also infers 3d density field.
* Peek at the paper: from data, get redshift, find density, from density, iterate for better redshift, then density. Redshift space distortion appears to disappear. Then get P(k)
* I'm not sure if this is a "methods to improve photoz" paper. I guess it is. I don't think the abstract was crystal clear, or maybe I'm easily confused (well the latter is definitely true).
1106.2770
The stellar content of obscured galactic giant HII regions. VII. W3
Navarete, Figueredo, Damineli, Moises, Blum, Conti
* obscured by what? what is the significance of HII regions (ionized H)? There are stellar contents there?
W3 star forming complex is well studied, located in the Perseus arm, allows study of HII region distances based on K-band spectrophotometry and radial velocities. K-band-based distances are reliable, based on agreement with OB stars, as well as parallax. Radio-derived kinematic distance is off scale; indicating this region of Perseus arm does not follow the Galactic rotation curve. There may be other HII regions like this.
* I actually understood this abstract.
1106.2798
Oscillations in the inflation potential: Exact numerical analysis and comparison with the recent and forthcocming CMB datasets
Aich, Hazra, Sriramkumar, Souradeep
* inflation potentials have oscillations?
Inflation model described by a quadratic potential, superposed by a sinusoidal modulation and the axion monodromy model. Compare with WMAP and ACT (small scales). Monodromy model leads to better fit to the data compared to std power law spectrum. Quadratic potential superposed with sinusoidal modulation does not improve the fit. Planck mock data performs better in constraining the model parameters.
* axion monodromy model? ...couldn't find anything comprehensible on the web.
1104.3862
Cosmology without cosmic variance
Bernstein, Cai
* I'm going to read this paper to the end soon, I swear.
Use McDonald & Seljak to get real-space galaxy clustering without peculiar velocity signal. Use Pen 2004 to get bias by combining WL and transverse clustering. Combine these two to get matter density in every mode. Measure growth rate free of sample variance; increasing number counts in finite volume will reduce uncertainty in f, but limited by the range of bias modulation among dark-matter halos. The addition of BG WL data to a redshift survey increases information on G and f by an amount equivalent to a 10-fold increase in the volume of a standard z-space distortion measurement, if WL can be measured to sub-percent accuracy. Combined redshift and WL survey is more powerful in testing GR than isolate redshift survey over larger volume at high z. 1e6 redshifts over half the sky in the redshift range z=0.45 to 0.55 can determine the growth exponent gamma for the model f=Omega_m^gamma to an accuracy of 0.015, using only modes with k<0.1 h/Mpc, but only if WL survey is conducted in concert.
* nice. I want to write a paper like this.
1105.1641
Morphological evolution of galaxies from ultradeep HST WFC3 imaging: the Hubble sequence at z~2
Szomoru, Franx, Bouwens, van Dokkum, Labbe, Illingworth, Trenti
* Hubble sequence study!
Morphological studies at z~2. Large, blue, disk-like galaxies to compact, red, early-type galaxies---wide range. u-g color profiles show negative color gradients (cores are red). Older stellar populations in the centers of z~2 galaxies? Consistent with "inside-out" scenario of galaxy growth [what is that?]. Color gradient fairly constant from z~2, z~1, to z~0. z~2 morphology correlates well with specific star formation rate. SF galaxies have larger effective radii, bluer rest-frame u-g colors, and lower Sersic indicies than quiescent galaxies. these correlations very similar to those at lower redshift. Hubble sequence already in place for massive galaxies at this redshift.
* inside-out galaxy growth = gas is accumulated at large radii later in the galaxy life span, while gas at the core becomes exhausted.
1106.1646
Empirical determination of the shape of dust attenuation curves in star-forming galaxies
Wild, Charlot, Brinchmann, Heckman, Vince, Pacifici, Chevallard
Shape of dust attenuation curve in SF galaxies from FUV to NIR, as a function of sSFR and b/a, for galaxies with and without a significant bulge. Study 23000 galaxies with median z of 0.07. Use photometry from SDSS, UKIDSS-LAS and GALEX-AIS and spectro (emission line). isolate dust attenuation curves from stellar continuum emission. Slope varies weakly with sSFR, strongly with b/a, and steeper than the MW extinction law in bulge dominated gals; the NIR slope is constant, and matches MW; UV slow change consistent with dust bump at 2175A, and varies strongly in strength with b/a in bulge-dominated sample; strong increase in emission line-to-continuum dust attenuation with increasing b/a and decreasing sSFR; radial gradients in dust attenuation increase strongly with increasing sSFR, presence of bulge does not affect the strength of gradients. Consistent with picture in which young stars are surrounded by dense 'birth clouds' with low covering factor with disperse on timescales of 1e7 years and the diffuse interstellar dust is distributed in a centrally concentrated disk with a smaller scaleheight than the oder stars that contributed the majority of the red and NIR light.
* Yeech, galaxy formation details.
1106.1745
Probing cosmic star formation up to z=9.4 with GRBs
Ishida, de Souza, Ferrara
Use GRB as proves of cosmic star formation history probe.
* I didn't quite understand how. Seems like SFH model can predict GRB's, and then compare with observation. Results: SFH as high as z=0 at z~9. [if i read it correctly]
1106.2092
Star and dust formation activities in AzTEC-3: a starburst galaxy at z~5.3
Dwek, Capak et al.
Must consider mass of dust giving rise to the IR emission, when estimating the dynamical mass and staf formation rate, stellar mass and age through optical to submm SED of high-z ULIRGs.
1106.2165
Resolved optical-infrared SEDs of galaxies: universal relations and their break-down on local scales
Zibetti, Groves
disconnect in optical and IR correlation when galaxies observed in zoom-up, due to local dust clouds. observe 7 nearby galaxies on a pixel-by-pixel basis, and demonstrate disconnect. decompose this disconnect between optical and IR through PCA--each correlated to the variation within.
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