Friday. The weather the past two days have been uncomfortably warm and humid; hard to concentrate at work. Hopefully it won't be too hot today. Thunderstorms coming?
1207.1100
The progenitor dependence of the preexplosion neutrino emission in core-collapse supernovae
O'Connor Ott
Spherically symetric GR simulations of core collapse and the post bounce pre explosion phase in 32 pre supernova stellar models of solar metallicity, with 12Msun to 120 Msun. Energy-dependent three-species neutrino transport, two-moment approximation, analytic closure. Show: emitted neutrino luminosities and spectra follow systematic trends that are correlated with the compactness (M/R) of the progenitor's inner regions via the accretion rate in the pre explosion phase. Simulate water Cherenkov detectors to electron anti-neutrino fluxes, and find that the large statistics of galactic core collapse event may allow robust conclusions on the inter structure of the progenitor star.
1207.1102
Optimal weighting in galaxy surveys: application to redshift-space distortions
Hamaus, Seljak, Desjacques
Evade sampling variance by using multiple tracers of LSS; demonstrate optimal way of carrying out a multi tracer analysis in galaxy redshift survey by considering the principal components of the shot noise matrix from 2pt clustering statistics. Optimal weights for 2 tracers, benefits of sampling variance and shot noise cancellation. Apply to z-space distortion; demonstrate improvement of constraints on growth rate. Primary limitations: NL effects starting at k=0.1 h/Mpc. Need to develop NL models of z-space distortions to extract maximum information.
1207.1105
By Dawn's early light: CMB polarization impact on cosmological constraints
Das, Linder
CMB lensing encodes early universe info, DE, neutrino mass, and gravity in late universe; increases FoM of CMB by factor of 3-4. Fit for dynamical DE, neutrino mass, and modified gravitational growth index in a 2017 survey set (SNe, WL, galaxy clustering). Add SL time delay survey improves DE constraints by 32%, and an enhanced low-z SNe 6%.
1207.1120
Cosmological parameter constraints from galaxy-galaxy lensing and galaxy clustering with the SDSS DR7
Mandelbaum, Slosar, Baldauf, Seljak, Hirata, Nakajima, Reyes, Smith
* Yay!
Possible to determine the DM clustering from measurements of gg WL and galaxy clustering, since X-corr coefficient between galaxies and dark matter is very close to unity (ouside a few virial radii of galaxy halos). Remove small scale info (below 2 and 4 Mpc/h for lensing and clustering measurements, respectively), where the X-corr coefficient differs from unity. Derive constraints for 3 galaxy samples covering 7131 sq deg in SDSS DR7, with mean redshifts of 0.11, 0.28, and 0.40. Clearly detect scale-dependent galaxy bias for the more luminous galaxy samples, at a level consistent with theoretical expectations. Constrain sigma_8 and Omega_m with other params fixed (marginalize over NL galaxy bias), the best-constrained quantity is sigma_8 (Omega_m)^0.57 = 0.80 pm 0.05 (1 sigma, stat+sys), where statistical and systematic errors have comparable contributions. Strong constraints on the DM clustering suggest that this methods is competitive with cosmic shear in current data, while having very complementary and in some ways less serious systematics. Expect that this method will play a prominent role in future WL surveys. Combine with WMAP7 CMB data, constraints on sigma_8, Omega_m, H0, w_de and Sum(m_nu) become 30-80 per cent tighter than with CMB data alone, since data break several parameter degeneracies.
1207.1121
Dark matter and Ricci-like holographic dark energy coupled through a quadratic interaction
Chimento, Richarte
* Chapligin gas: in cosmology, when the EoS of a hypothetic substance is p = -A/rho.
Modified holographic Ricci dark energy and interacting DM, in spatially flat FRW. Conference proceedings. MHRDE gets the accelerated expansion faster than the LCDM model. ...
1207.1162
Rapid disappearance of a warm, dusty circumstellar disk
Melis et al
As the title says. Nature paper.
1207.1170
Acoustic events in the solar atmosphere from Hinode/SOT NFI observations
Malherbe et al
Acoustic events (AEs): spatially concentrated and short duration energy flux. More than 1e6 events could exist permanently on the Sun, with a birth and decay rate of 3500/s. Most events occur in inter granular lanes, downward velocity regions, and areas of converging motions.
1207.1183
Limits on second-order non-Gaussianity from Minkowski functionals of WMAP data
Hikage, Matsubara
* Minkowski functionals: a function that recovers a notion of distance in linear space.
Analyze NG due to primordial bispectrum and trispectrum using WMAP7 CMB temperature maps. Apply perturbative formulae of Minkowski functionals up to 2nd order. Find no signature of primordial NG, but constrains f_NL (local, equilateral, orthogonal), tau_NL, and g_NL. Constraints consistent with limits from skewness and kurtosis parameters.
1207.1193
Optical/near-infrared selection of red QSOs
Fynbo et al
Selection based on SDSS and UKIDSS imaging; 46/58 candidates confirmed to be QSOs, predominantly dust-reddened except for a few at z>3.5. 4 were late-type stars, 4 were compact galaxies, 4 were unidentified.
1207.1121
Dark matter and Ricci-like holographic dark energy coupled through a quadratic interaction
Chimento, Richarte
* Chapligin gas: in cosmology, when the EoS of a hypothetic substance is p = -A/rho.
Modified holographic Ricci dark energy and interacting DM, in spatially flat FRW. Conference proceedings. MHRDE gets the accelerated expansion faster than the LCDM model. ...
1207.1162
Rapid disappearance of a warm, dusty circumstellar disk
Melis et al
As the title says. Nature paper.
1207.1170
Acoustic events in the solar atmosphere from Hinode/SOT NFI observations
Malherbe et al
Acoustic events (AEs): spatially concentrated and short duration energy flux. More than 1e6 events could exist permanently on the Sun, with a birth and decay rate of 3500/s. Most events occur in inter granular lanes, downward velocity regions, and areas of converging motions.
1207.1183
Limits on second-order non-Gaussianity from Minkowski functionals of WMAP data
Hikage, Matsubara
* Minkowski functionals: a function that recovers a notion of distance in linear space.
Analyze NG due to primordial bispectrum and trispectrum using WMAP7 CMB temperature maps. Apply perturbative formulae of Minkowski functionals up to 2nd order. Find no signature of primordial NG, but constrains f_NL (local, equilateral, orthogonal), tau_NL, and g_NL. Constraints consistent with limits from skewness and kurtosis parameters.
1207.1193
Optical/near-infrared selection of red QSOs
Fynbo et al
Selection based on SDSS and UKIDSS imaging; 46/58 candidates confirmed to be QSOs, predominantly dust-reddened except for a few at z>3.5. 4 were late-type stars, 4 were compact galaxies, 4 were unidentified.
1207.1195
NGC 3627: a galaxy-dwarf collision?
Wezgowiec, Soida, Bomans
Analyze soft X-ray (0.2-1keV) emission to study the distribution of the hot gas and its temperature; change reflect distortions visible in the radio polarized emission. Polarized radio ridge most likely from ram-pressure effects from galaxy moving through IGM (intra group medium). Asymmetry of bar and distortion of eastern arm perhaps from a collision with dwarf companion galaxy.
1207.1219
Growing magnetic fields of young pulsars
Güneydas, Eksi
A nascent NS may be exposed to fallback accretion; this high-accretion episode can submerge the B-field deep in the crust; diffusion of B-field back to the surface will take few 1e8 years, depending on the amount of mass accreted and the consequent depth the field is buried. Confirm predicted inverse relation between measured transverse velocities (large kick velocity, hence less fallback material) and the field growth time-scales inferred from measured breaking indices.
1207.1220
Interferometric identification of a pre-brown dwarf
Andre et al
Are M<0.075 Msun objects (less than the H-burning limit) formed the same way as solar-type stars, or by some other process? Report self-gravitating condensation of gas and dust in brown-dwarf regime. Thermal emission show 0.02-0.03 Msun dynamical mass with small radius (<460 AU) and narrow spectral lines. ID of such a pre-brown dwarf core supports models in which they formed in the same way as ordinary stars (Science paper).
1207.1286
Do stochastic inhomogeneities affect dark-energy precision measurements?
Ben-Dayan et al
Effect of a stochastic background of cosmological perturbations on the L-z relation (Hubble diagram) computed to second order through a recently proposed covariant and gauge-invariant light-cone averaging procedure. Such perturbations cannot mimic a sizable fraction of DE. Different averages estimated and depend on the particular function of the luminosity distance being averaged. Energy flux (minimally affected by perturbations at large z) is proposed as the best choice for precision estimates of dark-energy parameters. Irreducible (stochastic) variance induces statistical errors on Omega_Lambda(z) typically lying in the few-percent range.
1207.1301
Mapping the cold dust temperatures and masses of nearby Kingfish galaxies with Herschel
Galametz, Kennicutt, Albrecht, Aniano, Arums, Bertoldi, ... et al
Study robustness of the parameters derived using different modified blackbody models. Working resolution affects total dust mass estimates: masses increase from global fits to spatially-resolved fits.
1207.1306
PTF11kx: a type-Ia supernova with symbiotic Nova pregenitor
Dilday et al
Direct observation of SNIa progenitors lacking; precise nature of binary companion remains uncertain. High-res optical spectra of PTF 11kx show complex circmstellar environment that provides an unprecedented ly detailed view of the progenitor system. Multiple shells of circumstellar detected; SN ejecta seen to intact with circumstellar material starting 59 days after explosion. Similar to RS Ophiuchi (WD and red giant binary in a close orbit, irregular outbursts; a possible SNIa progenitor).
1207.1332
Proper size of the visible universe in FRW metrics with constants space-time curvature
Melia
* a -1 vote
What is the proper size of the visible universe? "Difficulty usually arises from an inconsistent use of the coordinates, or an over-interpretation of the physical meaning of quantities such as the so-called proper distance R(t)=a(t)r, written in terms of the (unchanging) co-moving radius r and the universal expansion factor a(t)." Show size of universe at R_h(t_0/2) for static FRW metric [why static?] that began from an initial singularity.
[Fri **/32] Jul 6
NGC 3627: a galaxy-dwarf collision?
Wezgowiec, Soida, Bomans
Analyze soft X-ray (0.2-1keV) emission to study the distribution of the hot gas and its temperature; change reflect distortions visible in the radio polarized emission. Polarized radio ridge most likely from ram-pressure effects from galaxy moving through IGM (intra group medium). Asymmetry of bar and distortion of eastern arm perhaps from a collision with dwarf companion galaxy.
1207.1219
Growing magnetic fields of young pulsars
Güneydas, Eksi
A nascent NS may be exposed to fallback accretion; this high-accretion episode can submerge the B-field deep in the crust; diffusion of B-field back to the surface will take few 1e8 years, depending on the amount of mass accreted and the consequent depth the field is buried. Confirm predicted inverse relation between measured transverse velocities (large kick velocity, hence less fallback material) and the field growth time-scales inferred from measured breaking indices.
1207.1220
Interferometric identification of a pre-brown dwarf
Andre et al
Are M<0.075 Msun objects (less than the H-burning limit) formed the same way as solar-type stars, or by some other process? Report self-gravitating condensation of gas and dust in brown-dwarf regime. Thermal emission show 0.02-0.03 Msun dynamical mass with small radius (<460 AU) and narrow spectral lines. ID of such a pre-brown dwarf core supports models in which they formed in the same way as ordinary stars (Science paper).
1207.1286
Do stochastic inhomogeneities affect dark-energy precision measurements?
Ben-Dayan et al
Effect of a stochastic background of cosmological perturbations on the L-z relation (Hubble diagram) computed to second order through a recently proposed covariant and gauge-invariant light-cone averaging procedure. Such perturbations cannot mimic a sizable fraction of DE. Different averages estimated and depend on the particular function of the luminosity distance being averaged. Energy flux (minimally affected by perturbations at large z) is proposed as the best choice for precision estimates of dark-energy parameters. Irreducible (stochastic) variance induces statistical errors on Omega_Lambda(z) typically lying in the few-percent range.
1207.1301
Mapping the cold dust temperatures and masses of nearby Kingfish galaxies with Herschel
Galametz, Kennicutt, Albrecht, Aniano, Arums, Bertoldi, ... et al
Study robustness of the parameters derived using different modified blackbody models. Working resolution affects total dust mass estimates: masses increase from global fits to spatially-resolved fits.
1207.1306
PTF11kx: a type-Ia supernova with symbiotic Nova pregenitor
Dilday et al
Direct observation of SNIa progenitors lacking; precise nature of binary companion remains uncertain. High-res optical spectra of PTF 11kx show complex circmstellar environment that provides an unprecedented ly detailed view of the progenitor system. Multiple shells of circumstellar detected; SN ejecta seen to intact with circumstellar material starting 59 days after explosion. Similar to RS Ophiuchi (WD and red giant binary in a close orbit, irregular outbursts; a possible SNIa progenitor).
1207.1332
Proper size of the visible universe in FRW metrics with constants space-time curvature
Melia
* a -1 vote
What is the proper size of the visible universe? "Difficulty usually arises from an inconsistent use of the coordinates, or an over-interpretation of the physical meaning of quantities such as the so-called proper distance R(t)=a(t)r, written in terms of the (unchanging) co-moving radius r and the universal expansion factor a(t)." Show size of universe at R_h(t_0/2) for static FRW metric [why static?] that began from an initial singularity.
[Fri **/32] Jul 6
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