1203.2915
A new Monte Carlo Method for Time-Dependent neutrino radiation transport
Abdikamalov, Burrows, Ott, Löffler, O'Conner, Dolence, Schnetter
MC attractive: cimple to implement, high accuracy, good parallel scaling; can handle complicated geometries, easy to extend to multiple spatial dimensions. Explore MC for modeling neutrino transport in core-collapse SNe. Photon transport and gray discrete-diffusion schemes to energy-, time- and velocity-dependent neutrino transport. The implicit scheme enables larger time steps compared to explicit time discretization without sacrificing accuracy, while discrete-diffusion method leads to speed-ups at high optical depth. Results suggest that a combination of spectral, velocity-dependent, implicit MC and discrete-diffusion MC methods represent an attractive approach for neutrino radiation-hydrodynamics simulations of core-collpase SNe. Velocity-dependent scheme easily adapted to photon transport.
1203.2916
Linking Type Ia supernova progenitors and their resulting explosions
Foley, Simon, Burns, Gal-Yam, Hamuy, Kirshner, Morrell, Phillips, Shields, Sternberg
Compare eject velocities at maximum brightness in Na D absorption line of 23 SNIa: determine that the properties of SNIa progenitor systems and explosions are intimately connected; half of detectable Na D have their lines blue shifted relative to the strongest absorption component; indicates a large fraction of SNIa progenitor systems have strong winds (and other evidence); Confirmation that some SNIa are produced from a single-degenerate progenitor channel. Additional implication: highly asymmetric winds aligned with the SN explosion or SNIa came from a variety of progenitor systems where those with strong winds tend to have more kinetic energy per unit mass than those from systems with weak or no winds.
1203.2920
Effects of post-Newtonian spin alignment on the distribution of black hole recoils
Berti, Kesden, Sperhake
BH binary merger can recoil with a velocity as large as 5000 km/s; maximum recoil occurs when BH spins are partially aligned with the orbital angular momentum. Study how post-Newtonisn spin alignment affects the ejection probabilities of SMBH from host galaxies.
1203.2926
Direct numerical simulation of radiation pressure-driven turbulence and winds in star clusters and galactic disks
Krumholz, Thompson
Numerical experiments on radiation-hydrodynamics code ORION: drive strong radiation fluxes through columns of dusty matter confined by gravity, to study how efficiently radiation couples to matter in high optical depth environments. Find in sub-Eddington at atmosphere: radiation-matter interaction gives rise to radiation-driven RT instability, which drives supersonic turbulence at a level sufficient to fully explain the turbulence seen in Galactic protocluster gas clouds, contribute to turbulence observed in starburst galaxy disks. Instability also produces a channel structure in which the radiation-matter interaction is reduced compared to time-steady analytic models because the radiation fields is not fully trapped, reducing the net momentum deposition rate in the dusty gas. In steady state, Eddington ratio = 1, and no strong winds. Provide approximate formula for the force extorted by the IR radiation in this regime.
1203.2927
Evidence of nuclear disks in starburst galaxies from their radial distribution of supernovae
Herrero-Illana, Perez-Torres, Alberdi
Galaxy interactions trigger massive SF, sends dense molecular gas to the central kilo parsec region. Several scenarios drive them down to the central ~100pc, that can then SF and generate SNe. Probe radial distribution of SNe and SNe remnants of M82 and 2 more galaxies, using high resolution (<0.1") radio observations. Scale lengths of the putative nuclear disks of the order 10 to 100 pc; supporting scenarios where a nuclear disk of size 100pc is formed in ULIRGs, and sustained by gas pressure, in which case the accretion onto the BH could be lowered by SNe feedback.
1203.2949
A NIR template derived from I Zw 1 for the FeII emission in active galaxies
Garcia-Rissmann, Rodriguez-Ardila, Sigut, Pradhan
In AGN spectra, Ly-alpha fluorescence is likely the key process to understand the FeII spectrum on the pseudo-continuum (pure photoionization fails to reproduce it in the most extreme cases, as does collisional-excitation alone).
A new Monte Carlo Method for Time-Dependent neutrino radiation transport
Abdikamalov, Burrows, Ott, Löffler, O'Conner, Dolence, Schnetter
MC attractive: cimple to implement, high accuracy, good parallel scaling; can handle complicated geometries, easy to extend to multiple spatial dimensions. Explore MC for modeling neutrino transport in core-collapse SNe. Photon transport and gray discrete-diffusion schemes to energy-, time- and velocity-dependent neutrino transport. The implicit scheme enables larger time steps compared to explicit time discretization without sacrificing accuracy, while discrete-diffusion method leads to speed-ups at high optical depth. Results suggest that a combination of spectral, velocity-dependent, implicit MC and discrete-diffusion MC methods represent an attractive approach for neutrino radiation-hydrodynamics simulations of core-collpase SNe. Velocity-dependent scheme easily adapted to photon transport.
1203.2916
Linking Type Ia supernova progenitors and their resulting explosions
Foley, Simon, Burns, Gal-Yam, Hamuy, Kirshner, Morrell, Phillips, Shields, Sternberg
Compare eject velocities at maximum brightness in Na D absorption line of 23 SNIa: determine that the properties of SNIa progenitor systems and explosions are intimately connected; half of detectable Na D have their lines blue shifted relative to the strongest absorption component; indicates a large fraction of SNIa progenitor systems have strong winds (and other evidence); Confirmation that some SNIa are produced from a single-degenerate progenitor channel. Additional implication: highly asymmetric winds aligned with the SN explosion or SNIa came from a variety of progenitor systems where those with strong winds tend to have more kinetic energy per unit mass than those from systems with weak or no winds.
1203.2920
Effects of post-Newtonian spin alignment on the distribution of black hole recoils
Berti, Kesden, Sperhake
BH binary merger can recoil with a velocity as large as 5000 km/s; maximum recoil occurs when BH spins are partially aligned with the orbital angular momentum. Study how post-Newtonisn spin alignment affects the ejection probabilities of SMBH from host galaxies.
1203.2926
Direct numerical simulation of radiation pressure-driven turbulence and winds in star clusters and galactic disks
Krumholz, Thompson
Numerical experiments on radiation-hydrodynamics code ORION: drive strong radiation fluxes through columns of dusty matter confined by gravity, to study how efficiently radiation couples to matter in high optical depth environments. Find in sub-Eddington at atmosphere: radiation-matter interaction gives rise to radiation-driven RT instability, which drives supersonic turbulence at a level sufficient to fully explain the turbulence seen in Galactic protocluster gas clouds, contribute to turbulence observed in starburst galaxy disks. Instability also produces a channel structure in which the radiation-matter interaction is reduced compared to time-steady analytic models because the radiation fields is not fully trapped, reducing the net momentum deposition rate in the dusty gas. In steady state, Eddington ratio = 1, and no strong winds. Provide approximate formula for the force extorted by the IR radiation in this regime.
1203.2927
Evidence of nuclear disks in starburst galaxies from their radial distribution of supernovae
Herrero-Illana, Perez-Torres, Alberdi
Galaxy interactions trigger massive SF, sends dense molecular gas to the central kilo parsec region. Several scenarios drive them down to the central ~100pc, that can then SF and generate SNe. Probe radial distribution of SNe and SNe remnants of M82 and 2 more galaxies, using high resolution (<0.1") radio observations. Scale lengths of the putative nuclear disks of the order 10 to 100 pc; supporting scenarios where a nuclear disk of size 100pc is formed in ULIRGs, and sustained by gas pressure, in which case the accretion onto the BH could be lowered by SNe feedback.
1203.2949
A NIR template derived from I Zw 1 for the FeII emission in active galaxies
Garcia-Rissmann, Rodriguez-Ardila, Sigut, Pradhan
In AGN spectra, Ly-alpha fluorescence is likely the key process to understand the FeII spectrum on the pseudo-continuum (pure photoionization fails to reproduce it in the most extreme cases, as does collisional-excitation alone).
1203.2954
Extracting limits on dark matter annihilation from dwarf spheroidal galaxies at gamma-rays
Cholis, Salucci
Dwarf spheroidals: more DM dominated class of objects, a good target for DM annihilation signal. No clear excess of gamma-rays have been confirmed from these targets. Uncertainties important, which include DM distribution properties and underlying background uncertainty. Derive upper limits.
1203.2957
Confined population III enrichment and the prospects for prompt second-generation star formation
Ritter, Safranek-Shrader, Gnat, Milosavljevic, Bromm
If Pop III stars were extremely massive, then upon SNe would completely unbind the baryons in the most cosmic mini halo, and disperse the synthesized metals into the IGM. If first stars were less extreme in mass (~few tens Msun), they promptly enriched the host mini halos and triggered Pop II star formation. Simulation show SNe shock expands, ~50% of ejecta turn around, 10% reach back the center in 10Myr; average metallicity of combined returning ejecta and pristine filaments feeding into the halo center from cosmic web is 0.001-0.01 Zsun, but two remain unmixed until accreting onto the central hydrostatic core (unresolved in the simulation).
1203.2994
Turbulence and radio mini-halos in the sloshing cores of galaxy clusters
ZuHone, Markevitch, Brunetti, Giacintucci
A number of relaxed, cool-core galaxy clusters exhibit diffuse, steep-spectrum radio sources in their central regions, known as radio mini-halos. The high gamma electrons (100-500) combined with the enhanced B-field in the core, allows these electrons to produce diffuse radio synchrotron emission that is coincident with the region bounded by the sloshing cold fronts, simulation in agreement wit observations in x-ray and radio.
1203.3011
Runnings in the Curvaton
Kobayashi, Takahashi
Runnings: scale-dependence of (linear and second order) density perturbations. Present analytic formulae for the runnings from curvatons. ...
1203.3019
Ultraluminous star-forming galaxies and extremely luminous warm molecular Hydrogen emission at z=2.16 in the PKS 1138-26 Radio galaxy protocluster
Ogle, Davies, Appleton, Bertincourt, Seymour, Helou
PAH emission infer SFR of 500-1100 Msun/yr, a rate that would double galaxy stellar mass in 0.6-1.1 Gyr. Possibly 1e7-9 Msun of T>300K molecular gas, heated by the radio jet, which is quenching SF.
1203.3024
The luminosity function and stellar mass to light ratio of the massive globular cluster NGC2419
Bellazzini, Dalessandro, Sollima, Ibata
This globular cluster, orbiting MW at radius further away then the Magellanic clouds, has mass to light ratio of 1.5 in the V band.
1203.3027
Violent and mild relaxation of an isolated self-gravitating uniform and spherical cloud of particles
Labini
Collpase of an isolated, uniform and spherical cloud of self-gravitationg particles represents a paradigmatic example of relaxation process leading to virial equilibrium. N-body sim of such system with initial velocity dispersion as free parameter. Show: clear difference between structures when the initial virial ratio is b0<b0^c ~ -1.2 and b0>b0^c. These two sets of initial conditions give rise respectively to a mild and violent relaxation occurring in about the same time scale: However in the latter case, the system contracts by a large factor, while in the former it approximately maintains the original size. The resulting virial state is characterized by a density profile decaying at large distances as r^-4 or with a shape cut-off. For b0<b0^c: collision less relaxation; for the other, ejection of particles and energy. Simple physical model to explain the formation of such a power-law density profile. Behavior n(r)~r^-4 is the typical density profile that is obtained when the initial conditions are cold enough that mass and energy ejection occurs. Clarify the origin of the critical value b0^c.
1203.3060
Fermi bubbles in the Milky Way: the closest AGN feedback laboratory courtesy of Sgr A*?
Zubovas, Nayakshin
Deposition of a massive GMC (1e4-5 Msun) to the inner parsec of MW is believe to be the origin of a hundred unusually massive young stars born there ~ 6Myr ago. Some fraction of that gas could have been accreted by Sgr A*, possibly causing the gamma-ray bubble. Run simulations to test whether the observed morphology of the bubbles could be due to the collimation of a wide angle outflow from Sgr A* by the disc-like CMZ, a repository of molecular gas in the central 200 pc. Require Eddington-limited outburst of ~1Myr duration required to produce the Fermi bugle; GMC mass suggested to be 1e5Msun, mainly accreted by Sgr A*. Also find: outflow from Sgr A* enforces strong angular momentum mixing in the CMZ disc, robustly sculpting into a much narrower structure (a ring, the same one as the Herschel-detected one?); induce formation of SF GMCs in CMZ. [so the answer is yes, the simulation supports the hypothesis]
Extracting limits on dark matter annihilation from dwarf spheroidal galaxies at gamma-rays
Cholis, Salucci
Dwarf spheroidals: more DM dominated class of objects, a good target for DM annihilation signal. No clear excess of gamma-rays have been confirmed from these targets. Uncertainties important, which include DM distribution properties and underlying background uncertainty. Derive upper limits.
1203.2957
Confined population III enrichment and the prospects for prompt second-generation star formation
Ritter, Safranek-Shrader, Gnat, Milosavljevic, Bromm
If Pop III stars were extremely massive, then upon SNe would completely unbind the baryons in the most cosmic mini halo, and disperse the synthesized metals into the IGM. If first stars were less extreme in mass (~few tens Msun), they promptly enriched the host mini halos and triggered Pop II star formation. Simulation show SNe shock expands, ~50% of ejecta turn around, 10% reach back the center in 10Myr; average metallicity of combined returning ejecta and pristine filaments feeding into the halo center from cosmic web is 0.001-0.01 Zsun, but two remain unmixed until accreting onto the central hydrostatic core (unresolved in the simulation).
1203.2994
Turbulence and radio mini-halos in the sloshing cores of galaxy clusters
ZuHone, Markevitch, Brunetti, Giacintucci
A number of relaxed, cool-core galaxy clusters exhibit diffuse, steep-spectrum radio sources in their central regions, known as radio mini-halos. The high gamma electrons (100-500) combined with the enhanced B-field in the core, allows these electrons to produce diffuse radio synchrotron emission that is coincident with the region bounded by the sloshing cold fronts, simulation in agreement wit observations in x-ray and radio.
1203.3011
Runnings in the Curvaton
Kobayashi, Takahashi
Runnings: scale-dependence of (linear and second order) density perturbations. Present analytic formulae for the runnings from curvatons. ...
1203.3019
Ultraluminous star-forming galaxies and extremely luminous warm molecular Hydrogen emission at z=2.16 in the PKS 1138-26 Radio galaxy protocluster
Ogle, Davies, Appleton, Bertincourt, Seymour, Helou
PAH emission infer SFR of 500-1100 Msun/yr, a rate that would double galaxy stellar mass in 0.6-1.1 Gyr. Possibly 1e7-9 Msun of T>300K molecular gas, heated by the radio jet, which is quenching SF.
1203.3024
The luminosity function and stellar mass to light ratio of the massive globular cluster NGC2419
Bellazzini, Dalessandro, Sollima, Ibata
This globular cluster, orbiting MW at radius further away then the Magellanic clouds, has mass to light ratio of 1.5 in the V band.
1203.3027
Violent and mild relaxation of an isolated self-gravitating uniform and spherical cloud of particles
Labini
Collpase of an isolated, uniform and spherical cloud of self-gravitationg particles represents a paradigmatic example of relaxation process leading to virial equilibrium. N-body sim of such system with initial velocity dispersion as free parameter. Show: clear difference between structures when the initial virial ratio is b0<b0^c ~ -1.2 and b0>b0^c. These two sets of initial conditions give rise respectively to a mild and violent relaxation occurring in about the same time scale: However in the latter case, the system contracts by a large factor, while in the former it approximately maintains the original size. The resulting virial state is characterized by a density profile decaying at large distances as r^-4 or with a shape cut-off. For b0<b0^c: collision less relaxation; for the other, ejection of particles and energy. Simple physical model to explain the formation of such a power-law density profile. Behavior n(r)~r^-4 is the typical density profile that is obtained when the initial conditions are cold enough that mass and energy ejection occurs. Clarify the origin of the critical value b0^c.
1203.3060
Fermi bubbles in the Milky Way: the closest AGN feedback laboratory courtesy of Sgr A*?
Zubovas, Nayakshin
Deposition of a massive GMC (1e4-5 Msun) to the inner parsec of MW is believe to be the origin of a hundred unusually massive young stars born there ~ 6Myr ago. Some fraction of that gas could have been accreted by Sgr A*, possibly causing the gamma-ray bubble. Run simulations to test whether the observed morphology of the bubbles could be due to the collimation of a wide angle outflow from Sgr A* by the disc-like CMZ, a repository of molecular gas in the central 200 pc. Require Eddington-limited outburst of ~1Myr duration required to produce the Fermi bugle; GMC mass suggested to be 1e5Msun, mainly accreted by Sgr A*. Also find: outflow from Sgr A* enforces strong angular momentum mixing in the CMZ disc, robustly sculpting into a much narrower structure (a ring, the same one as the Herschel-detected one?); induce formation of SF GMCs in CMZ. [so the answer is yes, the simulation supports the hypothesis]
1203.2877
Cosmological constraints from the capture of non-Gaussianity in weak lensing data
Piers, Leonard, Starck
Most WL methods derive constraints on cosmo parameters on second-order statistics of the cosmic shear, although not optimal, with degeneracies. Combine with non-Gaussianity statistic for tighter constraints. Additional information to be extracted from statistical analysis of convergence maps. Use cosmo-sims with sigma8-Omega_m degeneracies to show information extraction with 3 different statistics commonly used for non-Gaussian features: skewness, kurtosis and peak count. To be able to investigate non-Gaussianity directly in the shear field, use aperture mass definition of these 3 statistics at different scales. Compare results from convergence maps. Shear statistics give similar constraints to those given by convergence statistics; Find peak count statistic is the best to capture non-Gaussianities in the WL field and to break the sigma8-Omega_m degeneracy. This statistical analysis should be conducted in the convergence maps: (1) there exists fast algorithms to compute the convergence map for different scales, and (2) it offers the opportunity to denies the reconstructed convergence map, which improves non-Gaussian features extraction.
Cosmological constraints from the capture of non-Gaussianity in weak lensing data
Piers, Leonard, Starck
Most WL methods derive constraints on cosmo parameters on second-order statistics of the cosmic shear, although not optimal, with degeneracies. Combine with non-Gaussianity statistic for tighter constraints. Additional information to be extracted from statistical analysis of convergence maps. Use cosmo-sims with sigma8-Omega_m degeneracies to show information extraction with 3 different statistics commonly used for non-Gaussian features: skewness, kurtosis and peak count. To be able to investigate non-Gaussianity directly in the shear field, use aperture mass definition of these 3 statistics at different scales. Compare results from convergence maps. Shear statistics give similar constraints to those given by convergence statistics; Find peak count statistic is the best to capture non-Gaussianities in the WL field and to break the sigma8-Omega_m degeneracy. This statistical analysis should be conducted in the convergence maps: (1) there exists fast algorithms to compute the convergence map for different scales, and (2) it offers the opportunity to denies the reconstructed convergence map, which improves non-Gaussian features extraction.
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