1306.5235
PAH and mid-infrared continuum emission in a z>4 submillimeter galaxy
Riechers, et al
Investigation provides an improved understanding of the energy sources that power these systems (submm galaxies), which represent the extreme and of massive galaxy formation at early cosmic times. PAH emission at z>4 detected, strength of this emission feature is consistent with a very high SFR of ~1800 Msun/yr. This intense starburst powers at least ~1/3 of the faint underlying 6um continuum emission, with an additional (perhaps dominant) contribution due to a power-law-like hot dust source, which is interpreted to likely be a faint, dust-obscured AGN. Despite the strong power-law component enhancing the MIR continuum emission, the intense SB associated with the photon-dominated regions that give rise to the PA emission appears to dominate the total energy output in the IR. Also find evidence (by comparing upper X-ray limit to 6um AGN continuum luminosity) that the previously undetected AGN in this source is Compton-thick, consistent with the finding at optical/IR wavelengths that the galaxy and its nucleus are heavily dust-obscured.
1306.5236
Star/galaxy separation at faint magnitudes: application to a simulated Dark Energy Survey
Soumagnac, Abdalla, Lahav, Kirk, ... Bertin, Rowe, Annis, Busha, ... Jarvis [!], Lin, Percival, ... Wechsler, Yanny et al
Address the problem of separating stars from the galaxies in future large photometric surveys. Focus analysis on simulations of DES. Derive the science requirements on star/galaxy separation, for measurement of cosmo parameters with WL and LSS probes. Requirements are dictated by the need to control both the statistical and systematic errors on the cosmological parameters, and by PSF calibration [for WL]. Formulate the requirements in terms of the completeness and purity provided by a given star/galaxy classifier. In order to achieve these requirements at faint magnitudes, propose a new method for star/galaxy separation. First use PCA to outline the correlations between the objects parameters and extract from it the most relevant information. Then use the reduced set of parameters as input to an Artificial Neural Network. This multi-parameter approach improves upon purely morphometric classifiers (such as the classifier implemented in SExtractor), especially at faint magnitudes: it increases the purity by up to 20% for stars and by up to 12% for galaxies, at i-magnitude fainter than 23.
1306.5240
Galaxy halo truncation and giant arc surface brightness reconstruction in the cluster MACSJ1206.2-0847
Eichner, Seitz, Suyu, ... Umetsu, Zitrin, Coe, ... Koekemoer, Broadhurst, Moustakas, et al
Analyze mass distribution of this cluster, especially focusing on the halo properties of its cluster members. The cluster appears relaxed in its X-ray emission, but has significant amounts of intracluster light which is not centrally concentrated, suggesting that galaxy-scale interactions are still ongoing despite the overall relaxed state. The cluster lenses 12 background galaxies into multiple images and one galaxy at z=1.033 into a giant arc and its counterimage. The multiple image positions and the surface brightness distribution (SFB) of the arc which is bent around several cluster members are sensitive to the cluster galaxy halo properties. Model the cluster mass distribution with a NFW profile and the galaxy haloes with two parameters for the mass normalization and extent of a reference halo assuming scalings with their observed NIR-light. Match the multiple image positions at an r.m.s. level of 0.85"; construct the SFB distribution of the arc in several filters to a remarkable accuracy based on this cluster model. [still no mass-sheet degeneracy info!] The length scale where the enclosed galaxy halo mass is best constrained is about 5 effective radii -- a scale in between those accessible to dynamical and field SL mass estimates on one hand and gg WL results on the other hand. The velocity dispersion and halo size of a galaxy with m_160W,AB=19.2 or M_B,Vega=-20.7 are sigma=150 km/s and r~26pm6kpc, indicating that the halos of the cluster galaxies are tidally stripped. Also reconstruct the unlensed source (which is smaller by a factor of ~5.8 in area), demonstrating the increase of morphological information due to lensing and conclude that this galaxy has likely SF spiral arms with a red (older) central component.
1306.5324
Density mapping with weak lensing and phase information
Szepietowski, Bacon, Dietrich, Busha, Wechsler, Melchior
Investigate reconstruction the projected density field using the complementarity of WL (weak S/N, but unbiased) and galaxy positions (high resolution, but biased tracer). Propose a maximum-probability reconstruction of the 2d lensing convergence with a likelihood term for shear data and a prior on the Fourier phases constructed from the galaxy positions. By considering only the phases of the galaxy field, evade the unknown value of the bias and allow it to be calibrated by lensing on a mode-by-mode basis. Apply this method to a realistic simulated galaxy shear catalogue, find that a weak prior on phases provides a good quality reconstruction down to scales beyond l=1000, far in to the noise domain of the lensing signal alone.
1306.5333
A high erath, lunar resonant orbit for lower cost space science missions
Gangestad, Henning, Persinger, Ricker
NASA astrophysics robotic science missions often require continuous, unobstructed FoV of the celestial sphere and orbits that provide stable thermal-and attitude-control environments. To date, the more expensive "flagship" missions use the second Earth/Sun Lagrange point (L2) approximately 1.5 million km from the Earth outside the orbit of the Moon or a "drift away" orbit to distances >10 Mkm. A High Earth Orbit (HEO) offers similar advantages with regard to continuous, unobstructed FoV and a thermally stable environment with minimal station-keeping requirements. The "P/2-HEO", an orbit in 2:1 resonance with the orbit of the Moon, also provides the opportunity for data downlink at orbit perigee distances close to the Earth allowing for lower-cost communications systems. The P/2-HEO oscillates on the order of 12 years and trades orbit eccentricity for orbit inclination. This orbit variability can be selected for optimum spacecraft performance by proper choice of the conditions using a lunar flyby for gravitational assist. The lunar flyby and the shorter distance for science data downlink offer lower cost astrophysics missions the advantages of the more expensive L2 or "drift away" orbits. [WMAP, Planck at L2; Kepler is in a "drift away" orbit around the Sun.]
1306.5367
Beam patterns of the five hundred metre aperture spherical telescope: optimization
Dong, Han
FAST uses adaptive spherical panels to realize the huge collecting area for radio waves. Explore the optimal parameters for the curvature radius of spherical panels and the focal distance by comparison of the calculated beam patterns. Show that the get the best beam shape and maximum gain, the optimal curvature radius of panels is around 300m, and a small shift of focal distance of a few cm is needed. The aperture efficiency can be improved by ~10 at 3GHz by this small shift. Also try to optimize the panel positioning for the best beam, and find that panel shifts of a few mm can improve the beam pattern by a similar extent. Results indicate that the accurate control of the feed and panel position to the mm level is very crucial to the stability of FAST performance.
1306.5407
Photometric study of five open star clusters
Lata et al
As the title says; UBVRI photometry of 5 open clusters. Fundamental cluster parameters such as FG reddening E(B-V), distance, and age have been derived by means of the observed 2 color and color-magntiude diagrams, coupled to comparisons with theoretical models. E(B-V) values range from 0.55 to 0.74 mag, while ages derived for these clusters range from ~10 to ~500 Myr. Studied the spatial structure, mass fraction and mass segregation effects. The present study shows that evaporation of low mass stars from the halo of the clusters increases as they evolve.
1306.5534
Constraints on dark matter in the solar system
Pitjev, Pitjeva
Searched for and estimated the possible gravitational influence of DM in the Solar System based on the EPM 2011 planetary ephemerides using about 677k positional observations of planets and spacecraft. Most of the observations belong to present-day ranging measurements. Estimates of the DM density and mass at various distances from the Sun are generally overridden by their errors (sigma). This suggests that the density of DM rho_dm, if present, is very low and is much less than the currently achieved error of these parameters. We have found that rho_dm is less than 1.1e-20 g/cm3 at the orbital distance of Saturn, <1.4e-20 g/cm3 at the orbital distance of Mars, and <1.4e-19 g/cm3 at the orbital distance of the Earth. Also have considered the case of a possible concentration of DM to the Solar system center. The DM mass in the sphere within Saturn's orbit should be less than 1.7e-10 M_sun even if its possible concentration is taken into account.
1306.5544
Constraints on neutrino masses from Planck and galaxy clustering data
Giusarma, de Putter, Ho, Mena
Spectroscopic galaxy clustering measurements improve significantly the existing neutrino mass bounds from Planck data in LCDM. Find sum m_nu < 0.39 eV at 95% CL by combining 3d PS with Planck CMB (including lensing) and WMAP9 polarization. Robust neutrino mass constraints can be obtained without the addition of the prior on the Hubble constant from HST. In extended cosmological scenarios with a DE fluid or with non flat geometries, galaxy clustering measurements are essential to pin down the neutrino mass bounds, providing the majority of cases better results than those obtained from the associated measurement of the Baryon Acoustic Oscillation scale only. In the presence of a freely varying (constant) DE EoS, find sum m_nu<0.49 eV at 95% CL for the combination of the 3d PS with Planck CMB data (with lensing included) and WMAP9 polarization measurements. This same data combination in non flat geometries provides the neutrino mass bound sum m_nu<0.35 eV at 95% CL.
1306.5730
How close is Earth to a runaway greenhouse?
Ramirez, Kopparapu, Lindner, Kasting
Recent calculations suggest that the inner edge of the habitable zone around the Sun could be as far out as 0.99 AU--much closer to the orbit of Earth than had been thought. This reopens the question of whether future increases in atmospheric CO2 might trigger a runaway or moist greenhouse. A runaway greenhouse implies complete ocean vaporization; a moist greenhouse implies that the stratosphere becomes wet, leading to ocean loss via hydrogen escape to space. Previous studies had indicated that neither a moist nor a runaway greenhouse could be triggered by CO2 increases of any magnitude. Revisit this question with a 1d climate model that includes updated absorption coefficients for CO2 and H2O, along with an improved parameterization of tropospheric relative humidity. Find that a runaway greenhouse is still precluded. However, a moist greenhouse could conceivably be triggered by an 11-fold increase in atmospheric CO2, and humans could be subject to fatal heat stress for CO2 increases of (4-8)-fold. When this relative humidity parameterization is used in the habitable zone calculations, the inner edge moves inward to 0.97 AU. Both of these calculations remain overly pessimistic, as relative humidity may increase more slowly than assumed and cloud feedback is probably negative in this temperature regime. Reexamine the lifetime of the biosphere against solar luminosity increases and show that older calculations suggesting ~0.5 Ga and 0.9 Ga as the lifetime for C3 and C4 photosynthesis are still approximately correct. Improvements in all of these estimates could be made with a properly formulated 3d climate model that can self-consistently calculate relative humidity and cloud feedbacks.
PAH and mid-infrared continuum emission in a z>4 submillimeter galaxy
Riechers, et al
Investigation provides an improved understanding of the energy sources that power these systems (submm galaxies), which represent the extreme and of massive galaxy formation at early cosmic times. PAH emission at z>4 detected, strength of this emission feature is consistent with a very high SFR of ~1800 Msun/yr. This intense starburst powers at least ~1/3 of the faint underlying 6um continuum emission, with an additional (perhaps dominant) contribution due to a power-law-like hot dust source, which is interpreted to likely be a faint, dust-obscured AGN. Despite the strong power-law component enhancing the MIR continuum emission, the intense SB associated with the photon-dominated regions that give rise to the PA emission appears to dominate the total energy output in the IR. Also find evidence (by comparing upper X-ray limit to 6um AGN continuum luminosity) that the previously undetected AGN in this source is Compton-thick, consistent with the finding at optical/IR wavelengths that the galaxy and its nucleus are heavily dust-obscured.
1306.5236
Star/galaxy separation at faint magnitudes: application to a simulated Dark Energy Survey
Soumagnac, Abdalla, Lahav, Kirk, ... Bertin, Rowe, Annis, Busha, ... Jarvis [!], Lin, Percival, ... Wechsler, Yanny et al
Address the problem of separating stars from the galaxies in future large photometric surveys. Focus analysis on simulations of DES. Derive the science requirements on star/galaxy separation, for measurement of cosmo parameters with WL and LSS probes. Requirements are dictated by the need to control both the statistical and systematic errors on the cosmological parameters, and by PSF calibration [for WL]. Formulate the requirements in terms of the completeness and purity provided by a given star/galaxy classifier. In order to achieve these requirements at faint magnitudes, propose a new method for star/galaxy separation. First use PCA to outline the correlations between the objects parameters and extract from it the most relevant information. Then use the reduced set of parameters as input to an Artificial Neural Network. This multi-parameter approach improves upon purely morphometric classifiers (such as the classifier implemented in SExtractor), especially at faint magnitudes: it increases the purity by up to 20% for stars and by up to 12% for galaxies, at i-magnitude fainter than 23.
1306.5240
Galaxy halo truncation and giant arc surface brightness reconstruction in the cluster MACSJ1206.2-0847
Eichner, Seitz, Suyu, ... Umetsu, Zitrin, Coe, ... Koekemoer, Broadhurst, Moustakas, et al
Analyze mass distribution of this cluster, especially focusing on the halo properties of its cluster members. The cluster appears relaxed in its X-ray emission, but has significant amounts of intracluster light which is not centrally concentrated, suggesting that galaxy-scale interactions are still ongoing despite the overall relaxed state. The cluster lenses 12 background galaxies into multiple images and one galaxy at z=1.033 into a giant arc and its counterimage. The multiple image positions and the surface brightness distribution (SFB) of the arc which is bent around several cluster members are sensitive to the cluster galaxy halo properties. Model the cluster mass distribution with a NFW profile and the galaxy haloes with two parameters for the mass normalization and extent of a reference halo assuming scalings with their observed NIR-light. Match the multiple image positions at an r.m.s. level of 0.85"; construct the SFB distribution of the arc in several filters to a remarkable accuracy based on this cluster model. [still no mass-sheet degeneracy info!] The length scale where the enclosed galaxy halo mass is best constrained is about 5 effective radii -- a scale in between those accessible to dynamical and field SL mass estimates on one hand and gg WL results on the other hand. The velocity dispersion and halo size of a galaxy with m_160W,AB=19.2 or M_B,Vega=-20.7 are sigma=150 km/s and r~26pm6kpc, indicating that the halos of the cluster galaxies are tidally stripped. Also reconstruct the unlensed source (which is smaller by a factor of ~5.8 in area), demonstrating the increase of morphological information due to lensing and conclude that this galaxy has likely SF spiral arms with a red (older) central component.
1306.5324
Density mapping with weak lensing and phase information
Szepietowski, Bacon, Dietrich, Busha, Wechsler, Melchior
Investigate reconstruction the projected density field using the complementarity of WL (weak S/N, but unbiased) and galaxy positions (high resolution, but biased tracer). Propose a maximum-probability reconstruction of the 2d lensing convergence with a likelihood term for shear data and a prior on the Fourier phases constructed from the galaxy positions. By considering only the phases of the galaxy field, evade the unknown value of the bias and allow it to be calibrated by lensing on a mode-by-mode basis. Apply this method to a realistic simulated galaxy shear catalogue, find that a weak prior on phases provides a good quality reconstruction down to scales beyond l=1000, far in to the noise domain of the lensing signal alone.
1306.5333
A high erath, lunar resonant orbit for lower cost space science missions
Gangestad, Henning, Persinger, Ricker
NASA astrophysics robotic science missions often require continuous, unobstructed FoV of the celestial sphere and orbits that provide stable thermal-and attitude-control environments. To date, the more expensive "flagship" missions use the second Earth/Sun Lagrange point (L2) approximately 1.5 million km from the Earth outside the orbit of the Moon or a "drift away" orbit to distances >10 Mkm. A High Earth Orbit (HEO) offers similar advantages with regard to continuous, unobstructed FoV and a thermally stable environment with minimal station-keeping requirements. The "P/2-HEO", an orbit in 2:1 resonance with the orbit of the Moon, also provides the opportunity for data downlink at orbit perigee distances close to the Earth allowing for lower-cost communications systems. The P/2-HEO oscillates on the order of 12 years and trades orbit eccentricity for orbit inclination. This orbit variability can be selected for optimum spacecraft performance by proper choice of the conditions using a lunar flyby for gravitational assist. The lunar flyby and the shorter distance for science data downlink offer lower cost astrophysics missions the advantages of the more expensive L2 or "drift away" orbits. [WMAP, Planck at L2; Kepler is in a "drift away" orbit around the Sun.]
1306.5367
Beam patterns of the five hundred metre aperture spherical telescope: optimization
Dong, Han
FAST uses adaptive spherical panels to realize the huge collecting area for radio waves. Explore the optimal parameters for the curvature radius of spherical panels and the focal distance by comparison of the calculated beam patterns. Show that the get the best beam shape and maximum gain, the optimal curvature radius of panels is around 300m, and a small shift of focal distance of a few cm is needed. The aperture efficiency can be improved by ~10 at 3GHz by this small shift. Also try to optimize the panel positioning for the best beam, and find that panel shifts of a few mm can improve the beam pattern by a similar extent. Results indicate that the accurate control of the feed and panel position to the mm level is very crucial to the stability of FAST performance.
1306.5407
Photometric study of five open star clusters
Lata et al
As the title says; UBVRI photometry of 5 open clusters. Fundamental cluster parameters such as FG reddening E(B-V), distance, and age have been derived by means of the observed 2 color and color-magntiude diagrams, coupled to comparisons with theoretical models. E(B-V) values range from 0.55 to 0.74 mag, while ages derived for these clusters range from ~10 to ~500 Myr. Studied the spatial structure, mass fraction and mass segregation effects. The present study shows that evaporation of low mass stars from the halo of the clusters increases as they evolve.
1306.5534
Constraints on dark matter in the solar system
Pitjev, Pitjeva
Searched for and estimated the possible gravitational influence of DM in the Solar System based on the EPM 2011 planetary ephemerides using about 677k positional observations of planets and spacecraft. Most of the observations belong to present-day ranging measurements. Estimates of the DM density and mass at various distances from the Sun are generally overridden by their errors (sigma). This suggests that the density of DM rho_dm, if present, is very low and is much less than the currently achieved error of these parameters. We have found that rho_dm is less than 1.1e-20 g/cm3 at the orbital distance of Saturn, <1.4e-20 g/cm3 at the orbital distance of Mars, and <1.4e-19 g/cm3 at the orbital distance of the Earth. Also have considered the case of a possible concentration of DM to the Solar system center. The DM mass in the sphere within Saturn's orbit should be less than 1.7e-10 M_sun even if its possible concentration is taken into account.
1306.5544
Constraints on neutrino masses from Planck and galaxy clustering data
Giusarma, de Putter, Ho, Mena
Spectroscopic galaxy clustering measurements improve significantly the existing neutrino mass bounds from Planck data in LCDM. Find sum m_nu < 0.39 eV at 95% CL by combining 3d PS with Planck CMB (including lensing) and WMAP9 polarization. Robust neutrino mass constraints can be obtained without the addition of the prior on the Hubble constant from HST. In extended cosmological scenarios with a DE fluid or with non flat geometries, galaxy clustering measurements are essential to pin down the neutrino mass bounds, providing the majority of cases better results than those obtained from the associated measurement of the Baryon Acoustic Oscillation scale only. In the presence of a freely varying (constant) DE EoS, find sum m_nu<0.49 eV at 95% CL for the combination of the 3d PS with Planck CMB data (with lensing included) and WMAP9 polarization measurements. This same data combination in non flat geometries provides the neutrino mass bound sum m_nu<0.35 eV at 95% CL.
1306.5730
How close is Earth to a runaway greenhouse?
Ramirez, Kopparapu, Lindner, Kasting
Recent calculations suggest that the inner edge of the habitable zone around the Sun could be as far out as 0.99 AU--much closer to the orbit of Earth than had been thought. This reopens the question of whether future increases in atmospheric CO2 might trigger a runaway or moist greenhouse. A runaway greenhouse implies complete ocean vaporization; a moist greenhouse implies that the stratosphere becomes wet, leading to ocean loss via hydrogen escape to space. Previous studies had indicated that neither a moist nor a runaway greenhouse could be triggered by CO2 increases of any magnitude. Revisit this question with a 1d climate model that includes updated absorption coefficients for CO2 and H2O, along with an improved parameterization of tropospheric relative humidity. Find that a runaway greenhouse is still precluded. However, a moist greenhouse could conceivably be triggered by an 11-fold increase in atmospheric CO2, and humans could be subject to fatal heat stress for CO2 increases of (4-8)-fold. When this relative humidity parameterization is used in the habitable zone calculations, the inner edge moves inward to 0.97 AU. Both of these calculations remain overly pessimistic, as relative humidity may increase more slowly than assumed and cloud feedback is probably negative in this temperature regime. Reexamine the lifetime of the biosphere against solar luminosity increases and show that older calculations suggesting ~0.5 Ga and 0.9 Ga as the lifetime for C3 and C4 photosynthesis are still approximately correct. Improvements in all of these estimates could be made with a properly formulated 3d climate model that can self-consistently calculate relative humidity and cloud feedbacks.
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