1309.1820
Is the Sunyaev-Zeldovich effect responsible for the observed steepening in the spectrum of the Coma radio halo?
Brunetti et al
The spectrum of the radio halo in the Coma cluster is measured over almost two decades in frequency. The current radio data show a steepening of the spectrum at higher frequencies, which has implications for models of the radio halo origin. There is an on-going debate on the possibility that the observed steepening is not intrinsic to the emitted radiation, but is instead caused by the SZ effect. Recently, the Planck satellite measured the SZ signal and its spatial distribution in the Coma cluster allowing to test this hypothesis. Using the Planck results, calculate the modification of the radio halo spectrum by the SZ effect in three different ways. With the first two methods measure the SZ-decrement within the aperture radii used for flux measurements of the halo at the different frequencies. First, adopt the global compilation of data, and a reference aperture radius consistent with those used by the various authors. Second, sue the available brightness profiles of the halo at different frequencies to derive the spectrum within two fixed apertures, and derived the SZ-decrement using these apertures. As a third method, use the quasi-linear correlation between the y and the radio-halo brightness at 330 MHz discovered by Planck to derive the modification of the radio spectrum by the SZ-decreement in a way that is almost independent of the adopted aperture radius. Found that the spectral modification induced by the SZ-decrement is 4-5 times smaller than that necessary to explain the observed steepening. Consequently, a break or cut-off in the spectrum of the emitting electrons is necessary to explain current data. ALso show that, if a steepening is absent from the emitted spectrum, future deep observations at 5 GHz with single dishes are expected to measure a halo flux in a 40 arcmin radius that would be 7-8 times higher than currently seen. [does this mean that this conclusion is inconsistent?]
1309.1827
Towards reconstruction of unlensed, intrinsic CMB power spectra from lensed map
Pal, Padmanabhan, Pal
Use matrix inversion technique to reconstruct intrinsic CMB power directly from lensed data for both flat sky and full sky analyses. In principle, this methodology may help in subtracting out the E-mode lensing contribution in order to obtain the intrinsic B-mod power, thereby resolving the degeneracy between CMB E and B polarizations, when a more realistic situation can be taken into account.
1309.2045
First measurement of gravitational lensing by cosmic voids in SDSS
Melchior, Sutter, Sheldon, Krause, Wandelt
Report first measurement of the diminutive lensing signal arising from matter underdensities associated with cosmic voids. While undetectable individually, by stacking the WL around 901 voids detected in SDSS DR7 by Sutter+, find substantial evidence for a depression of the lensing signal compared to the cosmic mean. This depression is most pronounced at the void radius, in agreement with analytical models of void matter profiles. Even with the largest void sample and imaging survey available today, cannot put useful constraints on the radial DM void profile. Invite independent investigations of this finding by releasing data and analysis code to the public on GitHub.
1309.2072
Point spread function due to multiple scattering of light in the atmosphere
Pekala, Wilczynski
The atmospheric scattering if light has a significant influence on results of optical observations of air showers. It causes attenuation of direct light from the shower, but also contributes a delayed signal to the observed light. The scattering of light therefore should be accounted for, both in simulations of air shower detection and reconstruction of observed events. In this work a Monte Carlo simulation of multiple scattering of light has been used to determine the contribution of the scattered light in observations of a point source of light. Results of the simulations and a parameterization of the angular distribution of the scattered light contributions to the observed signal (the PSF) are presented. [which part of EM? apply to optical too? or is this HE?]
1309.2159
Rotation periods, variability properties and ages for Kepler exoplanet candidate host stars
Walkowicz, Basri
Report rotation periods, variability characteristics, gyrochronological ages for ~950 of the Kepler Object of Interest host stars. Find a wide dispersion in the amplitude of the photometric variability as a function of rotation, likely indicating differences in the spot distribution among stars. Use these rotation periods in combination with published spectroscopic measurements of vsini and stellar parameters to derive the stellar inclination in the line-of-sight, and find a number of systems with possible spin-orbit misalignment. Additionally find several systems with close-in planet candidates whose stellar rotation periods are equal to or twice the planetary period, indicative of possible tidal interactions between these planets and their parent stars. If these systems survive validation to become confirmed planets, they will provide important clues to the evolutionary history of these systems.
1309.2170
A multi-scale filament extraction method: getfilaments
Men'shchikov
As the title says. A mutli-scale, multi-wavelength filament extraction method: getfilament. Solves the problem in automated source extraction due to fluctuating BG and noise, as well as from the filamentary structure itself. Now the filaments extracted by getfilaments are now subtracted by get sources from detection images during source extraction, greatly reducing the chances of contaminating catalogs with spurious sources.
1309.2206
Clues to the formation of lenticular galaxies using spectroscopic bulge-disk decomposition
Johnston et al
Lenticular galaxies have long been thought of as evolved spirals, but the processes involved to quench the SF are still unclear. By studying the individual SFHs of the bulges and the disks of lenticulars, it is possible to look for clues to the processes that triggered their transformation from spirals. To accomplish this feat, present a new method for spectroscopic bulge-disk decomposition, in which a long-slit spectrum is decomposed into two one-dimensional spectra representing purely the bulge and disk light. Present preliminary results from applying this method to lenticular galaxies in the Virgo and Fornax clusters; show that the most recent SF activity in these galaxies occurred within the bulges. Also find that the SF timescales of the bulges are longer than the disks, and that more massive galaxies take longer to lose their gas during the transformation. These results point towards slow processes, such as ram-pressure stripping or harassment, being the mechanism responsible for the quenching of SF in spirals, followed by a burst of SF in the central regions from the gas that has been funneled inwards through the disk.
Is the Sunyaev-Zeldovich effect responsible for the observed steepening in the spectrum of the Coma radio halo?
Brunetti et al
The spectrum of the radio halo in the Coma cluster is measured over almost two decades in frequency. The current radio data show a steepening of the spectrum at higher frequencies, which has implications for models of the radio halo origin. There is an on-going debate on the possibility that the observed steepening is not intrinsic to the emitted radiation, but is instead caused by the SZ effect. Recently, the Planck satellite measured the SZ signal and its spatial distribution in the Coma cluster allowing to test this hypothesis. Using the Planck results, calculate the modification of the radio halo spectrum by the SZ effect in three different ways. With the first two methods measure the SZ-decrement within the aperture radii used for flux measurements of the halo at the different frequencies. First, adopt the global compilation of data, and a reference aperture radius consistent with those used by the various authors. Second, sue the available brightness profiles of the halo at different frequencies to derive the spectrum within two fixed apertures, and derived the SZ-decrement using these apertures. As a third method, use the quasi-linear correlation between the y and the radio-halo brightness at 330 MHz discovered by Planck to derive the modification of the radio spectrum by the SZ-decreement in a way that is almost independent of the adopted aperture radius. Found that the spectral modification induced by the SZ-decrement is 4-5 times smaller than that necessary to explain the observed steepening. Consequently, a break or cut-off in the spectrum of the emitting electrons is necessary to explain current data. ALso show that, if a steepening is absent from the emitted spectrum, future deep observations at 5 GHz with single dishes are expected to measure a halo flux in a 40 arcmin radius that would be 7-8 times higher than currently seen. [does this mean that this conclusion is inconsistent?]
1309.1827
Towards reconstruction of unlensed, intrinsic CMB power spectra from lensed map
Pal, Padmanabhan, Pal
Use matrix inversion technique to reconstruct intrinsic CMB power directly from lensed data for both flat sky and full sky analyses. In principle, this methodology may help in subtracting out the E-mode lensing contribution in order to obtain the intrinsic B-mod power, thereby resolving the degeneracy between CMB E and B polarizations, when a more realistic situation can be taken into account.
1309.2045
First measurement of gravitational lensing by cosmic voids in SDSS
Melchior, Sutter, Sheldon, Krause, Wandelt
Report first measurement of the diminutive lensing signal arising from matter underdensities associated with cosmic voids. While undetectable individually, by stacking the WL around 901 voids detected in SDSS DR7 by Sutter+, find substantial evidence for a depression of the lensing signal compared to the cosmic mean. This depression is most pronounced at the void radius, in agreement with analytical models of void matter profiles. Even with the largest void sample and imaging survey available today, cannot put useful constraints on the radial DM void profile. Invite independent investigations of this finding by releasing data and analysis code to the public on GitHub.
1309.2072
Point spread function due to multiple scattering of light in the atmosphere
Pekala, Wilczynski
The atmospheric scattering if light has a significant influence on results of optical observations of air showers. It causes attenuation of direct light from the shower, but also contributes a delayed signal to the observed light. The scattering of light therefore should be accounted for, both in simulations of air shower detection and reconstruction of observed events. In this work a Monte Carlo simulation of multiple scattering of light has been used to determine the contribution of the scattered light in observations of a point source of light. Results of the simulations and a parameterization of the angular distribution of the scattered light contributions to the observed signal (the PSF) are presented. [which part of EM? apply to optical too? or is this HE?]
1309.2159
Rotation periods, variability properties and ages for Kepler exoplanet candidate host stars
Walkowicz, Basri
Report rotation periods, variability characteristics, gyrochronological ages for ~950 of the Kepler Object of Interest host stars. Find a wide dispersion in the amplitude of the photometric variability as a function of rotation, likely indicating differences in the spot distribution among stars. Use these rotation periods in combination with published spectroscopic measurements of vsini and stellar parameters to derive the stellar inclination in the line-of-sight, and find a number of systems with possible spin-orbit misalignment. Additionally find several systems with close-in planet candidates whose stellar rotation periods are equal to or twice the planetary period, indicative of possible tidal interactions between these planets and their parent stars. If these systems survive validation to become confirmed planets, they will provide important clues to the evolutionary history of these systems.
1309.2170
A multi-scale filament extraction method: getfilaments
Men'shchikov
As the title says. A mutli-scale, multi-wavelength filament extraction method: getfilament. Solves the problem in automated source extraction due to fluctuating BG and noise, as well as from the filamentary structure itself. Now the filaments extracted by getfilaments are now subtracted by get sources from detection images during source extraction, greatly reducing the chances of contaminating catalogs with spurious sources.
1309.2206
Clues to the formation of lenticular galaxies using spectroscopic bulge-disk decomposition
Johnston et al
Lenticular galaxies have long been thought of as evolved spirals, but the processes involved to quench the SF are still unclear. By studying the individual SFHs of the bulges and the disks of lenticulars, it is possible to look for clues to the processes that triggered their transformation from spirals. To accomplish this feat, present a new method for spectroscopic bulge-disk decomposition, in which a long-slit spectrum is decomposed into two one-dimensional spectra representing purely the bulge and disk light. Present preliminary results from applying this method to lenticular galaxies in the Virgo and Fornax clusters; show that the most recent SF activity in these galaxies occurred within the bulges. Also find that the SF timescales of the bulges are longer than the disks, and that more massive galaxies take longer to lose their gas during the transformation. These results point towards slow processes, such as ram-pressure stripping or harassment, being the mechanism responsible for the quenching of SF in spirals, followed by a burst of SF in the central regions from the gas that has been funneled inwards through the disk.
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