1306.4673
Atmospheric heat redistribution on hot Jupiters
Perez-Becker, Showman
IR light curves of transiting hot Jupiters present a trend in which the atmospheres of the hottest planets are less efficient at redistributing the stellar energy absorbed on their daysides--and thus have a larger day-night temperature contrast--than colder planets. No predictive atmospheric model has been published that identifies which dynamical mechanisms determine the atmospheric heat redistribution efficiently on tidally locked exoplanets. Present a two-layer shallow water model of the atmospheric dynamics on synchronously rotating planets that explains the observed trend. Model shows that planets with weak friction and weak irradiation exhibit a banded zonal flow with minimal day-night temperature differences, while models with strong irradiation and/or strong friction exhibit a day-night flow pattern with order-unity fractional day-night temperature differences. To interpret the model, develop a scaling theory that shows that the timescale for gravity waves to propagate horizontally over planetary scales, t_wave, plays a dominant role in controlling the transition from small to large temperature contrasts. This implies that hiat redistribution is governed by a wave-like process, similar to the one responsible for the weak temerature gradients in the Earth's tropics. When atmospheric drag can be neglected, the transition from small to large day-night temperature contrasts occurs when t_wave ~ sqrt(t_rad/Omega), where t_rad is the radiative relaxation time, and Omega is the planetary rotation frequency. Alternatively, this transition criterion can be expressed as t_rad ~ t_vert, where t_vert is the timescale for a fluid parcel to move vertically over the difference in day-night thickness. These results subsume the commonly used timescale comparison for estimating heat redistribution efficiency between t_rad and the global horizontal advection timescale, t_adv.
1306.4674
ARCONS: a 2024 pixel optical through near-IR Cryogenic imaging spectrophotometer
Mazin et al
Array Camera for Optical to Near-IR Spectrophotometry (design, construction and commissioning results). Based on Microwae Kinetic Inductance Detectors (MKIDs), a cryogenic detector capable of detecting single photons and measuring their energy without filters or gratings, similar to an X-ray microcalorimeter. MKIDs are nearly ideal, noiseless photon detectors, as they do not suffer from read noise or dark current and have nearly perfect cosmic ray rejection. ARCONS is an integral field spectrograph (IFS) containing a lens-coupled 2024 pixel MKID array yielding a 20"x20" FoV, and has been deployed on the Palomar 200" and Lick 120" telescopes for 24 nights of observing. Present initial results showing that ARCONS and its MKID arrays are now a fully operational and powerful tool for astronomical observations.
1306.4675
Source-position transformation -- an approximate invariance in strong gravitational lensing
Schneider, Sluse
Obstacle for GL in determine accurate masses of deflectors, or to determine precise estimates for the Hubble constant, is the degeneracy of lensing observables with respect to the mass-sheet transformation (MST). The MST is a global modification of the mass distribution which leaves all image positions, shapes and flux ratios invariant, but which changes the time delay. Show that another global transformation of lensing mass distributions exists which almost leaves image positions and flux ratios invariant, and of which the MST is a special case. Whereas for axi-symmetric lenses this source position transformation exactly reproduces all strong lensing observables, it does so only approximately for more general lens situations. Provide crude estimates for the accuracy with which the transformed mass distribution can reproduce the same image positions as the original lens model, and present an illustrative example of its performance. This new invariance transformation most likely is the reason why the same SL information can be accounted for with rather different mass models.
1306.4684
Cosmological parameters from weak lensing power spectrum and bispectrum tomography: including the non-Gaussian errors
Kayo, Takada
Re-examine a genuine power of WL bispectrum tomography for constraining cosmological parameters, when combined with the power spectrum tomography, based on the Fisher information matrix formalism. To account for the full information at 2- and 3-pt levels, include all the PS and bispectrum information built from all-scales (up to L_max=2000, fiducial). For the parameter forecast, use the halo model approach in Kay, Takada & Jain (2013) to model the non-Gaussian error covariances as well as the cross-covariance between the PS and the bispectrum, including the halo sample variance or the NL version of beat-coupling. Find that adding the bispectrum information leads to about 60% improvement in the DE FoM compared to the lensing PS tomography alone, for 3 redshift-bin tomography and Subaru-type survey probing galaxies at z_s~1. The improvement is equivalent to a 1.6 larger survey area. Thus results show that the bispectrum or more generally any 3-pt correlation based statistics carries complementary information on cosmological parameters to the PS. However, the improvement is modest compared to the previous claim derived using the Gaussian error assumption, and therefore results imply less additional information in even higher-order moments such as the 4-pt correlation function.
1306.4686
Cosmological constraints from galaxy clustering and the mass-to-number ratio of galaxy clusters: marginalizing over the physics of galaxy formation
Reddick, Tinker, Wechsler, Lu
Many cosmo info rely on connection between galaxies and DM. The distribution of galaxies is dependent on their formation and evolution as well as the cosmological model, and galaxy formation is still not a well-constrined process. Thus, methods that probe cosmology using galaxies as a tracer for DM must be able to accurately estimate the cosmological parameters without knowing the details of galaxy formation a priori. Apply this reasoning to the method of obtaining Omega_m and sigma_8 from galaxy clustering combined with the mass-to-number ratio of galaxy clusters. To test the sensitivity of this method to variations due to galaxy formation, consider several different [SAM?] models applied to the same cosmological DM simulation. The cosmological parameters are then estimated using the observables in each model, marginalizing over the parameters of the HOD. Find that for models where the galaxies can be well represented by a parameterized HOD, this method can successfully extract the desired cosmological parameters for a wide range of galaxy formation prescriptions.
1306.4732
Cosmology from gravitational lens time delays and Planck data
Suyu, Treu, Hilbert, Sonnenfeld, Auger, Blandford, Collett, Courbin, Fassnacht, Koopmans, Marshall, Meylan, Spiniello, Tewes
With LCDM, Planck data points to a H0 that is in tension with that measured by SL time delays and by local distance ladder. Could be from systematics, or (if systematics ruled out) a departure from LCDM, introducing e.g. a modest amount of spatial curvature, or a non-trivial DE EoS. Present analysis of RXJ1131-1231 with improvement in systematics analysis in the lens model density profile. Use more flexible gravitational lens models with baryonic and DM components, and found that the HST image with thousands of pixels within Einstein ring contains sufficient information to constrain the more flexible models. The total uncertainty on the time-delay distance is 6.5% for a single system, including the uncertainty over the two lens models considered. Thus proceed to combine the improved time-delay distance measurements with WMAP9 and Planck posteriors. In an open LCDM model, the data for RXJ1131-1231 in combination with Planck favor a flat universe with Omega_k=-0.01pm0.02 (68%CL). In a flat wCDM model, the combination of SL data and Planck yields w=-1.55pm0.2 (68% CL). [no mass sheet degeneracy mentioned! Mass sheet degeneracy still allows for the lens modeling to succeed, but with degenerate H0 values, so HST pixels and images are irrelevant with regards to this degeneracy.]
1306.4736
A curious relation between the flat cosmological model and the elliptic integral of the first kind
Meszaros, Ripa
Present luminosity distance-redshift relation for non-zero cosmological constant (for zero cosmological constant, relation is given by standard functions). Use definite integrals. The integration ends in the elliptic integral of the first kind. The results shows that no numerical integration is needed for the non-zero cosmological constant, if the universe is spatially flat.
1306.4786
A new way to measure supermassive black hole spin in accretion disc dominated active galaxies
Done, Jin, Middleton, Ward
Show that disc continuum fitting can be used to constrain BH spin in a subclass of Narrow Line Seyfert 1 (NLS1) AGN as their low mass and high mass accretion rate [?] means that the disc peaks at energies just below the soft X-ray bandpass. Apply the technique to the NLS1 PG1244+026, where the optical/UV/X-ray spectrum is consistent with being dominated by a standard disc component. This gives a best estimate for BH spin which is low, with a firm upper limit of a*<0.86. This contrasts with the recent X-ray determinations of (close to) maximal BH spin in other NLS1 based on relativistic smearing of the Fe profile. While data does not have sufficient statistics at high energy to give a good measure of BH spin from the Fe line profile, cosmological simulations predict that BHs with similar masses have similar growth histories and so should have similar spins.
1306.4963
Galaxy and mass assembly (GAMA): galaxy radial alignments in GAMA groups
Schneider, Cole, Frenk, Kelvin, Mandelbaum, ... et al
Constrain distributions of projected radial alignment angles of satellite galaxy shapes within GAMA group catalogue. Identify the galaxy groups using spectro-z and measure galaxy projected ellipticities from SDSS images. With a sample of 3,850 groups with 13,655 satellite galaxies with high quality shape measurements, find a less than 2-sigma signal of radial alignments in the mean projected ellipticity components and the projected position angle when using galaxy shape estimates optimized for WL measurements. Radial alignment measurement increases to greater than 3 sigma significance relative to the expectation for no alignments if we use 2d Sersic model fits to define galaxy orientations. Weak measurement of radial alignments is in conflict with predictions from DM N-body simulations, which we interpret as evidence for large mis-alignments of baryons and DM in group and cluster satellites. Within uncertainties, that are dominated by the small sample size, find only weak and marginally significant trends of the radial alignment angle distributions on projected distance from the group center, host halo mass, and redshift that could be consistent with a tidal torquing mechanism for radial alignments. Using lensing optimized shape estimators, estimate that IA of galaxy group members may contribute a systematic error to the mean differential projected surface mass density of groups inferred from WL observations by -1 pm 20% at scales around 300 kpc/h from the group centre assuming a photometric redshift RMS error of 10%, and given our group sample with median redshift of 0.17 and median virial masses 1e13 Msun/h.
1306.4968
The ALHANBRA survey: Bayesian photometric redshifts with 23 bands for 3 squared degrees
Molino, Benitez, et al
Advance Large Homogeneous Area Medium Band Redshift Astronomical (ALHAMBRA) survey has observed 8 different regions of the sky, including COSMOS, DEEP2, ELAIS, GOODS-N, SDSS and Groth fields using 20 continuous ~300A width filters covering the optical range, combining with deep JHKs imaging. Observations at Calar Alto 3.5M telescope, 0.25 sq deg FoV with optical and NIR instruments, ~700 hrs on-target science images. Photometric system designed to maximize the effective depth of the survey in terms of accurate spectral-type and photo-zs estimation along the capability of identification of relatively faint emission lines. Present multicolor photometry and photo-zs for ~438k galaxies, detected in synthetic F814W images, down to I~24.5 AB (takes in to account realistic noise estimates, and correcting PSF and aperture effects with software). The photometric ZP have been calibrated using stellar transformation equations and refined internally, using a new technique based on the highly robust photometric redshifts measured for emission line galaxies. Calculate photometric redshifts with the BPZ2 code, which includes new empirically calibrated templates and priors. Photo-zs have precision of dz/(1+z_s)=1% for I<22.5 and 1.4% for 22.5<I<24.5. Precisions of less than 0.5% are reached for the brighter spectro sample, showing the potential of medium-band photometric surveys. The global P(z) shows a mean redshift <z>=0.56 for I<22.5 AB and <z>=0.86 for I<24.5AB. The data presented here covers and effective area of 2.79 sq. deg, split into 14 strips of 5.5'x15.5' and represents ~32 hrs of on-target.
Cosmological constraints from galaxy clustering and the mass-to-number ratio of galaxy clusters: marginalizing over the physics of galaxy formation
Reddick, Tinker, Wechsler, Lu
Many cosmo info rely on connection between galaxies and DM. The distribution of galaxies is dependent on their formation and evolution as well as the cosmological model, and galaxy formation is still not a well-constrined process. Thus, methods that probe cosmology using galaxies as a tracer for DM must be able to accurately estimate the cosmological parameters without knowing the details of galaxy formation a priori. Apply this reasoning to the method of obtaining Omega_m and sigma_8 from galaxy clustering combined with the mass-to-number ratio of galaxy clusters. To test the sensitivity of this method to variations due to galaxy formation, consider several different [SAM?] models applied to the same cosmological DM simulation. The cosmological parameters are then estimated using the observables in each model, marginalizing over the parameters of the HOD. Find that for models where the galaxies can be well represented by a parameterized HOD, this method can successfully extract the desired cosmological parameters for a wide range of galaxy formation prescriptions.
1306.4732
Cosmology from gravitational lens time delays and Planck data
Suyu, Treu, Hilbert, Sonnenfeld, Auger, Blandford, Collett, Courbin, Fassnacht, Koopmans, Marshall, Meylan, Spiniello, Tewes
With LCDM, Planck data points to a H0 that is in tension with that measured by SL time delays and by local distance ladder. Could be from systematics, or (if systematics ruled out) a departure from LCDM, introducing e.g. a modest amount of spatial curvature, or a non-trivial DE EoS. Present analysis of RXJ1131-1231 with improvement in systematics analysis in the lens model density profile. Use more flexible gravitational lens models with baryonic and DM components, and found that the HST image with thousands of pixels within Einstein ring contains sufficient information to constrain the more flexible models. The total uncertainty on the time-delay distance is 6.5% for a single system, including the uncertainty over the two lens models considered. Thus proceed to combine the improved time-delay distance measurements with WMAP9 and Planck posteriors. In an open LCDM model, the data for RXJ1131-1231 in combination with Planck favor a flat universe with Omega_k=-0.01pm0.02 (68%CL). In a flat wCDM model, the combination of SL data and Planck yields w=-1.55pm0.2 (68% CL). [no mass sheet degeneracy mentioned! Mass sheet degeneracy still allows for the lens modeling to succeed, but with degenerate H0 values, so HST pixels and images are irrelevant with regards to this degeneracy.]
1306.4736
A curious relation between the flat cosmological model and the elliptic integral of the first kind
Meszaros, Ripa
Present luminosity distance-redshift relation for non-zero cosmological constant (for zero cosmological constant, relation is given by standard functions). Use definite integrals. The integration ends in the elliptic integral of the first kind. The results shows that no numerical integration is needed for the non-zero cosmological constant, if the universe is spatially flat.
1306.4786
A new way to measure supermassive black hole spin in accretion disc dominated active galaxies
Done, Jin, Middleton, Ward
Show that disc continuum fitting can be used to constrain BH spin in a subclass of Narrow Line Seyfert 1 (NLS1) AGN as their low mass and high mass accretion rate [?] means that the disc peaks at energies just below the soft X-ray bandpass. Apply the technique to the NLS1 PG1244+026, where the optical/UV/X-ray spectrum is consistent with being dominated by a standard disc component. This gives a best estimate for BH spin which is low, with a firm upper limit of a*<0.86. This contrasts with the recent X-ray determinations of (close to) maximal BH spin in other NLS1 based on relativistic smearing of the Fe profile. While data does not have sufficient statistics at high energy to give a good measure of BH spin from the Fe line profile, cosmological simulations predict that BHs with similar masses have similar growth histories and so should have similar spins.
1306.4963
Galaxy and mass assembly (GAMA): galaxy radial alignments in GAMA groups
Schneider, Cole, Frenk, Kelvin, Mandelbaum, ... et al
Constrain distributions of projected radial alignment angles of satellite galaxy shapes within GAMA group catalogue. Identify the galaxy groups using spectro-z and measure galaxy projected ellipticities from SDSS images. With a sample of 3,850 groups with 13,655 satellite galaxies with high quality shape measurements, find a less than 2-sigma signal of radial alignments in the mean projected ellipticity components and the projected position angle when using galaxy shape estimates optimized for WL measurements. Radial alignment measurement increases to greater than 3 sigma significance relative to the expectation for no alignments if we use 2d Sersic model fits to define galaxy orientations. Weak measurement of radial alignments is in conflict with predictions from DM N-body simulations, which we interpret as evidence for large mis-alignments of baryons and DM in group and cluster satellites. Within uncertainties, that are dominated by the small sample size, find only weak and marginally significant trends of the radial alignment angle distributions on projected distance from the group center, host halo mass, and redshift that could be consistent with a tidal torquing mechanism for radial alignments. Using lensing optimized shape estimators, estimate that IA of galaxy group members may contribute a systematic error to the mean differential projected surface mass density of groups inferred from WL observations by -1 pm 20% at scales around 300 kpc/h from the group centre assuming a photometric redshift RMS error of 10%, and given our group sample with median redshift of 0.17 and median virial masses 1e13 Msun/h.
1306.4968
The ALHANBRA survey: Bayesian photometric redshifts with 23 bands for 3 squared degrees
Molino, Benitez, et al
Advance Large Homogeneous Area Medium Band Redshift Astronomical (ALHAMBRA) survey has observed 8 different regions of the sky, including COSMOS, DEEP2, ELAIS, GOODS-N, SDSS and Groth fields using 20 continuous ~300A width filters covering the optical range, combining with deep JHKs imaging. Observations at Calar Alto 3.5M telescope, 0.25 sq deg FoV with optical and NIR instruments, ~700 hrs on-target science images. Photometric system designed to maximize the effective depth of the survey in terms of accurate spectral-type and photo-zs estimation along the capability of identification of relatively faint emission lines. Present multicolor photometry and photo-zs for ~438k galaxies, detected in synthetic F814W images, down to I~24.5 AB (takes in to account realistic noise estimates, and correcting PSF and aperture effects with software). The photometric ZP have been calibrated using stellar transformation equations and refined internally, using a new technique based on the highly robust photometric redshifts measured for emission line galaxies. Calculate photometric redshifts with the BPZ2 code, which includes new empirically calibrated templates and priors. Photo-zs have precision of dz/(1+z_s)=1% for I<22.5 and 1.4% for 22.5<I<24.5. Precisions of less than 0.5% are reached for the brighter spectro sample, showing the potential of medium-band photometric surveys. The global P(z) shows a mean redshift <z>=0.56 for I<22.5 AB and <z>=0.86 for I<24.5AB. The data presented here covers and effective area of 2.79 sq. deg, split into 14 strips of 5.5'x15.5' and represents ~32 hrs of on-target.
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