Day 1270

Wednesday.


1706.03770
Testing for a redshift evolution of Type Ia supernovae using the strongly lensed PS1-10afx at z=1.4
Petrushevska, et al

The light from stint supernovae She can be magnified through gravitational lensing when a foreground galaxy is located along the line of sight.  This line-up allows for detailed studies of SNe at high redshift that otherwise would not be possible.  Spectroscopic observations of lensed high-z She Ia are of particular interest since they can be used to test for evolution of their intrinsic properties.  The use of SNe Ia for probing the cosmic expansion history has proven to be an extremely powerful method for measuring cosmological parameters.  However, if systematic z-dependent properties are found, their usefulness for future surveys could be challenged.  Investigate whether the spectroscopic properties of the strongly lensed and very distant SN Ia PS1-10afx at z=1.4 deviates from the well-studied populations of normal SNe Ia at nearby or intermediate distance.  Create median spectra from nearby and intermediate-z spectroscopically normal She Ia from the literature at -5 and +1 days from light-curve maximum.  Then compared these median spectra to those of PS1-10afx.  Do not find signs of spectral evolution in PS1-10afx.  The observed deviation between PA1-10afx and the median templates are within what is found for She at low- and intermediate-z.  There is a noticeable broad feature centered at lambda~3500 A, which is present only to a lesser extent in individual low and intermediate redshift SN Ia spectra.  From a comparison with a recently developed explosion model, find this feature to be dominated by Fe peak elements, in  particular, singly ionized Co and Cr.


1706.03798
Ten billion years of brightest cluster galaxy alignments
West, De Props, Bremer, Phillipps

A galaxy's orientation is one of its most basic observable properties.  Astronomers once assumed that galaxies are randomly oriented in space, however it is now clear that some have preferred orientations with respect to their surroundings.  Chief among these are giant elliptical galaxies found in the centers of rich galaxy clusters.  Numerous studies have shown that the major axes of these galaxies often share the same orientation as the surrounding matter distribution on large scales.  Using HST observations of 65 distant galaxy clusters, show for the first time that similar alignments are seen at earlier epochs when the universe was only one-third its current age.  These results suggest that the brightest galaxies in clusters are the product of a special formation history, one influenced by development of the cosmic web over billions of years.


1706.03834
Diffuse neutrino supernova background as a cosmological test
Barranco, Bernal, Delepine

The future detection and measurement of the diffuse neutrino SN background will shed light on the rate of SNe events in the Universe, the SFR and the neutrino spectrum from each SN.  Little has been said about what those measurements will tell us about the expansion history of the universe.  The purpose of this article is to show that the detection of the diffuse SN neutrino background will be a complementary tool for the study and possible discrimination of cosmological models.  In particular, study 3 different cosmological models: the LCDM model, the Logotropic universe and a bulk viscous matter-dominated universe.  By fitting the free parameters of each model with the SN Ia probe, find that the predicted number of events computed with the best fit parameters for the LCDM model and with the Logotropic model are the same, while a bulk viscous matter-dominated cosmological model predicts ~3x more events.  Show that the current limit set by Super-Kamiokande on the diffuse SN neutrino background flux gives complementary constraints on the free parameters of a bulk viscous matter-dominated universe.  Furthermore, this limit implies, within a LCDM model, that the universe should be expanding with H0>21.5 km/s/Mpc independently of the content of dark matter Omega_m.


1706.03903
Pixel noise effect and its correction method by ERA method for precise weak gravitational lensing shear measurement
Okura, Futamase

Highly precise weak lensing shear measurement is required for statistical WL analysis such as cosmic shear to achieve stringent constraint on the cosmological parameters.  For this purpose any systematic error in the measurement should be corrected.  One of the main systematic error comes from [Poisson pixel noise of flux through the atmosphere].  Investigate how the pixel noise makes systematic error in shear measurement based on ERA method and develop a correction method.  This method is tested by simulations with various conditions and it is confirmed that the correction method can correct 80-90% of the systematic error except very low signal to noise galaxies.