Day 545

Wednesday.  Thursday.

1311.1614
The effect of large-scale structure on the magnification of high-redshift sources by cluster-lenses
D'Aloisio, Natarajan, Shapiro

JWST will probe dwarf galaxies at z>7; in the meanwhile, GL are capable of detecting sources that are 10-50x fainter than any distant galaxy observed to date.  To get LF, must be able to measure accurate intrinsic luminosities of magnified galaxies, which depends on magnification maps built from SL constraints.  Potential source of error: assuming that only clusters and nearby correlated structures are the only significant sources of lensing; light rays are also subject to WL by uncorrelated LSS along the LoS.  Statistically quantify effects of cosmic WL (CWL) on the magnification maps of cluster lenses in terms of matter PS.  Use a simple model for the magnification profiles of cluster lenses at z=0.3-0.5 based on the NFW density profile.  Show that fluctuations in the magnification of sources at z=6-10 due to CWL are 10-20 (20-30)% for typical absolute magnifications ~5 (10).  However, the fluctuations rise to grater than order unity near critical curves, indicating that CWL tends to have its largest impact on the most magnified images.  Hence, although it is commonly assumed that the effect of CWL is negligible in cluster-lensing systems, conclude that measurements of intrinsic luminosities of highly-magnified galaxies must account for it.

1311.1633
Origin of a bottom-heavy stellar initial mass function in elliptical galaxies
Bekki

Use chemical evolution models with a non-universal IMF.  Adopt the Kroupa IMF with the 3 slopes (a1, a2, and a3) dependent on metallicities ([Fe/H]) and densities (rho_g) of star-forming gas clouds and thereby search for the best IMF model that can reproduce (i) the observed steep IMF slope (a2~3==bottom heavy) for the low stellar masses (m<1Msun) and (ii) the correlation of a2 with chemcial properties of elliptical galaxies in a self-consistent manner.  Find that if the IMF slope a2 depends both on [Fe/H] and rho_g, then elliptical galaxies with higher [Mg/Fe] can have steeper a2 (~3) in the models; also find observed positive correlation of stellar M/L with [Mg/Fe] in elliptical galaxies can be quantitatively reproduce in our models with a2=beta[Fe/H]+gamma log rho_g, where beta~0.5 and gamma~2.  Discuss whether the IMF slopes for low-mass (a2) and high-mass stars (a3) need to vary independently from each other to explain a number of IMF-related observational results self-consistently.  Also briefly discuss why a2 depends differently on [Fe/H] in dwarf and giant elliptical galaxies.

1311.1733
The unexpected 2012 draconic meteor storm
Ye et al

Unexpected intense outburst on 8Oct2012; sims indicate outburst was caused by dust particles during the 1966 perihelion passage of parent comet, whose approach to Jupiter during 1966-1972 probably caused.  Based on sims, more outbursts on 2018, 2019, 2021 and 2025.