Day 880

Tuesday.


1505.00270
Ultra-stripped supernovae: progenitors and fate
Tauris, Langer, Podsiadlowski

The explosion of intra-stripped stars in close binaries can lead to eject masses <0.1 Msun and may explain some of the recent discoveries of weak and fast optical transients.  In Taurs+2013, it was demonstrated that helium star companions to NSs may experience mass transfer and evolve into naked ~1.5 Msun metal core, barely above Chandrasekhar mass limit.  Here, present a systematic investigation of the progenitor evolution leading to ultra-stripped SNe.  In particular, examine the binary parameter space leading to electron-capture (ED SNe) and iron core-collapse SNe (Fe CCSNe), respectively, and determine the amount of He ejected with applications to their observational classification as Type Ib or Type Ic.  Mainly evolve systems where the SN progenitors are He star donors of initial mass M_He=2.5-3.5 Msun in tight binaries with orbital periods of P_orb=0.06-2.0 days, and hosting an accreting NS, but also discuss the evolution of wider systems and of both more massive and lighter - as well as single - He stars.  In some cases, able to follow the evolution until the onset of Si burning, just a few days prior to the SN explosion.  Find that ultra-stripped SNe are possible for both EC SNe and Fe CCSNe, and that the amount of He ejected is correlated with P_orb - the tightest systems even having donors being stripped down to envelopes of less than 0.01 Msun.  Estimate the rise time of ultra-stripped SNe to be in the range 12 hr  - 8 days, and light curve decay times between 1 and 50 days.  Ultra-stripped SNe may produce NSs in the mass range 1.10-1.80 Msun and are highly relevant for LIGO/VIRGO since most (possibly all) merging double NS systems have evolved through this phase.  finally, discuss the low momentum kicks which might be imparted on these resulting NSs at birth.


1505.00502
Comparison of strong gravitational lens model software III. direct and indirect semi-independent lens model comparisons of COSMOS J095930+023427, SDSS J1320+1644, SDSSJ1430+4105 and J1000+0021
Lefor, Futamase

The objective of the present study is to directly compare the analysis of SL systems using different lens model software and similarly parameterized models to understand the differences and limitations of the resulting models.  The software lens model translation tool, HydraLens, was used to generate multiple models for four strong lens systems including COSMOS ... SDSS... . All four lens systems were modeled with PixLens, Lenstool, glafic, and Lensmodel.  The input data and parameterization of each lens model was similar for the four model programs used to highlight differences in the output results.  The calculation of the Einstein radius and enclosed mass for each lens model was comparable.  The results were more dissimilar if the masses of more than one lens potential were free-parameters.  The image tracing algorithms of the software are different, resulting in different output image positions and differences in time delay and magnification calculations, as well as ellipticity and position angle of the resulting lens model.   In a comparison of different software versions using identical model input files, results differed significantly when using two versions of the same software.  These results further support the need for future lensing studies to include multiple lens models, use of open software, availability of lens model files use in studies, and computer challenges to develop new approaches.  Further suited ned a standard nomenclature and specification of the SW used to allow improved interpretation, reproducibility and transparency of results.