Day 1395

Friday.

1804.01748
Mr-Moose: an advanced SED-fitting tool for heterogeneous multi-wavelength datasets
Drouart, Falkendal

Present the public release of MrMoose, a fitting procedure that is able to perform multi-wavelength and multi-object SED fitting in a Bayesian framework.  This procedure is able to handle a large variety of cases, from an isolated source to blended multi-component sources from an heterogeneous dataset (i.e. a range of observation sensitivities and spectral/spatial resolutions).  Furthermore, MrMoose handles upper-limits during the fitting process in a continuous way allowing models to be gradually less probable as upper limits are approached.  The aim is to propose a simple-to-use, yet tightly-versatile fitting tool for handling increasing source complexity when combining multi-wavelength datasets with fully customizable filter/model databases.  The complete control of the use is one advantage, which avoids the traditional problems related to the "black box" effect, where parameter of model tuning are impossible and can lead to overfitting and/or over-interpretation of the results.  Also, while a basic knowledge of Python and statistics is required, the code aims to be sufficiently user-friendly for non-experts.  Demonstrate the procedure on 3 cases: two artificially-generated datasets and a previous result from the literature.  In particular, the most complex case (inspired by a real source, combining Herschel, ALMA and VLA data) in the context of extragalactic SED fitting makes MrMoose a particularly-attractive SED fitting tool when dealing with partially blended sources, without the need for data deconvolution.


1804.01755
Three-dimensional structure of the Magellanic System
Jacyszyn-Dobrzeniecka, The OGLE Team

Determined the 3d structure of the Magellanic Clouds and Magellanic Bridge using over 9000 classical Cepheids (CCs) and almost 23000 RR Lyrae (RRL) stars from the fourth phase of the OGLE project.  For the CCs, calculated distances based on period-luminosity relations.  CCs in the LMC are situated mainly in the bar that shows no offset from the plane of the LMC.  The northern arm is also very prominent with an additional smaller arm.  Both are located closer to us than the entire sample.  The SMC has a non-planar structure that can be described as an ellipsoid extended almost along the line of sight.  Also classified 9 of the CCs as Magellanic Bridge objects.  These Cepheids show a large spread in 3d.  For the RRL stars, calculated distances based on photometric metallicities and theoretical relations.  Both Magellanic Clouds revealed a very regular structure.  Fitted triaxial ellipsoids to the LMC and SMC samples.  In the LMC, noticed a very prominent, non-physical blend-artifact that prevented analysis of the central parts of the galaxies.  Do not see any evidence of a bridge-like connection between the Magellanic Clouds.


1804.01538
The demographics of neutron star - white dwarf mergers: rates, delay-time distributions and progenitors
Toonen, et al

Characterize the rates of NS and WD mergers.  Use binary populations synthesis models, and consider a wide rage of initial conditions and physical processes.  Consider different common-envelope evolution models and different NS natal kick distributions.  Provide detailed predictions arising from each of the models considered.  Find that the majority of NS-WD mergers are born in systems in which mass-transfer played an important role, and the WD formed before the NS.  For the majority of the mergers the WDs have a carbon-oxygen composition (60-80%) and most of the rest are with oxygen-neon WDs.  The rates of NS-WD mergers are in the rage fo 3-15% of the type Ia SNe rate.  Their delay time distribution is very similar to that of SNe Ia, but slightly biased towards earlier times.  They typically explode in young 0.1-1Gyr environments, but have attain distribution extending to long-Gyrs-timescales.  Models including significant kicks give rise to relatively wide offset distribution extending to hundreds of kpcs.  The demographic and physical properties of NS-WD mergers suggest they are likely to be peculiar type Ic-like SNe, mostly exploding in late type galaxies.  Their overall properties could be related to a class of rapidly evolving SNe recently observed, while they are less likely to be related to the class of Ca-rich SNe.