Day 1386

Thursday.

1803.07569
Prediction of supernova rates in known galaxy-galaxy strong-lens systems
Shu, et al

Propose a strategy of finding strongly-lensed SNe by monitoring known galaxy-scale SL systems.  Although being powerful tools in cosmology, galaxy evolution, and stellar physics, strongly-lensed SNe are extremely rare.  Built upon the prior knowledge of the lens nature, the strategy will significantly boost the detection efficiency compared with a blind search.  In particular, build a compilation of 128 gg SL systems from the Sloan Lens ACS survey (SLACS), the SLACS for the Masses Survey, and the BOSS Emission-Line Lens Survey.  Within this compilation, estimate the event rates of strongly-lensed Type Ia SN (SNIa) and core-collapse SN (CCSN) to be 1.23±0.12 and 10.4±1.1 per year, respectively.  The lensed SN images are expected to be widely separated with a median separation of 2 arcsec.  Forecast that a time-domain survey with a single-visit depth of 24.7 mag (5 sigma for point source, r band), which is the same as that of the LSST, can detect in this compilation 0.58 SL SNIa event and 2.4 SL CCSN events every year, when a conservative, fiducial lensing magnification factor of 5 is assumed for the most-magnified SN image.  The proposed strategy requires no extra time or any scanning strategy change to ongoing and scheduled high-cadence, all-sky surveys.  It also allows telescopes with much smaller field of views and limited time to deliver a comparable yield of strongly-lensed SNe with a pencil-beam scanning strategy.


1803.07570
Optimal target stars in the search for life
Lingam, Loeb

The selection of optimal targets in the search for life represents a highly important strategic issue.  In this paper, evaluate the relative benefits of searching for life around a potentially habitable planet orbiting a star of arbitrary mass relative to a Sun-like star.  If recent physical arguments implying that the habitability of planets orbiting low-mass stars is selectively suppressed are correct, find that planets around solar-type stars may represent the optimal targets.


1803.07601
Gravitationally lensed quasars in Gaia: II. Discovery of 24 lensed quasars
Lemon, Auger, McMahon, Ostrovski

Report the discovery, spectroscopic confirmation and preliminary characterization of 24 gravitationally lensed quasars identified using Gaia observations.  Candidates were selected in the Pan-STARRS footprint with quasar-like WISE colors or as photometric quasars from SDSS, requiring either multiple detections in Gaia or a single Gaia detection near a morphological galaxy.  The Pan-STARRS grizY images were modeled for the most promising candidates and 60 candidate systems were followed up with Herschel.  13 of the lenses were discovered as Gaia multiples and 10 as single Gaia detections near galaxies.  Also discover 1 lens identified through a quasar emission line in an SDSS galaxy spectrum.  The lenses have median image separation 2..13 arcs and the source redshifts range from 1.06 to 3.36.  4 systems are quadruply-imaged and 20 are doubly-imaged.  Deep CFHT data reveal an Einstein ring in one double system.  Also report 12 quasar pairs, 10 of which have components at the same redshift and require further follow-up to rule out the lensing hypothesis. Compare the properties of these lenses and other known lenses recovered by this search method to a complete sample of simulated lenses to show the lenses lenses that are missing are mainly those with small separations and higher source redshifts.  The initial Gaia data release only catalogues all images of ~30% of known bright lensed quasars, however the improved completeness of Gaia data release 2 will help fill all bright lensed quasars on the sky.


1803.07851
Strong-lensing of gravitational waves by galaxy clusters
Smith, et al

Discovery of strongly-lensed GW sources will unveil binary compact objects at higher redshifts and lower intrinsic luminosities than is possible without lensing. Such systems will yield unprecedented constraints on the mass distribution in galaxy clusters, measurements of the polarization of GWs, tests of GR, and constraints on the Hubble parameter.  Excited by these prospects, and intrigued by the presence of so-called "heavy BHs" in the early detections by LIGO-Virgo, commence a search for strongly-lensed GWs and possible EM counterparts in the latter stages of the second LIGO observing run (O2).  Summarise the calculation of the detection rate of SL GWs, describe the review of BBH detections from O1, outline the observing strategy in O2, summarize the follow-up observations of GW170814, and discuss the future prospects of detection.