Query : 2016A&A...595A..53B

2016A&A...595A..53B - Astronomy and Astrophysics, volume 595A, 53-53 (2016/11-1)

The microlensing rate and distribution of free-floating planets towards the Galactic bulge.


Abstract (from CDS):

Context. Ground-based optical microlensing surveys have provided tantalising, if inconclusive, evidence for a significant population of free-floating planets (FFPs). Both ground- and space-based facilities are being used and developed which will be able to probe the distrubution of FFPs with much better sensitivity. It is also vital to develop a high-precision microlensing simulation framework to evaluate the completeness of such surveys.
Aims. We present the first signal-to-noise limited calculations of the FFP microlensing rate using the Besancon Galactic model. The microlensing distribution towards the Galactic centre is simulated for wide-area ground-based optical surveys (I-band) such as OGLE or MOA, a wide-area ground-based near-infrared survey (K-band), and a targeted space-based near-infrared survey (H-band) which could be undertaken with Euclid or WFIRST.
Methods. We present a calculation framework for the computation of the optical and near-infrared microlensing rate and optical depth for simulated stellar catalogues which are signal-to-noise limited, and take account of extinction, unresolved stellar background light, and finite source size effects, which can be significant for FFPs.
Results. We find that the global ground-based I-band yield over a central 200 deg2 region covering the Galactic centre ranges from 20 Earth-mass FFPs yr–1 up to 3500yr–1 for Jupiter FFPs in the limit of 100% detection efficiency, and almost an order of magnitude larger for a K-band survey. For ground-based surveys we find that the inclusion of finite source and the unresolved background reveals a mass-dependent variation in the spatial distribution of FFPs. For a targeted space-based H-band covering 2deg2, the yield depends on the target field but maximises close to the Galactic centre with around 76 Earth to 1700 Jupiter FFPs per year. For near-IR space-based surveys like Euclid or WFIRST the spatial distribution of FFPs is found to be largely insensitive to the FFP mass scale.

Abstract Copyright: © ESO, 2016

Journal keyword(s): infrared: ISM - planets and satellites: detection - gravitational lensing: micro - X-rays: bursts

Simbad objects: 3

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Number of rows : 3
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 13329 0
2 NAME Baade Window reg 18 03.5 -30 01           ~ 583 3
3 NAME Galactic Bulge reg ~ ~           ~ 3972 0

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