6 research outputs found
Estimating Finite Source Effects in Microlensing Events due to Free-Floating Planets with the Euclid Survey
In recent years free-loating planets (FFPs) have drawn a great interest among
astrophysicists. Gravitational microlensing is a unique and exclusive method
for their investigation which may allow obtaining precious information about
their mass and spatial distribution. The planned Euclid space-based observatory
will be able to detect a substantial number of microlensing events caused by
FFPs towards the Galactic bulge. Making use of a synthetic population
algorithm, we investigate the possibility of detecting finite source effects in
simulated microlensing events due to FFPs. We find a significant efficiency for
finite source effect detection that turns out to be between 20% and 40% for a
FFP power law mass function index in the range [0.9, 1.6]. For many of such
events it will also be possible to measure the angular Einstein radius and
therefore constrain the lens physical parameters. These kinds of observations
will also offer a unique possibility to investigate the photosphere and
atmosphere of Galactic bulge stars.Comment: 8 pages, 5 figures, published in Advances in Astronomy, Volume 2015,
Article ID 40230
Investigating the free-floating planet mass by Euclid observations
The detection of anomalies in gravitational microlensing events is nowadays
one of the main goals among the microlensing community. In the case of
single-lens events, these anomalies can be caused by the finite source effects,
that is when the source disk size is not negligible, and by the Earth rotation
around the Sun (the so-called parallax effect). The finite source and parallax
effects may help to define the mass of the lens, uniquely. Free-floating
planets (FFPs) are extremely dim objects, and gravitational microlensing
provides at present the exclusive method to investigate these bodies. In this
work, making use of a synthetic population algorithm, we study the possibility
of detecting the finite source and parallax effects in simulated microlensing
events caused by FFPs towards the Galactic bulge, taking into consideration the
capabilities of the space-based Euclid telescope. We find a significant
efficiency for detecting the parallax effect in microlensing events with
detectable finite source effect, that turns out to be about 51% for mass
function index .Comment: Astrophysics and Space Science 201
Estimating Finite Source Effects in Microlensing Events due to Free-Floating Planets with the Euclid Survey
In recent years free-floating planets (FFPs) have drawn a great interest among astrophysicists. Gravitational microlensing is a unique and exclusive method for their investigation which may allow obtaining precious information about their mass and spatial distribution. The planned Euclid space-based observatory will be able to detect a substantial number of microlensing events caused by FFPs towards the Galactic bulge. Making use of a synthetic population algorithm, we investigate the possibility of detecting finite source effects in simulated microlensing events due to FFPs. We find a significant efficiency for finite source effect detection that turns out to be between 20% and 40% for a FFP power law mass function index in the range [0.9, 1.6]. For many of such events it will also be possible to measure the angular Einstein radius and therefore constrain the lens physical parameters. These kinds of observations will also offer a unique possibility to investigate the photosphere and atmosphere of Galactic bulge stars
Investigating Gravitationally Lensed Quasars Observable by Nancy Grace Roman Space Telescope
In this work, we investigate the possibility of observing quasars, particularly lensed quasars, by the Nancy Grace Roman Space Telescope (Roman). To this aim, based on the capabilities of the Roman Space Telescope and the results from the quasar luminosity function (QLF) in the infrared band of the Spitzer Space Telescope imaging survey, we calculated the number of quasars expected to be in its field of view. In order to estimate the number of lensed quasars, we develop a Monte Carlo simulation to estimate the probability that a quasar is lensed once or more times by foreground galaxies. Using the mass–luminosity distribution function of galaxies and the redshift distributions of galaxies and quasars, we find that 1 per 180 observed quasars will be lensed by foreground galaxies. Further on, adopting a singular isothermal sphere (SIS) model for lens galaxies, we calculate the time delay between lensed images for single and multiple lensing systems and present their distributions. We emphasize that detailed studies of these lensing systems will provide a powerful probe of the physical properties of quasars and may allow testing the mass distribution models of galaxies in addition to being extremely helpful for constraining the cosmological parameters
The astrometric signal of microlensing events caused by free floating planets
Astrometric observations of microlensing events can be used to obtain important information about lenses. During these events, the shift of the position of the multiple image centroid with respect to the source star location can be measured. This effect, which is expected to occur on scales from micro-arcseconds to milli-arcseconds, depends on the lens-source-observer system physical parameters. Here, we consider the astrometric and photometric observations by space and ground-based telescopes of microlensing events towards the Galactic bulge caused by free floating planets (FFPs). We show that the efficiency of astrometric signal on photometrically detected microlensing events tends to increase for higher FFP masses in our Galaxy. In addition, we estimate that during five years of the Gaia observations, about a dozen of microlensing events caused by FFPs are expected to be detectable