A Theoretical Calculation of Microlensing Signatures Caused by Free-Floating Planets Towards the Galactic Bulge

Hamolli, Lindita; Hafizi, M.; Nucita, A. A.

doi:10.1142/s0218271813500727

Cited by 7 publications

(16 citation statements)

References 17 publications

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“…The efficiency to detect finite source effects in highly magnified events is less than 1%. However, taking into account that Euclid observations will allow detecting ∼10 3 microlensing events per month and ∼100 events per month due to FFPs [22,31], there will be a nonnegligible chance to detect finite source effects even in highly amplified events.…”

Section: Resultsmentioning

confidence: 99%

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Estimating Finite Source Effects in Microlensing Events due to Free-Floating Planets with the Euclid Survey

Hamolli

Hafizi

Paolis

et al. 2015

Advances in Astronomy

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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.

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Section: Resultsmentioning

confidence: 99%

“…Since the Euclid threshold amplification is th = 1.001 and the photometric error is ≃0.1% [22], these curves can be seen as distinct microlensing profiles by Euclid telescope observations.…”

Section: Finite Source Effects In Ffp Microlensing Eventsmentioning

confidence: 86%

Estimating Finite Source Effects in Microlensing Events due to Free-Floating Planets with the Euclid Survey

Hamolli

Hafizi

Paolis

et al. 2015

Advances in Astronomy

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“…Nemiroff 1994, Witt & Mao 1994, Witt 1995, Hamolli et al 2015 and the parallax effect (see Refs. Alcock 1995, Dominik 1998, Hamolli et al 2013, may be extremely useful to solve the parameter degeneracy problem and strongly constrain the lens mass. In particular, it is used for free floating planets (FFPs), which are dark objects with mass 0.01 MM  e that are not bound to a host star (Sumi et al 2011).…”

Section: Introductionmentioning

confidence: 99%

The astrometric signal of microlensing events caused by free floating planets

Hamolli

Hafizi

Paolis

et al. 2018

Astrophys Space Sci

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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 milliarcseconds, 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.

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“…At present, there are two space-based missions which are planned for detecting microlensing events towards the Galactic bulge: the Wide-Field Infrared Survey Telescope (WFIRST) [18] and Euclid [19], although the last news from Euclid seem to indicate that the microlensing program will not be actually performed. Based on the capabilities of their facilities, we have foreseen the detection of the FFP population in our Galaxy [20].Besides photometric observations, a microlensing event can be detected also astrometrically. The best instrument for such observations is the Gaia satellite.…”

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confidence: 99%

“…The optical depth and the microlensing rate of events caused by FFPs were calculated in Ref. [20] where it was found that these events are much fewer with respect to those due to main sequence stars, but more numerous than those due to BDs. Considering the lower limit of the FFPs per star, we found that by space-based telescopes (in particular by Euclid or WFIRST) will be detected about 100 microlensing events caused by FFPs during a month (see Ref.…”

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confidence: 99%

Free-floating planets in the Milky Way

et al. 2019

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Gravitational microlensing is a powerful method to search for and characterize exoplanets, and it was first proposed by Paczyński in 1986. We provide a brief historical excursus of microlensing, especially focused on the discoveries of free-floating planets (FFPs) in the Milky Way. We also emphasize that, thanks to the technological developments, it will allow to estimate the physical parameters (in particular the mass and distance) of FFPs towards the center of our Galaxy, through the measure of the source finite radius, Earth or satellite parallax, and/or astrometric effects.Mathematics Subject Classification 85-xx · 85-08 IntroductionDiscovery of the extrasolar planets in our Galaxy is one of the most discussed issues in the scientific community. These objects are outside our solar system and have masses smaller than about 0.01M . Their detection is being achieved using different methods and, until now, we have 3824 confirmed exoplanes (see the website http://exoplanet.eu). Most exoplanets are discovered by the Transit method (∼ 74%) and by Radial Velocity method (∼ 20%). A few exoplanets have been detected using the Direct Imaging technique. Until now, only ∼ 2% of exoplanets have been detected through gravitational microlensing.In recent years, several unbound objects with mass possibly as small as a few times that of Jupiter (M J = 9.5 × 10 −4 M ) have been found in many young star-forming region using infrared imaging surveys [1]. These objects are called free-floating planets or also rogue planets, nomads, or orphan planets (see [2] and references therein). Examples of objects of this kind are WISE 0855-0714, about 2.4 pc away from the Earth [3], and Cha 110913-773444 in the Chamaeleon I star-forming region at a distance of about 160 pc. It is difficult to find this kind of objects by infrared imaging at large distances, so we need the development of alternative methods to search for them. The origin of the FFPs is doubtful, and their formation mechanism remains an open theoretical question in astrophysics. One possibility is that they originally formed around a host star and then scattered out from orbit. A second option is that they may form on their own through gas cloud direct collapse, similarly to star formation.Paczyński [4] first envisaged the search of Galactic dark matter in compact form using gravitational lensing method, which happens when a massive object passes close enough to the line of sight to a distant source star. Since the angular separation of the lensed images are of the order of microarcseconds, such phenomena are often called microlensing [5,6]. In his calculations, Paczyński showed that the chance (or optical depth) of a massive object in the Galactic halo to serve as a lens and magnify a background star in nearby galaxy is 10 −6 . Also, he suggested that, based on modern instruments, we could be able to catch such microlensing events by monitoring a dense stellar field with several millions of stars simultaneously. Therefore, several groundbased experiments such as MACHO (Massiv...

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A Theoretical Calculation of Microlensing Signatures Caused by Free-Floating Planets Towards the Galactic Bulge

Cited by 7 publications

References 17 publications

Estimating Finite Source Effects in Microlensing Events due to Free-Floating Planets with the Euclid Survey

Estimating Finite Source Effects in Microlensing Events due to Free-Floating Planets with the Euclid Survey

The astrometric signal of microlensing events caused by free floating planets

Free-floating planets in the Milky Way

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