The astrometric signal of microlensing events caused by free floating planets

Hamolli, Lindita; Hafizi, M.; Paolis, F. De; Nucita, A. A.

doi:10.1007/s10509-018-3374-2

Cited by 2 publications

(7 citation statements)

References 29 publications

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“…Following the analysis by Dominik [43] and based on the capabilities of space telescopes, we found that nearly 30% of the events caused by FFPs towards the Galactic bulge may have detectable orbital parallax effect. We also found that the best period during the year to observe the parallax effect is June, due to the orientation of the Earth orbital plane with respect to the line of sight towards the bulge [44].…”

Section: π E In Microlensing Events Caused By Ffpsmentioning

confidence: 69%

“…First, the orbital motion of the Earth (annual parallax) creates on the light curve a shift relative to the simple straight motion between the source and lens (see Refs. [40,43,44]). Second, two observers at different locations looking contemporarily towards the same event can compare their observations [14].…”

Section: Basics Of Photometric Microlensingmentioning

confidence: 99%

“…In Ref. [64], the astrometric signal in microlensing events caused by FFPs by the Gaia space telescope is discussed. These measurements, in combination with photometric observations, can be used to precisely constrain the FFP mass.…”

Section: θ E In Microlensing Event Caused By Ffpsmentioning

confidence: 99%

“…Of course, the efficiency of the astrometric effect (that is, in other words, the percentage of events with detectable astrometric shift) depends on the value of the FFP mass function index and it decreases when the value of D L is increased (see [64] for details). In Table 1, we give the efficiency values of the second-order effects in microlensing events caused by the FFPs towards Galactic bulge.…”

Section: θ E In Microlensing Event Caused By Ffpsmentioning

confidence: 99%

“…As one can see, the finite source efficiency is increased with α PL , while the efficiency of the orbital parallax, satellite parallax (for the pairs: Earth-K2C9 and Earth-Spitzer) and astrometric shift decreases with increasing α PL (see Refs. [13,20,39,64] for details).…”

Section: θ E In Microlensing Event Caused By Ffpsmentioning

confidence: 99%

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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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Section: π E In Microlensing Events Caused By Ffpsmentioning

confidence: 69%

Section: Basics Of Photometric Microlensingmentioning

confidence: 99%

Section: θ E In Microlensing Event Caused By Ffpsmentioning

confidence: 99%

Section: θ E In Microlensing Event Caused By Ffpsmentioning

confidence: 99%

Section: θ E In Microlensing Event Caused By Ffpsmentioning

confidence: 99%

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Free-floating planets in the Milky Way

et al. 2019

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Astrometric microlensing of primordial black holes with Gaia

Verma

Rentala

2023

J. Cosmol. Astropart. Phys.

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The Gaia space telescope allows for unprecedented accuracy for astrometric measurements of stars in the Galaxy. In this work, we explore the sensitivity of Gaia to detect primordial black hole (PBH) dark matter through the distortions that PBHs would create in the apparent trajectories of background stars, an effect known as astrometric microlensing (AML). We present a novel calculation of the lensing probability, and we combine this with the existing publicly released Gaia eDR3 stellar catalog to predict the expected rate of AML events that Gaia will see. We also compute the expected distribution of a few event observables, which will be useful for reducing backgrounds. Assuming that the astrophysical background rate of AML like events due to other sources is negligible, we then compute the potential exclusion that could be set on the parameter space of PBHs with a monochromatic mass function. We find that Gaia is sensitive to PBHs in the range of 0.4 M ⊙–5 × 107 M ⊙, and has peak sensitivity to PBHs of ∼ 10 M ⊙ for which it can rule out as little as a fraction 3 × 10-4 of dark matter composed of PBHs. With this exquisite sensitivity, Gaia has the potential to rule out a PBH origin for the gravitational wave signals seen at LIGO/Virgo. Our novel calculation of the lensing probability includes for the first time, the effect of intermediate duration lensing events, where the lensing event lasts for a few years, but for a period which is still shorter than the Gaia mission lifetime. The lower end of our predicted mass exclusion is especially sensitive to this class of lensing events. As and when time-series data for Gaia is released, and once we have a better understanding of the astrophysical background rate to AML signals, our prediction of the lensing rate and event observable distributions will be useful to estimate the true exclusion/discovery of the PBH parameter space utilizing this data.

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The astrometric signal of microlensing events caused by free floating planets

Cited by 2 publications

References 29 publications

Free-floating planets in the Milky Way

Free-floating planets in the Milky Way

Astrometric microlensing of primordial black holes with Gaia

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