Detection of exoplanet as a binary source of microlensing events in WFIRST survey

Bagheri, Fatemeh; Sajadian, Sedighe; Rahvar, S.

doi:10.1093/mnras/stz2682

Cited by 22 publications

(11 citation statements)

References 49 publications

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“…Using the specified parameters, e.g., ρ * , tE, u0, t0, ..., we make the microlensing lightcurves. For each simulated lightcurve, we generate synthetic data points taken during the Roman observing program, as described in Bagheri et al (2019); Sajadian & Salehi (2020). The cadence of data is fixed at 15.16 min.…”

Section: Detecting the Hz Planets In Thementioning

confidence: 99%

Sensitivity to habitable planets in the \textit{Roman} microlensing survey

Sajadian

2021

Preprint

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We study the Roman sensitivity to exoplanets in the Habitable Zone (HZ). The Roman efficiency for detecting habitable planets is maximized for three classes of planetary microlensing events with close caustic topologies. (a) The events with the lens distances of D l 7 kpc, the host lens masses of M h 0.6M . By assuming Jupiter-mass planets in the HZs, these events have q 0.001 and d 0.17 (q is their mass ratio and d is the projected planet-host distance on the sky plane normalized to the Einstein radius). The events with primary lenses, M h 0.1M , while their lens systems are either (b) close to the observer with D l 1 kpc or (c) close to the Galactic bulge, D l 7 kpc. For Jupiter-mass planets in the HZs of the primary lenses, the events in these two classes have q 0.01, d 0.04. The events in the class (a) make larger caustics. By simulating planetary microlensing events detectable by Roman, we conclude that the Roman efficiencies for detecting Earth-and Jupiter-mass planets in the Optimistic HZs (OHZs, which is the region between [0.5, 2] AU around a Sun-like star) are 0.01% and 5%, respectively. If we assume that one exoplanet orbits each microlens in microlensing events detectable by Roman ( i.e., ∼ 27000 ), this telescope has the potential to detects 35 exoplanets with the projected planet-host distances in the OHZs with only one having a mass 10M ⊕ . According to the simulation, 27 of these exoplanets are actually in the OHZs.

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Section: Detecting the Hz Planets In Thementioning

confidence: 99%

Sensitivity to habitable planets in the \textit{Roman} microlensing survey

Sajadian

2021

Preprint

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“…In order to study the statistic of the discs which can be detected in microlensing observations by RST, we generate a big ensemble of microlensing events towards the Galactic bulge by considering the relevant distribution functions of the lens and the source stars. Many details about this simulation can be found in the previous papers (Sajadian & Poleski 2019;Moniez et al 2017;Bagheri et al 2019). We indicate the absolute magnitude of the source stars in W149 as MW149 = (H + J + K)/3, where H, J, K are their absolute magnitudes in the standard Johnson-Cousin photometry system (Montet et al 2017).…”

Section: Rst Capability For Disc Detection In Microlensing Observationsmentioning

confidence: 99%

Detecting the inner regions of discs around sources of microlensing with Roman Space Telescope

Sajadian,

Salehi

2020

Preprint

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The inner region of circumstellar discs makes an extra near-infrared emission (NIR bump). Detecting and studying these NIR bumps from nearby stars have been done mostly through infrared interferometry. In this work, we study the feasibility of detecting NIR bumps for Galactic bulge stars through microlensing from observations by The Nancy Grace Roman Space Telescope (RST) survey. We first simulate microlensing light curves from source stars with discs in near-infrared. Four main conclusions can be extracted from the simulations. (i) If the lens is crossing the disc inner radius, two extra and wide peaks appear and the main peak of microlensing light curve is flattened. (ii) In microlensing events with the lens impact parameters larger than the disc inner radius, the disc can break the symmetry of light curves with respect to the time of closest approach. (iii) In caustic-crossing binary microlensing, the discs produce wide peaks right before entering and immediately after exiting from the caustic curves. (iv) The disc-induced perturbations are larger in the W149 filter than in the Z087 filter, unless the lens crosses the disc condensation radius. By performing a Monte Carlo simulation, the probabilities of detecting the disc perturbations by RST are estimated ∼ 3 and 20 per cent in single and binary microlensing, respectively. We anticipate that RST detects around 109 disc-induced perturbations during its microlensing survey if 5 per cent of its source stars have discs.

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“…Typical flux ratios between solar-type stars and hot Jupiters in the W 146 band is on the order of ∼ 10 −3 to 10 −4 . Using this detection channel, Bagheri et al (2019) estimated that Roman will discover ∼ 70 exoplanets from single-lens events and ∼ 3 exoplanets from binary-lens events. 7 We expect that the binary source effect might be observed in the Roman xallarap single-lens events of P < 5 days, which corresponds to ∼ 50% of the total yields.…”

Section: How To Distinguish Lens Orbital Motionmentioning

confidence: 99%

Revealing Short-period Exoplanets and Brown Dwarfs in the Galactic Bulge using the Microlensing Xallarap Effect with the \textit{Nancy Grace Roman Space Telescope}

Miyazaki,

Johnson,

Sumi

et al. 2020

Preprint

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The Nancy Grace Roman Space Telescope (Roman) will provide an enormous number of microlensing light curves with much better photometric precisions than ongoing ground-based observations. Such light curves will enable us to observe high-order microlensing effects which have been previously difficult to detect. In this paper, we investigate Roman's potential to detect and characterize short-period planets and brown dwarfs (BDs) in source systems using the orbital motion of source stars, the socalled xallarap effect. We analytically estimate the measurement uncertainties of xallarap parameters using the Fisher matrix analysis. We show that the Roman Galactic Exoplanet Survey (RGES) can detect warm Jupiters with masses down to 0.5 M Jup and orbital period of 30 days via the xallarap effect. Assuming a planetary frequency function from Cumming et al. (2008), we find Roman will detect ∼ 10 hot and warm Jupiters and ∼ 30 close-in BDs around microlensed source stars during the microlensing survey. These detections are likely to be accompanied by the measurements of the companion's masses and orbital elements, which will aid in the study of the physical properties for close-in planet and BD populations in the Galactic bulge.

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Detection of exoplanet as a binary source of microlensing events in WFIRST survey

Cited by 22 publications

References 49 publications

Sensitivity to habitable planets in the \textit{Roman} microlensing survey

Sensitivity to habitable planets in the \textit{Roman} microlensing survey

Detecting the inner regions of discs around sources of microlensing with Roman Space Telescope

Revealing Short-period Exoplanets and Brown Dwarfs in the Galactic Bulge using the Microlensing Xallarap Effect with the \textit{Nancy Grace Roman Space Telescope}

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