Exoplanet Detection Methods

Wright, Jason T.; Gaudi, B. Scott

doi:10.1007/978-94-007-5606-9_10

Cited by 55 publications

(49 citation statements)

References 166 publications

(194 reference statements)

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“…Nevertheless, the light curve shape deviates from a pure sinusoid. In order to see if such deviations naturally arise within our model, we maximised the Bayesian likelihood over five parameters (period P , velocity amplitude K, eccentricity e, argument of pericentre ω, and an arbitrary ref-erence time t 0 ) of a Kepler orbit 23 and fit the observed optical light-curve. In this procedure, we accounted for additional stochastic physical variability with a broken power-law power spectrum (i.e.…”

mentioning

confidence: 99%

Relativistic boost as the cause of periodicity in a massive black-hole binary candidate

D’Orazio

Haiman

Schiminovich

2015

Nature

171

172

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Because most large galaxies contain a central black hole, and galaxies often merge 1 , blackhole binaries are expected to be common in galactic nuclei 2 . Although they cannot be imaged, periodicities in the light curves of quasars have been interpreted as evidence for binaries [3][4][5] , most recently in PG 1302-102, with a short rest-frame optical period of 4 yr 6 . If the orbital period matches this value, then for the range of estimated black hole masses the components would be separated by 0.007-0.017 pc, implying relativistic orbital speeds. There has been much debate over whether black hole orbits could be smaller than 1 pc 7 . Here we show that the amplitude and the sinusoid-like shape of the variability of PG 1302-102 can be fit by relativistic Doppler boosting of emission from a compact, steadily accreting, unequal-mass binary. We predict that brightness variations in the ultraviolet light curve track those in the optical, but with a 2-3 times larger amplitude. This prediction is relatively insensitive to the details of the emission process, and is consistent with archival UV data. Follow-up UV and optical observations in the next few years can test this prediction and confirm the existence of a binary black hole in the relativistic regime.Assuming PG 1302-102 is a binary, it is natural to attribute its optical emission to gas that is bound to each black hole, forming circumprimary and circumsecondary accretion flows. Such flows, forming "minidisks", are generically found in high-resolution 2D and 3D hydrodynamical simulations that include the black holes in their simulated domain [8][9][10][11][12][13][14][15] . Assuming a circular orbit, the velocity of the lower-mass secondary black hole isor ∼ 0.03c for the fiducial parameters above, where M = M 1 + M 2 is the total binary mass, M 1,2 are the individual masses, q = M 2 /M 1 ≤ 1 is the mass ratio, P is the orbital period, and c is the speed of light. The primary's orbital velocity is v 1 = qv 2 . Even if a minidisk has a steady intrinsic rest-frame luminosity, its apparent flux on Earth is modulated by relativistic Doppler beaming. The photon frequencies suffer relativistic Doppler shift by the factor D = [Γ(1 − β || )] −1 , where Γ = (1 − β 2 ) −1/2 is the Lorentz factor, β = v/c is the three-dimensional velocity v in units of the speed of light, and β || = β cos φ sin i is the component of the velocity along the line of sight, with i and φ the orbital inclination and phase. Because the photon phase-space density ∝ F ν /ν 3 is invariant in special relativity, the apparent flux F ν at a fixed observed frequency ν is modified from the flux of 1 arXiv:1509.04301v1 [astro-ph.HE] 14 Sep 2015The last step assumes an intrinsic power-law spectrum F 0 ν ∝ ν α . To first order in v/c, this causes a sinusoidal modulation of the apparent flux along the orbit, by a fractional amplitude ∆F ν /F ν = ±(3 − α)(v cos φ/c) sin i. Although lighttravel time modulations appear at the same order, they are subdominant to the Doppler modulation. This modulation is analogo...

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mentioning

confidence: 99%

Relativistic boost as the cause of periodicity in a massive black-hole binary candidate

D’Orazio

Haiman

Schiminovich

2015

Nature

171

172

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“…However, even in the best candidate systems, any signatures seem to be transient (Shkolnik et al 2008). As a striking counterexample, the extreme WASP-18 system, which contains a ≃ 10M Jup planet in a 0.94 d period, shows no evidence for planet-linked activity (Miller et al 2012;Pillitteri et al 2014b); such interaction must be either absent, only rarely present, or 8 We ignore the distinction between M P and the minimum mass of explanets derived from radial velocity work, since the sin i inclination term is unknown for most of these systems but provides a typical correction of only ∼15% (Wright & Gaudi 2013). rendered inefficient by an extremely weak stellar magnetic field 9 Shkolnik et al 2013; but see also Miller et al 2012).…”

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confidence: 99%

A Comprehensive Statistical Assessment of Star-Planet Interaction

Miller

Gallo

Wright

et al. 2015

ApJ

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We investigate whether magnetic interaction between close-in giant planets and their host stars produce observable statistical enhancements in stellar coronal or chromospheric activity. New Chandra observations of 12 nearby (d < 60 pc) planet-hosting solar analogs are combined with archival Chandra, XMM-Newton, and ROSAT coverage of 11 similar stars to construct a sample inoculated against inherent stellar class and planet-detection biases. Survival analysis and Bayesian regression methods (incorporating both measurements errors and X-ray upper limits; 13/23 stars have secure detections) are used to test whether "hot Jupiter" hosts are systematically more X-ray luminous than comparable stars with more distant or smaller planets. No significant correlations are present between common proxies for interaction strength (M P /a 2 or 1/a) versus coronal activity (L X or L X /L bol ). In contrast, a sample of 198 FGK main-sequence stars does show a significant (∼ 99% confidence) increase in X-ray luminosity with M P /a 2 . While selection biases are incontrovertibly present within the main-sequence sample, we demonstrate that the effect is primarily driven by a handful of extreme hot-Jupiter systems with M P /a 2 > 450 M Jup AU −2 , which here are all X-ray luminous but to a degree commensurate with their Ca II H and K activity, in contrast to presented magnetic star-planet interaction scenarios that predict enhancements relatively larger in L X . We discuss these results in the context of cumulative tidal spin-up of stars hosting close-in gas giants (potentially followed by planetary infall and destruction). We also test our main-sequence sample for correlations between planetary properties and UV luminosity or Ca II H and K emission, and find no significant dependence.

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“…However, in the present state of exoplanet detection techniques, most likely none of the rocky planets of the solar system would be discovered, even around a star as close as α Centauri, our closest Sun-like neighbor, located at the distance of 1.34 pc (Wright & Gaudi 2013). Rocky planets would only be found if the observer (located in a random direction near the solar system) was lucky enough to observe their transits.…”

Section: Introductionmentioning

confidence: 94%

A detector interferometric calibration experiment for high precision astrometry

Crouzier

Malbet

Hénault

et al. 2016

A&A

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Context. Exoplanet science has made staggering progress in the last two decades, due to the relentless exploration of new detection methods and refinement of existing ones. Yet astrometry offers a unique and untapped potential of discovery of habitable-zone lowmass planets around all the solar-like stars of the solar neighborhood. To fulfill this goal, astrometry must be paired with high precision calibration of the detector. Aims. We present a way to calibrate a detector for high accuracy astrometry. An experimental testbed combining an astrometric simulator and an interferometric calibration system is used to validate both the hardware needed for the calibration and the signal processing methods. The objective is an accuracy of 5 × 10 −6 pixel on the location of a Nyquist sampled polychromatic point spread function. Methods. The interferometric calibration system produced modulated Young fringes on the detector. The Young fringes were parametrized as products of time and space dependent functions, based on various pixel parameters. The minimization of function parameters was done iteratively, until convergence was obtained, revealing the pixel information needed for the calibration of astrometric measurements. Results. The calibration system yielded the pixel positions to an accuracy estimated at 4×10 −4 pixel. After including the pixel position information, an astrometric accuracy of 6 × 10 −5 pixel was obtained, for a PSF motion over more than five pixels. In the static mode (small jitter motion of less than 1 × 10 −3 pixel), a photon noise limited precision of 3 × 10 −5 pixel was reached.

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Exoplanet Detection Methods

Cited by 55 publications

References 166 publications

Relativistic boost as the cause of periodicity in a massive black-hole binary candidate

Relativistic boost as the cause of periodicity in a massive black-hole binary candidate

A Comprehensive Statistical Assessment of Star-Planet Interaction

A detector interferometric calibration experiment for high precision astrometry

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