A Statistical Analysis of Seeds and Other High-Contrast Exoplanet Surveys: Massive Planets or Low-Mass Brown Dwarfs?

Brandt, Timothy D.; McElwain, Michael W.; Turner, Edwin L.; Mede, Kyle; Spiegel, David S.; Kuzuhara, Masayuki; Schlieder, Joshua E.; Wisniewski, John P.; Abe, Lyu; Biller, Beth; Brandner, W.; Carson, J.; Currie, Thayne; Egner, Sebastian; Feldt, M.; Golota, Taras; Goto, Miwa; Grady, C. A.; Guyon, Olivier; Hashimoto, Jun; Hayano, Yutaka; Hayashi, Masao; Hayashi, Saeko S.; Henning, Thomas; Hodapp, Klaus W.; Inutsuka, Shu‐ichiro; Ishii, Miki; Iye, Masanori; Janson, Markus; Kandori, Ryo; Knapp, G. R.; Kudo, Tomoyuki; Kusakabe, Nobuhiko; Kwon, Jungmi; Matsuo, Taro; Miyama, Shoken M.; Morino, Jun-Ichi; Moro‐Martín, Amaya; Nishimura, Tetsuo; Pyo, Tae‐Soo; Serabyn, Eugene; Shimada, Hiroshi; Suzuki, Ryuji; Takami, M.; Takato, Naruhisa; Terada, Hiroshi; Thalmann, Christian; Tomono, Daigo; Watanabe, Makoto; Yamada, Tōru; Takami, Hideki; Usuda, Tomonori; Tamura, Motohide

doi:10.1088/0004-637x/794/2/159

Cited by 135 publications

(111 citation statements)

References 173 publications

(303 reference statements)

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“…This also argues for an extension of the stellar/BD formation mechanisms in the planetary-mass regime. Our results are also consistent with the conclusions of Brandt et al (2014b) that some of the so-far directly imaged exoplanets could have formed by either core or disk fragmentation and constitute the low-mass tail of the BD mass distribution.…”

Section: Discussionsupporting

confidence: 91%

“…Instead of trying to fit the substellar CMF with a single power-law distribution (see, e.g., Brandt et al 2014b), we assume the overall frequency of substellar companions to be the sum of two contributions as follows:…”

Section: Model For the Substellar Cmfmentioning

confidence: 99%

“…Companions in this mass range could be the lower mass tail of the stellar CMRD as well as the higher mass end of the planet CMF, but they have usually been excluded by the statistical analyses of direct imaging surveys. Different features in the frequency of BD companions and planets as a function of mass and semimajor axis could help distinguish different formation mechanisms (see also Brandt et al 2014b). Although spectroscopy may help in investigating whether a given detected object formed by one process or another, large surveys could contribute in assessing whether a stellar-like or planet-like formation process dominates the CMF in a given companion mass range.…”

Section: Introductionmentioning

confidence: 99%

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The VLT/NaCo large program to probe the occurrence of exoplanets and brown dwarfs at wide orbits

Reggiani

Meyer

Chauvin

et al. 2016

A&A

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Context. In recent years there have been many attempts to characterize the occurrence and distribution of stellar, brown dwarf (BD), and planetary-mass companions to solar-type stars with the aim of constraining formation mechanisms. From radial velocity observations a dearth of companions with masses between 10-40 M Jupiter has been noticed at close separations, suggesting the possibility of a distinct formation mechanism for objects above and below this range. Aims. We present a model for the substellar companion mass function (CMF). This model consists of the superposition of the planet and BD companion mass distributions, assuming that we can extrapolate the radial velocity measured CMF for planets to larger separations and the stellar companion mass-ratio distribution over all separations into the BD mass regime. By using both the results of the VLT/NaCo large program (NaCo-LP) and the complementary archive datasets, which probe the occurrence of planets and BDs on wide orbits around solar-type stars, we place some constraints on the planet and BD distributions. Methods. We developed a Monte Carlo simulation tool to predict the outcome of a given survey, depending on the shape of the orbital parameter distributions (mass, semimajor axis, eccentricity, and inclination). Comparing the predictions with the results of the observations, we calculate the likelihood of different models and which models can be ruled out. Results. Current observations are consistent with the proposed model for the CMF, as long as a sufficiently small outer truncation radius ( 100 AU) is introduced for the planet separation distribution. Some regions of parameter space can be excluded by the observations. Conclusions. We conclude that the results of the direct imaging surveys searching for substellar companions around Sun-like stars are consistent with a combined substellar mass spectrum of planets and BDs. This mass distribution has a minimum between 10 and 50 M Jupiter , in agreement with radial velocity measurements. In this picture the dearth of objects in this mass range would naturally arise from the shape of the mass distribution, without the introduction of any distinct formation mechanism for BDs. This kind of model for the CMF allows us to determine the probability for a substellar companion as a function of mass to have formed in a disk or from protostellar core fragmentation, as such mechanisms overlap in this mass range.

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Section: Discussionsupporting

confidence: 91%

Section: Model For the Substellar Cmfmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The VLT/NaCo large program to probe the occurrence of exoplanets and brown dwarfs at wide orbits

Reggiani

Meyer

Chauvin

et al. 2016

A&A

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“…The main objectives of these surveys were to populate the mass vs. semi-major axis diagram at large separations, and to clarify the mechanisms of planetary formation. Among the most recent of these surveys we can cite the NACO-Large Program at the Very Large Telescope (Desidera et al 2014;Chauvin et al 2014), the Strategic Exploration of Exoplanets and Disk with Subaru (SEEDS) at the Subaru Telescope (Janson et al 2013;Brandt et al 2014), the Near-Infrared Coronagraphic Imager (NICI) campaign at the Gemini South Telescope (Nielsen et al 2013;Biller et al 2013), the International Deep Planet Survey (Vigan et al 2012) at the Very Large Telescope (VLT) and Gemini North, and a survey of young, nearby, and dusty stars to understand the formation of wide-orbit giant planets (Rameau et al 2013b) at VLT.…”

Section: Introductionmentioning

confidence: 99%

Performance of the VLT Planet Finder SPHERE

Zurlo

Vigan

Mesa

et al. 2014

A&A

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Context. The new planet finder for the Very Large Telescope (VLT), the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE), just had its first light in Paranal. A dedicated instrument for the direct detection of planets, SPHERE, is composed of a polametric camera in visible light, the Zurich IMager POLarimeter (ZIMPOL), and two near-infrared sub-systems: the Infra-Red Dual-beam Imager and Spectrograph (IRDIS), a multi-purpose camera for imaging, polarimetry, and long-slit spectroscopy, and the integral field spectrograph (IFS), an integral field spectrograph. Aims. We present the results obtained from the analysis of data taken during the laboratory integration and validation phase, after the injection of synthetic planets. Since no continuous field rotation could be performed in the laboratory, this analysis presents results obtained using reduction techniques that do not use the angular differential imaging (ADI) technique. Methods. To perform the simulations, we used the instrumental point spread function (PSF) and model spectra of L and T-type objects scaled in contrast with respect to the host star. We evaluated the expected error in astrometry and photometry as a function of the signal to noise of companions, after spectral differential imaging (SDI) reduction for IRDIS and spectral deconvolution (SD) or principal component analysis (PCA) data reductions for IFS. Results. We deduced from our analysis, for example, that β Picb, a 12 Myr old planet of ∼10 M Jup and semi-major axis of 9-10 AU, would be detected with IRDIS with a photometric error of 0.16 mag and with a relative astrometric position error of 1.1 mas. With IFS, we could retrieve a spectrum with error bars of about 0.15 mag on each channel and astrometric relative position error of 0.6 mas. For a fainter object such as HR 8799d, a 13 M Jup planet at a distance of 27 AU, IRDIS could obtain a relative astrometric error of 3 mas.

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“…The field of view (FoV) is rotating with the parallactic angle with an alt-az telescope, allowing temporally substracting the speckle pattern and recovering any off-axis companion by de-rotating the final residual images. ADI has been widely used during the past years in deep-imaging surveys of exoplanets (Lafrenière et al 2007;Vigan et al 2012;Rameau et al 2013;Biller et al 2013;Brandt et al 2014;Chauvin et al 2015). However, ADI is not efficient in calibrating and subtracting the fast atmospheric speckles.…”

Section: Introductionmentioning

confidence: 99%

Detection limits with spectral differential imaging data

Rameau

Chauvin

Lagrange

et al. 2015

A&A

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Context. Direct imaging of exoplanets is polluted by speckle noise that severely limits the achievable contrast. Angular and spectral differential imaging have been proposed to make use of the temporal and chromatic properties of the speckles. Both modes, associated with extreme adaptive-optics and coronagraphy, are at the core of the new generation of planet imagers SPHERE and GPI. Aims. We aim to illustrate and characterize the impact of the SDI and SDI+ADI (ASDI) data reduction on the detection of giant planets. We also propose an unbiased method to derive the detection limits from SDI/ASDI data. Methods. Observations of AB Dor B and β Pictoris made with VLT/NaCo were used to simulate and quantify the effects of SDI and ASDI. The novel method is compared to the traditional injection of artificial point sources.Results. The SDI reduction process creates a typical radial positive-negative pattern of any point-source. Its characteristics and its selfsubtraction depend on the separation, but also on the spectral properties of the object. This work demonstrates that the self-subtraction cannot be reduced to a simple geometric effect. As a consequence, the detection performances of SDI observations cannot be expressed as a contrast in magnitude with the central star without the knowledge of the spectral properties of detectable companions. In addition, the residual noise cannot be converted into contrast and physical characteristics (mass, temperature) by standard calibration of flux losses. The proposed method takes the SDI bias into account to derive detection limits without the cost of massively injecting artificial sources into the data. Finally, the sensitivity of ASDI observations can be measured only with a control parameter on the algorithms that controls the minimum rotation that is necessary to build the reference image.

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A Statistical Analysis of Seeds and Other High-Contrast Exoplanet Surveys: Massive Planets or Low-Mass Brown Dwarfs?

Cited by 135 publications

References 173 publications

The VLT/NaCo large program to probe the occurrence of exoplanets and brown dwarfs at wide orbits

The VLT/NaCo large program to probe the occurrence of exoplanets and brown dwarfs at wide orbits

Performance of the VLT Planet Finder SPHERE

Detection limits with spectral differential imaging data

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