Issue |
A&A
Volume 632, December 2019
|
|
---|---|---|
Article Number | A113 | |
Number of page(s) | 15 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361/201936729 | |
Published online | 12 December 2019 |
Circumbinary exoplanets and brown dwarfs with the Laser Interferometer Space Antenna
1
AIM, CEA, CNRS, Université Paris-Saclay, Université Paris Diderot, Sorbonne Paris Cité,
91191
Gif-sur-Yvette,
France
e-mail: camilla.danielski@cea.fr
2
Institut d’Astrophysique de Paris, CNRS, UMR 7095, Sorbonne Université,
98 bis bd Arago,
75014
Paris,
France
3
Leiden Observatory, Leiden University, PO Box 9513,
2300 RA
Leiden,
The Netherlands
4
School of Physics and Astronomy, University of Birmingham,
Edgbaston,
Birmingham
B15 2TT,
UK
5
Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut,
Am Mühlenberg 1,
14476
Potsdam-Golm, Germany
Received:
18
September
2019
Accepted:
11
October
2019
Aims. We explore the prospects for the detection of giant circumbinary exoplanets and brown dwarfs (BDs) orbiting Galactic double white dwarfs (DWDs) binaries with the Laser Interferometer Space Antenna (LISA).
Methods. By assuming an occurrence rate of 50%, motivated by white dwarf pollution observations, we built a Galactic synthetic population of P-type giant exoplanets and BDs orbiting DWDs. We carried this out by injecting different sub-stellar populations, with various mass and orbital separation characteristics, into the DWD population used in the LISA mission proposal. We then performed a Fisher matrix analysis to measure how many of these three-body systems show a periodic Doppler-shifted gravitational wave perturbation detectable by LISA.
Results. We report the number of circumbinary planets (CBPs) and BDs that can be detected by LISA for various combinations of mass and semi-major axis distributions. We identify pessimistic and optimistic scenarios corresponding, respectively, to 3 and 83 (14 and 2218) detections of CBPs (BDs), observed during the length of the nominal LISA mission. These detections are distributed all over the Galaxy following the underlying DWD distribution, and they are biased towards DWDs with higher LISA signal-to-noise ratio and shorter orbital period. Finally, we show that if LISA were to be extended for four more years, the number of systems detected will be more than doubled in both the optimistic and pessimistic scenarios.
Conclusions. Our results present promising prospects for the detection of post-main sequence exoplanets and BDs, showing that gravitational waves can prove the existence of these populations over the totality of the Milky Way. Detections by LISA will deepen our knowledge on the life of exoplanets subsequent to the most extreme evolution phases of their hosts, clarifying whether new phases of planetary formation take place later in the life of the stars. Such a method is strongly complementary to electromagnetic studies within the solar region and opens a window into the investigation of planets and BDs everywhere in the entire Galaxy, and possibly even in nearby galaxies in the Local Group.
Key words: planets and satellites: detection / brown dwarfs / white dwarfs / gravitational waves / planets and satellites: gaseous planets
© C. Danielski et al. 2019
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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