Microlensing Results Challenge the Core Accretion Runaway Growth Scenario for Gas Giants

Suzuki, Daisuke; Bennett, David P.; Ida, Shigeru; Mordasini, Christoph; Bhattacharya, Aparna; Bond, Ian A.; Donachie, Martin; Fukui, Akihiko; Hirao, Yuki; Koshimoto, Naoki; Miyazaki, Shota; Nagakane, Masayuki; Ranc, Clément; Rattenbury, Nicholas J.; Sumi, Takahiro; Alibert, Yann; Lin, Douglas N. C. (2018). Microlensing Results Challenge the Core Accretion Runaway Growth Scenario for Gas Giants. Astrophysical Journal Letters, 869(2), L34. Institute of Physics Publishing IOP 10.3847/2041-8213/aaf577

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We compare the planet-to-star mass-ratio distribution measured by gravitational microlensing to core accretion theory predictions from population synthesis models. The core accretion theory's runaway gas accretion process predicts a dearth of intermediate-mass giant planets that is not seen in the microlensing results. In particular, the models predict ∼10× fewer planets at mass ratios of 10⁻⁴≤q≤4×10⁻⁴ than inferred from microlensing observations. This tension implies that gas giant formation may involve processes that have hitherto been overlooked by existing core accretion models or that the planet-forming environment varies considerably as a function of host-star mass. Variation from the usual assumptions for the protoplanetary disk viscosity and thickness could reduce this discrepancy, but such changes might conflict with microlensing results at larger or smaller mass ratios, or with other observations. The resolution of this discrepancy may have important implications for planetary habitability because it has been suggested that the runaway gas accretion process may have triggered the delivery of water to our inner solar system. So, an understanding of giant planet formation may help us to determine the occurrence rate of habitable planets.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute

UniBE Contributor:

Mordasini, Christoph and Alibert, Yann

Subjects:

500 Science > 530 Physics
500 Science
500 Science > 520 Astronomy

ISSN:

2041-8205

Publisher:

Institute of Physics Publishing IOP

Language:

English

Submitter:

Janine Jungo

Date Deposited:

13 Jun 2019 11:52

Last Modified:

13 Jun 2019 11:59

Publisher DOI:

10.3847/2041-8213/aaf577

ArXiv ID:

1812.11785v1

BORIS DOI:

10.7892/boris.128661

URI:

https://boris.unibe.ch/id/eprint/128661

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