The impact of the free-floating planet (FFP) mass function on the event rate for the accurate microlensing parallax determination: application to Euclid and Roman parallax observation
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arXiv
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| Format: | Preprint |
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2023
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| _version_ | 1866914891651088384 |
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| author | Ban, Makiko |
| author_facet | Ban, Makiko |
| contents | A microlensing event is mainly used to search for free-floating planets (FFPs). To estimate the FFP mass and distance via the microlensing effect, a microlensing parallax is one of the key parameters. A short duration of FFP microlensing is difficult to yield a parallax by the observer's motion at a recognisable level, so the FFP microlensing parallax is expected on the simultaneous observation by multiple telescopes. Here, we approach the FFP detection by considering a variation of FFP mass functions and the event rate of accurately measured microlensing parallax. We used our FFP microlensing simulator assuming a parallax observation between upcoming space-based missions (Euclid and Roman) with full kinematics. As a result, we confirmed that the event rate of accurately measured microlensing parallax (i.e. within a factor of 2 uncertainty) does not simply follow the number of FFPs at a given mass but the ratio of the FFP population per star. This is because the population ratio determines the optical depth for a given mass and potential sources. In addition, we found that the probability of the event that can estimate the FFP mass and distance within a factor of 2 is not so high: approx. 40% of Earth-mass, 16% of Neptune-mass, and 4% of Jupiter-mass FFP events under our criteria. The probability can be improved by some technical approach such as using high cadence and observation in parallax more than two observers. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2310_19615 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | The impact of the free-floating planet (FFP) mass function on the event rate for the accurate microlensing parallax determination: application to Euclid and Roman parallax observation Ban, Makiko Earth and Planetary Astrophysics Astrophysics of Galaxies Instrumentation and Methods for Astrophysics Solar and Stellar Astrophysics 85A99 A microlensing event is mainly used to search for free-floating planets (FFPs). To estimate the FFP mass and distance via the microlensing effect, a microlensing parallax is one of the key parameters. A short duration of FFP microlensing is difficult to yield a parallax by the observer's motion at a recognisable level, so the FFP microlensing parallax is expected on the simultaneous observation by multiple telescopes. Here, we approach the FFP detection by considering a variation of FFP mass functions and the event rate of accurately measured microlensing parallax. We used our FFP microlensing simulator assuming a parallax observation between upcoming space-based missions (Euclid and Roman) with full kinematics. As a result, we confirmed that the event rate of accurately measured microlensing parallax (i.e. within a factor of 2 uncertainty) does not simply follow the number of FFPs at a given mass but the ratio of the FFP population per star. This is because the population ratio determines the optical depth for a given mass and potential sources. In addition, we found that the probability of the event that can estimate the FFP mass and distance within a factor of 2 is not so high: approx. 40% of Earth-mass, 16% of Neptune-mass, and 4% of Jupiter-mass FFP events under our criteria. The probability can be improved by some technical approach such as using high cadence and observation in parallax more than two observers. |
| title | The impact of the free-floating planet (FFP) mass function on the event rate for the accurate microlensing parallax determination: application to Euclid and Roman parallax observation |
| topic | Earth and Planetary Astrophysics Astrophysics of Galaxies Instrumentation and Methods for Astrophysics Solar and Stellar Astrophysics 85A99 |
| url | https://arxiv.org/abs/2310.19615 |