Occurrence rate of hot Jupiters around early-type M dwarfs based on TESS data

We present an estimate of the occurrence rate of hot Jupiters ($7R_{\oplus }\le R_p\le 2R_J$, $0.8\le P_b\le 10$ days) around early-type M dwarfs based on stars observed by TESS during its Primary Mission. We adopt stellar parameters from the TESS Input Catalog, and construct a sample of 60,819 M dwarfs with $10.5\le T_{\mathrm{m}\mathrm{a}\mathrm{g}}\le 13.5$, effective temperature $2900\le T_{\mathrm{e}\mathrm{f}\mathrm{f}}\le 4000K$ and stellar mass $0.45\le M_{\ast }\le 0.65M_{\odot }$. We conduct a uninformed transit search using a detection pipeline based on the box least square search and characterize the searching completeness through an injection and recovery experiment. We combine a series of vetting steps including light centroid measurement, odd/even and secondary eclipse analysis, rotation and transit period synchronization tests as well as inspecting the ground-based photometric, spectroscopic and imaging observations. Finally, we find a total of nine planet candidates, all of which are known TESS objects of interest. We obtain an occurrence rate of $0.27\pm 0.09\mathrm{\%}$ for hot Jupiters around early-type M dwarfs that satisfy our selection criteria. Compared with previous studies, the occurrence rate of hot Jupiters around early-type M dwarfs is smaller than all measurements for FGK stars, although they are consistent within 1–2$\sigma$. Combining results from transit, radial velocity and microlensing surveys, we find that hot Jupiters around early-type M dwarfs possibly show a steeper decrease in occurrence rate per logarithmic semi-major axis bin ($\mathrm{d}N\mathrm{/}\mathrm{d}{\log }_{10}a$) when compared with FGK stars.