James Schombert, Stacy McGaugh, Federico Lelli

We explore the use of the baryonic Tully-Fisher relation (bTFR) as a new distance indicator. Advances in near-IR imaging and stellar population models, plus precise rotation curves, have reduced the scatter in the bTFR such that distance is the dominant source of uncertainty. Using 50 galaxies with accurate distances from Cepheids or tip magnitude of the red giant branch, we calibrate the bTFR on a scale independent of $H_o$. We then apply this calibrated bTFR to 95 independent galaxies from the SPARC sample, using CosmicFlows-3 velocities, to deduce the local value of $H_o$. We find $H_o$ = 75.1 +/- 2.3 (stat) +/- 1.5 (sys) km s$^{-1}$ Mpc$^{-1}$.

E. Aprile, J. Aalbers, F. Agostini, M. Alfonsi, L. Althueser, F. D. Amaro, V. C. Antochi, E. Angelino, J. R. Angevaare, F. Arneodo, D. Barge, L. Baudis, B. Bauermeister, L. Bellagamba, M. L. Benabderrahmane, T. Berger, A. Brown, E. Brown, S. Bruenner, G. Bruno, R. Budnik, C. Capelli, J. M. R. Cardoso, D. Cichon, B. Cimmino, M. Clark, D. Coderre, A. P. Colijn, J. Conrad, J. P. Cussonneau, M. P. Decowski, A. Depoian, P. Di Gangi, A. Di Giovanni, R. Di Stefano, S. Diglio, A. Elykov, G. Eurin, A. D. Ferella, W. Fulgione, P. Gaemers, R. Gaior, M. Galloway, F. Gao, L. Grandi, C. Hasterok, C. Hils, K. Hiraide, L. Hoetzsch, J. Howlett, M. Iacovacci, Y. Itow, F. Joerg, N. Kato, S. Kazama, M. Kobayashi, G. Koltman, A. Kopec, H. Landsman, R. F. Lang, L. Levinson, Q. Lin, S. Lindemann, M. Lindner, F. Lombardi, et al. (74 additional authors not shown)

We report results from searches for new physics with low-energy electronic recoil data recorded with the XENON1T detector. With an exposure of 0.65 tonne-years and an unprecedentedly low background rate of $76\pm2_{stat}$ events/(tonne$\times$year$\times$keV) between 1-30 keV, the data enables competitive searches for solar axions, an enhanced neutrino magnetic moment using solar neutrinos, and bosonic dark matter. An excess over known backgrounds is observed below 7 keV, rising towards lower energies and prominent between 2-3 keV. The solar axion model has a 3.5$\sigma$ significance, and a three-dimensional 90% confidence surface is reported for axion couplings to electrons, photons, and nucleons. This surface is inscribed in the cuboid defined by $g_{ae}<3.7\times10^{-12}$, $g_{ae}g_{an}^{eff}<4.6\times10^{-18}$, and $g_{ae}g_{a\gamma}<7.6\times10^{-22}~{GeV}^{-1}$, and excludes either $g_{ae}=0$ or $g_{ae}g_{a\gamma}=g_{ae}g_{an}^{eff}=0$. The neutrino magnetic moment signal is similarly favored over background at 3.2$\sigma$ and a confidence interval of $\mu_\nu\in(1.4,2.9)\times10^{-11} \mu_B$ (90% C.L.) is reported. Both results are in tension with stellar constraints. The excess can also be explained by $\beta$ decays of tritium, which was initially not considered, at 3.2$\sigma$ significance with a corresponding tritium concentration in xenon of $(6.2\pm2.0)\times10^{-25}$ mol/mol. Such a trace amount can be neither confirmed nor excluded with current knowledge of production and reduction mechanisms. The significances of the solar axion and neutrino magnetic moment hypotheses are decreased to 2.1$\sigma$ and 0.9$\sigma$, respectively, if an unconstrained tritium component is included in the fitting. This analysis also sets the most restrictive direct constraints to date on pseudoscalar and vector bosonic dark matter for most masses between 1 and 210 keV/c$^2$.