%0 Generic %1 filion2022faint %A Filion, Carrie %A Platais, Imants %A Wyse, Rosemary F. G. %A Kozhurina-Platais, Vera %D 2022 %K function initial mass %T Faint Stars in a Faint Galaxy: II. The Low Mass Stellar Initial Mass Function of the Boötes I Ultrafaint Dwarf Spheroidal Galaxy %U http://arxiv.org/abs/2209.10461 %X This paper presents improved constraints on the low-mass stellar initial mass function (IMF) of the Boötes I (Boo~I) ultrafaint dwarf galaxy, based on our analysis of recent deep imaging from the Hubble Space Telescope. The identification of candidate stellar members of Boo~I in the photometric catalog produced from these data was achieved using a Bayesian approach, informed by complementary archival imaging data for the Hubble Ultra Deep Field. Additionally, the existence of earlier-epoch data for the fields in Boo~I allowed us to derive proper motions for a subset of the sources and thus identify and remove likely Milky Way stars. We were also able to determine the absolute proper motion of Boo~I, and our result is in agreement with, but completely independent of, the measurement(s) by Gaia. The best-fitting parameter values of three different forms of the low-mass IMF were then obtained through forward modeling of the color-magnitude data for likely Boo~I member stars within an approximate Bayesian computation Markov chain Monte Carlo algorithm. The best-fitting single power-law IMF slope is $= -1.95_-0.28^+0.32$, while the best-fitting broken power-law slopes are $\alpha_1 = -1.67_-0.57^+0.48$ and $\alpha_2 = -2.57_-1.04^+0.93$. The best-fitting lognormal characteristic mass and width parameters are $M_c = 0.17_-0.11^+0.05 M_ødot$ and $\sigma=0.49_-0.20^+0.13$. These broken power-law and lognormal IMF parameters for Boo~I are consistent with published results for the stars within the Milky Way and thus it is plausible that Boötes I and the Milky Way are populated by the same stellar IMF.

@misc{filion2022faint, abstract = {This paper presents improved constraints on the low-mass stellar initial mass function (IMF) of the Bo\"otes I (Boo~I) ultrafaint dwarf galaxy, based on our analysis of recent deep imaging from the Hubble Space Telescope. The identification of candidate stellar members of Boo~I in the photometric catalog produced from these data was achieved using a Bayesian approach, informed by complementary archival imaging data for the Hubble Ultra Deep Field. Additionally, the existence of earlier-epoch data for the fields in Boo~I allowed us to derive proper motions for a subset of the sources and thus identify and remove likely Milky Way stars. We were also able to determine the absolute proper motion of Boo~I, and our result is in agreement with, but completely independent of, the measurement(s) by \textit{Gaia}. The best-fitting parameter values of three different forms of the low-mass IMF were then obtained through forward modeling of the color-magnitude data for likely Boo~I member stars within an approximate Bayesian computation Markov chain Monte Carlo algorithm. The best-fitting single power-law IMF slope is $\alpha = -1.95_{-0.28}^{+0.32}$, while the best-fitting broken power-law slopes are $\alpha_1 = -1.67_{-0.57}^{+0.48}$ and $\alpha_2 = -2.57_{-1.04}^{+0.93}$. The best-fitting lognormal characteristic mass and width parameters are $\rm{M}_{\rm{c}} = 0.17_{-0.11}^{+0.05} \cal M_\odot$ and $\sigma=0.49_{-0.20}^{+0.13}$. These broken power-law and lognormal IMF parameters for Boo~I are consistent with published results for the stars within the Milky Way and thus it is plausible that Bo{\"o}tes I and the Milky Way are populated by the same stellar IMF.}, added-at = {2022-09-22T14:12:16.000+0200}, author = {Filion, Carrie and Platais, Imants and Wyse, Rosemary F. G. and Kozhurina-Platais, Vera}, biburl = {https://www.bibsonomy.org/bibtex/295c7610888681a2fcd40a276043c6276/quark75}, description = {Faint Stars in a Faint Galaxy: II. The Low Mass Stellar Initial Mass Function of the Bo\"otes I Ultrafaint Dwarf Spheroidal Galaxy}, interhash = {ada1c8b285003573e529c352faca150c}, intrahash = {95c7610888681a2fcd40a276043c6276}, keywords = {function initial mass}, note = {cite arxiv:2209.10461Comment: 27 pages, 14 figures, 4 tables, 3 appendices. Accepted for publication in ApJ}, timestamp = {2022-09-22T14:12:16.000+0200}, title = {Faint Stars in a Faint Galaxy: II. The Low Mass Stellar Initial Mass Function of the Bo\"otes I Ultrafaint Dwarf Spheroidal Galaxy}, url = {http://arxiv.org/abs/2209.10461}, year = 2022 }