J/ApJ/939/96 Milky Way field giants from Gaia & APASS I-band (Li+, 2022) ================================================================================ A maximum likelihood calibration of the tip of the red giant branch luminosity from high latitude field giants using Gaia Early Data Release 3 parallaxes. Li S., Casertano S., Riess A.G. =2022ApJ...939...96L ================================================================================ ADC_Keywords: Stars, giant; Milky Way; Colors; Photometry, UBVRI; Extinction; Parallaxes, trigonometric Keywords: Milky Way Galaxy ; Calibration ; Red giant tip ; Distance indicators ; Hubble constant ; Parallax ; Maximum likelihood estimation ; Absolute magnitude ; Field stars Abstract: The calibration of the tip of the red giant branch (TRGB) in the I-band has a direct role in determinations of the Hubble constant, a subject of recent interest due to the discrepancy between direct and indirect estimates of its value. We present a maximum likelihood method designed to obtain an independent calibration of the brightness of TRGB using Gaia parallaxes from the Early Data Release 3 (EDR3) of Milky Way field giants at high Galactic latitude. We adopt simple parameterizations for the Milky Way stellar luminosity function and density law and optimize the likelihood of the observed sample as a function of those parameters. Using parameters to partially constrain the luminosity function from other galaxies similar to the Milky Way for which high-quality TRGB data are available, we find values of the TRGB magnitude of M_I_^TRGB^=-3.91+/-0.05(stat)+/-0.09(sys)mag, where the systematic uncertainty covers the range of shape parameters found in our Milky Way sample and in reference galaxies. While APASS Data Release 9 all-sky photometry is insufficient to provide a reliable constraint on the shape of the Milky Way luminosity function, we estimate that the photometry from Gaia Data Release 3 (mid-2022) will allow better constraints on the shape, and lower statistical uncertainties on the tip by a factor of 3. With the expected releases of improved parallax measurements from Gaia, the method of calibrating the TRGB luminosity from field giants is expected to reach ~0.01mag uncertainty, which is an important step toward a precise TRGB-based determination of the Hubble constant. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 75 5288 Milky Way field giants in final sample; updated version by the author -------------------------------------------------------------------------------- See also: II/336 : AAVSO Photometric All Sky Survey (APASS) DR9 (Henden+, 2016) I/350 : Gaia EDR3 (Gaia Collaboration, 2020) I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022) J/ApJ/845/146 : Carnegie-Chicago Hubble Program. II. IC 1613 (Hatt+, 2017) J/MNRAS/482/5138 : Gal. GC mean proper motions & velocities (Baumgardt+, 2019) J/ApJ/886/61 : OGLE-III, MCPS and HST VI obs. of LMC & SMC (Yuan+, 2019) J/ApJ/904/13 : RVel for 10 giant eclipsing binaries (Graczyk+, 2020) J/ApJ/906/125 : The Carnegie-Chicago Hubble Program IX. M106 (Jang+, 2021) J/AJ/161/176 : KISOGP: 7055 eclipsing binaries with KWFC (Ren+, 2021) J/ApJS/252/23 : E(V-I) reddening map of MCs from OGLE-IV (Skowron+, 2021) J/ApJ/908/L5 : Color-magnitude diagram for {omega} Centauri (Soltis+, 2021) J/MNRAS/505/5978 : Gaia EDR3 view on Gal. globular clusters (Vasiliev+, 2021) Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 19 I19 --- Gaia Gaia EDR3 identifier 21- 26 F6.3 mag Gmag [9.8/13] Gaia EDR3 G-band magnitude 28- 32 F5.3 mag BP-RP [1.3/6] Gaia EDR3 GBP-RBP color 34- 39 F6.3 mag Imag [8.6/11.7] Johnson-Cousins I magnitude from APASS (1) 41- 45 F5.3 mag e_Imag [0.009/0.5] Dispersion in Imag 47- 51 F5.3 mas omega [0.046/0.5] Measured parallax (2) 53- 57 F5.3 mas e_omega [0.009/0.4] Parallax error 59- 63 F5.3 deg b [0.58/1] Galactic latitude 65- 69 F5.3 mag AImag [0.005/1.5] I-band extinction (3) 71- 75 F5.3 mag e_AImag [0/0.12] Uncertainty in AImag -------------------------------------------------------------------------------- Note (1): Converted Sloan i'r' magnitudes from APASS to Johnson-Cousins I magnitudes using photometric conversions provided by SDSS; see Equations 2 and 3 of the accepted manuscript. Note (2): Lindegren+ 2021A&A...649A...4L and Lindegren L. (2021 Gaia EDR3 Online Worshop, http://www.edr3workshop.com/) offsets applied Note (3): Extinction corrections from the Schlafly & Finkbeiner 2011ApJ...737..103S dust maps using the NASA/IPAC Galactic Dust Reddening and Extinction tool, doi:10.26131/IRSA537 -------------------------------------------------------------------------------- Acknowledgments: Siyang Li [sli185 _at_ jhu.edu] History: From electronic version of the journal * Several Gaia identifiers have been corrected by the author. ================================================================================ (End) Prepared by [AAS], Emmanuelle Perret [CDS] 21-Mar-2025