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We study how several published baryonic Tully-Fisher relations (BTFRs) fit a large sample of galaxies from the Arecibo legacy fast ALFA (ALFALFA) 21cm survey to determine which BTFR is a better template for calculating the distances and peculiar velocities of the ALFALFA galaxies. In particular, the BTFRs studied were those published by Papastergis et al. (2016) and Lelli et al. (2019). To do so, we first derived the rotational velocities and baryonic masses of a sub sample of galaxies with ”good” data, which make up 68% of the ALFALFA galaxies. We then calculated the best-fit line of the sample using fivedifferent fitting methods: (1) the ordinary least squares (OLS), (2) the maximum likelihood method assuming no intrinsic scatter as defined by Papastergis et al. (2016), (3) the maximum likelihood method with intrinsic scatter along the perpendicular direction (σ⊥,intr) also defined by Papastergis et al. (2016), (4) the maximum likelihood method assuming intrinsic scatter along the vertical direction (σy) as defined by Lelli et al. (2019)., and (5) the maximum likelihood method with intrinsic scatter along the perpendicular direction (σ⊥) also defined by Lelli et al. (2019). We find that fitting method (2) yields the steepest slope, 3.42, which agrees well with the values obtained in previous studies. We use this fit-line to compare with the two published BTFRs and determine that the BTFR derived by Papastergis et al.(2016) is the better template for calculating the distances and pecu-liar velocities of the ALFALFA catalog. This work was supported by NSF/AST-1714828 and by grants from the Brinson Foundation. 

We present our work on constructing a template Baryonic Tully-Fisher Relation (BTFR) from galaxies in the local universe that have primary distances. We utilize HI 21 cm line data from the complete Arecibo Legacy Fast ALFA (ALFALFA) survey and the digital HI archive from Springob et al. 2005; we also use photometry from the Sloan Digital Sky Survey (SDSS) and the NASA Sloan Atlas (NSA) MANGA v1_0_2 database; lastly, we have also made use of the Extragalactic Distance Database (EDD) for identifying galaxies with primary distances. After cross-matching the galaxies in these catalogues, we identify some 144 galaxies which meet our requirements for having all the necessary HI and photometry data, having primary distances, residing within 30 Mpc, and having low enough uncertainties to be considered reliable data points. An important trait of this data set is the prominence of low-mass, low-luminosity dwarves. Notably, we find the values for the slope, intercept and intrinsic scatter of the relation to be around 2.3, 4.8, and 0.4, respectively. Further, while unresolved velocity widths have historically produced shallower slopes, and while the BTFR has been shown to have a higher intrinsic scatter for low-mass galaxies, these precedents are not enough to explain the deviation of our data from the “standard” values of the BTFR. This work therefore raises several questions about why this discrepancy exists, how it can be resolved, and what we can learn from it. The authors would like to acknowledge the support of NSF/AST-1714828 and the Brinson Foundation.