Measuring the baryonic Tully–Fisher relation below the detection threshold

• Published in: Monthly notices of the Royal Astronomical Society 2021-12, Vol.508 (2), p.1897-1907
• Main Authors: Pan, Hengxing, Jarvis, Matt J, Ponomareva, Anastasia A, Santos, Mario G, Allison, James R, Maddox, Natasha, Frank, Bradley S
• Format: Article
• Language: English
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stab2601

ABSTRACT We present a novel 2D flux density model for observed H i emission lines combined with a Bayesian stacking technique to measure the baryonic Tully–Fisher relation below the nominal detection threshold. We simulate a galaxy catalogue, which includes H i lines described with either Gaussian or busy function profiles, and H i data cubes with a range of noise and survey areas similar to the MeerKAT International Giga-Hertz Tiered Extragalactic Exploration (MIGHTEE) survey. With prior knowledge of redshifts, stellar masses, and inclinations of spiral galaxies, we find that our model can reconstruct the input baryonic Tully–Fisher parameters (slope and zero-point) most accurately in a relatively broad redshift range from the local Universe to z = 0.3 for all the considered levels of noise and survey areas and up to z = 0.55 for a nominal noise of 90 $\mu$Jy/channel over 5 deg2. Our model can also determine the $M_{\rm H\, \small {I}} - M_{\star }$ relation for spiral galaxies beyond the local Universe and account for the detailed shape of the H i emission line, which is crucial for understanding the dynamics of spiral galaxies. Thus, we have developed a Bayesian stacking technique for measuring the baryonic Tully–Fisher relation for galaxies at low stellar and/or H i masses and/or those at high redshift, where the direct detection of H i requires prohibitive exposure times.