http://arxiv.org/abs/2211.16455
Modelling the integrated H I spectra of galaxies has been a difficult task due to their diverse shapes, but more dynamical information is waiting to be explored in Hi line profiles. Based on simple assumptions, we construct a physically motivated model for the integrated Hi spectra: Parametrized Asymmetric Neutral hydrogen Disk Integrated Spectrum Characterization (PANDISC). The model shows great flexibility in reproducing the diverse Hi profiles. We use Monte-Carlo Markov Chain (MCMC) for fitting the model to global H I profiles, producing statistically robust quantitative results. Comparing with several samples of H I data available in the literature , we find the model-fitted results agree with catalogued velocity widths (e.g., W50) down to the lowest S/N. The model is also shown to be useful for applications like the baryonic Tully-Fisher relation (BTFR) and profile-based sample control. By comparing v_r to v_flat , we uncover how the H I width is affected by the structure of the rotation curve, following a trend consistent with the difference in the BTFR slope. We also select a sample of spectra with broad wing-like features suggestive of a population of galaxies with unusual gas dynamics. The PANDISC model bears both promise and limitations for potential use beyond H I lines. Further application on the whole ALFALFA sample will enable us to perform large scale ensemble studies of the H I properties and dynamics in nearby galaxies.
B. Peng, M. Haynes, C. Ball, et. al.
Wed, 30 Nov 22
12/81
Comments: 27 pages, 18 figures, submitted to ApJ
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