PHANGS–ALMA Data Processing and Pipeline

Adam Leroy , Annie Hughes , Daizhong Liu , Jérôme Pety (1) , Erik Rosolowsky , Toshiki Saito , Eva Schinnerer , Andreas Schruba , Antonio Usero , Christopher Faesi , Cinthya Herrera , Mélanie Chevance , Alexander Hygate , Amanda Kepley , Eric Koch , Miguel Querejeta , Kazimierz Sliwa , David Will , Christine Wilson , Gagandeep Anand , Ashley Barnes , Francesco Belfiore , Ivana Bešlić , Frank Bigiel , Guillermo Blanc , Alberto Bolatto , Médéric Boquien , Yixian Cao , Rupali Chandar , Jérémy Chastenet , I-Da Chiang , Enrico Congiu , Daniel Dale , Sinan Deger , Jakob den Brok , Cosima Eibensteiner , Eric Emsellem , Axel García-Rodríguez , Simon Glover , Kathryn Grasha , Brent Groves , Jonathan Henshaw , María Jiménez Donaire , Jaeyeon Kim , Ralf Klessen , Kathryn Kreckel , J. Kruijssen , Kirsten Larson , Janice Lee , Ness Mayker , Rebecca Mcelroy , Sharon Meidt , Angus Mok , Hsi-An Pan , Johannes Puschnig , Alessandro Razza , Patricia Sánchez-Bl’azquez , Karin Sandstrom , Francesco Santoro , Amy Sardone , Fabian Scheuermann , Jiayi Sun , David Thilker , Jordan Turner , Leonardo Ubeda , Dyas Utomo , Elizabeth Watkins , Thomas Williams

1 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres

We describe the processing of the PHANGS-ALMA survey and present the PHANGS-ALMA pipeline, a public software package that processes calibrated interferometric and total power data into science-ready data products. PHANGS-ALMA is a large, high-resolution survey of CO(2-1) emission from nearby galaxies. The observations combine ALMA's main 12 m array, the 7 m array, and total power observations, and use mosaics of dozens to hundreds of individual pointings. We describe the processing of the u - v data, imaging and deconvolution, linear mosaicking, combining interferometer and total power data, noise estimation, masking, data product creation, and quality assurance. Our pipeline has a general design and can also be applied to Very Large Array and ALMA observations of other spectral lines and continuum emission. We highlight our recipe for deconvolution of complex spectral line observations, which combines multiscale clean, single-scale clean, and automatic mask generation in a way that appears robust and effective. We also emphasize our two-track approach to masking and data product creation. We construct one set of "broadly masked" data products, which have high completeness but significant contamination by noise, and another set of "strictly masked" data products, which have high confidence but exclude faint, low signal-to-noise emission. Our quality assurance tests, supported by simulations, demonstrate that 12 m+7 m deconvolved data recover a total flux that is significantly closer to the total power flux than the 7 m deconvolved data alone. In the appendices, we measure the stability of the ALMA total power calibration in PHANGS-ALMA and test the performance of popular short-spacing correction algorithms.

Mots clés: Radio interferometry; Interstellar medium; CO line emission; Millimeter astronomy; Astronomy data reduction; Galaxies; Star formation; 1346; 847; 262; 1061; 1861; 573; 1569; Astrophysics - Instrumentation and Methods for Astrophysics

Domaines: Physique [physics]; Astrophysique [astro-ph]

Adam Leroy, Annie Hughes, Daizhong Liu, Jérôme Pety, Erik Rosolowsky, et al.. PHANGS–ALMA Data Processing and Pipeline. The Astrophysical Journal Supplement Series, 2021, 255 (1), pp.19. ⟨10.3847/1538-4365/abec80⟩. ⟨hal-03480537⟩