ALMA Large Program | Project Code: 2025.1.00576.L | Cycle 12

PI: Adam Leroy (Ohio State University)

1. Program Abstract

sSCALES is combining ALMA and JWST to survey the molecular gas and young stellar populations in four of the nearest, best-studied star-forming galaxies: NGC 253 (Sculptor), NGC 300, NGC 5236 (M83), and NGC 7793. The program aims to achieve ~ 10 pc resolution or better (down to ~ 1-2 pc in the short wavelength JWST filters) and observe the whole star-forming area of each target using multiple tracers of gas, dust, and recent star formation activity.

We expect sSCALES resolve 10s of thousands of molecular clouds and measure the molecular gas and dust associated with 10,000 HII regions and young stellar clusters - and to achieve a complete view of star forming regions over each of our targets. These are the key observations needed to measure the efficiency and timescale of stellar feedback into cold gas and the physical state and demographics of molecular clouds.

By pushing to ~10 pc resolution, sSCALES aims for a major advance compared to previous large extragalactic surveys of gas and dust at ~ 100 pc-resolution by resolving star forming regions across their evolution in multiple tracers (our targets have excellent VLT/MUSE and HST coverage in addition to ALMA and JWST). The survey will also forge strong links between Galactic and extragalactic work and observations and numerical simulations.

In detail, sSCALES is observing the CO 2-1, 13CO 2-1, and C18O 2-1 lines targeting ~ 10 pc physical resolution and combining multiple 12-m arrays with the ACA 7m and total power antennas. Complementary JWST observations observe the stellar populations, recombination line emission, PAH emission, and dust continuum in the near- and mid-infrared.

2. ALMA Large Program Project Codes

sSCALES is an ALMA Large Program approved in Cycle 12. The project details are listed below.

3. Team Members

PI: Adam Leroy

Co-PIs: Angela Adamo, Eric Koch, Erik Rosolowsky, Eva Schinnerer, Jiayi Sun, Karin Sandstrom, Alberto Bolatto

Co-Is Amirnezam Amiri, Ashley Barnes, Cara Battersby, Francesco Belfiore, Ivana Beslic, Frank Bigiel, Mederic Boquien, Jakob den Brok, Melanie Chevance, I-Da Chiang, Dario Colombo, Enrico Congiu, Serena Cronin, Daniel Dale, Cosima Eibensteiner, Oleg Egorov, Kimberly Emig, Eric Emsellem, Christopher Faesi, Helena Faustino Vieira, Simon Glover, Alyssa Goodman, Kathryn Grasha, Hamid Hassani, Annie Hughes, Remy Indebetouw. Maria Jesus Jimenez-Donaire, Jaeyeon Kim, Ralf Klessen, Grace Krahm, Rebecca Levy, Sean Linden, Daizhong Liu, Rebecca McClain, Sharon Meidt, Eric Murphy, Justus Neumann, Elias Oakes, Eve Ostriker, Hsi-An Pan, Debosmita Pathak, Alex Pedrini, Jerome Pety, Miguel Querejeta, Toshiki Saito, Rowan Smith, David Thilker, Todd Thompson, Robin Tress, Antonio Usero, Elizabeth Watkins, Thomas Williams, Catherine Zucker