A sensitive, high-resolution, wide-field IRAM NOEMA CO(1-0) survey of the very nearby spiral galaxy IC 342

• Main Authors: Querejeta, M, Pety, J, Schruba, A, Leroy, A. K, Herrera, C. N, Chiang, I-D, Meidt, S. E, Rosolowsky, E, Schinnerer, E, Schuster, K, Sun, J, Herrmann, K. A, Barnes, A. T, Beslic, I, Bigiel, F, Cao, Y, Chevance, M, Eibensteiner, C, Emsellem, E, Faesi, C. M, Hughes, A, Kim, J, Klessen, R. S, Kreckel, K, Kruijssen, J. M. D, Liu, D, Neumayer, N, Pan, H. -A, Saito, T, Sandstrom, K, Teng, Y. -S, Usero, A, Williams, T. G, Zakardjian, A
• Format: Journal Article
• Language: English
• Published: 10-10-2023
• Subjects: Physics - Astrophysics of Galaxies
• DOI: 10.48550/arxiv.2310.06501

A&A 680, A4 (2023) We present a new wide-field 10.75 x 10.75 arcmin^2 (~11x11 kpc^2),
high-resolution (theta = 3.6" ~ 60 pc) NOEMA CO(1-0) survey of the very nearby
(d=3.45 Mpc) spiral galaxy IC 342. The survey spans out to about 1.5 effective
radii and covers most of the region where molecular gas dominates the cold
interstellar medium. We resolved the CO emission into >600 individual giant
molecular clouds and associations. We assessed their properties and found that
overall the clouds show approximate virial balance, with typical virial
parameters of alpha_vir=1-2. The typical surface density and line width of
molecular gas increase from the inter-arm region to the arm and bar region, and
they reach their highest values in the inner kiloparsec of the galaxy (median
Sigma_mol~80, 140, 160, and 1100 M_sun/pc^2, sigma_CO~6.6, 7.6, 9.7, and 18.4
km/s for inter-arm, arm, bar, and center clouds, respectively). Clouds in the
central part of the galaxy show an enhanced line width relative to their
surface densities and evidence of additional sources of dynamical broadening.
All of these results agree well with studies of clouds in more distant galaxies
at a similar physical resolution. Leveraging our measurements to estimate the
density and gravitational free-fall time at 90 pc resolution, averaged on 1.5
kpc hexagonal apertures, we estimate a typical star formation efficiency per
free-fall time of 0.45% with a 16-84% variation of 0.33-0.71% among such 1.5
kpc regions. We speculate that bar-driven gas inflow could explain the large
gas concentration in the central kiloparsec and the buildup of the massive
nuclear star cluster. This wide-area CO map of the closest face-on massive
spiral galaxy demonstrates the current mapping power of NOEMA and has many
potential applications. The data and products are publicly available.