Spatially resolved spectrophotometric SED modeling of NGC 253's central molecular zone: I. Star formation in extragalactic giant molecular clouds
Journal article, 2025
Context. Studying the interstellar medium in nearby starbursts is essential for gaining insights into the physical mechanisms driving these extreme objects, which are thought to be analogs of young, primeval, star-forming galaxies. This task is now feasible due to deep spectro-photometric data enabled by rapid advancements in ground- and space-based facilities. To fully leverage this wealth of information, extracting insights from the spectral line properties and the spectral energy distribution (SED) is imperative.
Aims. This study aims to produce and analyze the physical properties of the first spatially resolved multiwavelength SED of an extragalactic source that covers six decades in frequency (from near-ultraviolet, NUV, to centimeter, cm, wavelengths) at an angular resolution of 3 '', which corresponds to a linear scale of similar to 51 pc at the distance of NGC 253. We focus on the central molecular zone (CMZ) of this starburst galaxy, which contains giant molecular clouds (GMCs) responsible for half of the galaxy's star formation.
Methods. We retrieved archival data from near-UV to centimeter wavelengths, covering six decades of spectral range. We computed the SEDs to fit the observations, using the GalaPy code and confronting the results with the CIGALE code for validation. We also employed the STARLIGHT code to analyze the stellar optical spectra of the GMCs.
Results. Our results reveal significant differences between internal and external GMCs in terms of stellar and dust masses, star formation rates (SFRs), and bolometric luminosities, among others, with internal GMCs doubling maximum values of the external ones in most of the cases. We obtained tight relations between monochromatic stellar tracers and star-forming conditions obtained from panchromatic emission. We find that the best SFR tracers are radio continuum bands at 33 GHz, radio recombination lines (RRLs), and the total infrared (IR) luminosity range (L-IR; 8-1000 mu m) as well as the IR emission at 60 mu m. The emission line diagnostics based on the BPT and WHAN diagrams suggest that the nuclear region of NGC 253 exhibits shock signatures, placing it in the composite zone typically associated with hybrids of active galactic nucleus (AGN) hosting and star-forming regions, while the AGN fraction from panchromatic emission is negligible (<= 7.5%).
Conclusions. Our findings demonstrate the significant heterogeneity within the CMZ of NGC 253, with central GMCs exhibiting high densities, elevated SFRs, and greater dust masses compared to their external counterparts. We confirm the effectiveness of certain centimeter photometric bands as a reliable method to estimate the global SFR, in accordance with previous studies - this time on GMC scales.
Aims. This study aims to produce and analyze the physical properties of the first spatially resolved multiwavelength SED of an extragalactic source that covers six decades in frequency (from near-ultraviolet, NUV, to centimeter, cm, wavelengths) at an angular resolution of 3 '', which corresponds to a linear scale of similar to 51 pc at the distance of NGC 253. We focus on the central molecular zone (CMZ) of this starburst galaxy, which contains giant molecular clouds (GMCs) responsible for half of the galaxy's star formation.
Methods. We retrieved archival data from near-UV to centimeter wavelengths, covering six decades of spectral range. We computed the SEDs to fit the observations, using the GalaPy code and confronting the results with the CIGALE code for validation. We also employed the STARLIGHT code to analyze the stellar optical spectra of the GMCs.
Results. Our results reveal significant differences between internal and external GMCs in terms of stellar and dust masses, star formation rates (SFRs), and bolometric luminosities, among others, with internal GMCs doubling maximum values of the external ones in most of the cases. We obtained tight relations between monochromatic stellar tracers and star-forming conditions obtained from panchromatic emission. We find that the best SFR tracers are radio continuum bands at 33 GHz, radio recombination lines (RRLs), and the total infrared (IR) luminosity range (L-IR; 8-1000 mu m) as well as the IR emission at 60 mu m. The emission line diagnostics based on the BPT and WHAN diagrams suggest that the nuclear region of NGC 253 exhibits shock signatures, placing it in the composite zone typically associated with hybrids of active galactic nucleus (AGN) hosting and star-forming regions, while the AGN fraction from panchromatic emission is negligible (<= 7.5%).
Conclusions. Our findings demonstrate the significant heterogeneity within the CMZ of NGC 253, with central GMCs exhibiting high densities, elevated SFRs, and greater dust masses compared to their external counterparts. We confirm the effectiveness of certain centimeter photometric bands as a reliable method to estimate the global SFR, in accordance with previous studies - this time on GMC scales.
galaxies: individual: NGC 253
galaxies: star formation
evolution
galaxies: starburst
stars: formation
Author
Pedro K. Humire
University of Sao Paulo (USP)
Subhrata Dey
Jagiellonian University in Kraków
National Centre for Nuclear Research
Tommaso Ronconi
International School for Advanced Studies (SISSA
Istituto nazionale di astrofisica (INAF)
Fondazione ICSC Centro Nazionale di Ricerca in High Performance Computing, Big Data e Quantum Computing
IFPU—Institute for Fundamental Physics of the Universe
Victor H. Sasse
Universidade Federal de Santa Catarina
Roberto Cid Fernandes
Universidade Federal de Santa Catarina
Sergio Martin
European Southern Observatory Santiago
Atacama Large Millimeter-submillimeter Array (ALMA)
Darko Donevski
International School for Advanced Studies (SISSA
National Centre for Nuclear Research
Katarzyna Malek
National Centre for Nuclear Research
Juan A. Fernandez-Ontiveros
CEFCA
Yiqing Song
Atacama Large Millimeter-submillimeter Array (ALMA)
European Southern Observatory Santiago
Mahmoud Hamed
National Centre for Nuclear Research
Spanish National Research Council (CSIC)
Jeffrey G. Mangum
National Radio Astronomy Observatory
Christian Henkel
Chinese Academy of Sciences
Max Planck Society
Victor M. Rivilla
Spanish National Research Council (CSIC)
Laura Colzi
Spanish National Research Council (CSIC)
Nanase Harada
The Graduate University for Advanced Studies (SOKENDAI)
Academia Sinica
National Astronomical Observatory of Japan
Ricardo Demarco
Universidad Andrés Bello
Arti Goyal
Jagiellonian University in Kraków
David S. Meier
New Mexico Institute of Mining and Technology
Swayamtrupta Panda
NSF's National Optical-Infrared Astronomy Research Laboratory (NOIRLab)
angela C. Krabbe
University of Sao Paulo (USP)
Yaoting Yan
Max Planck Society
Amanda R. Lopes
National University of La Plata
Kazushi Sakamoto
Academia Sinica
Sebastien Muller
Chalmers, Space, Earth and Environment, Onsala Space Observatory
Kunihiko Tanaka
Keio University
Yuki Yoshimura
University of Tokyo
Kouichiro Nakanishi
The Graduate University for Advanced Studies (SOKENDAI)
National Astronomical Observatory of Japan
Antonio Kanaan
Universidade Federal de Santa Catarina
Tiago Ribeiro
National Optical Astronomy Observatory
William Schoenell
GMTO Corporation
Claudia Mendes de Oliveira
University of Sao Paulo (USP)
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 699 A183Subject Categories (SSIF 2025)
Astronomy, Astrophysics, and Cosmology
DOI
10.1051/0004-6361/202553897