Fire in the Heart: A Characterization of the High Kinetic Temperatures and Heating Sources in the Nucleus of NGC253
Artikel i vetenskaplig tidskrift, 2019

The nuclear starburst within the central similar to 15 '' (similar to 250 pc; 1 '' similar or equal to 17 pc) of NGC 253 has been extensively studied as a prototype for the starburst phase in galactic evolution. Atacama Large Millimeter/submillimeter Array (ALMA) imaging within receiver Bands 6 and 7 has been used to investigate the dense gas structure, kinetic temperature, and heating processes that drive the NGC 253 starburst. A total of 29 transitions from 15 molecular species/isotopologues have been identified and imaged at 1.'' 5-0.'' 4 resolution, allowing for the identification of five of the previously studied giant molecular clouds within the central molecular zone (CMZ) of NGC 253. Ten transitions from the formaldehyde (H2CO) molecule have been used to derive the kinetic temperature within the similar to 0.'' 5-5 '' dense gas structures imaged. On similar to 5 '' scales we measure T-K greater than or similar to 50 K, while on size scales less than or similar to 1 '' we measure T-K greater than or similar to 300 K. These kinetic temperature measurements further delineate the association between potential sources of dense gas heating. We have investigated potential heating sources by comparing our measurements to models that predict the physical conditions associated with dense molecular clouds that possess a variety of heating mechanisms. This comparison has been supplemented with tracers of recently formed massive stars (Br gamma) and shocks ([Fe II]). Derived molecular column densities point to a radially decreasing abundance of molecules with sensitivity to cosmic-ray and mechanical heating within the NGC 253 CMZ. These measurements are consistent with radio spectral index calculations that suggest a higher concentration of cosmic-ray-producing supernova remnants within the central 10 pc of NGC 253.

galaxies: active

galaxies: nuclei

galaxies: individual (NGC 253)

galaxies: spiral

galaxies: starburst

ISM: molecules

Författare

Jeffrey G. Mangum

National Radio Astronomy Observatory

Adam G. Ginsburg

Natl Radio Astron Observ, POB O, 1003 Lopezville Rd

Christian Henkel

King Abdulaziz University

Max Planck-institutet

Karl M. Menten

Max Planck-institutet

Susanne Aalto

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik

Paul van der Werf

Universiteit Leiden

Astrophysical Journal

0004-637X (ISSN) 1538-4357 (eISSN)

Vol. 871 2 170

Ämneskategorier

Astronomi, astrofysik och kosmologi

Atom- och molekylfysik och optik

Annan fysik

DOI

10.3847/1538-4357/aafa15

Mer information

Senast uppdaterat

2019-03-05