English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The nuclear starburst within the central $\sim 15^{\prime\prime}$ ($\sim 250$pc; $1^{\prime\prime} \simeq 17$ pc) of NGC253 has been extensively studied asa prototype for the starburst phase in galactic evolution. Atacama LargeMillimeter/submillimeter Array (ALMA) imaging within receiver Bands 6 and 7have been used to investigate the dense gas structure, kinetic temperature, andheating processes which drive the NGC253 starburst. Twenty-nine transitionsfrom fifteen molecular species/isotopologues have been identified and imaged at$1.^{\prime\prime}5$ to $0.^{\prime\prime}4$ resolution, allowing for theidentification of five of the previously-studied giant molecular clouds (GMCs)within the central molecular zone (CMZ) of NGC253. Ten transitions from theformaldehyde (H$_2$CO) molecule have been used to derive the kinetictemperature within the $\sim 0.^{\prime\prime}5$ to $5^{\prime\prime}$dense-gas structures imaged. On $\sim 5^{\prime\prime}$ scales we measure $T_K\gtrsim 50$ K, while on size scales $\lesssim 1^{\prime\prime}$ we measure $T_K\gtrsim 300$ K. These kinetic temperature measurements further delineate theassociation between potential sources of dense gas heating. We haveinvestigated potential heating sources by comparing our measurements to modelswhich predict the physical conditions associated with dense molecular cloudsthat possess a variety of heating mechanisms. This comparison has beensupplemented with tracers of recently-formed massive stars (Br$\gamma$) andshocks ([FeII]). Derived molecular column densities point to aradially-decreasing abundance of molecules with sensitivity to cosmic ray andmechanical heating within the NGC253 CMZ. These measurements are consistentwith radio spectral index calculations which suggest a higher concentration ofcosmic ray producing supernova remnants within the central 10 pc of NGC253.

Fire in the Heart: A Characterization of the High Kinetic Temperatures and Heating Sources in the Nucleus of NGC253