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

We present new IRAM 30m spectroscopic observations of the $\sim88$ GHz band,including emission from the CCH (n=1-0) multiplet, HCN (1-0), HCO+ (1-0), andHNC (1-0), for a sample of 58 local luminous and ultraluminous infraredgalaxies from the Great Observatories All-sky LIRG Survey (GOALS). By combiningour new IRAM data with literature data and Spitzer/IRS spectroscopy, we studythe correspondence between these putative tracers of dense gas and the relativecontribution of active galactic nuclei (AGN) and star formation to themid-infrared luminosity of each system. We find the HCN (1-0) emission to beenhanced in AGN-dominated systems ($\langle$L'$_{HCN (1-0)}$/L'$_{HCO^+(1-0)}\rangle=1.84$), compared to composite and starburst-dominated systems($\langle$L'$_{HCN (1-0)}$/L'$_{HCO^+ (1-0)}\rangle=1.14$, and 0.88,respectively). However, some composite and starburst systems have L'$_{HCN(1-0)}$/L'$_{HCO^+ (1-0)}$ ratios comparable to those of AGN, indicating thatenhanced HCN emission is not uniquely associated with energetically dominantAGN. After removing AGN-dominated systems from the sample, we find a linearrelationship (within the uncertainties) between $\log_{10}$(L'$_{HCN (1-0)}$)and $\log_{10}$(L$_{IR}$), consistent with most previous findings. L'$_{HCN(1-0)}$/L$_{IR}$, typically interpreted as the dense gas depletion time,appears to have no systematic trend with L$_{IR}$ for our sample of luminousand ultraluminous infrared galaxies, and has significant scatter. Thegalaxy-integrated HCN (1-0) and HCO+ (1-0) emission do not appear to have asimple interpretation, in terms of the AGN dominance or the star formationrate, and are likely determined by multiple processes, including density andradiative effects.

Excitation Mechanisms for HCN (1-0) and HCO+ (1-0) in Galaxies from the Great Observatories All-sky LIRG Survey