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 use Spitzer IRS spectroscopy to study the nature 65 IR-luminous galaxiesat 0.02 < z < 0.6 with F(24micron) > 1.2mJy. The IRS spectra cover wavelengthsspanning the PAH features and important atomic diagnostic lines. Our samplecorresponds to L(IR) = L(8-1000micron) = 10^10-10^12 Lsun. We divide ourgalaxies into those with Spitzer IRAC colors indicative of warm dust heated byan AGN (IRAGN) and those whose colors indicate star-formation processes(non-IRAGN). Compared to the non-IRAGN, the IRAGN show smaller PAH emissionEWs, which we attribute to an increase in mid-IR continuum from the AGN. Wefind that in both the IRAGN and non-IRAGN samples, the PAH luminositiescorrelate strongly with the [Ne II] emission, from which we conclude that thePAH luminosity directly traces the instantaneous SFR in both the IRAGN andnon-IRAGN galaxies. We compare the ratio of PAH luminosity to the total IRluminosity and show that for most IRAGN star-formation accounts for 10-50% ofthe L(IR). We also find no measurable difference between the PAH luminosityratios of L(11.3)/L(7.7) and L(6.2)/L(7.7) for the IRAGN and non-IRAGN,suggesting that AGN do not significantly excite or destroy PAH molecules ongalaxy-wide scales. A small subset of galaxies show excess of [O IV] emissioncompared to their PAH emission, which indicates the presence ofheavily-obscured AGN, including 3 galaxies that are not otherwise selected asIRAGN. The low PAH emission and low [Ne II] emission of the IRAGN and [OIV]-excess objects imply they have low SFRs and their IR luminosity isdominated by processes associated with the AGN.

Spitzer Spectroscopy of Infrared-Luminous Galaxies: Diagnostics of AGN and Star Formation and Contribution to Total Infrared Luminosity