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 Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The cores of ultra-luminous infrared galaxies (ULIRGs) are very denseenvironments, with a high rate of star formation and supernova explosions. Theyare thought to be sites of cosmic-ray acceleration, and are predicted to emit$\gamma$-rays in the GeV to TeV range. So far, no ULIRG has been detected in$\gamma$-rays. Arp 220, the closest ULIRG to Earth, has been well studied, anddetailed models of $\gamma$-ray production in this galaxy are available. Theypredict a rather hard $\gamma$-ray spectrum up to several TeV. Due to its largerate of star formation, high gas density, and its close proximity to Earth, Arp220 is thought to be a very good candidate for observations in very-high-energy(VHE; 100 GeV - 100 TeV) $\gamma$-rays. Arp 220 was observed by the VERITAStelescopes for more than 30 hours with no significant excess over thecosmic-ray background. The upper limits on the VHE $\gamma$-ray flux of Arp 220derived from these observations are the most sensitive limits presented so farand are starting to constrain theoretical models. We also present upper limitsfor the VHE flux from the ULIRG IRAS 17204-0014, the starburst galaxy IC 342,and the active galaxy 3C321.

Upper limits on the VHE $\gamma$-ray flux from the ULIRG Arp 220 and other galaxies with VERITAS