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 MAGIC collaboration has recently reported the detection of the stronggamma-ray blazar 3C279 during a 1-2 day flare. They have used their spectralobservations to draw conclusions regarding upper limits on the opacity of theUniverse to high energy gamma-rays and, by implication, upper limits on theextragalactic mid-infrared background radiation. In this paper we examine theeffect of gamma-ray absorption by the extragalactic infrared radiation onintrinsic spectra for this blazar and compare our results with theobservational data on 3C279. We find agreement with our previous results,contrary to the recent assertion of the MAGIC group that the Universe is moretransparent to \gray s than our calculations indicate. Our analysis indicatesthat in the energy range between ~80 and ~500 GeV, 3C279 has a best-fitintrinsic spectrum with a spectral index ~1.78 using our fast evolution modeland ~2.19 using our baseline model. However, we also find that spectral indicesin the range of 0.0 to 3.0 are almost as equally acceptable as the best fitspectral indices. Assuming the same intrinsic spectral index for this flare asfor the 1991 flare from 3C279 observed by EGRET, viz., 2.02, which lies betweenour best fit indices, we estimate that the MAGIC flare was ~3 times brighterthan the EGRET flare observed 15 years earlier.

Is the Universe More Transparent to Gamma Rays Than Previously Thought?