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 TeV BL Lac object Markarian 501 has been the subject of a 4.5 monthmulti-instrument campaign conducted in 2009, which provided an excellenttemporal and energy coverage from radio to very high energy gamma rays (>100GeV, VHE). During the campaign, Mrk 501 was mostly in a comparably low state,but for two flares at VHE with very different characteristics. While the secondflare seems to be correlated with a moderate increase in the X-ray flux, thefirst one is most likely accompanied by a shift of the synchrotron bump towardshigher energies. Moreover, the first flare occurs during an abrupt change inthe polarized optical flux, and was preceded by a rotation of the electricfield vector position angle. This is the first time that such behavior isobserved in a high-frequency-peaked BL Lac object, while similar events havebeen seen in the low-frequency peaked BL Lac object BL Lacertae and the flatspectrum radio quasar PKS 1510-089, hence suggesting that similar physicalprocesses occur in the jets of different blazar subclasses.

Unprecedented temporal evolution of the broad-band emission of the BL Lac Mrk 501