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

In this paper we discuss the luminosity modulations and spectral analysisresults of the recent deep observations of XMMU 122939.7+075333, the firstblack hole discovered in a globular cluster. The source has been detected manytimes, typically with L$_X$ > 10$^{39}$ erg s$^{-1}$, but in a 2010 observationhad faded to L$_X$ ~ 10$^{38}$ erg s$^{-1}$. In our 2011 observations, it hasrebrightened to L$_X$ ~ 2x10$^{39}$ erg s$^{-1}$. This significant increase inluminosity over a a relatively short time period is not consistent with theidea that the long term flux modulations displayed by XMMU 122939.7+075333 arecaused by the Kozai mechanism alone as had previously been suggested. Instead,given that the source shows "spiky" behaviour in its light curve, it seemslikely that the faintness in 2010 was a result of a short observation that didnot catch any bright epochs. We also find that when the source is brighter thanaverage, it has an excess of soft ($<$0.7 keV) photons. The spectral analysisreveals strong, albeit model-dependent, evidence of emission from highlyionised oxygen (O VIII) when the source is brighter than average.

monthly notices of the royal astronomical society

Deep $Chandra$ observations of the NGC 4472 globular cluster black hole  XMMU 122939.7+075333: Short term variability from the first globular cluster  black hole binary