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 Tools annual

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 monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

We present a comprehensive study of the thermonuclear bursts and millihertzquasi-periodic oscillations (mHz QPOs) from the neutron star (NS) transient and11 Hz X-ray pulsar IGR J17480-2446, located in the globular cluster Terzan 5.The increase in burst rate that we found during its 2010 outburst, whenpersistent luminosity rose from 0.1 to 0.5 times the Eddington limit, is inqualitative agreement with thermonuclear burning theory yet opposite to allprevious observations of thermonuclear bursts. Thermonuclear bursts graduallyevolved into a mHz QPO when the accretion rate increased, and vice versa. ThemHz QPOs from IGR J17480-2446 resemble those previously observed in otheraccreting NSs, yet they feature lower frequencies (by a factor ~3) and occurwhen the persistent luminosity is higher (by a factor 4-25). We find fourdistinct bursting regimes and a steep (close to inverse cubic) decrease of theburst recurrence time with increasing persistent luminosity. We compare thesefindings to nuclear burning models and find evidence for a transition betweenthe pure helium and mixed hydrogen/helium ignition regimes when the persistentluminosity was about 0.3 times the Eddington limit. We also point out importantdiscrepancies between the observed bursts and theory, which predicts brighterand less frequent bursts, and suggest that an additional source of heat in theNS envelope is required to reconcile the observed and expected burstproperties. We discuss the impact of NS magnetic field and spin on the expectednuclear burning regimes, in the context of this particular pulsar.

Millihertz quasi-periodic oscillations and thermonuclear bursts from Terzan 5: A showcase of burning regimes