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

We present an analysis of the energy and frequency dependence of the Fouriertime lags of the hectoHertz quasi-periodic oscillations (QPOs) and of the QPOsat the frequency at which the power density spectrum shows a break in theneutron-star low-mass X-ray binary 4U 1636-53, using a large data set obtainedwith the Rossi X-ray Timing Explorer. We found that: (i) For the breakfrequency QPO: for low frequencies, in general the time lag is positive, but itis decreasing with increasing frequency, reaching zero lag at 20 Hz. Between 20and 35 Hz there is a small fluctuation around zero, from where the time lagsbecome positive again and increase slightly above zero up to 65 Hz. (ii) Forthe hHz QPO: we see that when the frequency is 100 Hz the time lag is negative,but it increases to zero already at 110 Hz, being consistent with this value upto 130 Hz from where it increases to 0.5 msec at around 140 Hz. From 140 Hz thetime lag decreases sharply, being strongly negative for hHz greater than 220Hz. We compare these lags with our previous results for the lags of thekiloHertz QPOs in this same source and discuss possible scenarios for producingthe lags in this system in the context of reflection off the accretion disc or(up-)down-scattering in a hot medium close to the neutron star.

New Results on the Time lags of the Quasi-Periodic Oscillations in the Low-mass X-ray Binary 4U 1636--53