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 the results of detailed analysis of X-ray data in 3-20 keV rangefrom a ~70 day outburst of the neutron star transient Aquila X-1 duringSeptember-November 2000. Optical monitoring with the YALO 1m telescope was usedto trigger X-ray observations with Rossi X-ray Timing Explorer (RXTE) in orderto follow the outburst from a very early stage. In this paper we discuss thecorrelated evolution in time of features in the spectral and temporal domains,for the entire outburst. The state transition from low/hard state to high/softstate during the rise of the outburst occurs at higher luminosity than thetransition back to low/hard state during the decay, as has also been observedin other outbursts. Fourier power spectra at low frequencies show a brokenpower law continuum during the rising phase, with the break frequencyincreasing with time. During the decline from maximum the source evolves to aposition in the hardness-intensity plane as well as in the color-color diagramwhich is similar to, but distinct from, the canonical high/soft state. Highfrequency quasi-periodic oscillations from 636-870 Hz were seen only duringthis transitional state.Comment: 25 pages, 11 figures. Accepted for publication in Ap

Evolution of Spectral States of Aquila X‐1 during the 2000 Outburst