532 research outputs found
Using optical spectroscopy to map the geometry and structure of the irradiated accretion discs in low-mass X-ray binaries:the pilot study of MAXI J0637-430
The recurring transient outbursts in low-mass X-ray binaries (LMXBs) provide
us with strong test-beds for constraining the poorly understood accretion
process. While impossible to image directly, phase-resolved spectroscopy can
provide a powerful diagnostic to study their highly complex, time-dependent
accretion discs. We present an 8-month long multi-wavelength (UV, optical,
X-ray) monitoring campaign of the new candidate black hole LMXB MAXI
J0637430 throughout its 2019/2020 outburst, using the {\em Neil Gehrels
Swift Observatory}, as well as three quasi-simultaneous epochs of Gemini/GMOS
optical spectroscopy. We find evidence for the existence of a correlation
between the X-ray irradiation heating the accretion disc and the evolution of
the He {\sc ii} 4686 \AA emission line profiles detected in the optical
spectra. Our results demonstrate a connection between the line emitting regions
and physical properties of the X-ray irradiation heating the discs during
outburst cycles of LMXBs. Further, we are able to show that changes in the
physical properties of the irradiation heating the disc in outburst can be
imprinted within the H/He emission line profiles themselves in these systems.Comment: 23 pages (including 3 appendices), 10 figures, supplementary figures
included in the appendices, accepted for publication in MNRA
Beyond Control-Flow: Extending Business Process Configuration to Roles and Objects
A configurable process model is an integrated representation of multiple variants of a business process. It is designed to be individualized to meet a particular set of requirements. As such, configurable process models promote systematic reuse of proven or common practices. Existing notations for configurable process modeling focus on capturing tasks and control-flow dependencies, neglecting equally important aspects of business processes such as data flow, material flow and resource management. This paper fills this gap by proposing an integrated meta-model for configurable processes with advanced features for capturing resources involved in the performance of tasks (through task-role associations) as well as flow of data and physical artifacts (through task-object associations). Although embodied as an extension of a popular process modeling notation, namely EPC, the meta-model is defined in an abstract and formal manner to make it applicable to other notations
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