  Coronal X-ray sources (CXSs) are phenomenon very often occurring in solar
flares regardless of a flare size, duration or power. The nature of the sources
was difficult to uncover for many years. It seems that at last, combining data
from RHESSI and SDO/AIA, there is a unprecedented possibility to 'look inside'
CXSs and to answer the questions about their formation, evolution and
structure. We present a study of a CXS of the SOL2011-10-22T11:10 long-duration
flare observed simultaneously with RHESSI and SDO/AIA. We focus our attention
on the following questions: What was responsible for the CXS presence and long
duration? Was there any fine structure in the CXS? Available data enables us to
study a relation between the CXS and structures observed in EUV during the
decay phase of the flare. X-ray emission recorded by RHESSI during the decay
phase of the flare came from about 10 MK hot CXS. The source was observable for
5 hours. This long presence of the source could be supported by magnetic
reconnection ongoing during the decay phase. Supra-arcade downflows, which are
considered to be a manifestation of magnetic reconnection, were observed at the
same time as the CXS. The source was co-spatial with the part of the hot
supra-arcade region that had the highest emission measure and simultaneously
the temperature within the range of RHESSI thermal-response. However, while the
supra-arcade region was a dynamic region consisting of small-scale structures,
the CXS seemed to be smooth, structureless. We run simulations using real and
synthetic RHESSI data, but we did not find any strong evidence that the CXS had
any small-scale structure.
