The origin of the soft X-ray excess in the narrow-line Seyfert 1 galaxy
  SBS 1353+564
  We present for the first time the timing and spectral analyses for a
narrow-line Seyfert 1 galaxy, SBS 1353+564, using \it{XMM-Newton} and
\it{Swift} multi-band observations from 2007 to 2019. Our main results are as
follows: 1) The temporal variability of SBS 1353+564 is random, while the
hardness ratio is relatively constant over a time span of 13 years; 2) We find
a prominent soft X-ray excess feature below 2 keV, which cannot be well
described by a simple blackbody component; 3) After comparing the two most
prevailing models for interpreting the origin of the soft X-ray excess, we find
that the relativistically smeared reflection model is unable to fit the data
above 5 keV well and the X-ray spectra do not show any reflection features,
such as the Fe K\alpha emission line. However, the warm corona model can obtain
a good fitting result. For the warm corona model, we try to use three different
sets of spin values to fit the data and derive different best-fitting parameter
sets; 4) We compare the UV/optical spectral data with the extrapolated values
of the warm corona model to determine which spin value is more appropriate for
this source, and we find that the warm corona model with non-spin can
sufficiently account for the soft X-ray excess in SBS 1353+564.
