The Suzaku broadband X-ray spectrum of the dwarf Seyfert galaxy NGC4395
  We present a Suzaku observation of the dwarf Seyfert galaxy NGC4395 with an
estimated black hole mass of ~10^5 Msun. Rapid and strong X-ray variability
with an rms amplitude of ~60 per cent is observed in the 0.4-10 keV band with
the XIS cameras. The shape of the light curve appears to depend on energies.
The hard X-ray emission is detected up to 35 keV with the HXD-PIN detector at a
similar flux level as observed with the INTEGRAL IBIS. The X-ray spectrum below
10 keV is strongly absorbed by partially ionized (xi~35) gas with a mean
equivalent hydrogen column density of ~2e22 cm^-2, when a simple absorption
model is applied. The spectral shape is also strongly variable but not a simple
function of the source brightness. The spectral variability appears to be
accounted for mainly by continuum slope changes, but variability in the ionized
absorber may also play some part. The apparently flat spectral slope with
photon index of 1.4 below 10 keV, obtained after correcting for absorption, is
marginally inconsistent with the photon index of 2 inferred from the 14-35 keV
PIN spectrum. If the true spectral slope was as steep as that measured in the
hard X-ray band, there would be an extra absorption component, which we are
unable to detect. Combined with the INTEGRAL measurements, the hard X-ray
emission above 10 keV exceeds the optical emission in terms of luminosity and
dominates the broadband energy output, unless a large excess of UV disk
emission is yet to be detected in the unobservable band. A weak Fe K line is
seen at 6.4 keV with the average equivalent width of 110 eV, which does not
show clear flux changes over the 3-day observation.
