Short time-scale optical variability of the dwarf Seyfert nucleus in NGC 4395
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2004-10-14Metadata
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Skelton, J. E.
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Short time-scale optical variability of the dwarf Seyfert nucleus in NGC 4395
Abstract
We present optical spectroscopic observations of the least-luminous known Seyfert 1 galaxy,
NGC 4395, which was monitored every half-hour over the course of three nights. The continuum
emission varied by ∼35 per cent over the course of three nights and we find marginal
evidence for greater variability in the blue continuum than the red. A number of diagnostic
checks were performed on the data in order to constrain any systematic or aperture effects.
No correlations were found that adequately explained the observed variability, hence we conclude
that we have observed real intrinsic variability of the nuclear source. No simultaneous
variability was measured in the broad Hβ line, although given the difficulty in deblending
the broad and narrow components it is difficult to comment on the significance of this result.
The observed short time-scale continuum variability is consistent with NGC 4395 having an
intermediate-mass (∼105M ) central supermassive black hole, rather than a very low accretion
rate. Comparison with the Seyfert 1 galaxy NGC 5548 shows that the observed variability
seems to scale with black hole mass in roughly the manner expected in accretion models.
However, the absolute time-scale of variability differs by several orders of magnitude from
that expected in simple accretion disc models in both cases.
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Artículo de publicación ISI.
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URI: https://repositorio.uchile.cl/handle/2250/126146
DOI: doi:10.1111/j.1365-2966.2005.08722.x
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RAS, MNRAS 358, 781–794
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