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Variability and the size-luminosity relation of the intermediate mass AGN in NGC 4395
We present the variability study of the lowest-luminosity Seyfert 1 galaxy NGC 4395 based on the photometric monitoring campaigns in 2017 and 2018. Using 22 ground-based and space telescopes, we monitored NGC 4395 with a \(\sim\)5 minute cadence during a period of 10 days and obtained light curves i...
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Published in: | arXiv.org 2020-03 |
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Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
Format: | Article |
Language: | English |
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Online Access: | Get full text |
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Summary: | We present the variability study of the lowest-luminosity Seyfert 1 galaxy NGC 4395 based on the photometric monitoring campaigns in 2017 and 2018. Using 22 ground-based and space telescopes, we monitored NGC 4395 with a \(\sim\)5 minute cadence during a period of 10 days and obtained light curves in the UV, V, J, H, and K/Ks bands as well as the H\(\alpha\) narrow-band. The RMS variability is \(\sim\)0.13 mag on \emph{Swift}-UVM2 and V filter light curves, decreasing down to \(\sim\)0.01 mag on K filter. After correcting for continuum contribution to the H\(\alpha\) narrow-band, we measured the time lag of the H\(\alpha\) emission line with respect to the V-band continuum as \({55}^{+27}_{-31}\) to \({122}^{+33}_{-67}\) min. in 2017 and \({49}^{+15}_{-14}\) to \({83}^{+13}_{-14}\) min. in 2018, depending on the assumption on the continuum variability amplitude in the H\(\alpha\) narrow-band. We obtained no reliable measurements for the continuum-to-continuum lag between UV and V bands and among near-IR bands, due to the large flux uncertainty of UV observations and the limited time baseline. We determined the AGN monochromatic luminosity at 5100\AA\ \(\lambda L_\lambda = \left(5.75\pm0.40\right)\times 10^{39}\,\mathrm{erg\,s^{-1}}\), after subtracting the contribution of the nuclear star cluster. While the optical luminosity of NGC 4395 is two orders of magnitude lower than that of other reverberation-mapped AGNs, NGC 4395 follows the size-luminosity relation, albeit with an offset of 0.48 dex (\(\geq\)2.5\(\sigma\)) from the previous best-fit relation of Bentz et al. (2013). |
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ISSN: | 2331-8422 |
DOI: | 10.48550/arxiv.2002.08028 |