Hα Reverberation Mapping from Broad-band Photometry of Dwarf Seyfert 1 Galaxy NGC 4395

NGC 4395 is a dwarf Seyfert 1 galaxy with a possible intermediate-mass black hole of several 10⁴ solar masses in its center. As a well-studied object, its broad line region size has been measured via Hα time lag in numerous spectroscopic reverberation mapping (SRM) and narrow-band photometric reverberation mapping (PRM) campaigns. Here we present its Hα time lag measurement using broad-band photometric data, with the application of our newly-developed ICCF-Cut method as well as the JAVELIN and χ ² methods. utilizing the minute-cadence multi-band light curves obtained from the 2m FTN and 10.4m GTC telescopes in recent works, we measured its Hα lag as approximately 40 ~ 90 minutes from broad-band PRM. With the Hα emission line velocity dispersion, we calculated its central black hole mass as MBH = (8±4) × 10³\, M. These results are comparable with previous results obtained by narrow-band PRM and SRM, providing further support to an intermediate-mass black hole in NGC 4395. In addition, our study also validates the ICCF-Cut as an effective method for broad-band PRM, which holds the potential for widespread application in the era of large multi-epoch, high-cadence photometric surveys.