We searched the HST Science Archive for the nuclei of elliptical galaxies with images obtained in different epochs, to detect the presence of far-ultraviolet variability. We found multi-epochs observations only for the elliptical galaxy NGC 4278. It hosts a barely resolved nuclear source which increased its UV flux by a factor 4 between June 1994 and January 1995. The properties of the UV flare of NGC 4278 are remarkably similar to the UV-bright nuclear transients discovered earlier in other low-luminosity AGNs. This supports the idea that UV flaring near the center of galaxies may be a common event and offers a way to search for black-hole-related activities in otherwise quiescent galaxies.
Ultraviolet variability in the nucleus of the elliptical galaxy NGC 4278
CARDULLO, ANDREA
;CORSINI, ENRICO MARIA;PIZZELLA, ALESSANDRO;BERTOLA, FRANCESCO
2007
Abstract
We searched the HST Science Archive for the nuclei of elliptical galaxies with images obtained in different epochs, to detect the presence of far-ultraviolet variability. We found multi-epochs observations only for the elliptical galaxy NGC 4278. It hosts a barely resolved nuclear source which increased its UV flux by a factor 4 between June 1994 and January 1995. The properties of the UV flare of NGC 4278 are remarkably similar to the UV-bright nuclear transients discovered earlier in other low-luminosity AGNs. This supports the idea that UV flaring near the center of galaxies may be a common event and offers a way to search for black-hole-related activities in otherwise quiescent galaxies.Pubblicazioni consigliate
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