SDSS1133: An Unusually Persistent Transient in a Nearby Dwarf Galaxy

Understand

While performing a survey to detect recoiling supermassive black holes, we have identified an unusual source having a projected offset of 800 pc from a nearby dwarf galaxy.

• The object, SDSS J113323.97+550415.8, exhibits broad emission lines and strong variability.
• While originally classified as a supernova (SN) because of its nondetection in 2005, we detect it in recent and past observations over 63 yr and find over a magnitude of rebrightening in the last 2 years.
• Using high-resolution adaptive optics observations, we constrain the source emission region to be <12 pc and find a disturbed host-galaxy morphology indicative of recent merger activity.