Ansky is the nickname for a supermassive black hole located in the galaxy SDSS J133519.91+072807.4 (SDSS1335+0728), approximately 300 million light-years from Earth in the Virgo constellation. The black hole gained attention in 2019 when it transitioned from dormancy to an active state, producing extreme quasi-periodic eruptions (QPEs) of X-ray radiation. It represents the first observed case of a supermassive black hole awakening in real time.
The galaxy SDSS1335+0728 remained inactive for two decades before suddenly brightening in December 2019. The Zwicky Transient Facility (ZTF) detected this optical brightening and assigned the designation ZTF19acnskyy. [1] The nickname "Ansky" derives from the suffix "acnskyy" in this original identifier. [2] [3]
The initial brightening was discovered through the ALeRCE (Automatic Learning for the Rapid Classification of Events) machine learning classification system. [4] [1] For four years following the 2019 event, the galaxy exhibited optical variability without detectable X-ray emissions. [4]
The central black hole has an estimated mass of approximately 10^6 solar masses. [1] The host galaxy SDSS1335+0728 is classified as an early-type galaxy located at redshift z=0.024. [1] The galaxy is now classified as a galaxy with active galactic nucleus. [4]
In February 2024, astronomers detected recurring X-ray flares from Ansky, marking the beginning of unprecedented quasi-periodic eruptions. [5] These eruptions exhibit several extreme characteristics: each eruption lasts approximately 1.5 days; QPEs repeat every 4.5 days, the longest interval observed for any QPE source. Each burst releases approximately 10^48 ergs, representing 100 times more energy than typical QPEs, ten times more luminous than standard QPEs. A longer 25-day cycle containing cascades of five consecutive eruptions was also found. [5] The eruptions involve the ejection of approximately one Jupiter mass of material at velocities reaching 15% of the speed of light. [3] Ansky is the first supermassive black hole observed transitioning from dormancy to activity. Observed QPEs are the most energetic and longest-duration QPEs on record. The source lacks evidence of recent stellar destruction, suggesting QPEs can occur through newly formed accretion flows rather than only after star disruption events. [5]
Multiple space-based telescopes have monitored Ansky since its activation: [5] [3]
These observations detected 165 QPE events during the initial monitoring period and captured 12 near-consecutive flares over a 60-day campaign. [5]
Current theories propose that QPEs result from interactions between the black hole's accretion disk and orbiting objects. For Ansky, researchers suggest a larger debris disk around the black hole, which is "larger and can involve objects farther away" than usually theorised. [3]
Since activation, Ansky has shown systematic changes across the electromagnetic spectrum: [1] [4]