LEDA 735555: WISE detection of long-term infrared brightening and a flare in 2021
ATel #17778; Patrik Milan Veres (Ruhr-University Bochum)
on 7 May 2026; 12:46 UT
Credential Certification: Patrik Milan Veres (veres@astro.ruhr-uni-bochum.de)
Subjects: Infra-Red, AGN, Transient
A recent X-ray flare from the galaxy LEDA 735555 detected by Einstein Probe was reported in ATel #17775, along with a contemporaneous optical brightening. Another X-ray flare, detected by eROSITA and reported in ATel #17777, showed an increase in flux by a factor of 9 over the first 1.5 years, then faded. This flare was also coincident with an optical flare at the position of AT 2021jbt an optical transient discovered by ATLAS.
We retrieved the WISE infrared light curve of LEDA 735555 using timewise. This shows a general increasing trend (both in W1 and W2) similar to the optical Gaia light curve (the transient appears as Gaia21daz in Gaia Alerts). An infrared flare occurs around the time of the first optical flare and the eROSITA peak, after which the infrared emission remains enhanced. The W1-W2 color suggests dust heating following the peak but is still below the widely used AGN color selection criterion (0.8) in all epochs used for the mid-infrared selection of AGNs with WISE (about the reliability and completeness of this selection method see Fig. 6. in Stern et al. 2012).
Further observations especially optical spectroscopic follow-up are encouraged.
Stern, D. et al. 2012 ApJ,753,30
timewise: https://jannisnecker.pages.desy.de/timewise_sup/docs/
Gaia21daz: https://gsaweb.ast.cam.ac.uk/alerts/alert/Gaia21daz/
WISE light curve of LEDA 735555
