A newly found lensed Mrk231-like blazar in archival mm/radio image monitoring

The quest to understand physics of jets associated with super-massive black holes (SMBHs) has had a recent boost with very long-baseline interferometry (VLBI) observations conducted at (sub-)mm wavelengths. Nevertheless, such observations are still limited to small sample sizes. The usual approach thus turns its focus onto the blazar population, ie, radio emitting jets pointing closely parallel with our line of sight. The jet emission from these sources dominates the whole electromag netic spectrum (from radio to gamma-rays) and is highly variable, enabling one to infer different jet formation scenarios in thousands of sources. An even rarer chance alignment is when such blazars are gravitationally lensed. In such a case, a whole new window opens, including testing Cosmology. Here, we report a candidate for a lensed blazar, with its observed morphology split in two images at long-wavelengths (mm to cm), each showing a forward jet plus core morphology and similar light curve trends, with a burst detected in 2017 identified by two independent observing facilities at long-wavelengths. This source has remained unidentified by optical surveys (e.g., Gaia) since one of the two images is completely missing likely due to foreground obscuration (eg, as in PKS1830-211). Its UV through mid-IR broad-band spectral energy distribution and the optical spectroscopy very much resemble that of Mrk231, while both the high and low-energy spectral ranges are a factor of a 1000x brighter than the Mrk231 expectation