Is Fermi 1544-0649 a Misaligned Blazar? Discovering the Jet Structure with Very Long Baseline Interferometry

Abstract

Abstract Fermi J1544-0649 is a transient GeV source first detected during its GeV flares in 2017. Multiwavelength observations during the flaring time demonstrate variability and spectral energy distributions that are typical of a blazar. Other than the flare time, Fermi J1544-0649 is quiet in the GeV band and has looked rather like a quiet galaxy (2MASX J15441967-0649156) for a decade. Together with the broad absorption-lines-like feature we further explore the “misaligned blazar scenario.” We analyzed the Very Long Baseline Array (VLBA) and East Asian VLBI Network (EAVN) data from 2018 to 2020 and discovered the four jet components from Fermi J1544-0649. We found a viewing angle around 3.°7 to 7.°4. The lower limit of the viewing angle indicates a blazar with an extreme low duty cycle of gamma-ray emission; the upper limit of it supports the “misaligned blazar scenario.” Follow-up multiwavelength observations after 2018 show Fermi J1544-0649 remains quiet in GeV, X-ray, and optical bands. A multimessenger search of neutrinos is also performed, and an excess of 3.1σ significance is found for this source.