3C 279: ALMA detection of a new polarized mm/sub-mm flare
ATel #17713; Seiji Kameno, Carolina Finlez, Claudio Hernandez Vera, Ruediger Kneissl, Gabriel Marinello, Jorge Morgado, Suma Murthy, Matias Radiszcz, Dylan Pare, Andres Perez, Kurt Plarre, Gerald Schieven, Celia Verdugo (Joint ALMA Observatory)
on 6 Mar 2026; 20:49 UT
Credential Certification: Seiji Kameno (seiji.kameno@alma.cl)
Subjects: Radio, Millimeter, Sub-Millimeter, AGN, Black Hole, Blazar, Quasar
The Atacama Large Millimeter/submillimeter Array (ALMA) is monitoring full-Stokes parameters of extragalactic radio sources. The telescope detected a polarized mm/sub-mm flare of the blazar J1256-0547 (3C 279) started since 2025-11-08 coupled with electric vector position angle (EVPA) change. In Atel #17018, we reported polarization drop with EVPA swing around 2024-10-27. While the total flux density started to increase after the polarization drop, low polarization state had continued until this polarized flare.
The table lists the total flux density (I), polarized flux density (P) and, EVPA with 10-day binning. The errors in parentheses are derived by linear regression for binning measurements in 10-day cadence. The raw measurements are plotted in the link.
---- 40.0 GHz ----
Date : I [Jy] P [Jy] EVPA [deg]
2025-10-20 : 14.03 (0.84) 0.42 (0.02) -78.5 (0.9)
2025-12-09 : 13.80 (0.82) 0.54 (0.06) -19.9 (2.2)
2025-12-19 : 14.48 (0.51) 0.61 (0.04) -15.7 (1.4)
2025-12-29 : 15.98 (0.16) 0.72 (0.06) -13.3 (1.3)
2026-01-08 : 17.75 (0.27) 0.98 (0.17) -14.0 (3.3)
2026-01-28 : 18.73 (0.53) 0.84 (0.38) -14.7 (6.5)
2026-02-27 : 20.37 (0.11) 0.99 (0.09) 0.9 (2.0)
---- 97.5 GHz ----
Date : I [Jy] P [Jy] EVPA [deg]
2025-10-20 : 9.66 (0.13) 0.30 (0.03) -80.2 (1.8)
2025-10-30 : 10.06 (0.04) 0.28 (0.03) -77.2 (2.1)
2025-11-09 : 10.27 (0.07) 0.18 (0.03) -71.1 (3.4)
2025-11-19 : 11.02 (0.07) 0.23 (0.03) -40.2 (2.7)
2025-11-29 : 11.50 (0.03) 0.31 (0.03) -28.1 (1.7)
2025-12-09 : 11.84 (0.04) 0.44 (0.03) -23.9 (1.5)
2025-12-19 : 12.29 (0.04) 0.58 (0.03) -23.3 (1.1)
2025-12-29 : 12.81 (0.04) 0.67 (0.02) -17.3 (0.8)
2026-01-08 : 13.63 (0.07) 0.82 (0.03) -14.5 (0.7)
2026-01-18 : 14.13 (0.07) 0.95 (0.04) -16.3 (0.9)
2026-01-28 : 14.06 (0.28) 0.79 (0.09) -18.1 (2.3)
2026-02-27 : 16.60 (0.11) 0.87 (0.05) -4.1 (1.3)
---- 233.0 GHz ----
Date : I [Jy] P [Jy] EVPA [deg]
2025-10-30 : 6.04 (0.11) 0.12 (0.03) -75.8 (3.9)
2025-11-09 : 6.54 (0.10) 0.09 (0.01) -61.2 (2.6)
2025-11-19 : 6.87 (0.09) 0.17 (0.03) -33.0 (4.3)
2026-01-28 : 8.48 (0.22) 0.82 (0.09) -30.3 (2.3)
---- 343.5 GHz ----
Date : I [Jy] P [Jy] EVPA [deg]
2025-10-30 : 4.75 (0.09) 0.11 (0.02) -74.2 (4.6)
2025-11-09 : 4.96 (0.08) 0.04 (0.02) -59.6 (8.9)
2025-11-19 : 5.51 (0.05) 0.15 (0.02) -33.7 (2.8)
2025-11-29 : 5.69 (0.04) 0.19 (0.01) -31.2 (1.2)
2025-12-09 : 5.77 (0.15) 0.30 (0.05) -24.7 (3.7)
2025-12-19 : 5.75 (0.08) 0.34 (0.02) -21.2 (1.4)
2025-12-29 : 6.41 (0.13) 0.35 (0.02) -19.3 (1.2)
2026-01-08 : 6.73 (0.12) 0.42 (0.04) -17.8 (1.8)
2026-01-18 : 7.07 (0.04) 0.60 (0.05) -21.2 (1.5)
2026-01-28 : 7.24 (0.15) 0.56 (0.05) -21.5 (1.9)
2026-02-27 : 8.35 (0.10) 0.62 (0.04) 1.0 (0.8)
Total and polarized flux densities and EVPA
