MAPCAT: Monitoring AGN with Polarimetry at the Calar Alto Telescopes

TL;DR

MAPCAT is a long-term polarimetric monitoring program of blazars using the Calar Alto Telescopes, providing multi-spectral data crucial for understanding high-energy emission mechanisms and magnetic fields in these objects.

Contribution

It introduces a systematic, multi-spectral-range polarimetric observation program for blazars, enhancing the understanding of their emission regions and magnetic fields.

Findings

Monthly optical polarimetric measurements of 34 blazars since 2007.

Improved identification of polarized flares across the spectrum.

Enhanced modeling of magnetic fields in blazars.

Abstract

We introduce MAPCAT, a long-term observing program for "Monitoring of AGN with Polarimetry at the Calar Alto Telescopes". Multi-spectral-range studies are critical to understand some of the most relevant current problems of high energy astrophysics of blazars such as their high energy emission mechanisms and the location of their gamma-ray emission region through event associations across the spectrum. Adding multi-spectral-range polarimetry allows for even more reliable identification of polarized flares across the spectrum in these kind of objects, as well as for more accurate modeling of their magnetic field. As part of a major international effort to study the long term multi-spectral range polarimetric behavior of blazars, MAPCAT uses -since mid 2007- CAFOS on the 2.2m Telescope at the Calar Alto Observatory (Almeria, Spain) to obtain monthly optical (R-band) photo-polarimetric measurements of a sample of 34 of the brightest gamma-ray, optical, and radio-millimeter blazars accessible from the northern hemisphere.