High Energy Polarization of Blazars : Detection Prospects
  Emission from blazar jets in the ultraviolet, optical, and infrared is
polarized. If these low-energy photons were inverse-Compton scattered, the
upscattered high-energy photons retain a fraction of the polarization. Current
and future X-ray and gamma-ray polarimeters such as INTEGRAL-SPI, PoGOLITE,
X-Calibur, Gamma-Ray Burst Polarimeter, GEMS-like missions, ASTRO-H, and
POLARIX have the potential to discover polarized X-rays and gamma-rays from
blazar jets for the first time. Detection of such polarization will open a
qualitatively new window into high-energy blazar emission; actual measurements
of polarization degree and angle will quantitatively test theories of jet
emission mechanisms. We examine the detection prospects of blazars by these
polarimetry missions using examples of 3C 279, PKS 1510-089, and 3C 454.3,
bright sources with relatively high degrees of low-energy polarization. We
conclude that while balloon polarimeters will be challenged to detect blazars
within reasonable observational times (with X-Calibur offering the most
promising prospects), space-based missions should detect the brightest blazars
for polarization fractions down to a few percent. Typical flaring activity of
blazars could boost the overall number of polarimetric detections by nearly a
factor of five to six purely accounting for flux increase of the brightest of
the comprehensive, all-sky, Fermi-LAT blazar distribution. The instantaneous
increase in the number of detections is approximately a factor of two, assuming
a duty cycle of 20% for every source. The detectability of particular blazars
may be reduced if variations in the flux and polarization fraction are
anticorrelated. Simultaneous use of variability and polarization trends could
guide the selection of blazars for high-energy polarimetric observations.
