Doppler term in the galaxy two-point correlation function: wide-angle,
  velocity, Doppler lensing and cosmic acceleration effects
  We study the parity-odd part (that we shall call Doppler term) of the linear
galaxy two-point correlation function that arises from wide-angle, velocity,
Doppler lensing and cosmic acceleration effects. As it is important at low
redshift and at large angular separations, the Doppler term is usually
neglected in the current generation of galaxy surveys. For future wide-angle
galaxy surveys such as Euclid, SPHEREx and SKA, however, we show that the
Doppler term must be included. The effect of these terms is dominated by the
magnification due to relativistic aberration effects and the slope of the
galaxy redshift distribution and it generally mimics the effect of the local
type primordial non-Gaussianity with the effective nonlinearity parameter
$f_{\rm NL}^{\rm eff}$ of a few, we show that this would affect forecasts on
measurements of $f_{\rm NL}$ at low-redshift. Our results show that a survey at
low redshift with large number density over a wide area of the sky could detect
the Doppler term with a signal-to-noise ratio of $\sim 1-20$, depending on
survey specifications.
