The Atacama Cosmology Telescope: Combined kinematic and thermal
  Sunyaev-Zel'dovich measurements from BOSS CMASS and LOWZ halos
  The scattering of cosmic microwave background (CMB) photons off the
free-electron gas in galaxies and clusters leaves detectable imprints on high
resolution CMB maps: the thermal and kinematic Sunyaev-Zel'dovich effects (tSZ
and kSZ respectively). We use combined microwave maps from the Atacama
Cosmology Telescope (ACT) DR5 and Planck in combination with the CMASS and LOWZ
galaxy catalogs from the Baryon Oscillation Spectroscopic Survey (BOSS DR10 and
DR12), to study the gas associated with these galaxy groups. Using individual
reconstructed velocities, we perform a stacking analysis and reject the no-kSZ
hypothesis at 6.5$\sigma$, the highest significance to date. This directly
translates into a measurement of the electron number density profile, and thus
of the gas density profile. Despite the limited signal to noise, the
measurement shows at high significance that the gas density profile is more
extended than the dark matter density profile, for any reasonable baryon
abundance (formally $>90\sigma$ for the cosmic baryon abundance). We
simultaneously measure the tSZ signal, i.e. the electron thermal pressure
profile of the same CMASS objects, and reject the no-tSZ hypothesis at
10$\sigma$. We combine tSZ and kSZ measurements to estimate the electron
temperature to 20% precision in several aperture bins, and find it comparable
to the virial temperature. In a companion paper, we analyze these measurements
to constrain the gas thermodynamics and the properties of feedback inside
galaxy groups. We present the corresponding LOWZ measurements in this paper,
ruling out a null kSZ (tSZ) signal at 2.9 (13.9)$\sigma$, and leave their
interpretation to future work. Our stacking software ThumbStack is publicly
available at https://github.com/EmmanuelSchaan/ThumbStack and directly
applicable to future Simons Observatory and CMB-S4 data.
