  We investigate a population of swarmalators, a mobile version of phase
oscillators that both sync in time and swarm through space. We focus on a
XY-type model of identical swarmalators running on a one-dimensional ring and
subject to thermal noise. We uncover four distinct collective states, some of
which capture the behavior of real-world swarmalators such as vinegar eels and
sperm. Among these, the most intriguing is the `mixed state', which blends two
of the other states. We present a comprehensive phase diagram from the Fourier
mode analysis with a high accuracy, which is in excellent agreement with
numerical simulation results. Our model serves as a tractable toy model for
thermal systems that both self-synchronize and self-assemble interdependently.
