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Disc stars from the Gaia DR3 RVS catalogue are selected to explore the phasespiral as a function of position in the Galaxy. The data reveal a two-armedphase spiral pattern in the local $z-v_z$ plane inside the solar radius, whichappears clearly when colour-coded by $\langle v_R \rangle (z,v_z)$: this ischaracteristic of a breathing mode that can in principle be produced byin-plane non-axisymmetric perturbations. We note the phase spiral patternbecomes single armed outside the solar radius. When a realistic analytic modelwith an axisymmetric background potential plus a steadily rotating bar and2-armed spiral arms as perturbation is used to perform particle testintegrations, the pseudo stars get a prominent spiral pattern in the $\langlev_R \rangle$ map in the $x-y$ plane. Additionally, clear breathing modeevidence at a few $\rm{kms}^{-1}$ level can be seen in the $\langle v_z\rangle$ map on the $x-z$ plane, confirming that such breathing modes arenon-negligible in the joint presence of a bar and spiral arms. However, nophase-spiral is perceptible in the $(z, v_z)$ plane. When an initial verticalperturbation is added to all pseudo stars to carry out the simulation, theone-armed phase spirals can clearly be seen 500~Myr after the perturbation andgradually disappear inside-out. Finally, we show as a proof of concept how atoy model of a time-varying non-axisymmetric in-plane perturbation with varyingamplitude and pattern speed can produce a strong two-armed phase-spiral. Weconclude a time-varying strong internal perturbation together with an externalvertical perturbation could perhaps explain the transition between thetwo-armed and one-armed phase-spirals around the Solar radius.

Gaia DR3 features of the phase spiral and its possible relation to internal perturbations