tokens: however, need to find more stars with similar travel times as S5-HVS1. It is remarkable that the age of S5-HVS1 ejection is close to both the age of the disc of young stars around the GC (Lu etal. 2013 ) and the age of the Fermi bubbles (Bland-Hawthorn Cohen 2003 ; Su, Slatyer Finkbeiner 2010 ) which have been potentially associated with the recent accretion event in the GC (Zubovas, King Nayakshin 2011 ; Guo Mathews 2012 ), thus potentially linking these different astrophysical objects. An alternative scenario that would naturally produce a time-variable HVS spectrum is that involving an Intermediate Mass Black Hole (IMBH) orbiting the GC (Yu Tremaine 2003 ; Levin 2006 ). In this mechanism, during the inspiral of the IMBH, the HVS production rate peaks and then subsides due to dynamical friction around the SMBH (Baumgardt, Gualandris Portegies Zwart 2006 ; Darbha etal. 2019 ), with the fastest HVS being ejected in the final phase of the in-spiral. This mechanism produces a strongly anisotropic distribution with the fastest stars in the orbital plane of the IMBH (Rasskazov etal. 2019 ). There is also some indication that the HVSs produced by this mechanism tend to have higher velocities and a flatter velocity spectrum than the classical Hills mechanism (Sesana, Haardt Madau 2007 ). While there is currently not much evidence for the presence of an IMBH in the GC (Gualandris Merritt 2009 ) other than a shallow stellar density slope that can be produced by an IMBH scattering (Baumgardt etal. 2006 ), if an IMBH inspiral happened a few Myr ago, then it would produce an excess of nearby and fast HVSs with a narrow range of ejection times. To test for this possibility we need to search for other nearby HVS and see if there is an excess of stars that were ejected at roughly the same time as S5-HVS1 (5Myr ago), are strongly anisotropic and that have a velocity spectrum inconsistent with the Hills mechanism. An interesting consequence of the fact that S5-HVS1 has lower mass than most other HVS in the halo is that its expected lifetime given the stellar mass of 2.3M is quite long around a 1Gyr. By the end of its life the star would have travelled a distance of 2Mpc, traversing a large fraction of the Local Group. This suggests that searching for such ejected stars at large distances from the MW or Andromeda (Sherwin, Loeb OLeary 2008 ) is quite promising. On top of being well separated in colourmagnitude space from other contaminants, an S5-HVS1-like star would eventually evolve on to the red giant branch and thus be detectable much more easily. Searches for S5-HVS1-like stars within the whole Local Group will be possible with upcoming deep imaging surveys like LSST (LSST Science Collaboration etal. 2009 ). In this paper, we tried to use the positionvelocity information on S5-HVS1 to constrain the distance from the Sun to the GC and the Galactic Solar velocity. We have not been able to constrain those simultaneously, mainly due to the precision of
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