al. 2007).

The MSP was recently enriched with an extra problem, spawned from the analysis of the Aquarius and the Via Lactea simulations. Simulated haloes produced $\simeq10$ subhaloes (Boylan-Kolchin, Bullock, and Kaplinghat 2011, 2012) that were too massive and dense to be the host of the MW brightest satellites: while those $\Lambda$CDM simulations predicted in excess of 10 subhaloes with $V_{max}>25$ km/s, the dSphs of the MW all have $12<V_{max}<25$ km/s. This discrepancy in the kinematics between simulations and the MW brightest dSphs (Boylan-Kolchin, Bullock, and Kaplinghat 2011, 2012), which is an extra problem of the MSP, has been dubbed the Too-Big-To-fail (TBTF) problem[^4] (Ogiya & Burkert 2014).

Similarly to the solutions to other small scale problems, the resolution of the MSP can be classified as either cosmological or astrophysical solutions. Cosmological solutions modify either the power spectrum at small scales (e.g. Zentner & Bullock 2003), the constituent DM particles (Colin, Avila-Reese & Valenzuela 2000; Sommer-Larsen & Dolgov 2001; Hu, Barkana & Gruzinov 2000; Goodman 2000; Peebles 2000; Kaplinghat, Knox, & Turner, M. S. 2000) or the gravity theories, like $f(R)$ (Buchdahl 1970; Starobinsky 1980), $f(T)$ (see Ferraro 2012), and MOND (Milgrom 1983a,b).

Several different kinds of astrophysical solutions have 