The Λ cold dark matter(ΛCDM) paradigm (Blumenthal et al. 1984) predicted cuspy DM density profiles in the centre of galaxies (Navarro, Frenk & White 1996) and recent results with higher resolution seem to suggest a shallower DM density profile (Navarro et al. 2004, 2010). None the less, the past and newer developments are in contradiction with observational results of cored DM density profiles in dwarf galaxies (de Blok, McGaugh & Rubin 2001; de Blok & Bosma 2002; Swaters et al. 2003; Chemin, de Blok & Mamon 2011). This discrepancy is known as the cuspy-core problem. Many other authors, in an attempt to contribute to the solution of the cuspy-core problem, performed the RC decomposition considering a constant M/L (Carignan & Freeman 1985, 1988; Jobin & Carignan 1990; Persic & Salucci 1990; Martimbeau, Carignan & Roy 1994; Persic, Salucci & Stel 1996; Blais-Ouellette, Amram & Carignan 2001; de Blok, McGaugh & Rubin 2001; de Blok & Bosma 2002; Swaters et al. 2003; Kuzio de Naray et al. 2006; Fuentes-Carrera et al. 2007; Spano et al. 2008; Kuzio de Naray, McGaugh & de Blok 2008; Repetto et al. 2010; Chemin et al. 2011) and reinforce the evidence of a cored DM distribution in the central part of galaxies. Conversely, other authors pursue spectrophotometric and SPS studies to derive the M/L of the stellar component (Salucci, Yegorova & Drory 2008; de Denus-Baillargeon et al. 2013; Repetto et al. 2013) or at least to constrain the stellar component (Dutton et al. 2005) to avoid the disc–halo degeneracy. Salucci et al. (2008) accomplished RCs mass modelling and spectral energy distribution (SED) fitting with spectrophotometric models to obtain the disc masses of 18 Sa spiral galaxies (principally bulgeless systems) finding that by decomposing the RCs with the spectrophotometric disc masses the results are consistent with the corresponding maximum disc solution. Repetto et al. (2013) employed the Zibetti et al. (2009) method to optical (SDSS) and NIR (2MASS) images of NGC 5278 (KPG 390A) to obtain the stellar disc mass profile of that galaxy from SPS models to reproduce the RC of KPG 390A. The new strategy relied on fitting only the DM RC, obtained by subtracting the SPS baryonic disc from the observed RC of NGC 5278. The most important finding of Repetto et al. (2013) is that the favoured DM distribution is cored when the disc mass approximate to the maximum disc solution in agreement with the general belief. de Denus-Baillargeon et al. (2013) used a chemo-spectrophotometric galactic evolution model to determine the stellar M/L and perform the RC decomposition of 10 spiral and dwarf irregular galaxies from the SINGS survey (Kennicutt et al. 2003). The authors employed the settled baryonic disc as a weighting function to fit the model DM halo to the RCs of the studied subsample of galaxies, and concluded that the stellar discs obtained from their chemo-spectrophotometric models were compatible with the MDH. The few examples presented indicate that a growing effort to break the disc–halo degeneracy exists; however, the most significant contributions trying to address the cuspy-core problem still rely on the general assumption of considering the stellar M/L constant along the galactic disc. In general, it is still missing a significant endeavour to earn the DM distribution, through RC fitting, determining the disc stellar mass from SPS studies. For this reason, it is worth considering the cuspy-core problem with a different observational approach, focusing on the formulation of a general procedure to better constrain the baryonic disc mass in galaxies.
Citation: Kuzio de Naray et al. 2006
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