In this paper , we study how the presence of bulge formation in galaxies influence their inner density profile , by means of an extended version of the Del Popolo ( 2009 ) semi-analytical model .
As in Del Popolo ( 2009 ) , the model takes into account the effect of baryons adiabatic contraction , ordered and random angular momentum , dynamical friction , and adds to the previous the effect of gas cooling , star formation , supernova feedback , and reionization .
Our model shows that dwarf galaxies are bulgeless , in agreement with observations showing that the large majority of them has no stellar bulges , and are characterized by a flat profile well described by a Burkert profile .
We then studied the effect of a bulge , added to the cored DM halo , on the density profile .
In the case of a galaxy having a mass 10 ^ { 11 } M _ { \odot } the inner density profile has a slope \alpha \simeq 0.65 , for a bulge of 4.5 \times 10 ^ { 9 } M _ { \odot } , while if bulge formation is not considered , the slope would be \alpha \simeq 0.55 .
If the bulge is larger , 6.5 \times 10 ^ { 9 } M _ { \odot } the slope is \alpha \simeq 0.7 .
In the case of a larger galaxy with 10 ^ { 12 } M _ { \odot } the slope is \alpha \simeq 0.85 , while in absence of bulge it is \alpha \simeq 0.75 .
We finally study how the inner slope \alpha changes with the bulge mass , and we find a correlation among the two quantities .
The result shows that bulge formation has an important role in shaping the inner DM density profile in agreement with Inoue & Saitoh ( 2011 ) result .
The result implies that going from Sc to SO Hubble type the slope is slightly steepening due to the bulge formation , and due to the fact that early type galaxies have larger bulges .