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PHYS08200605006 D.K. Hazra - Homi Bhabha National Institute

PHYS08200605006 D.K. Hazra - Homi Bhabha National Institute

PHYS08200605006 D.K. Hazra - Homi Bhabha National Institute

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CHAPTER 6. EFFECTS OF PRIMORDIAL FEATURES ON THE FORMATION OF HALOS<br />

100000<br />

1000<br />

Quadratic potential<br />

Quadratic potential with a step<br />

Quadratic potential with sinusoidal modulation<br />

Axion monodromy model<br />

P M<br />

(k)h −3 Mpc 3<br />

1<br />

10000<br />

1000<br />

0.01 0.1<br />

0.001<br />

0.0001 0.01 1 100<br />

khMpc −1<br />

Figure 6.4: The best fit matter power spectrum P M<br />

(k) corresponding to the different inflationary<br />

scalar power spectra we had plotted in the earlier figure. The inset highlights the<br />

imprints of the primordial features on the matter power spectrum in the domain where<br />

the baryon acoustic oscillations also play a role. The black dots with bars corresponds<br />

to the power spectrum data from SDSS obtained upon combining main galaxies and the<br />

LRGs with error bars arrived at from the diagonal elements of the corresponding covariance<br />

matrix. It should be noted that, since we have plotted the linear power spectrum,<br />

without taking into account the non-linear effects, the theoretical best fit curves are unable<br />

to fit the data for k > 0.1hMpc −1 .<br />

potential.<br />

In order to arrive at the maximum possible change in the number density of halos<br />

when compared to the conventional nearly scale invariant primordial spectrum, for the<br />

models with oscillations in the potential, we have chosen values for the parametersαand<br />

β that lie within2-σ from the best fit values. We have chosen the parameters in such a way<br />

that they create the largest deviation from the nearly scale invariant power spectra that<br />

are allowed by the CMB and the LSS data. In Figure 6.5, apart from the results for the best<br />

fit values, we have plotted the number density and the formation rates of halos for the<br />

cases wherein[α,ln(β/M Pl<br />

)] is set to(2×10 −3 ,−1.7) and(2×10 −4 ,−3.5) for the quadratic<br />

potential with the sinusoidal modulations and the axion monodromy model, respectively.<br />

118

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