Volume : III, Issue : I, January - 2013

Seven Puzzles for LCDM Cosmology

Mohammed Sajid Iqbal

Abstract :

the ΛCDM cosmological model is a well defined, simple and predictive model whichis consistent with the majority of current cosmological observations. despite of these successes there are specific cosmological observations which differ from the predictions of ΛCDM at a level of 2Λ or higher. these observations include the following: 1. large scale velocity flows (ΛCDM predicts significantly smaller amplitude and scale of flows than what observations indicate),2. ightness of type Ia supernovae (SnIa) at high redshift z (ΛCDM predicts fainter SnIa at high z), 3. emptiness of voids (ΛCDM predicts more dwarf or irregular galaxies in voids than observed), 4. profiles of cluster haloes (ΛCDM predicts shallow low concentration and density profiles in contrast to observations which indicate denser high concentration cluster haloes) 5. profiles of galaxy haloes (ΛCDM predicts halo mass proles with cuspy cores and low outer density while lensing and dynamical observations indicate a central core of constant density and a fattish high dark mass density outer profile), 6. sizable population of disk galaxies (ΛCDM predicts a smaller fraction of disk galaxies due to recent mergers expected to disrupt cold rotationally supported disks). 7. The dark energy may be almost impossible to detect in laboratory and its value is un naturally small Compare to naïve theoretical prediction even though the origin of some of the above challenges may be astrophysical or related to dark matter properties, it should be stressed that even on galactic and cluster scales, the effects of dark energy on the equiliium and stability of astrophysical systems are not negligible and they may play a key role in the resolution of the above puzzles. here, iefy review these six challenges of and discuss the possible dark energy properties required for their resolution.

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Article: Download PDF   DOI : 10.36106/ijar  

Cite This Article:

MOHAMMED SAJID IQBAL Seven Puzzles for LCDM Cosmology Indian Journal of Applied Research, Vol.III, Issue.I January 2013

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