TITLE:
Constraints on local primordial non-Gaussianity from large scale structure.
AUTHOR(S):
Anze Slosar, Christopher Hirata, Uros Seljak, Shirley Ho, Nikhil Padmanabhan.
DATE:
2008 May 23 (arXiv, v1, posted); 2008 Jun 04 (JCAP, submitted); 2008 Jul (revised); 2008 Jul 29 (JCAP, accepted);
2008 Aug 06 (arXiv, v2, posted); 2008 Aug 27 (JCAP, published).
AVAILABILITY:
arXiv 0805.3580 (free);
IoP (requires subscription).
PUBLICATION INFORMATION:
JCAP 08, 031, 2008.
ABSTRACT:
Recent work has shown that the local non-Gaussianity parameter f_nl induces a scale-dependent large scale structure bias, whose amplitude is growing
with scale. Here we first rederive this result within the context of peak-background split formalism and show that it only depends on the assumption of
universality of mass function, assuming halo bias only depends on mass. We then use extended Press-Schechter formalism to argue that this assumption
may be violated and the scale dependent bias will depend on other properties, such as merging history of halos. In particular, in the limit of recent
mergers we find the effect is suppressed. Next we use these predictions in conjunction with a compendium of large scale data to put a limit on the
value of $\fnl$. When combining all data assuming that halo occupation depends only on halo mass, we get a limit of -29(-57)<f_nl<+69(+89) at 95%
(99.7%) confidence. While we use a wide range of datasets, our combined result is dominated by the signal from the SDSS luminous red galaxy and
photometric quasar samples. If the latter are modelled as recent mergers then the limits become -29(-85)<f_nl<+70(+90). These limits are
comparable to
the strongest current limits from the WMAP 5-year analysis, with no evidence of a positive signal in f_nl. The combination of our measurement with
the WMAP f_nl value gives -1(-23)<f_nl<+70(+86). While the method needs to be thoroughly tested against large scale structure simulations with
realistic quasar and galaxy formation models, our results indicate that this is a competitive method relative to CMB and should be further pursued both
observationally and theoretically.
ADS BIBLIOGRAPHIC CODE: 2008JCAP...08..031S
COMMENTS: N/A.