60 research outputs found
Local Primordial Non-Gaussianities and Super-Sample Variance
Fluctuations with wavelengths larger than the volume of a galaxy survey
affect the measurement of the galaxy power spectrum within the survey itself.
In the presence of local Primordial Non- Gaussianities (PNG), in addition to
the super-sample matter density and tidal fluctuations, the large-scale
gravitational potential also induces a modulation of the observed power
spectrum. In this work we investigate this modulation by computing for the
first time the response of the redshift-space galaxy power spectrum to the
presence of a long wavelength gravitational potential, fully accounting for the
stochastic contributions. For biased tracers new response functions arise due
to couplings between the small-scale fluctuations in the density, velocity and
gravitational fields, the latter through scale dependent bias operators, and
the large-scale gravitational potential. We study the impact of the
super-sample modes on the measurement of the amplitude of the primordial
bispectrum of the local-shape, , accounting for
modulations of both the signal and the covariance of the galaxy power spectrum
by the long modes. Considering DESI-like survey specifications, we show that in
most cases super-sample modes cause little or no degradation of the
constraints, and could actually reduce the errorbars on
by (10 - 30)\%, if external information on the bias parameters is available.Comment: 15 pages, 4 figure
Comments on the Starobinsky Model of Inflation and its Descendants
We point out that the ability of some models of inflation, such as Higgs
inflation and the universal attractor models, in reproducing the available data
is due to their relation to the Starobinsky model of inflation. For large field
values, where the inflationary phase takes place, all these classes of models
are indeed identical to the Starobinsky model. Nevertheless, the inflaton is
just an auxiliary field in the Jordan frame of the Starobinsky model and this
leads to two important consequences: first, the inflationary predictions of the
Starobinsky model and its descendants are slightly different (albeit not
measurably); secondly the theories have different small-field behaviour,
leading to different ultra-violet cut-off scales. In particular, one
interesting descendant of the Starobinsky model is the non-minimally- coupled
quadratic chaotic inflation. Although the standard quadratic chaotic inflation
is ruled out by the recent Planck data, its non-minimally coupled version is in
agreement with observational data and valid up to Planckian scales.Comment: 18 page
Towards a Precision Measurement of Binary Black Holes Formation Channels Using Gravitational Waves and Emission Lines
The formation of compact objects--neutron stars, black holes, and
supermassive black holes--and its connection to the chemical composition of the
galaxies is one of the central questions in astrophysics. We propose a novel
data-driven, multi-messenger technique to address this question by exploiting
the inevitable correlation between gravitational waves and atomic/molecular
emission line signals. We show that the minimum delay time of Gyr and the
power-law index of the fiducial scenario of the probability
distribution function is possible to measure with
a standard deviation (and ) and (and ) respectively
from five years of LIGO-Virgo-KAGRA observation in synergy with SPHEREx line
intensity mapping (and DESI emission-line galaxies).Comment: 8 pages, 3 figure
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