Radio Galaxy populations and the multi-tracer technique: pushing the limits on primordial non-Gaussianity

We explore the use of different radio galaxy populations as tracers of different mass halos and therefore, with different bias properties, to constrain primordial non-Gaussianity of the local type. We perform a Fisher matrix analysis based on the predicted auto and cross angular power spectra of these populations, using simulated redshift distributions as a function of detection flux and the evolution of the bias for the different galaxy types (Star forming galaxies, Starburst galaxies, Radio-Quiet Quasars, FRI and FRII AGN galaxies). We show that such a multi-tracer analysis greatly improves the information on non-Gaussianity by drastically reducing the cosmic variance contribution to the overall error budget. By using this method applied to future surveys, we predict a constraint of sigma_fnl=3.6 on the local non-Gaussian parameter for a galaxy detection flux limit of 10 \muJy and sigma_fnl=2.2 for 1 \muJy. We show that this significantly improves on the constraints obtained when using the whole undifferentiated populations (sigma_fnl=48 for 10 \muJy and sigma_fnl=12 for 1 \muJy). We conclude that continuum radio surveys alone have the potential to constrain primordial non-Gaussianity to an accuracy at least a factor of two better than the present constraints obtained with Planck data on the CMB bispectrum, opening a window to obtain sigma_fnl~1 with the Square Kilometer Array.Comment: 9 pages, 5 figures, submitted to MNRA

The HH34 outflow as seen in [FeII]1.64um by LBT-LUCI

Dense atomic jets from young stars copiously emit in [FeII] IR lines, which can, therefore, be used to trace the immediate environments of embedded protostars. We want to investigate the morphology of the bright [FeII] 1.64um line in the jet of the source HH34 IRS and compare it with the most commonly used optical tracer [SII]. We analyse a 1.64um narrow-band filter image obtained with the Large Binocular Telescope (LBT) LUCI instrument, which covers the HH34 jet and counterjet. A Point Spread Function (PSF) deconvolution algorithm was applied to enhance spatial resolution and make the IR image directly comparable to a [SII] HST image of the same source. The [FeII] emission is detected from both the jet, the (weak) counter-jet, and from the HH34-S and HH34-N bow shocks. The deconvolved image allows us to resolve jet knots close to about 1\arcsec from the central source. The morphology of the [FeII] emission is remarkably similar to that of the [SII] emission, and the relative positions of [FeII] and [SII] peaks are shifted according to proper motion measurements, which were previously derived from HST images. An analysis of the [FeII]/[SII] emission ratio shows that Fe gas abundance is much lower than the solar value with up to 90% of Fe depletion in the inner jet knots. This confirms previous findings on dusty jets, where shocks are not efficient enough to remove refractory species from grains.Comment: 5 pages, 4 figures, note accepted by A&

Cosmology with two compactification scales

We consider a (4+d)-dimensional spacetime broken up into a (4-n)-dimensional Minkowski spacetime (where n goes from 1 to 3) and a compact (n+d)-dimensional manifold. At the present time the n compactification radii are of the order of the Universe size, while the other d compactification radii are of the order of the Planck length.Comment: 16 pages, Latex2e, 7 figure

A Correspondence-Theoretic Approach to Dynamic Optimization

This paper introduces a method of optimization in infinite-horizon economies based on the theory of correspondences. The proposed approach allow us to study time-separable and non-time-separable dynamic economic models without resorting to fixed point theorems or transversality conditions. When our technique is applied to the standard time-separable model it provides an alternative and straightforward way to derive the common recursive formulation of these models by means of Bellman equations

Matching and Anonymity

This work introduces a rigorous set-theoretic foundation of deterministic bilateral matching processes and studies systematically their properties. In particular, it formalizes a link between matching and informational constraints by developing a notion of anonymity that is based on the agents\u27 matching histories. It also explains why and how various matching processes generate different degrees of informational isolation in the economy. We illustrate the usefulness of our approach to modeling matching frameworks by discussing the classical turnpike model of Townsend

Contagion Equilibria in a Monetary Model

This article explores the Monetary Models

Anonymous Markets and Monetary Trading

We study infinite-horizon monetary economies characterized by trading frictions that originate from random pairwise meetings, and commitment and enforcement limitations. We prove that introducing occasional trade in \u27centralized markets\u27 opens the door to an informal enforcement scheme that sustains a non-monetary efficient allocation. All is required is that trading partners be patient and their actions be observable. We then present a matching environment in which trade may occur in large markets and yet agents\u27 trading paths cross at most once. This allows the construction of models in which infinitely lived agents trade in competitive markets where money plays an essential role

A Random Matching Theory.

We develop the theoretical underpinnings of pairwise random matching mechanisms. We formalize the mechanics of matching, and study the links between properties of the different mechanisms and trade frictions. A particular emphasis is placed on providing exact mappings between matching technologies and informational constraints.Random matching ; frictions ; anonymous trading ; spatial intersections ; search

Monetary Equilibrium and the Differentiability of the Value Function

In this study we offer a new approach to proving the differentiability of the value function, which complements and extends the literature on dynamic programming. This result is then applied to the analysis of equilibrium in the recent class of monetary economies developed in [Lagos, R., Wright, R., 2005. A unified framework for monetary theory and policy analysis. journal of Political Economy 113, 463-484]. For this type of environments we demonstrate that the value function is differentiable and this guarantees that the marginal value of money balances is well defined

A Theoretical Foundation for Bilateral Matching Mechanisms.

This work introduces a rigorous set-theoretic foundation of bilateral matching mechanisms and studies their properties in a systematic manner. By providing a unified framework to study bilateral matching mechanisms, we formalize how different spatial/informational constraints can be implemented via a careful selection of matching mechanisms. In particular, this paper explains why and how various matching mechanisms generate different degrees of information isolation in the economy.Bilateral matching ; Frictions ; Anonymous trading ; Spatial interactions