Patrick C. Breysse

Carbon monoxide intensity mapping at moderate redshifts

We present a study of the feasibility of an intensity-mapping survey targeting the 115 GHz CO(1-0) rotational transition at

Oscillations and stability of polytropic filaments

z\sim3

Black hole mass function from gravitational wave measurements

. We consider four possible models and estimate the spatial and angular power spectra of CO fluctuations predicted by each of them. The frequency bandwidths of most proposed CO intensity mapping spectrographs are too small to use the Limber approximation to calculate the angular power spectrum, so we present an alternative method for calculating the angular power spectrum. The models we consider span two orders of magnitude in signal amplitude, so there is a significant amount of uncertainty in the theoretical predictions of this signal. We then consider a parameterized set of hypothetical spectrographs designed to measure this power spectrum and predict the signal-to-noise ratios expected under these models. With the spectrographs we consider we find that three of the four models give an SNR greater than 10 within one year of observation. We also study the effects on SNR of varying the parameters of the survey in order to demonstrate the importance of carefully considering survey parameters when planning such an experiment.

The high-redshift star formation history from carbon-monoxide intensity maps

We study the oscillations and stability of self-gravitating cylindrically symmetric fluid systems and collisionless systems. This is done by studying small perturbations to the equilibrium system and finding the normal modes, using methods similar to those used in astroseismology. We find that there is a single sequence of purely radial modes that become unstable if the adiabatic exponent is less than 1. Nonradial modes can be divided into p modes, which are stable and pressure-driven, and g modes, which are are gravity driven. The g modes become unstable if the adiabatic exponent is greater than the polytrope index. These modes are analogous to the modes of a spherical star, but their behavior is somewhat different because a cylindrical geometry has less symmetry than a spherical geometry. This implies that perturbations are classified by a radial quantum number, an azimuthal quantum number, and wavelength in the z direction, which can become arbitrarily large. We find that decreasing this wavelength increases the frequency of stable modes and increases the growth rate of unstable modes. We use use variational arguments to demonstrate that filaments of collisionless matter with ergodic distribution functions are stable to purely radial perturbations, and that filaments with ergodic power-law distribution functions are stable to all perturbations.

Feeding cosmic star formation: Exploring high-redshift molecular gas with CO intensity mapping

We examine how future gravitational-wave measurements from merging black holes (BHs) can be used to infer the shape of the black-hole mass function, with important implications for the study of star formation and evolution and the properties of binary BHs. We model the mass function as a power law, inherited from the stellar initial mass function, and introduce lower and upper mass cutoff parameterizations in order to probe the minimum and maximum BH masses allowed by stellar evolution, respectively. We initially focus on the heavier BH in each binary, to minimize model dependence. Taking into account the experimental noise, the mass measurement errors and the uncertainty in the redshift-dependence of the merger rate, we show that the mass function parameters, as well as the total rate of merger events, can be measured to <10% accuracy within a few years of advanced LIGO observations at its design sensitivity. This can be used to address important open questions such as the upper limit on the stellar mass which allows for BH formation and to confirm or refute the currently observed mass gap between neutron stars and BHs. In order to glean information on the progenitors of the merging BH binaries, we then advocate the study of the two-dimensional mass distribution to constrain parameters that describe the two-body system, such as the mass ratio between the two BHs, in addition to the merger rate and mass function parameters. We argue that several years of data collection can efficiently probe models of binary formation, and show, as an example, that the hypothesis that some gravitational-wave events may involve primordial black holes can be tested. Finally, we point out that in order to maximize the constraining power of the data, it may be worthwhile to lower the signal-to-noise threshold imposed on each candidate event and amass a larger statistical ensemble of BH mergers.

CCAT-Prime: science with an ultra-widefield submillimeter observatory on Cerro Chajnantor

We demonstrate how cosmic star-formation history can be measured with one-point statistics of carbon-monoxide intensity maps. Using a P(D) analysis, the luminosity function of CO-emitting sources can be inferred from the measured one-point intensity PDF. The star-formation rate density (SFRD) can then be obtained, at several redshifts, from the CO luminosity density. We study the effects of instrumental noise, line foregrounds, and target redshift, and obtain constraints on the CO luminosity density of order 10%. We show that the SFRD uncertainty is dominated by that of the model connecting CO luminosity and star formation. For pessimistic estimates of this model uncertainty, we obtain an error of order 50% on SFRD for surveys targeting redshifts between 2 and 7 with reasonable noise and foregrounds included. However, comparisons between intensity maps and galaxies could substantially reduce this model uncertainty. In this case our constraints on SFRD at these redshifts improve to roughly 5-10%, which is highly competitive with current measurements.

Insights from probability distribution functions of intensity maps

The study of molecular gas is crucial for understanding star formation, feedback, and the broader ecosystem of a galaxy as a whole. However, we have limited understanding of its physics and distribution in all but the nearest galaxies. We present a new technique for studying the composition and distribution of molecular gas in high-redshift galaxies inaccessible to existing methods. Our proposed approach is an extension of carbon monoxide intensity mapping methods, which have garnered significant experimental interest in recent years. These intensity mapping surveys target the 115 GHz

Masking line foregrounds in intensity-mapping surveys

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Line-Intensity Mapping: 2017 Status Report

CO (1-0) line, but also contain emission from the substantially fainter 110 GHz

Joint power spectrum and voxel intensity distribution forecast on the CO luminosity function with COMAP

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