51 research outputs found
Leveraging Cross-Correlations: Cosmology with the kinematic Sunyaev Zel'dovich Effect
No full text99 pagesThe current era is one of a wealth of incoming high precision cosmological data from cosmic microwave background (CMB) and large scale structure (LSS) surveys. Yielding precise measurements of the kinematic Sunyaev-Zel'dovich (kSZ) effect, by cross-correlations between the two, has the potential to take advantage of this unique time. In the first chapter of this thesis, we conduct a study on how to achieve this, focusing primarily on systematic effects such as miscentering. Photometric and spectroscopic galaxy tracers from SDSS, WISE, and DECaLs are considered in combination with CMB data from Planck and WMAP. With two complementary techniques, analytic offset modeling and direct comparisons of redMaPPer brightest and central catalog samples, we find that miscentering uncertainties average to for the Planck kSZ statistical error budget obtained with a jackknife (JK) estimator. Our results demonstrate that uncertainties introduced through using galaxy proxies for cluster locations will need to be fully incorporated, and actively mitigated, for the kSZ to reach its full potential as a cosmological constraining tool for dark energy and neutrino physics. A 5.1 detection of the pairwise kSZ signal results is obtained with four seasons of ACTPol data in combination with Planck CMB with the luminous red galaxy sample from the Sloan Digital Sky Survey Baryonic Acoustic Oscillation Survey (SDSS BOSS) DR15 catalog, in Chapter 2. We utilize the constraining power of the kSZ effect by fitting each of nine luminosity selected samples to theoretical pairwise predictions, to find kSZ-derived mass-averaged optical depths, , and their evolution as a function of cluster mass assuming a Planck cosmology
Modeling the Emission from Turbulent Relativistic Jets in Active Galactic Nuclei
No full textWe present a numerical model developed to calculate observed fluxes of relativistic jets in active galactic nuclei. The observed flux of each turbulent eddy is dependent upon its variable Doppler boosting factor, computed as a function of the relativistic sum of the individual eddy and bulk jet velocities and our viewing angle to the jet. The total observed flux is found by integrating the radiation from the eddies over the turbulent spectrum. We consider jets that contain turbulent eddies that have either standard Kolmogorov or recently derived relativistic turbulence spectra. We also account for the time delays in receiving the emission of the eddies due to their different simulated positions in the jet, as well as due to the varying beaming directions as they turn over. We examine these theoretical light curves and compute power spectral densities (PSDs) for a range of viewing angles, bulk velocities of the jet, and turbulent velocities. These PSD slopes depend significantly on the turbulent velocity and are essentially independent of viewing angle and bulk velocity. The flux variations produced in the simulations for realistic values of the parameters tested are consistent with the types of variations observed in radio-loud AGN as, for example, recently measured with the Kepler satellite, as long as the turbulent velocities are not too high
The Atacama Cosmology Telescope: Detection of the pairwise kinematic Sunyaev-Zel\u27dovich effect with SDSS DR15 galaxies
No full textThe Atacama Cosmology Telescope: Probing the baryon content of SDSS DR15 galaxies with the thermal and kinematic Sunyaev-Zel\u27dovich effects
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The Atacama Cosmology Telescope: Probing the Baryon Content of SDSS DR15 Galaxies with the Thermal and Kinematic Sunyaev-Zel'dovich Effects
No full textWe present high signal-to-noise measurements (up to 12) of the
average thermal Sunyaev Zel'dovich (tSZ) effect from optically selected galaxy
groups and clusters and estimate their baryon content within a 2.1
radius aperture. Sources from the Sloan Digital Sky Survey (SDSS) Baryon
Oscillation Spectroscopic Survey (BOSS) DR15 catalog overlap with 3,700 sq.
deg. of sky observed by the Atacama Cosmology Telescope (ACT) from 2008 to 2018
at 150 and 98 GHz (ACT DR5), and 2,089 sq. deg. of internal linear combination
component-separated maps combining ACT and data (ACT DR4). The
corresponding optical depths, , which depend on the baryon content
of the halos, are estimated using results from cosmological hydrodynamic
simulations assuming an AGN feedback radiative cooling model. We estimate the
mean mass of the halos in multiple luminosity bins, and compare the tSZ-based
estimates to theoretical predictions of the baryon content for a
Navarro-Frenk-White profile. We do the same for estimates
extracted from fits to pairwise baryon momentum measurements of the kinematic
Sunyaev-Zel'dovich effect (kSZ) for the same data set obtained in a companion
paper. We find that the estimates from the tSZ measurements in
this work and the kSZ measurements in the companion paper agree within
for two out of the three disjoint luminosity bins studied, while they
differ by 2-3 in the highest luminosity bin. The optical depth
estimates account for one third to all of the theoretically predicted baryon
content in the halos across luminosity bins. Potential systematic uncertainties
are discussed. The tSZ and kSZ measurements provide a step towards empirical
Compton-- relationships to provide new tests of cluster
formation and evolution models
The Atacama Cosmology Telescope: a measurement of the Cosmic Microwave Background power spectra at 98 and 150 GHz
No full textAtacama Cosmology Telescope: Combined kinematic and thermal Sunyaev-Zel’dovich measurements from BOSS CMASS and LOWZ halos
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The Atacama Cosmology Telescope: DR4 maps and cosmological parameters
No full textWe present new arcminute-resolution maps of the Cosmic Microwave Background temperature and polarization anisotropy from the Atacama Cosmology Telescope, using data taken from 2013–2016 at 98 and 150 GHz. The maps cover more than 17,000 deg2, the deepest 600 deg2 with noise levels below 10μK-arcmin. We use the power spectrum derived from almost 6,000 deg2 of these maps to constrain cosmology. The ACT data enable a measurement of the angular scale of features in both the divergence-like polarization and the temperature anisotropy, tracing both the velocity and density at last-scattering. From these one can derive the distance to the last-scattering surface and thus infer the local expansion rate, H0. By combining ACT data with large-scale information from WMAP we measure H0=67.6± 1.1 km/s/Mpc, at 68% confidence, in excellent agreement with the independently-measured Planck satellite estimate (from ACT alone we find H0=67.9± 1.5 km/s/Mpc). The ΛCDM model provides a good fit to the ACT data, and we find no evidence for deviations: both the spatial curvature, and the departure from the standard lensing signal in the spectrum, are zero to within 1σ; the number of relativistic species, the primordial Helium fraction, and the running of the spectral index are consistent with ΛCDM predictions to within 1.5–2.2σ. We compare ACT, WMAP, and Planck at the parameter level and find good consistency; we investigate how the constraints on the correlated spectral index and baryon density parameters readjust when adding CMB large-scale information that ACT does not measure. The DR4 products presented here will be publicly released on the NASA Legacy Archive for Microwave Background Data Analysis
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