Matching Items (11)

The Long Alchemy of Becoming: Aqua es Vida Film

Description

“The Long Alchemy of Becoming: Aqua es Vida” is a short, artistic film depicting the history of the Universe shown through the microcosm of the Mexican town, Cuatro Ciénegas, in

“The Long Alchemy of Becoming: Aqua es Vida” is a short, artistic film depicting the history of the Universe shown through the microcosm of the Mexican town, Cuatro Ciénegas, in the state of Coahuila. The film takes the viewer from the start of the universe to what scientists believe will be its end, via a poem written by Dr. James Elser. “The Long Alchemy of Becoming: Aqua es Vida” starts with the Big Bang, through the formation of matter, stars, planets, including Earth. From there, the viewer witnesses how life evolved illustrated via scenes in the ciénegas (‘marsh’ in Spanish) found in Cuatro Ciénegas, Coahuila, Mexico. The film explores how life expanded out from water, producing plants and animals, including humans. Then, modern life in Cuatro Ciénegas is shown, including the modern agricultural practices that are threatening to destroy the ciénegas that sustain long histories of microbial evolution. The film concludes with the end mankind and the eventual destruction of Earth by the dying sun. Cuatro Ciénegas is a biologically and ecologically significant location, because its pools and marshes are home to many endemic species, including stromatolites, which are very rare, bio-chemical living structures. This film is part of a National Science Foundation grant, and reflects the extensive scientific research efforts in and around Cuatro Ciénegas and its unique pools.

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Created

Date Created
  • 2015-05

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A Guide to Large Binocular Telescope Data Reduction

Description

Abstract Located in southeastern Arizona, the Large Binocular Telescope is a great local resource for ASU astronomy/cosmology researchers. As a ground-based observatory, the Large Binocular Telescope can effectively provide deep,

Abstract Located in southeastern Arizona, the Large Binocular Telescope is a great local resource for ASU astronomy/cosmology researchers. As a ground-based observatory, the Large Binocular Telescope can effectively provide deep, complementary observations of science fields in the wavelength range of 3,500 to 10,000 Angstroms. This gives scientists a lot of opportunity for various science projects, which can lead to massive amounts of observations being taken by research schools with ties to the LBT. Such is the case with ASU, which has obtained over 30 hours of data in just the SDT Uspec filter on board the Large Binocular Camera (Blue) and much more time in other filters observing longer wavelengths. Because of this, there is a huge need for establishing a system that will allow the reduction of raw astronomical images from the LBT to be quickly, but accurately. This manuscript serves as a presentation of the work done over the 2015-2016 school year to establish a pipeline for reducing LBT raw science images as well as a guide for future undergraduates and graduates to reduce data on their own.

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Agent

Created

Date Created
  • 2016-05

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Environmental Systematics and the Impact on 21-cm Epoch of Reionization Measurements

Description

The Epoch of Reionization (EoR) is the period in the evolution of the universe during which neutral hydrogen was ionized by the first luminous sources, and is closely linked to

The Epoch of Reionization (EoR) is the period in the evolution of the universe during which neutral hydrogen was ionized by the first luminous sources, and is closely linked to the formation of structure in the early universe. The Hydrogen Epoch of Reionization Array (HERA) is a radio interferometer currently under construction in South Africa designed to study this era. Specifically, HERA is dedicated to studying the large-scale structure during the EoR and the preceding Cosmic Dawn by measuring the redshifted 21-cm line from neutral hydrogen. However, the 21-cm signal from the EoR is extremely faint relative to galactic and extragalactic radio foregrounds, and instrumental and environmental systematics make measuring the signal all the more difficult. Radio frequency interference (RFI) from terrestrial sources is one such systematic. In this thesis, we explore various methods of removing RFI from early science-grade HERA data and characterize the effects of different removal patterns on the final 21-cm power spectrum. In particular, we focus on the impact of masking narrowband signals, such as those characteristic of FM radio and aircraft or satellite communications, in the context of the algorithms currently used by the HERA collaboration for analysis.

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Agent

Created

Date Created
  • 2019-05

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Characterizing Low Frequency Delay Mode Contamination of the Hydrogen Epoch of Reionization Array

Description

The Hydrogen Epoch of Reionization Array, HERA, is a radio telescope currently being built in South Africa that plans to observe the early universe, specifically the earliest period of star

The Hydrogen Epoch of Reionization Array, HERA, is a radio telescope currently being built in South Africa that plans to observe the early universe, specifically the earliest period of star and galaxy formation. It plans to use a tool called a delay spectrum to separate signal emitted from this time from the much brighter radio foregrounds. It is the purpose of this paper to outline the method used to characterize the contamination of these delay spectra by bright emissions of radio here on Earth called radio frequency interference, RFI. The portion of the bandwidth containing the signal from the period of initial star formation was specifically examined. In order to receive usable data, the HERA commissioning team was assisted in the evaluation of the most recent data releases. On the first batch of usable data, flagging algorithms were run in order to mask all of the RFI present. A method of filling these masked values was determined, which allowed for the delay spectrum to be observed. Various methods of injecting RFI into the data were tested which portrayed the large dependence of the delay spectrum on its presence. Finally, the noise power was estimated in order to predict whether or not the limitations observed in the dynamic range were comparable to the noise floor. By examining the evolution of the delay spectrum's power as a range of noise power was introduced, there is a good amount of evidence that this limitation is in fact the noise floor. From this, we see that excision algorithms and interpolation used are capable of removing the effects of most all of the RFI contamination.

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Created

Date Created
  • 2019-05

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Galaxy evolution with hybrid methods

Description

I combine, compare, and contrast the results from two different numerical techniques (grid vs. particle methods) studying multi-scale processes in galaxy and structure formation. I produce a method for recreating

I combine, compare, and contrast the results from two different numerical techniques (grid vs. particle methods) studying multi-scale processes in galaxy and structure formation. I produce a method for recreating identical initial conditions for one method from those of the other, and explore methodologies necessary for making these two methods as consistent as possible. With this, I first study the impact of streaming velocities of baryons with respect to dark matter, present at the epoch of reionization, on the ability for small halos to accrete gas at high redshift. With the inclusion of this stream velocity, I find the central density profile of halos is reduced, overall gas condensation is delayed, and infer a delay in the inevitable creation of stars.

I then combine the two numerical methods to study starburst outflows as they interact with satellite halos. This process leads to shocks catalyzing the formation of molecular coolants that lead to bursts in star formation, a process that is better captured in grid methods. The resultant clumps of stars are removed from their initial dark matter halo, resemble precursors to modern-day globular clusters, and their formation may be observable with upcoming telescopes.

Finally, I perform two simulation suites, comparing each numerical method's ability to model the impact of energetic feedback from accreting black holes at the core of giant clusters. With these comparisons I show that black hole feedback can maintain a hot diffuse medium while limiting the amount of gas that can condense into the interstellar medium, reducing the central star formation by up to an order of magnitude.

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Agent

Created

Date Created
  • 2014

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Techniques for the analysis and understanding of cosmic evolution

Description

The Cosmic Microwave Background (CMB) has provided precise information on the evolution of the Universe and the current cosmological paradigm. The CMB has not yet provided definitive information on the

The Cosmic Microwave Background (CMB) has provided precise information on the evolution of the Universe and the current cosmological paradigm. The CMB has not yet provided definitive information on the origin and strength of any primordial magnetic fields or how they affect the presence of magnetic fields observed throughout the cosmos. This work outlines an alternative method to investigating and identifying the presence of cosmic magnetic fields. This method searches for Faraday Rotation (FR) and specifically uses polarized CMB photons as back-light. I find that current generation CMB experiments may be not sensitive enough to detect FR but next generation experiments should be able to make highly significant detections. Identifying FR with the CMB will provide information on the component of magnetic fields along the line of sight of observation.

The 21cm emission from the hyperfine splitting of neutral Hydrogen in the early universe is predicted to provide precise information about the formation and evolution of cosmic structure, complementing the wealth of knowledge gained from the CMB.

21cm cosmology is a relatively new field, and precise measurements of the Epoch of Reionization (EoR) have not yet been achieved. In this work I present 2σ upper limits on the power spectrum of 21cm fluctuations (Δ²(k)) probed at the cosmological wave number k from the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER) 64 element deployment. I find upper limits on Δ²(k) in the range 0.3 < k < 0.6 h/Mpc to be (650 mK)², (450 mK)², (390 mK)², (250 mK)², (280mK)², (250 mK)² at redshifts z = 10.87, 9.93, 8.91, 8.37, 8.13 and 7.48 respectively

Building on the power spectrum analysis, I identify a major limiting factor in detecting the 21cm power spectrum.

This work is concluded by outlining a metric to evaluate the predisposition of redshifted 21cm interferometers to foreground contamination in power spectrum estimation. This will help inform the construction of future arrays and enable high fidelity imaging and

cross-correlation analysis with other high redshift cosmic probes like the CMB and other upcoming all sky surveys. I find future

arrays with uniform (u,v) coverage and small spectral evolution of their response in the (u,v,f) cube can minimize foreground leakage while pursuing 21cm imaging.

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Agent

Created

Date Created
  • 2018

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Antenna design and foreground characterization for improved detection of the redshifted 21 cm global signature during the Epoch of Reionization

Description

The Universe transitioned from a state of neutral hydrogen (HI) shortly after recombination to its present day ionized state, but this transition, the Epoch of Reionization (EoR), has been poorly

The Universe transitioned from a state of neutral hydrogen (HI) shortly after recombination to its present day ionized state, but this transition, the Epoch of Reionization (EoR), has been poorly constrained by observational data. Estimates place the EoR between redshifts 6 < z <13 (330-770 Myr).

The interaction of the 21 cm hyperfine ground state emission/absorption-line of HI with the cosmic microwave background (CMB) and the radiation from the first luminous sources in the universe can be used to extract cosmological information about the EoR. Theorists have created global redshifted 21 cm EoR models of this interaction that predict the temperature perturbations to the CMB in the form of a sky-averaged difference temperature, Tb. The difficulty in measuring Tb is that it is

predicted to be on the order of 20 to 100 mK, while the sky foreground is dominated

by synchrotron radiation that is 105 times brighter. The challenge is to subtract the much brighter foreground radiation without subtracting the Tb signal and can only be done when the data has small error levels.

The Experiment to Detect the Global EoR Signature (EDGES) is an effort to measure Tb with a single wide field-of-view well-calibrated antenna. This dissertation focuses on reducing systematic errors by quantifying the impact of the chromatic nature of the antenna’s beam directivity and by measuring the variability of the spectral index of the radio sky foreground. The chromatic beam study quantified the superior qualities of the rectangular blade-shaped antenna and led to its adoption over the previously used fourpoint-shaped antenna and determined that a 5 term polynomial was optimum for removing the foreground. The spectral index, β, of the sky was measured, using 211 nights of data, to be −2.60 > β > −2.62 in lower LST regions, increasing to −2.50 near the Galactic plane. This matched simulated results using the Guzm´an et al. (2011) sky map (∆β < 0.05) and demonstrated the exceptional stability of the EDGES instrument. Lastly, an EoR model by Kaurov & Gnedin (2016) was shown to be inconsistent with measured EDGES data at a significance level of 1.9.

Contributors

Agent

Created

Date Created
  • 2017

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Highly multiplexed superconducting detectors and readout electronics for balloon-borne and ground-based far-infrared imaging and polarimetry

Description

This dissertation details the development of an open source, frequency domain multiplexed (FDM) readout for large-format arrays of superconducting lumped-element kinetic inductance detectors (LEKIDs). The system architecture is designed to

This dissertation details the development of an open source, frequency domain multiplexed (FDM) readout for large-format arrays of superconducting lumped-element kinetic inductance detectors (LEKIDs). The system architecture is designed to meet the requirements of current and next generation balloon-borne and ground-based submillimeter (sub-mm), far-infrared (FIR) and millimeter-wave (mm-wave) astronomical cameras, whose science goals will soon drive the pixel counts of sub-mm detector arrays from the kilopixel to the megapixel regime. The in-flight performance of the readout system was verified during the summer, 2018 flight of ASI's OLIMPO balloon-borne telescope, from Svalbard, Norway. This was the first flight for both LEKID detectors and their associated readout electronics. In winter 2019/2020, the system will fly on NASA's long-duration Balloon Borne Large Aperture Submillimeter Telescope (BLAST-TNG), a sub-mm polarimeter which will map the polarized thermal emission from cosmic dust at 250, 350 and 500 microns (spatial resolution of 30", 41" and 59"). It is also a core system in several upcoming ground based mm-wave instruments which will soon observe at the 50 m Large Millimeter Telescope (e.g., TolTEC, SuperSpec, MUSCAT), at Sierra Negra, Mexico.

The design and verification of the FPGA firmware, software and electronics which make up the system are described in detail. Primary system requirements are derived from the science objectives of BLAST-TNG, and discussed in the context of relevant size, weight, power and cost (SWaP-C) considerations for balloon platforms. The system was used to characterize the instrumental performance of the BLAST-TNG receiver and detector arrays in the lead-up to the 2019/2020 flight attempt from McMurdo Station, Antarctica. The results of this characterization are interpreted by applying a parametric software model of a LEKID detector to the measured data in order to estimate important system parameters, including the optical efficiency, optical passbands and sensitivity.

The role that magnetic fields (B-fields) play in shaping structures on various scales in the interstellar medium is one of the central areas of research which is carried out by sub-mm/FIR observatories. The Davis-Chandrasekhar-Fermi Method (DCFM) is applied to a BLASTPol 2012 map (smoothed to 5') of the inner ~1.25 deg2 of the Carina Nebula Complex (CNC, NGC 3372) in order to estimate the strength of the B-field in the plane-of-the-sky (B-pos). The resulting map contains estimates of B-pos along several thousand sightlines through the CNC. This data analysis pipeline will be used to process maps of the CNC and other science targets which will be produced during the upcoming BLAST-TNG flight. A target selection survey of five nearby external galaxies which will be mapped during the flight is also presented.

Contributors

Agent

Created

Date Created
  • 2019

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Cosmological and astrophysical probes of physics beyond the standard model

Description

Cosmology, carrying imprints from the entire history of the universe, has emerged as a precise observational science over the past 30 years. It can probe physics beyond the Standard Model

Cosmology, carrying imprints from the entire history of the universe, has emerged as a precise observational science over the past 30 years. It can probe physics beyond the Standard Model at energy scales much higher than the weak scale. This thesis reports on some important probes of beyond standard model physics derived in a cosmological setting - (I) It is shown that primordial gravitational waves left over from inflation carry unique detectable CMB signatures for neutrino masses, axions and any other relativistic species that may have been present. (II) Higgs Inflation, the most popular and compelling inflation model with a higgs boson is studied next and it is shown that quantum effects have so far been incorrectly incorporated. A spurious gauge ambiguity arising from quantum effects enters the canonical prediction for observables in Higgs Inflation that must be addressed. (III) A new novel mechanism for generating the observed baryon asymmetry of the universe via decaying gravitinos is proposed. If the Supersymmetry (SUSY) breaking scale is high, then in the presence of R-parity violation, gravitinos can successfully reproduce the baryon asymmetry and evade all low energy constraints. (IV) The final chapter reports on a new completely general analysis of simplified models used in direct detection of dark matter. This is useful to explore what high energy physics constraints can be obtained from direct detection experiments.

Contributors

Agent

Created

Date Created
  • 2015

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Following the cosmic evolution of the pristine gas: Pop III star formation and the first galaxies

Description

The formation of the firsts stars some 100-300 Myr after the Big Bang marked the end of the cosmic darks ages and created the elemental building blocks of not only

The formation of the firsts stars some 100-300 Myr after the Big Bang marked the end of the cosmic darks ages and created the elemental building blocks of not only rocky planets but eventually us. Understanding their formation, lifetimes, and contributions to the evolution of our universe is one of the current frontiers in astronomy and astrophysics.

In this work I present an improved model for following the formation of Pop III stars, their effects on early galaxy evolution, and how we might search for them. I make use of a new subgrid model of turbulent mixing to accurately follow the time scales required to mix supernova (SN) ejecta -- enriched with heavy elements -- into the pristine gas. I implement this model within a large-scale cosmological simulation and follow the fraction of gas with metallicity below a critical value marking the boundary between Pop III and metal enriched Population II (Pop II) star formation. I demonstrate that accounting for subgrid mixing results in a Pop III stars formation rate that is 2-3 times higher than standard models with the same physical resolution.

I also implement and track a new "Primordial metals" (PM) scalar that tracks the metals generated by Pop III SNe. These metals are taken up by second generation stars and likely result in a subclass of carbon-enhanced, metal-poor (CEMP) stars. By tracking both regular metals and PM, I can model, in post-processing, the elemental abundances of simulation stars. I find good agreement between observations of CEMP-no Milky Way halo stars and second generation stars within the simulation when assuming the first stars had a typical mass of 60 M☉, providing clues as to the Pop III initial mass function.

Contributors

Agent

Created

Date Created
  • 2018