Top PDF Data analysis of and results from observations of the cosmic microwave background with the Cosmic Background Imager

Data analysis of and results from observations of the cosmic microwave background with the Cosmic Background Imager

Data analysis of and results from observations of the cosmic microwave background with the Cosmic Background Imager

Thanks to the gang in Pasadena, too. They were a far more interesting, well-rounded, and fun group than one has any right to expect from a bunch of astronomers. The old guard were great at welcoming us and showing us the ropes when we were still wet behind the ears. Brad, Roy, Kern, everybody else (I know there are more, but this has to be in the mail in an hour if I want to graduate), thanks guys. Thanks also to John Yamasaki, both for his work on the CBI, and especially his youthful spirit. It is impossible not to enjoy one’s own life with Yama around. Thanks to Kathy and Pete for providing a home away from home. Dave Vakil was a great friend and roomate (not one late charge at the house the whole time he was there!) as well as a fun bridge partner. Dave, I finally cracked 50% on the Lehmans! I would thank Alice Shapley, but I feel I owe retribution for sicking people on my poor, sensitive sides. I thought a foreign country would finally provide refuge, but alas, I was in err. Dr. Green Cloud made the office fun, as well as providing an endless source of the odd and obscure. From whom else could I have learned about the albino sea-cucumber? And with whom else could I have hitch-hiked across the Andes? Rob Simcoe and Pat Udomprasert have been fast friends since the day I showed up, belatedly, to grad school. They have become family over the years - just ask my siblings. Thanks to Amy Mainzer who kept my life from turning into a monotony of matrices. Her friendship and insight kept life in perspective and made me think about many things that needed thinking about. Thanks to her also for providing such a good home for the fish.
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Hansen, Frode Kristian
  

(2002):


	Data Analysis of the Cosmic Microwave Background.


Dissertation, LMU München: Fakultät für Physik

Hansen, Frode Kristian (2002): Data Analysis of the Cosmic Microwave Background. Dissertation, LMU München: Fakultät für Physik

This section is a summary of the paper (Wandelt and G´orski 2000). The results and definitions here will be used in the next section. In (Wandelt and G´orski 2000) a fast method to make simulated time streams of a general CMB exper- iment is presented. To test the different steps of the data analysis pipeline of a CMB experiment one needs to simulate the experiment. Generally when the CMB telescope is looking in a certain direction, it does not only observe the CMB temperature in that given direction. There are also contributions from other di- rections. Usually one approximates this beam pattern to be a 2D Gaussian cen- tered in the direction in which the telescope is pointing. In general however, this beam pattern will be different and often not axissymmetric causing distortions of the CMB patterns. In addition, if the instrument allows diffraction of stray light into the detectors, the observed CMB temperature in one direction might have contributions from completely other directions. Because of high intensity radiation from the galactic plane (see section (2.2.2)) or reflected radiation from planets in the solar system this can contaminate the CMB data and should be taken into account in the data analysis.
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Semi analytic calculation of cosmic microwave background anisotropies from wiggly and superconducting cosmic strings

Semi analytic calculation of cosmic microwave background anisotropies from wiggly and superconducting cosmic strings

In figure 2 we show our results for network evolution and in figure 3 the corresponding CMB anisotropies com- puted in our modified version of CMBact. In both figures we also show the corresponding results of the original CMBact code [43] for comparison. Regarding figure 2, we note thet the accuracy of CMBact is comparatively worse at low redshifts; this explains why the effects of the matter to acceleration transition seemingly become visible around reshifts of a few, while the onset of accel- eration occurs below z = 1. This point is not crucial for our analysis, since our goal is to make a comparaive study of the effects of the additional degrees of freedom on the strings. Moreover, these low redshifts have a relatively small effect on the overall CMB signal. Nevertheless, this is an issue which should be adressed if this code is to be used for quantitative comparisons with current or forth- coming CMB data.
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Probing The Cosmic Microwave Background Radiation With Actpol: A Millimeter-Wavelength, Polarization-Sensitive Receiver For The Atacama Cosmology Telescope

Probing The Cosmic Microwave Background Radiation With Actpol: A Millimeter-Wavelength, Polarization-Sensitive Receiver For The Atacama Cosmology Telescope

not only the development of core science and technology objectives to enable the success of the project, but also the ability to join a spirit of exploration and adventure that are core to the pursuit of modern experimental cosmology research. Completion of the doctoral research central to this dissertation required travel to national laboratories, conferences, engineering subcontractors, data analysis supercomputing centers, and deployment sites, some located in extreme environments on all four continents of the Atlantic basin. To achieve the core science and technology development goals described herein, travel was completed to the Rocky Mountains of Boulder, Colorado to develop advanced millimeter- wavelength polarimeters along with teams at NIST, to Greenbelt, Maryland to complete subsystem validation testing at NASAs Goddard Space Flight Center, to the high-altitude Atacama Cosmology Telescope site for receiver deployment and operations in the Atacama Desert of Northern Chile, to Durban, South Africa to complete initial data analysis of the ACTPol galactic plane data set, and across Canada, and European capitals to present key science and technology development results while engaging with the broader experimental cosmology community. Invariably, pursuit of these science and technology objectives across such a large span of the globe led to memorable side adventures and experiences ranging from self-drive safaris in the KwaZulu-Natal region of South Africa, to expeditions to climb to the summit of Cerro Toco and other Atacama stratovolcanoes in Chile, to sorting through legal issues associated with an “expired visa in Calama, Chile and on the Chile-Bolivia border in the Bolivian altiplanico of the Atacama Desert, to a hike across the high-altitude Chile-Argentina desert border to retrieve a new visa (witnessing llama skeletons, scorpions, and active mine fields along the way), to a respite from the visa experience near Cape Horn, including dog sledding across Tierra del Fuego and navigation on the Beagle Channel.
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A limit on the polarization of the cosmic microwave background radiation

A limit on the polarization of the cosmic microwave background radiation

San Pedro de Atacama, Chile. Steve gave me a crash course in maximum likelihood as well as the nuanced arts of driving a 4 × 4 through the lava fields of Chajnantor. Brian served as a ready fount of radio astronomy wisdom, and his odd yet beguiling sense of humor has left its mark—for better or worse—on the entire CBI team. Pat provided many useful insights about the acquisition and analysis of the CBI data, and her good cheer ameliorated the many little nuisances of life in the Chilean hinterlands. Jon tutored me in maximum likelihood; I retained about 10% of what he told me, but it was the 10% that I needed to obtain my results. San Pedro does not offer many diversions, so we made our own in the kitchen: we dined like royalty on Tony’s beef bourguignon, Tim’s coq au vin, Steve’s Christmas pudding, and Pat’s beef panang—I only regret that we never served all of these dishes in a single, rapture-inducing feast! All members of the CBI team contributed to the observations for the 100+ nights of polarization data presented in Chapter 5.
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H_o from Cosmic Background Imager observations of the Sunyaev-Zeldovich effect in nearby clusters

H_o from Cosmic Background Imager observations of the Sunyaev-Zeldovich effect in nearby clusters

Mason et al. (2001) (hereafter MMR) and Myers et al. (1997) observed four of the clusters presented in this paper, A399, A401, A478, and A1651, with the OVRO 5-m telescope. We compare the CBI results with the OVRO 5-m observations. MMR reanalyzed A478 observations taken by Myers et al. (1997), and we use the MMR results here. There are a few differences between the CBI and OVRO 5-m observations which must be taken into account. First, for all 4 clusters, different lead and trail fields were observed by the 2 groups. These differing fields contribute significant errors to the results. Also, slightly different redshifts, electron temperatures, and cosmologies were assumed in the 2 analyses. If we take these into account and fit models to the CBI data using all the same parameters assumed by MMR, the results we would obtain are presented in Table 4.8. Errors from the CMB in the main fields will be correlated for the 2 observations, since the same patch of CMB is being observed. However, the CMB contribution should not be identical because the interferometer and single dish measurements are sensitive to different modes of the CMB. Calculating the correlated error in the main field is complicated, so instead we performed the following estimate. We compared our results to those of MMR assuming two different uncertainties. In our first comparison, we included the entire 68% confidence errors as quoted in MMR, which included errors due to contributions from the lead, main, and trail fields, whereas for the CBI measurements, we removed the contribution to the uncertainty from the CMB in the main field, but included uncertainties from CMB in the lead and trail field, as well as thermal noise from the main field. In the second comparison, we removed the contribution to the uncertainty from the main field CMB in the MMR result as well. Table 4.8 shows the results we obtain from these comparisons. We calculated χ 2 to determine the probability due to chance of our results differing by the observed
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Exploring The Universe With The Atacama Cosmology Telescope: Polarization-Sensitive Measurements Of The Cosmic Microwave Background

Exploring The Universe With The Atacama Cosmology Telescope: Polarization-Sensitive Measurements Of The Cosmic Microwave Background

Over the past twenty-five years, observations of the Cosmic Microwave Background (CMB) temperature fluctuations have served as an important tool for answering some of the most fundamental questions of modern cosmology: how did the universe begin, what is it made of, and how did it evolve? More recently, measurements of the faint polarization signatures of the CMB have offered a complementary means of probing these questions, helping to shed light on the mysteries of cosmic inflation, relic neutrinos, and the nature of dark energy. A second-generation receiver for the Atacama Cosmology Telescope (ACT), the Atacama Cosmology Telescope Polarimeter (ACTPol), was designed and built to take advantage of both these cosmic signals by measuring the CMB to high precision in both temperature and polarization. The receiver features three independent sets of cryogenically cooled optics coupled to transition-edge sensor (TES) based polarimeter arrays via monolithic silicon feedhorn stacks. The three detector arrays, two operating at 149 GHz and one operating at both 97 and 149 GHz, contain over 1000 detectors each and are continuously cooled to a temperature near 100 mK by a custom-designed dilution refrigerator insert. Using ACT's six meter diameter primary mirror and diffraction limited optics, ACTPol is able to make high-fidelity measurements of the CMB at small angular scales (l ~ 9000), providing an excellent complement to Planck. The design and operation of the instrument are discussed in detail, and results from the first two years of observations are presented. The data are broadly consistent with /\CDM and help improve constraints on model extensions when combined with temperature measurements from Planck.
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A Measurement of the Angular Power Spectrum of the Cosmic Microwave Background with a Long Duration Balloon borne Receiver

A Measurement of the Angular Power Spectrum of the Cosmic Microwave Background with a Long Duration Balloon borne Receiver

A Measurement of the Angular Power Spectrum of the Cosmic Microwave Background with a Long Duration Balloon-borne Receiver Thesis by Brendan P.. In Partial Ful..[r]

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Transformation of the Angular Power Spectrum of the Cosmic Microwave Background (CMB) Radiation into Reciprocal Spaces and Consequences of This Approach

Transformation of the Angular Power Spectrum of the Cosmic Microwave Background (CMB) Radiation into Reciprocal Spaces and Consequences of This Approach

A formalism of solid state physics has been applied to provide an additional tool for the research of cosmologi- cal problems. It was demonstrated how this new ap- proach could be useful in the analysis of the CMB data. After a transformation of the anisotropy spectrum of rel- ict radiation into a special two-fold reciprocal space it was possible to propose a simple and general description of the interaction of relict photons with the matter 380.000 years after the Big-Bang by a “relict radiation factor”. This factor, which may help in an improvement of the theoretical predictions of the CMB pattern, en- abled us to process the transformed CMB anisotropy spectrum by a Fourier transform and thus arrive to a ra- dial electron density distribution function (RDF) in a reciprocal space.
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Planck intermediate results  XLVIII  Disentangling Galactic dust emission and cosmic infrared background anisotropies

Planck intermediate results XLVIII Disentangling Galactic dust emission and cosmic infrared background anisotropies

Acknowledgements. The Planck Collaboration acknowledges the support of: ESA; CNES, and CNRS / INSU-IN2P3-INP (France); ASI, CNR, and INAF (Italy); NASA and DoE (USA); STFC and UKSA (UK); CSIC, MINECO, JA, and RES (Spain); Tekes, AoF, and CSC (Finland); DLR and MPG (Germany); CSA (Canada); DTU Space (Denmark); SER/SSO (Switzerland); RCN (Nor- way); SFI (Ireland); FCT / MCTES (Portugal); ERC and PRACE (EU). A descrip- tion of the Planck Collaboration and a list of its members, indicating which tech- nical or scientific activities they have been involved in, can be found at http:// www.cosmos.esa.int/web/planck/planck-collaboration. Some of the results in this paper have been derived using the HEALPix package. The research leading to these results has received funding from the ERC Grant No. 307209.
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The Derivation of the Cosmic Microwave Background Radiation Peak Spectral Radiance, Planck Time, and the Hubble Constant from the Neutron and Hydrogen

The Derivation of the Cosmic Microwave Background Radiation Peak Spectral Radiance, Planck Time, and the Hubble Constant from the Neutron and Hydrogen

all be derived and accurately predicted from subatomic data only. The predictions exceed the known experi- mental precision so they could be of experimental significance. These constants are also mathematically and conceptually closely inter-related. This is a new observation uniting cosmology within a harmonic system. These constants are all based on Planck time. Therefore all the observable cosmic phenomena including black holes are directly related to the single unifying force of gravity. It is assumed that the maximum cosmic ray energy will represent another harmonic fraction scaled by gravity as well.
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Chluba, Jens
  

(2005):


	Spectral Distortions of the Cosmic Microwave Background.


Dissertation, LMU München: Fakultät für Physik

Chluba, Jens (2005): Spectral Distortions of the Cosmic Microwave Background. Dissertation, LMU München: Fakultät für Physik

of the initial photons leading to a suppression of the total number of newly created photons as compared to the non-relativistic limit. On the other hand boosting leads to an enhancement of the double Compton emissivity the higher the electron temperature becomes. Furthermore, an expression for the effective double Compton Gaunt factor has been derived and shortly dis- cussed in comparison with the full numerical results (Sect. 4.5.1). We have argued that at least in situations close to thermodynamic equilibrium the evolution of the high frequency photons is not significantly affected by double Compton scattering, but a more detailed study should be undertaken to include cases far from equilibrium. Simple and accurate analytic expressions for the low frequency double Compton scattering emission coefficient of monochromatic initial photons (Sect. 4.4; in the most general situation see Eq. (4.45)) and in the case of Planck, Bose-Einstein and Wien spectra were given (see Sect. 4.5.4). We discussed in detail the double Compton emission for monochromatic initial photons and in the soft photon limit for an incom- ing Planck spectrum, but expect that our main conclusions also hold for Bose-Einstein, Wien and more general photon distributions. For more general incoming photon distributions two analytic approximations for the low frequency double Compton emission coefficient, equation (4.57) as a direct expansion up to fourth order in temperature and (4.58a) as a inverse ap- proximation, were deduced, which in combination should describe the full numerical results to better than 5 % in a very broad range of temperatures and involve only 1-dimensional integrals over the photon distribution and its derivatives (see Fig. 4.21 and Sec. 4.5.6 for discussion). If the photons and the electrons have similar temperatures, which is the case in most physical situations close to equilibrium, especially in the context of the thermalization of CMB spectral distortions, then the inverse formula (4.58a) may be applicable up to k T ∼ 100 keV with an accuracy of better than a few percent. Since only first order corrections are necessary for this inverse formula (4.58a), it it generally more suitable for numerical applications.
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Böhm, Vanessa
  

(2017):


	Cosmic lensing of galaxies and the cosmic microwave background beyond the linear regime.


Dissertation, LMU München: Fakultät für Physik

Böhm, Vanessa (2017): Cosmic lensing of galaxies and the cosmic microwave background beyond the linear regime. Dissertation, LMU München: Fakultät für Physik

In this chapter, we have presented a novel, fully Bayesian, lensing tomography algorithm that reconstructs the three-dimensional matter distribution from measurements of individ- ual galaxy shapes. The main difference to existing lensing reconstruction methods lies in the use of a lognormal prior on the density field instead of a Gaussian one. The lognormal model is an improvement over the Gaussian approximation in two ways: First, it enforces the strict positivity of the density while a Gaussian prior allows unphysical, negative den- sities. Second, it incorporates an a priori knowledge of the presence of odd moments in the matter distribution, which arise as a consequence of non-linear structure formation. These corrections are relevant since the cosmic shear signal probes structures down to scales that lie well in the non-linear regime. We note that the lognormal distribution does not describe the exact distribution of non-linearly evolved overdensities. However, since it is only used as a prior, it will be updated by the information contained in the data. In regions with high signal-to-noise, this prior model only supports the high-fidelity reconstruction. In less well constrained regions it prevents unphysical features in the reconstructed field.
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Studying the Extragalactic Background Light with the second Cosmic Infrared Background ExpeRiment, CIBER 2

Studying the Extragalactic Background Light with the second Cosmic Infrared Background ExpeRiment, CIBER 2

Much effort went into understanding the source of these excess fluctuations. Zem- cov et al [106] describe the process of developing theoretical models that are physi- cally realizable and match the observed the spectra; some model variations include changes to the number density and physical assumptions of populations of low metallicity stars (Pop II and III), changes to the underlying dark matter distribu- tion, and even inclusion of additional hypothetical early emission sources such as direct-collapse black holes. However, none of these matched the observed fluctua- tion amplitude and electromagnetic spectrum intensity that was observed. Addition of late time (z < 2) diffuse stellar emission associated with dark matter halos but outside of the traditional (masked and modeled) galaxy boundaries was the only model alteration that generated theoretical spectrum with notable similarities to the observational spectra. This rogue stellar emission is known as intra-halo light and is not well studied in astrophysics due to its diffuse nature. Based on this reconcili- ation modeling effort, the CIBER-1 data supports a conclusion that there are large, unanticipated and un-modeled foregrounds in the local universe that contribute sig- nificantly to the near-infrared EBL. Additional EBL fluctuation experiments with high sensitivity spanning both the near-infrared and optical wavelength bands are needed to further characterize this unexpected signal while continuing to probe for the emission attributable to early galaxies. CIBER-2 is a follow-on experiment to CIBER-1 that is designed to do just this.
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This - rather famous - image is a visualization of the data collected by NASA s WMAP mission. It shows the cosmic microwave background radiation

This - rather famous - image is a visualization of the data collected by NASA s WMAP mission. It shows the cosmic microwave background radiation

- So where are we now, in 2015? We are in the same position CERN found itself in 1989 – with some significant differences , though: We have more data, with much less structure, and the web has evolved into a very dynamic, highly sophisticated information management systems, available on an almost infinite number of devices. In addition, access to hardware resources and distributed computing has become very easy – thanks to Cloud Computing and Software such as Apache Hadoop. Maybe this ease of access does explain the recent hype around «Big Data» analysis – we now suddenly seem to believe that we can, somehow, leverage all the data to derive information that may be a game-changing for the way we present our information in the web. Specifically, we hope to find
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Observations of the anisotropy of cosmic rays at TeV–PeV

Observations of the anisotropy of cosmic rays at TeV–PeV

The causes of the differences between the IceCube data and the observations in the Northern Hemisphere are not yet understood, but there are several possible explanations. One possibility is that the small-scale structure has a strong en- ergy dependence, and so ARGO-YBJ and HAWC (1 TeV), Milagro (1 TeV), and IceCube (20 TeV) are not observing the same features. Another possibility is a difference in mass composition between the data. Above several TeV the flux of primary cosmic rays is dominated by helium over protons (Ahn et al., 2010). However, since IceCube detects cosmic rays by observing muons, it has a trigger bias against heav- ier nuclei at its energy threshold (Abbasi et al., 2011). This raises the possibility that IceCube is not observing a popula- tion of cosmic rays equivalent to that shown by lower-energy Northern Hemisphere experiments. The effect of mass com- position on the anisotropy has not been studied, so this issue must be resolved with future analysis.
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Constraints of hadronic interaction models from the cosmic muon observations

Constraints of hadronic interaction models from the cosmic muon observations

Abstract. A simple method of the vertical muon energy spectrum simulations has been suggested. These calculations have been carried out in terms of various models of hadronic interactions. The most energetic π ± -mesons and K ± -mesons produced in hadron interactions contribute mainly to this energy spectrum of muons due to the very steep energy spectrum of the primary particles. So, some constraints on the hadronic interaction models may be set from a comparison of calculated results with cosmic data on the vertical muon energy spectrum. This comparison showed that the most energetic secondary particles production is too high in the case of the QGSJET II-04 model and rather low in the case of the QGSJET II-03 model. These conclusion have been supported by the LHC data.
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Latest Cosmic Ray Results from IceTop and IceCube

Latest Cosmic Ray Results from IceTop and IceCube

full-sky view of cosmic ray anisotropies. For this study, five years of data taken with the IceCube-InIce detector (collected between May, 2011 and May, 2016 in its final configuration of 86 strings) and 1 year of HAWC (col- lected between April, 2015 and April, 2016 in its final configuration of 300 tanks) were utilized [21] and only data that are consistent between the two detectors were selected. The relative intensity as a function of equato- rial coordinates is computed by binning the sky into an equal-area grid with a bin size of 0.9 ◦ using the HEALPix library [22]. The expected flux is calculated from the data themselves in order to properly account for rate variations in both time and viewing angle (this is not possible with simulations). The likelihood-based reconstruction devel- oped in [23] is applied, which simultaneously fits cosmic ray anisotropies and detector acceptance. This likelihood method provides an optimal anisotropy reconstruction and the recovery of the dipole anisotropy for ground-based cosmic ray observatories located in the middle latitudes such as HAWC. A smoothing procedure is then applied. (Note the much higher number of events available in 5
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Cosmic ray observations at high zenith angles

Cosmic ray observations at high zenith angles

for a compound telescope consisting of 30 sub-units h = 240 cmo For the given geometry of the high zenith angle telescope for a 30-fold increase of the high zenith angle count-rate the a[r]

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The COsmic ray Soil Moisture Interaction Code (COSMIC) for use in data assimilation

The COsmic ray Soil Moisture Interaction Code (COSMIC) for use in data assimilation

Abstract. Soil moisture status in land surface models (LSMs) can be updated by assimilating cosmic-ray neutron intensity measured in air above the surface. This requires a fast and accurate model to calculate the neutron inten- sity from the profiles of soil moisture modeled by the LSM. The existing Monte Carlo N-Particle eXtended (MCNPX) model is sufficiently accurate but too slow to be practical in the context of data assimilation. Consequently an alter- native and efficient model is needed which can be calibrated accurately to reproduce the calculations made by MCNPX and used to substitute for MCNPX during data assimilation. This paper describes the construction and calibration of such a model, COsmic-ray Soil Moisture Interaction Code (COS- MIC), which is simple, physically based and analytic, and which, because it runs at least 50 000 times faster than MC- NPX, is appropriate in data assimilation applications. The model includes simple descriptions of (a) degradation of the incoming high-energy neutron flux with soil depth, (b) cre- ation of fast neutrons at each depth in the soil, and (c) scat- tering of the resulting fast neutrons before they reach the soil surface, all of which processes may have parameterized de- pendency on the chemistry and moisture content of the soil. The site-to-site variability in the parameters used in COS- MIC is explored for 42 sample sites in the COsmic-ray Soil Moisture Observing System (COSMOS), and the compar- ative performance of COSMIC relative to MCNPX when applied to represent interactions between cosmic-ray neu- trons and moist soil is explored. At an example site in Ari- zona, fast-neutron counts calculated by COSMIC from the average soil moisture profile given by an independent net- work of point measurements in the COSMOS probe foot- print are similar to the fast-neutron intensity measured by
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