9,116 research outputs found

    Combining Supernovae and LSS Information with the CMB

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    Observations of the Cosmic Microwave Background (CMB), large scale structure (LSS) and standard candles such as Type 1a Supernovae (SN) each place different constraints on the values of cosmological parameters. We assume an inflationary Cold Dark Matter model with a cosmological constant, in which the initial density perturbations in the universe are adiabatic. We discuss the parameter degeneracies inherent in interpreting CMB or SN data, and derive their orthogonal nature. We then present our preliminary results of combining CMB and SN likelihood functions. The results of combining the CMB and IRAS 1.2 Jy survey information are given, with marginalised confidence regions in the H_0, Omega_m, b_IRAS and Q_rms-ps directions assuming n=1, Omega_Lambda+Omega_m=1 and Omega_b h^2=0.024. Finally we combine all three likelihood functions and find that the three data sets are consistent and suitably orthogonal, leading to tight constraints on H_0, Omega_m, b_IRAS and Q_rms-ps, given our assumptions.Comment: 7 pages, 4 figures, submitted to ``The CMB and the Planck Mission'', proceedings of the workshop held in Santander, Spain, June 199

    Personal relatedness and attachment in infants of mothers with borderline personality disorder

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    The principal aim of this study was to assess personal relatedness and attachment patterns in 12-month-old infants of mothers with borderline personality disorder (BPD). We also evaluated maternal intrusive insensitivity toward the infants in semistructured play. We videotaped 10 mother-infant dyads with borderline mothers and 22 dyads where the mothers were free from psychopathology, in three different settings: a modification of Winnicott's Set Situation in which infants faced an initially unresponsive ("still-face") stranger, who subsequently tried to engage the infant in a game of give and take; the Strange Situation of Ainsworth and Wittig; and a situation in which mothers were requested to teach their infants to play with miniature figures and a toy train. In relation to a set of a priori predictions, the results revealed significant group differences as follows: (a) compared with control infants, toward the stranger the infants of mothers with BPD showed lower levels of "availability for positive engagement," lower ratings of "behavior organization and mood state," and a lower proportion of interpersonally directed looks that were positive; (b) in the Strange Situation, a higher proportion (8 out of 10) of infants of borderline mothers were categorized as Disorganized; and (c) in play, mothers with BPD were rated as more "intrusively insensitive" toward their infants. The results are discussed in relation to hypotheses concerning the interpersonal relations of women with BPD, and possible implications for their infants' development

    Systematic Errors in Cosmic Microwave Background Interferometry

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    Cosmic microwave background (CMB) polarization observations will require superb control of systematic errors in order to achieve their full scientific potential, particularly in the case of attempts to detect the B modes that may provide a window on inflation. Interferometry may be a promising way to achieve these goals. This paper presents a formalism for characterizing the effects of a variety of systematic errors on interferometric CMB polarization observations, with particular emphasis on estimates of the B-mode power spectrum. The most severe errors are those that couple the temperature anisotropy signal to polarization; such errors include cross-talk within detectors, misalignment of polarizers, and cross-polarization. In a B mode experiment, the next most serious category of errors are those that mix E and B modes, such as gain fluctuations, pointing errors, and beam shape errors. The paper also indicates which sources of error may cause circular polarization (e.g., from foregrounds) to contaminate the cosmologically interesting linear polarization channels, and conversely whether monitoring of the circular polarization channels may yield useful information about the errors themselves. For all the sources of error considered, estimates of the level of control that will be required for both E and B mode experiments are provided. Both experiments that interfere linear polarizations and those that interfere circular polarizations are considered. The fact that circular experiments simultaneously measure both linear polarization Stokes parameters in each baseline mitigates some sources of error.Comment: 19 pages, 9 figures, submitted to Phys. Rev.

    Bayesian `Hyper-Parameters' Approach to Joint Estimation: The Hubble Constant from CMB Measurements

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    Recently several studies have jointly analysed data from different cosmological probes with the motivation of estimating cosmological parameters. Here we generalise this procedure to take into account the relative weights of various probes. This is done by including in the joint \chi^2 function a set of `Hyper-Parameters', which are dealt with using Bayesian considerations. The resulting algorithm (in the case of uniform priors on the log of the Hyper-Parameters) is very simple: instead of minimising \sum \chi_j^2 (where \chi_j^2 is per data set j) we propose to minimise \sum N_j \ln (\chi_j^2) (where N_j is the number of data points per data set j). We illustrate the method by estimating the Hubble constant H_0 from different sets of recent CMB experiments (including Saskatoon, Python V, MSAM1, TOCO and Boomerang).Comment: submitted to MNRAS, 6 pages, Latex, with 3 figures embedde

    The effect of point sources on satellite observations of the cosmic microwave background

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    We study the effect of extragalactic point sources on satellite observations of the cosmic microwave background (CMB). In order to separate the contributions due to different foreground components, a maximum-entropy method is applied to simulated observations by the Planck Surveyor satellite. In addition to point sources, the simulations include emission from the CMB and the kinetic and thermal Sunyaev-Zel'dovich (SZ) effects from galaxy clusters, as well as Galactic dust, free-free and synchrotron emission. We find that the main input components are faithfully recovered and, in particular, that the quality of the CMB reconstruction is only slightly reduced by the presence of point sources. In addition, we find that it is possible to recover accurate point source catalogues at each of the Planck Surveyor observing frequencies.Comment: 12 pages, 9 figures, submitted to MNRA

    Cosmological Parameters from Velocities, CMB and Supernovae

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    We compare and combine likelihood functions of the cosmological parameters Omega_m, h and sigma_8, from peculiar velocities, CMB and type Ia supernovae. These three data sets directly probe the mass in the Universe, without the need to relate the galaxy distribution to the underlying mass via a "biasing" relation. We include the recent results from the CMB experiments BOOMERANG and MAXIMA-1. Our analysis assumes a flat Lambda CDM cosmology with a scale-invariant adiabatic initial power spectrum and baryonic fraction as inferred from big-bang nucleosynthesis. We find that all three data sets agree well, overlapping significantly at the 2 sigma level. This therefore justifies a joint analysis, in which we find a joint best fit point and 95 per cent confidence limits of Omega_m=0.28 (0.17,0.39), h=0.74 (0.64,0.86), and sigma_8=1.17 (0.98,1.37). In terms of the natural parameter combinations for these data sigma_8 Omega_m^0.6 = 0.54 (0.40,0.73), Omega_m h = 0.21 (0.16,0.27). Also for the best fit point, Q_rms-ps = 19.7 muK and the age of the universe is 13.2 Gyr.Comment: 8 pages, 5 figures. Submitted to MNRA

    Limits on Arcminute Scale Cosmic Microwave Background Anisotropy with the BIMA Array

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    We have used the Berkeley-Illinois-Maryland-Association (BIMA) millimeter array outfitted with sensitive cm-wave receivers to search for Cosmic Microwave Background (CMB) anisotropies on arcminute scales. The interferometer was placed in a compact configuration which produces high brightness sensitivity, while providing discrimination against point sources. Operating at a frequency of 28.5 GHz, the FWHM primary beam of the instrument is 6.6 arcminutes. We have made sensitive images of seven fields, five of which where chosen specifically to have low IR dust contrast and be free of bright radio sources. Additional observations with the Owens Valley Radio Observatory (OVRO) millimeter array were used to assist in the location and removal of radio point sources. Applying a Bayesian analysis to the raw visibility data, we place limits on CMB anisotropy flat-band power Q_flat = 5.6 (+3.0 -5.6) uK and Q_flat < 14.1 uK at 68% and 95% confidence. The sensitivity of this experiment to flat band power peaks at a multipole of l = 5470, which corresponds to an angular scale of approximately 2 arcminutes. The most likely value of Q_flat is similar to the level of the expected secondary anisotropies.Comment: 15 pages, 5 figures, LaTex, aas2pp4.sty, ApJ submitte
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