Motivated by an amazing range of reported distances to the nearby Local Group spiral galaxy M33, we have obtained deep near-infrared photometry for 26 long-period Cepheids in this galaxy with the ESO VLT. From the data we constructed period-luminosit
y relations in the J and K bands which together with previous optical VI photometry for the Cepheids by Macri et al. were used to determine the true distance modulus of M33, and the mean reddening affecting the Cepheid sample with the multiwavelength fit method developed in the Araucaria Project. We find a true distance modulus of 24.62 for M33, with a total uncertainty of +- 0.07 mag which is dominated by the uncertainty on the photometric zero points in our photometry. The reddening is determined as E(B-V)=0.19 +- 0.02, in agreement with the value used by the HST Key Project of Freedman et al. but in some discrepancy with other recent determinations based on blue supergiant spectroscopy and an O-type eclipsing binary which yielded lower reddening values. Our derived M33 distance modulus is extremely insensitive to the adopted reddening law. We show that the possible effects of metallicity and crowding on our present distance determination are both at the 1-2% level and therefore minor contributors to the total uncertainty of our distance result for M33.
We analyse WMAP 7-year temperature data, jointly modeling the cosmic microwave background (CMB) and Galactic foreground emission. We use the Commander code based on Gibbs sampling. Thus, from the WMAP7 data, we derive simultaneously the CMB and Galac
tic components on scales larger than 1deg with sensitivity improved relative to previous work. We conduct a detailed study of the low-frequency foreground with particular focus on the microwave haze emission around the Galactic center. We demonstrate improved performance in quantifying the diffuse galactic emission when Haslam 408MHz data are included together with WMAP7, and the spinning and thermal dust emission is modeled jointly. We also address the question of whether the hypothetical galactic haze can be explained by a spatial variation of the synchrotron spectral index. The excess of emission around the Galactic center appears stable with respect to variations of the foreground model that we study. Our results demonstrate that the new galactic foreground component - the microwave haze - is indeed present.
We present measurements of the V and I band magnitudes of red clump stars in 15 nearby galaxies obtained from recently published homogenous HST photometry. Supplementing these results with similar data for another 8 galaxies available in the literatu
re the populational effects on the V and I band magnitudes of red clump stars were investigated. Comparing red clump magnitudes with the I-band magnitude of the TRGB in a total sample of 23 galaxies possessing very different environments we demonstrate that population effects strongly affect both the V and I band magnitude of red clump stars in a complex way. Our empirical results basically confirm the theoretical results of Girardi and Salaris, and show that optical (VI) photometry of red clump stars is not an accurate method for the determination of distances to nearby galaxies at the present moment, as long as the population effects are not better calibrated, both empirically and theoretically. Near infrared photometry is a much better way to measure galaxy distances with red clump stars given its smaller sensitivity to population effects.
We present skeleton studies of non-Gaussianity in the CMB temperature anisotropy observed in the WMAP5 data. The local skeleton is traced on the 2D sphere by cubic spline interpolation which leads to more accurate estimation of the intersection posit
ions between the skeleton and the secondary pixels than conventional linear interpolation. We demonstrate that the skeleton-based estimator of non-Gaussianity of the local type (f_NL) - the departure of the length distribution from the corresponding Gaussian expectation - yields an unbiased and sufficiently converged f_NL-likelihood. We analyse the skeleton statistics in the WMAP5 combined V- and W-band data outside the Galactic base-mask determined from the KQ75 sky-coverage. The results are consistent with Gaussian simulations of the the best-fitting cosmological model, but deviate from the previous results determined using the WMAP1 data. We show that it is unlikely that the improved skeleton tracing method, the omission of Q-band data, the modification of the foreground-template fitting method or the absence of 6 extended regions in the new mask contribute to such a deviation. However, the application of the Kp0 base-mask in data processing does improve the consistency with the WMAP1 results. The f_NL-likelihoods of the data are estimated at 9 different smoothing levels. It is unexpected that the best-fit values show positive correlation with the smoothing scales. Further investigation argues against a point-source or goodness-of-fit explanation but finds that about 30% of either Gaussian or f_NL samples having better goodness-of-fit than the WMAP5 show a similar correlation. We present the estimate f_NL=47.3+/-34.9 (1sigma error) determined from the first four smoothing angles and f_NL=76.8+/-43.1 for the combination of all nine. The former result may be overestimated at the 0.21sigma-level because of point sources.
We present distance determinations for two Local Group dwarf spheroidal galaxies, Carina and Fornax, based on the near-infrared magnitudes of the tip of the red giant branch (TRGB). For Carina we derive true distance moduli of 20.09 and 20.13 mag in
the J and K bands, respectively, while for Fornax the same distance modulus of 20.84 mag was derived in both filters. The statistical errors of these determinations are of order 0.03-0.04 mag, whereas the systematic uncertainties on the distances are 0.12 mag in the J band and 0.14 mag in the K band. The distances obtained from the near-infrared TRGB method in this paper agree very well with those obtained for these two galaxies from optical calibrations of the TRGB method, their horizontal branches, RR Lyrae variables, and the near-infrared magnitudes of their red clumps.
We repeat and extend the analysis of Eriksen et al 2004 and Hansen et al 2004 testing the isotropy of the Cosmic Microwave Background (CMB) fluctuations. We find that the hemispherical power asymmetry previously reported for the largest scales l=2-40
extend to much smaller scales. In fact, for the full multipole range l=2-600, significantly more power is found in the hemisphere centered at (theta=107 deg., phi=226 deg.) in galactic co-latitude and longitude than in the opposite hemisphere consistent with the previously detected direction of asymmetry for l=2-40. We adopt a model selection test where the direction and amplitude of asymmetry as well as the multipole range are free parameters. A model with an asymmetric distribution of power for l=2-600 is found to be preferred over the isotropic model at the 0.4% significance level taking into account the additional parameters required to describe it. A similar direction of asymmetry is found independently in all six subranges of 100 multipoles between l=2-600 and none of our 9800 isotropic simulated maps show a similarly consistent direction of asymmetry over such a large multipole range. No known systematic effects or foregrounds are found to be able to explain the asymmetry.
