Sunday. Take care of Zahra today, then pick up apartment keys. I hope the rug that I bought yesterday will fit.
1111.5009
An investigation of SDSS imaging data and multi-band scaling relations of spiral galaxies (with dynamical information)
Hall, Courteau, Dutton, McDonald, Zhu
3041 spirals from SDSS DR7 with rotational velocities derived from HI line widths. Independent photometry comparison; use velocities (V) as independent metric to determine ideal galaxy sizes (R) and luminosities (L). Isophotal fits improves upon Petrosian radii, gauged via VL and RV relations, whose respective scatters are reduced by 8% and 30% compared to SDSS. [does the independent photometry go deeper?] Tightest VRL relations obtained with i-band radius R235i, measured at 23.5 mag/arcsec^2, and luminosity L235i, measured within R235i. Compute scaling relations in terms of the baryonic mass (stars+gas) Mbar, ranging from 1e8.7 Msol to 1e11.6 Msol.
* what's the use of this? They must use their photometry for something in another paper.
1111.5010
Cross-correlating SZ and WL maps
Munchi, Joudaki, Coles, Smidt
* cumulants kappa_n of a probability distribution are a set of quantities that provide an lternative to the moments of the distribution. The moments determine the cumulants in the sense that any two probability distributions whose moments are identical will have identical cumulants as well, and similarly the cumulants determine the moments.
* Polyspectrum: Fourier transform of a cumulant. Higher-order spectra. First order poly-spectrum is the usual power spectrum, second order polyspectrum is the bispectrum. If one considers a pair of time series, the first order polyspectrum is the cross-spectrum. Generalize to k-dimensional time series.
Present statistical tools to cross-correlate frequency cleaned tSZ maps and tomographic WL convergence maps. Introduce a hierarchy of mixed higher-order statistics (cumulants and cumulant correlators) to analyze non-Gaussianity in real space, as well as corresponding polyspectra in the harmonic domain. Derive analytical expressions for the joint two-point probability distribution function for smoothed tSZ (y_s) and convergence (kappa_s) maps. Tomographic information allows study of the evolution of higher order mixed tSZ-WL statistics with redshift. Express the joint PDFs p_kappa(kappa_s, y_s) in terms of individual one-point PDFs p_kappa(kappa_s), p_y(y_s) and the relevant bias functions b_kappa(kappa_s), b_y(y_s). Analytical results for two different regimes are presented that correspond to the small and large angular smoothing scales. Results are also obtained for corresponding hot spots in the tSZ and convergence maps. In additions to results based on hierarchical techniques and perturbative methods, present results of calculations based on the lognormal approximation. The analytical expressions derived here are generic and applicable to cross-correlation studies of arbitrary tracers of large scale structure including e.g. that of tSZ and soft X-ray background.
1111.5012
On the rarity of x-ray binaries with Wolf-Rayet donors
Linden, Valesecchi, Kalogera
* Wolf-Rayet: evolved, massive stars (initially >20 Msun) which are losing mass rapidly by means of a very strong stellar wind, with speeds up to 2000 km/s. WR stars lose 1e-5 Msun/yr (the Sun loses 1e-14 Msun/yr). WR stars are very hot, with surface temperatures in the range of 25000K to 50000K. Broad emission bands on an otherwise continuous spectrum (normal stars exhibit absorption lines). Strong Helium lines; C, O, and N also identified. WR stars are a normal stage in the evolution of very massive stars. Can be identified in nearby galaxies (from the strong emission lines). 300 identified in MW, and increasing. 100 in LMC, 12 in SMC. Characteristic emission lines are formed in the extended and dense high-velocity wind region enveloping the very hot stellar photosphere, which produces a flood of UV radiation that causes fluorescence in the line-forming wind region. This ejection process uncovers in succession, first the N-rich products of CNO cycle burning of H, and later the C-rich layer due to He burning. Most of these stars are believed to progress to become SNe Ib or Ic (core collapse, no H outer layer, lack Si absorption line. SN Ic are hypothesized to have lost more of their initial envelope, including most of their helium. Usually referred to as "stripped core-collapse supernovae". Otherwise similar to Type II SN).
Reconciling the large population of Be-HMXBs with the observation of only one WR-HMXB can help constrain the dynamics of common-envelope phase. Given the significant number of galactic HMXBs containing hydrogen-rich donors with are expected to be their progenitors, and the preponderance of loosely bound Be donors orbiting neutron stars, which would be expected to naturally evolve into WR-HMXBs through dynamical mass transfer onto the neutron star and common-envelope phase. Find binary mergers of HMZBs during CE events must be common in order to resolve the tension between these observed populations. We ifnd that, quantitatively, this scenario remains consistent with the typically adopted energy parameterization of CE evolution, yielding expected populations which are not at odds with current observations. Future observations of O/B-NS binaries are likely to place significant constraints on the efficiency of CE ejection.
1111.5027
A strong dichotomy in S0 disk profiles between the Virgo cluster and the field
Erwin, Gutierrez, Beckman
S0 galaxies: lenticular galaxies; bulge with disk of no discernible feature and no SF but with dust; tends to be more luminous than spirals]
S0 galaxies are classified as I, II and III (single-exponential, truncated, and anti-truncated, equally distributed in fields), their abundance are different between field and in clusters (Virgo cluster in this case). Virgo V0s appear to be entirely lacking in disk truncations, and instead populates single-exponential. S0 formation may be driven by different processes in cluster and field environments; outer-disk effects can be useful tests of S0 formation models.
[11] wed
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