Thursday. Found out about Phillipe's health yesterday. Saw another green shooting star last night, after playing Uno at Fiddlers with Zahra and Hananeh. Today will be a busy afternoon with meetings, get work done in the morning (but it's already 9am).
1112.3037
The cluster of class I/f/II YSOs discovered near the Cepheid SU Cas
Majess, Turner, Gieren
Cluster of YSOs in the field of the classical Cepheid SU Cas: IR images reveal that cluster deviates from spherical symmetry and exhibits an apparent diameter of 3x6'. SEDs constructed from IR photometry indicate that I/f/II class objects lie within r<3'. Approximately 50% of the class I sources within r<3' were classified solely using WISE photometry due to the absense of detections by 2MASS.
* Cepheids, classical (Pop I Cepheids): very regular pulsation period of the order of days to months, M ~ 4-20 Msun, up to 100,000x more luminous. Yellow supergiants of F6-K2 and their radii change by millions of kilometers in pulsations.
* Cepheids, Type II (Pop II Cepheids): Pulsate with period of 1-50 days. Typically metal-poor, old (~10 Gyr), low mass objects (0.5 Msun).
* Dynamics of the pulsation: Eddington valve (kappa-mechanism), where kappa = gas opacity. Doubly ionized helium is more opaque than singly ionized helium. Heating ionizes, star is opaque, heated by star's own radiation, and the increase in T causes the star to expand. As it expands, it cools, becomes more transparent, allows radiation to escape, expansion stops.
1112.3038
A global physical models for cepheids
Pejcha, Kochanek
Perform global fit to radial velocities and magnitude measurements in 29 photometric bands of 287 Galactic, LMC, and SMC Cepheids, with P>10 days; assume Cepheid light curves and radial velocities are fully characterized by distance, reddening, and time-dependent radius and temperature variations. Only 4-6 parameters per Cepheid, rms light and velocity curve of 0.05 mag and 3.5 km/s. Model derives the mean Cepheid spectral energy distribution and its derivative wrt T, which deviate from a BB in agreement with metal-line and molecular opacity effects. Determine a mean reddening law towards the Cepheids in our sample, which is not consistent with standard assumptions in the optical or NIR. Based on stellar atmosphere models predict the biases in distance, reddening, and T determinations due to the metallicity and quantify the signature expected in the fit residuals. Observed residuals as a function of wavelength show clear differences between the individual galaxies, which are compatible with these predictions. Find metal-poor Cepheids appear hotter. Provide a framework for optimally selecting filters that yield the smallest overall errors in Cepheid parameter determinations. Make templates publicly available.
* see the accompanying video!
1112.3071
Observational evidence of quasar feedback quenching star formation at high redshift
Cano-Diaz, Maiolino, Marconi, Netzer, Shemmer, Cresci
Quasar feedback regulate SF: first observational evidence in the luminous quasar at z=2.4. The OIII emission line reveals a massive outflow on scales of several kpc; the detection of narrow Halpha emission reveals star formation in the quasar host galaxy with 100 Msun/yr. The SF is not distributed univormly; it is strongly suppressed in the region with the highest outflow velocity and highest velocity dispersion. Result indicates that in thie region SF is strongly quenched by the quasar outflow, which is cleaning the galaxy disk of its molecular gas.
1112.3100
3D spherical analysis of BAO
Rassat, Refregier
Spherical Fourier-Bessel (SFB) decomposition is a natural basis for the analysis of fields in large surveys over radial and angular coverage. Present a new way to analyse BASs by studying the BAO wiggles from the SFB power spectrum. Ignoring evolution in the deep survey limit, the SFB power spectrum is purely radial and reduces to the Cartesian Fourier power spectrum. In the thin shell limit, all thei nformation is contained in the tangential modles described by the 3d spherical harmonic power spectrum. Find BAOs radialize more erapidly than the full SFB power spectrum [?]. Results suggest that the first peak of the BAOs in SFB space can be measured as radial out to l~10 for all-sky surveys with the same depth as SDSS or 2dF, and out to l~70 for an all-sky stage IV survey.
1112.3108
On the measurement of cosmological parameters
Croft, Dailey
Historical measurements (1990-2010) of cosmological parameters. Lesson: blind survey necessary.
1112.3116
Surface mass density of the Einasto family of DM haloes: are they Sersic-like?
Dhar, Williams
Einasto-model 3 parameter models are better able to produce fits to the 3d spatial density profiles than two-parameter models like NFW and Moore+ profiles. Models of projected 2d Einasto profile that fits from 0 to 3x~5x r200 for a wide range of shape parameter alpha. This model can thus be used in WL and SL fits of galaxies and clusters whose total spatial 3d density distributions are believed to be Einasto-like. Further, given the dependence of the model on the 3d parameters, one can reliably estimate structural parameters of the spatial 3d density from the 2d observations. Consider a Sersic-like parameterization of the above family of projected Einasto profiles, observe that fits with a Sersic profile are sensitive to whether one fits the projected density in linear scale of logarithmic scale and yield widely varying results. Structural parameters of Einasto-like systems, inferred from fits with a sersic profiles, should be used with caution.
1112.3120
Surface Brightness and intrinsic luminosity of ellpticals
Dhar, Williams
For a sample of 23 ellipticals with MV > -24, models indicate that i) the central component is more concentrated than the outer component, and ii) the central component of 'core' galaxies is much more luminous, extended and concentrated than that of 'cuspy' galaxies, with their near exponential central profiles indicating disk-like systems whose existence must be verified spectroscopically. Show that the existence, amount, radial extent and sign of mass deficits disagree substantially in the literature, both for a given galaxy and on an average over a sample. SMBH binaries are unlikely to be the sole mechanism for producing the large 'cores'. The outer component of the SB profiles of massive galaxies has 5<n<8 could imply 9) a common feature of collisionless systems, and ii) that galaxies with such n for their outer component are DM dominated.
1112.3122
On the initial shear field of the cosmic web
Rossi
* I don't know what he's talking about.
1112.3136
Sunlight refraction in the mesosphere of Venus during the transit on June 8th, 2004
Tanga et al
The spatially resolved data provide measurement of the aureole flux as a function of the planetocentric latitude along the limb. A new differential refraction model of solar disk through the upper atmosphere allows us to relate the variable photometry to the latitudinal dependency of scale-height with temperature in the South polar region, as well as the latitudinal variation of the cloud-top layer altitude.
1112.3143
Seeing in the dark -- II. Cosmic shear in the SDSS
Huff, Eifler, Hirata, Manelbaum, Schlegel, Seljak
Measure cosmic shear using coadded SDSS imaging in 168 sq. deg. of equatorial region, with r<23.5 and i<22.5, a source number density of 2.2 galaxies per square arcminute and median redshift of 0.52. Paper I describe coadd generation that intended to minimise systematic errors due to coherent PSF anisotropies. Present measurements of cosmic shear out to angular separation of 2 degrees, along with systematics test that demonstrate that the results are dominated by statistical rather than systematic errors. Assuming a WMAP7 cosmological model and allowing only the amplitude of matter fluctuations to vary, find a best-fit value of sigma8=0.636 pm 0.1x with systematic errors. Assuming a flat LCDM model, combined constraints with WMAP7 are sigma8=0.78 and omega_m h^2 = 0.13. The 2 sigma error ranges are ~15 % smaller than WMAP7 alone. Aside from intrinsic value of such cosmo constraints from the growth of structure, identify lessons for upcoming surveys that may face similar issues when combining multi-epoch data to measure cosmic shear.
1112.3264
A gas cloud on its way towards the SMBH in the galactic center
Gillessen, Genzel, Fritz, Quataert, ... et al
Report the presence of a dense gas cloud approximately 3 M_earth falling into the accretion zone of Sgr A*. Cloud's orbit highly eccentric, innermost raidus of approach 3100x Schwartzchild radius that will be reached in 2013. In the past 3 years, the cloud has begun to disrupt; observation of the next few years will probe the properties of the accretion flow and the feeding processes of the SMBH. The keV X-ray emission of Sgr A* may brighten significantly when the cloud reaches pericenter. There may also be a giant radiation flare several years from now if the cloud breaks up and its fragments feed gas into the central accretion zone.
1112.3300
Evolution of the stellar mass-metallicity relation since z=0.75
Moustakas, Zaritsky, Brown, Cool, Dey, Eisenstein, Gonzalez, Jannuzi, Jones, Kochanek, Murray, Wild
Find: at fixed stellar mass at z~0.7, galaxies have just 30-60% of the metal content of galaxies at the present epoch. No statistically significant evidence that the M-Z relation evolves in a mass-dependent way for M=1e9.9-1e11 Msun SF galaxies. This for thie range of redshifts and stellar masses, the M-Z relation simply shifts toward lower metallicity with increasing redshift without changing its shape.
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