Day 326

Tuesday.

1211.0543
Stellar mass versus velocity dispersion as tracer of the lensing signal around bulge-dominated galaxies
van Uitert, Hoekstra, et al

WL gg lensing to determine whether the stellar mass or the velocity dispersion is more closely related to the amplitude of the lensing signal around galaxies, and hence to the projected distribution of DM.  Lensing signal on scales smaller than the virial radius corresponds most closely to the lensing velocity dispersion in the case of a singular isothermal profile, but is on larger scales also sensitive to the clustering of the haloes.  Select >4k lens at z<0.2 with concentrated (or bulge-dominated) surface brightness profiles from the ~300 square degree overlap between the RCS2 and the SDSS DR7.  Consider both the spec. velocity dispersion and a model velocity dispersion (a combination of the stellar mass, the size and the Sersic index of a galaxy).  Comparing the model and dispersion, find that they correlate well for galaxies with concentrated brightness profiles.  Find that the stellar mass and the spectroscopic velocity dispersion trace the amplitude of the lensing signal on small scales equally well.  The model velocity dispersion, does significantly worse.  Possibly because the halo properties that determine the small-scale lensing signal (total mass) also depend on the structural parameters of galaxies, such as the effective radius and Sersic index, but lack data for a definitive conclusion.

1211.0547
Radio transients from the accretion induced collapse of white dwarfs
Piro, Kulkarni

Expect accretion onto WD can undergo accretion induced collapse (AIC) to form a rapidly rotating neutron star; but detection has evaded discovery, likely because the optical, SNe-like emission is expected to be dim and short-lived.  Novel signature of AIC: a transient radio source lasting for a few months.  Spindown of the newly born magnetar generates a pulsar wind nebula (PWN) within the 0.001-0.1 Msun of eject surrounding it.  Synchrotron emission from the PWN may be detectable in the radio, even if the magnetar has a rather modest magnetic field of 2e14 G and an initial spin period of ~10ms.  An all-sky survey with a detection limit of 1mJy at 1.4 Ghz would see ~4(f/1e-2) above threshold at any given time, where f is the ratio of the AIC rate to SNIa rate.  Similar scenario may result from binary NSs if some mergers produce massive neutron stars rather than BHs.

1211.0548
Supermassive seeds for supermassive black holes
Johnson, Whalen, Li, Holz

Simulations (limited role of mergers in growing seed BHs and sub-Eddington accretion rates of BHs expected at the earliest times) and observations (large radiative efficiencies of the most massive BHs) suggest that the initial BH seeds may have been as massive as >1e5 Msun.  Consistent with the prediction of direct collapse scenario of SMBH seed formation; collapses directly into a 1e4-6 Msun seed BH.  Corroborates the results of recent cosmo sims which suggest that these massive BHs were the seeds of a large fraction of the SMBHs residing in the centers of galaxies today.

1211.0668
Prospects for measuring the relative velocities of galaxy clusters in photometric surveys using the kinetic Sunyaev-Zel'dovich effect
Keisler, Schmidt

Prospects for measuring kSZ from clusters in DES.  In conjunction with SPT, yield a detection of the pairwise kSZ signal at the 8-13 sigma level, wich sensitivity peaking for clusters separated by ~100 Mpc distances.  Improvements with next-generation SPT or spectro-survey of DES.  High-precision measurements of pairwise kSZ will yield detailed information on the gas content of the galaxy clusters.  Alternatively, if the gas can be sufficiently characterized by other means (tSZ, X-ray or WL), then the relative velocities of the galaxy clusters can be isolated, thereby providing a precision measurement of gravity on 100 Mpc scales.  Modified gravity!

1211.0670
Filamentary star formation: observing the evolution toward flattened envelopes
Lee, Looney, Johnstone, Tobin

Filamentary structures in molecular clouds (few pc) to small-scale circumstellar envelopes (1000AU to 0.1 pc) are ubiquitous.  Observationally derived scenario: filamentary SF that describes the evolution of filaments as part of the process for formation of cores and circumstellar envelopes.  If correct, 0.1pc filaments with higher densities embedded in starless cores should exist.  Perform synthetic observations of L1157 with CARMA and ALMA; show that CARMA D-array at 3mm wavelengths is not able to detect such structure.  But CARMA D+E array at 3mm and CARMA E array at 1mm may detect them, because of a more appropriate resolution and sensitivity.  ALMA should also be able to detect them.  

1211.0679
X-ray spectroscopy of clusters of galaxies
Ota

X-ray spectrscopy of galaxy clusters, a review.

1211.0684
Giant stellar arcs in the large Magellanic cloud: a possible link with past activity of the Milky Way nucleus
Efremov

Origin of arcs: due to the bow shock from the jet, intermittently fired by MW nucleus and during the last episode, the jet was pointed to LMC.  Enough energy to trigger SF in LMC, jet opening angle about 2 deg, form cavity in LMC4; squeezed two dense clouds.  spherical segments of the stellar shells might arise.  Give data to confirm the hypothesis (radial velocities of stars inside and outside of the larger one of the LMC arcs).  

1211.0758
On the hot gas content of he milky way halo
Fang, Bullock, Boylan-Kolchin

MW appears to be missing baryons, as the observed in stars and gas are well below the cosmic mean.  One possibility: 1e6 K hot halo contains the baryons.  X-ray shows that gas does exist in our Glaaxy beyond the local hot bubble, but may be distributed in a hot disk configuration.  Any Galactic corona must be insignificant.  Re-examine observational data, particularly in the X-ray and radio bands, in order to determine whether it is possible for a substantial fraction of the Galaxy's baryons to exist in 1e6K gas.  Find baryonically closed halo is clearly ruled out, if assuming the hot corona is distributed with a cuspy NFW profile.  If hot corona of galaxy is an extended, low-density distribution with a large central core, then it may contain up to 1e11 Msun of material, possibly accounting for all of the missing Galactic baryons.  Discuss avenues for discriminating between a massive, extended hot halo and a local hot disk.

1211.0790
A low-scatter survey-based mass proxy for clusters of galaxies
Andreon

Computes the amplitude of the scatter for a newly introduced cluster mass proxy: product of the cluster total luminosity times the M/L ratio, usually referred as stellar mass.  Analysis of 12 galaxy clusters with excellent total masses show a tight correlation between the stellar mass, or stellar fraction, and total mass within r500 with negligible intrinsic scatter: the 90% upper limit is 0.06 dex, the posterior mean is 0.027 dex.  This scatter is similar to the one of best-determined mass proxies, such as Yx, i.e., the product of X-ray temperature and gas mass.  The size of the cluster sample used to determine the intrinsic scatter is small, as in previous works proposing low-scatter proxies because very accurate masses are needed to infer very small values of intrinsic scatter [that's not good, is it?].  3/4 of the studied clusters have lgM/Msol<~14, which is advantageous from a cosmological perspective because these clusters are far more abundant than more massive clusters.  At the difference of other mass proxies such as Yx, stellar mass can be determined with survey data up to at least z=0.9 using upcoming optical NIR surveys, such as DES and Euclid, or even with currently available surveys, covering however small solid angles.  On the other end, the uncertainty about the predicted mass of a single cluster is large, 0.21 to 0.32 dex, depending on cluster richness.  This is largely because the proxy itself has ~0.10 dex errors for clusters of this mass.

1211.0903
Dark matter chaos in the solar system
Lages, Shepelyansky

Study the capture of galactic DM particles in the SS produced by rotation of Jupiter.  Capture cross section is much larger than the area of Jupiter orbit being inversely diverging at small particle energy.  Show: dynamics of captured particles is chaotic, and is well described by a simple symplectic dark map.  This dark map description allows to simulate the scattering and dynamics of 1e14 DM particles during the lifetime of the SS and to determine DM density profile as a function of distance from the Sun.  The mass of captured DM in the radius of NEptune orbit is estimated to be 2e15g.  The radial density of captured DM is found to be approximately constant behind Jupiter orbit being similar to the density profile found in galaxies.

1211.0966
Flexion measurement in simulations of Hubble space telescope data
Rowe, Bacon, Massey, Heymans, Haeussler, Taylor, Rhodes, Mellier

Simulation analysis of flexion and shear measurement using shapelet decomposition, and identify apparent qualitative differences between flexion and shear measurement noise in deep survey data.  Taking models of galaxies from HUDF as a basis set and applying a correction for the HUDF PSF, generate lensed simulations of deep, optical imaging data from ACS with realistic galaxy morphologies.  Find that flexion and shear estimates differ in their measurement pipeline: whereas intrinsic galaxy shape is the largest contribution to noise in shear estimates, noise in flexion estimates is dominated by pixel noise due to finite photon counts and detector read noise.  The pixel noise also increases more rapidly as S/N decreases, than found for shear estimates.  Provide simple power law fitting functions for this behaviour, for both flexion and shear, allowing the effect to be properly accounted for in future forecasts for flexion measurement.  Using the simulations, also quantify the systematic biases of shapelet flexion and shear measurement pipeline for deep Hubble datasets (GEMS, STAGES, COSMOS).  Flexion measurement biases found to be significant, but consistent with previous studies.

1211.1005
Superdense galaxies and the mass-size relation at low redshift
Poggianti, Calvi, ... et al

Search for massive and compact galaxies (SDGs) at 0.03<z<0.11 in the Padova-Millennium Galaxy and Group Catalogue, a spectroscopically complete sample representative of the local Universe general field population.  Find that compact galaxies with radii and mass densities comparable to high-z massive and passive galaxies represent 4.4% of all galaxies with M* > 3e10 Msun, yielding a number dnesity of 4.3e-4 (Mpc/h)^3.  Most of them are S0's (70%) or Es (23%), are red and have intermediate-to-old stellar populations, with a median luminosity-weighted age of 5.4 Gyr and a median mass-weighted age of 9.2 Gyr.  Their velocity dispersions and dynamical masses are consistent with the small radii and high stellar mass estimates.  The fraction of SDGs is 3x smaller in the field than in clusters, and cluster SDGs are on average 4 Gyr older than field SDGs.  Confirm the existence of a universal trend of smaller radii for older luminosity-weighted ages at fixed galaxy mass.  On top of the well known dependence of stellar age on galaxy mass, the luminosity-weighted age of galaxies depends on galaxy compactness at fixed mass, and, for a fixed mass and radius, on environment.  This effect needs to be taken into account in order not to overestimate the evolution of galaxy sizes from high- to low-z.  Results and hierarchical simulations suggest that a significant fraction of the massive compact galaxies at high-z have evolved into compact galaxies in galaxy clusters today.  When stellar age and environmental effects are taken into account, the average amount of size evolution of individual galaxies between high-and low-z is mild, a factor of ~1.6.

1211.1010
A rest-fram optical view on z~4 galaxies I: color and age distributions from deep IRAC photometry of the IUDF10 and GOODS surveys

Results consistent with a gradual build-up of stars and dust in galaxies at z>4, with only a small fraction of stars being formed in short, intense bursts of star formation.

12110.1011
The Atlas3D project - XIV. the extent and kinematics of molecular gas in early-type galaxies
Davis, Alatalo, .. Blitz, ... et al

Find: in most galaxies, the molecular gas is relaxed and dynamically cold.  Molecular gas is a better direct tracer of the circular velocity than the ionized gas, justifying its use as a kinematic tracer for Tully-Fisher and similar analysis.

1211.1015
Calibration errors unleashed: effects on cosmological parameters and requirements for large-scale structure surveys
Huterer, Cunha, Fang

Imperfect photometric calibration of galaxy surveys due to astrophysical or instrumental effects leads to biases in measuring galaxy clustering and the resulting cosmo param measurements.  The spatially varying calibration also generically leads to violations of statistical isotropy of the galaxy clustering signal.  Here we develop, for the first time, a formalism to propagate the effects of photometric calibration variations with arbitrary spatial dependence across the sky to the observed power spectra and to the cosmo param constraints.  Specific examples include Galactic dust extinction and survey-dependent magnitude limits as a function of zenith angle of the telescope.  Establish requirements on the control of calibration so that it doesn't significantly bias constraints on DE and primordial non-Gaussianity.  (i) largest angle photometric calibration variations (dipole, quadrupole and a few more modes, but not the monopole) are the most damaging, and (ii) calibration will need to be understood at the 0.1%-1% level (rms variations mapped out to accuracy between 0.001 and 0.01 mag), though the precise requirement strongly depends on the faint-end slope of the luminosity function and the redshift distribution of galaxies in the survey.

1211.1034
Simulating the assembly of galaxies at redshifts z = 6-12
Dayal, Dunlop, Maio, Ciardi

Explore physical evolution of galaxies in the first Byr of cosmic time with simulations.  Model reproduces basic statistical properties of observed LBG population at z=6-8, including UV LF, stellar-mass density (SMD), and the sSFR or LBGs with M_UV<-18.  Present predictions for behavior of fainter LBGs down to M_UV<-15 (JWST-observable).  Find mass growth due to SF in the mass-dominatnt progenitor builds up about 90% of the total z~6 LBG stellar mass, dominating over the mass contributed by merging throughout this era.  Suggests that apparent "luminosity evolution" depends on the luminosity range probed: the steady brightening of the bright end of the LF is driven primarily by genuine physical luminosity evolution and arises due to a fairly steady increase in the UV luminosity (and hence SFR) in the most massive LBGs.  However, at fainter luminosities the situation is more complex, due in par to the more stochastic SFH of lower-mass objects; at this end, the evolution of the UV LF involves a mix of positive and negative luminosity evolution (as low-mass galaxies temporarily brighten then fade) coupled with both positive and negative density evolution (as new low-mass galaxies form, and other low-mass galaxies are consumed by merging).  Also predict the average sSFR of LBGs should rise from 4.5/Gyr at z=6 to about 11/Gyr by z=9.

1211.1051
Opening the 100-year window for time domain astronomy
Grindlay, Tang, Los, Servillat

Time domain astronomy (TDA):  Digital Access to a Sky Century @ Harvard (DASCH) project makes available to the community the full sky Historical TDA database and digitized images for a century (1890-1990) of coverage.  Describe the current DASCH developement and some initial results, and outline plans for the "production scanning" phase and  data distribution which is to begin in 2012.  Open a 100-year window into temporal astrophysics, revealing rare transients and (especially) astrophysical phenomena that vary on time-scales of a decade.  Provide context and archival comparisons for the deeper modern surveys.

1211.1091
SDSSJ2222+2745 A gravitationally lensed sextuple quasar with maximum image separation of 15.1" discovered in the Sloan giant arcs survey
Dahle et al

As the title says.  Pretty rare: maximum image separation of 15.1" and 6x multiple images.  Cluster-lensed multiple quasars are also pretty rare (only 3 known).  

1211.1108
Probing satellite halos with weak gravitational lensing
Gillis, Hudson, Hilbert, Hartlap

Demonstrate possibility of detecting tidal stripping of DM subhalos within galaxy groups using WL.  Millennium sim ray-tracing generated mock catalogues.  Assume halo model for galaxies and groups, using various models with different distributions of mass between galaxy and group halos to simulate different states of group evolution.  Using these mock catalogues, forecast the lensing signals that will be detected around galaxy groups and satellite galaxies, as well as test 2 different methods for isolating the satellites' lensing signals.   Key challenge: determine the accuracy to which group centers can be identified.  With current and ongoing surveys, it will be possible to detect stripping in groups of mass 1e12-15 Msun.

1211.1293
Looking for the rainbow on exoplanets covered by liquid and icy water clouds
Karalidi, Stam, Hovenier

As the title says.