Day 233

Tuesday.  Had Aikido yesterday.  Plan to go again Wednesday, tomorrow... we'll see what happens.

1203.6833

Intrinsic galaxy shapes and alignments I:  Measuring and modelling COSMOS intrinsic galaxy ellipticities

Joachimi, Semboloni, Bett, Harlap, Hilbert, Hoekstra, Schneider, Schrabback

Statistical properties of ellipticities of galaxy: WL intrinsic alignments, galaxy evolution, structure formation.  Construct model based on halo properties of Millennium Simulation and compare with 150k COSMOS galaxies (4 decades in luminosities, and out to z=2).  Ellipticity measurements show: early-type galaxies have 25% lower intrinsic ellipticity dispersion than late-type galaxies; no sample show z evolution; ellipticity dispersion for late-type galaxies scales strongly with absolute magnitude at the bright end.  Low ellipticity dispersions predicted by models based on reduced inertia tensors of simulated haloes are disfavored by observations.  Fraction of near circular late-type galaxy images in COSMOS is much lower than expected for a sample of circular inclined thick disks, indicating a substantial fraction of galaxies with irregular morphology.

1203.6842

The stellar IMF at very low metllicities

Dopcke, Glover, Clark, Klessen

Pop III formation theory predicts IMF dominated by high-mass stars (IMF today: dominated by <1Msun stars).  Difference due to extra cooling from increasing metallicity (dust overtakes H2 as leading coolant at very high densities).  Study influence of dust cooling o nthe fragmentation of very low metallicity gas; use high-res hydro sim with sink particles to replace contracting protostars; analyze collapse and further fragmentation of star-forming clouds.  Solve full thermal energy equation; track dust temperature and chemical evolution of gas.  4 clouds with various (1e-4, -5, -6 Zsol, and 0) metallicities, determine the properties of each cloud when it undergoes gravitational fragmentation.  Find fragmentation in all cases; no critical metallicity below which fragmentation is impossible, although change in behavior at 1e-5 Zsol.  At this meatllicity, fragmentation takes longer to occur than accretion, leading to a flat mass function at lower metallicities.

1203.6852

Ionized nitrogen at high redshift

Decarli, ..Bertoldi, ... Kneib, ... et al

NII detection at z=3.911 and 3.930, a good tracer of the ionized gas phase in interstellar medium.  Luminosity 1e9 Lsun/mu.  High resolution map of Einstein ring.  In agreement with the decrease of NII/FIR ratio at high FIR luminosities observed in local galaxies.

1203.6861

Galactoseismology: discovery of vertical waves in the galactic disk

Widrow, Gardner, Yanny, Dodelson, Chen

Evidence of galactic north-south asymmetry in the number density and bulk velocity of solar neighborhood stars.  SDSS data shows deficit at |z|~400pc and excess at |z|~800pc.  Bulk velocity profile from SEGUE shows a gradual trend across the Galctic mid plane as well as smaller-scale features.  Speculate that the NS asymmetry, which has the appearance of a wavelike perturbation, is intrinsic to the disk.  Compare against analytic and 1d simulations.  Perturbation may be excited by the passage of a satellite galaxy or DM sub halo through the galactic disk--a disk-heating event.

1203.6884

A note on the consistency condition of primordial fluctuations

Senatore, Zaldarriaga

* Leonardo!

Squeezed limit of (N+1) pt functions of primordial correlation functions (one of the modes have a very small wavenumber) can be inferred from the spatial variation of locally measured N-pt function.  Then show how in single clock inflation, a long wavelength perturbation can be re-absorbed in the background cosmology ... computing correlation functions; the integrals of the interaction Hamiltonian are dominated by conformal times of order of the short wavelength modes, when the long mode is already outside the horizon.  Can generalize the consistence condition for N-pt functions to the case in which the short wavelength fluctuations are inside the horizon and derivatives act on them.  Also discuss consistence condition of (N+M) pt function.  Relation useful to study infrared effects in Inflation.

1203.6876

What can the observation of nonzero curvature tell us?

Guth, Nomura

Eternally inflating multiverse condusive to coincidences and fine-tuning; another coincidence: if amount of slow-roll inflation was only slightly more than the anthropic threshold, then spatial curvature might be measurable.  If nonzero curvature observed: (1) diffusive (new or chaotic) eternal inflation did not occur in our immediate past; (2) universe was born by a bubble nucleation; (3) probability measures does not reward volume increase; (4) the origin of the observed slow-roll inflation is an accidental feature of the potential, not due to a theoretical mechanism.  Omega_k>1e-4 discovery will also give nontrivial information about the correlation between tunneling and slow-roll; a strong correlation favoring large N would be excluded in certain measures.  Current Omega_k consistent with multiverse expectations.

1204.0004

The magnetic field of IRAS 16293-2422 as traced by shock-induced H2O masers

Alves, Vlemmings, Girart, Torrelles

Shock-induced H2O masers important B-field tracers at very high density gas.  Water masers found in both high- and low-mass SF regions, acting as a powerful tool to compare magnetic field morphologies in both mass regimes.  Show one of the first magnetic field determinations in the low-mass protostellar core at high volume density (1e8-10 cm^-3).  Collapsing regime controlled by B-fields, or other (turbulence)?  Check Zeeman emission of H2O masers, estimate B-firled strength.  Maser spots aligned with some of the outflow, which are excited in zones of compressed gas produced by shocks.  Post-shock particle density consistent with typical water masers pumping densities.  Zeeman emission produced by a very strong LoS B-field (113 mG).

1204.0006

Mechanical feedback from active galactic nuclei in galaxies, groups and clusters

McNamara, Nulsen

Radiative cooling timescales at centers are much shorted than their ages (for gas around elliptical galaxies, groups and clusters).  Hot atmospheres are expected to cool and to form stars.  Cold gas and SF formation are observed in cluster center galaxies by at levels below those expected from an unimpeded cooling flow.  X-ray observations show wholesale cooling is being offset by mechanical heating from radio AGN.  Show: cooling X-ray atmospheres and ensuing SF and nuclear activity are coupled to a self-regulated feedback loop.  Energetics understood, but other aspects of feedback, not.  Highlight atmospheric heating and transport processes, accretion, and nuclear activity; discuss potential role of BH spin.  X-ray imagery show chemical elements produced by central galaxies dispersed on large scales by outflows from vicinities of SMBHs.  Comment on the growing evidence for mechanical heating of distant cluster atmospheres by radio jets and potential consequences for the excess entropy in hot haloes, possible decline in the number of distant cooling flows.

1204.0010

The Panchromatic Hubble Andromeda Treasury

Dalcanton, ..., Bell, ... et al

PHAT is an on-going HST Multicyle Treasury program to image ~1/3 of M31's star forming disk in 6 filters, from UV to the NIR; resolve galaxy into more than 1e8 stars with projected radii from 0-20 kpc over a contiguous 0.5 sq deg area in 828 orbits.  6 bands gives excellent constraints on stellar temperature, bolometric luminosity, and extinction for most spectral types.  Optical and NIR are crowding limited towards the inner bulge, central stars need to be 5 mag brighter for the same reliability.  

1204.0063

3-D radiative transfer calculations of radiation feedback from massive black holes: Outflow of mass from the dusty "Torus"

Roth, Kasen, Hopkins, Quataert

Observation and theory both suggest that the momentum carried in mass outflows from AGn can't reach several times L/c, corresponding to outflow rates of hundreds of solar masses peer year.  Radiation pressure on lines alone may not be sufficient to provide this momentum deposition, and the transfer of reprocessed IR radiation in dusty nuclear gas has been postulated to provide the extra enhancement.  The efficacy of this mechanism, however, will be sensitive to multi-dimensional effects such as the tendency for the reprocessed radiation to preferentially escape along sigh-lines of lower column density.  Use MC radiative transfer calculations to determine the radiation force on dusty gas residing within approximately 10 parsecs from an accreting SMBH.  Calculate the net rate of momentum deposition in the surrounding gas and estimate the mass-loss rate in the resulting outflow as a function of solid angle for different BH luminosities, sightline-averaged column densities, clumping parameters, and opening angles of the dusty gas.  Find dust-driven winds carry momentum fluxes of 1-5 times L/c and correspond to mass-loss rates of 10-100 Msun per year for a 1e8 Msun BH radiating at or near Eddington limit.  Results help explain the origin of high velocity molecular and atomic outflows in local ULIRGs, and can inform numerical simulations of galaxy evolution including AGN feedback.

1204.0129

Accelerated expansion and the virial theorem

Hansen

Matter release a significant amount of energy in order to obey the virial theorem, when DM structure form.  Since DM unable to radiate, implies that some of the accreted DM particles must be ejected with high velocities.  These ejected particles may then later hit other cosmological structures and deposit their momentum within these structures.  This induces a pressure between the cosmological structures which opposed the effect of gravity and may therefore mimic a cosmological constant.  Estimate the magnitude of this effect and find that it may be as large as the observed accelerated expansion (estimate accurate only within a few orders of magnitude).  Important to mae a much more careful calculation of this redshift dependent effect.

1204.0144

M-sigma relation btween SMBHs and the velocity dispersion of the globular cluster systems

Sadoun, Colin

As the title says.

1204.0145

Formaldehyde silhouettes against the cosmic microwave background: a mass-limited, distance-independent, extinction-free tracer of star formation across the epoch of galaxy evolution

Darling, Zeiger

Absorption of CMB photons by H2CO over cosmic time.  K-doublet rotational transitions of H2CO become "refrigerated" (excitation temperatures are driven below the CMB temperature) via collisional pumpkin by H2.  H2CO lines (anti-inverted) provide an accurate measurement of the H2 density in molecular clouds.  CMB an exceptionally uniform extended illumination source; H2CO is a distance-idependent, extinction-free molecular gas mass-limited tracer of dense gas in galaxies.   Map history of cosmic SF.  May provide a standardizable galaxy ruler similar to SZ in galaxy clusters, but applicable to much higher z and large samples.  Signal may contaminate HI 21 cm tomography of EoR.

1204.0151

Distribution of maximal luminosity of galaxies in the Sloan Digital Sky Survey

Taghizadeh-Popp, Ozogany, Racz, Regoes, Szalay

Extreme value statistics (EVS) on galaxy luminosities in SDSS: Main (blue/red) and LRG.  Small and positive tail index xi in Main sample rules out the possibility of having a finite maximum cutoff luminosity, and implies luminosity distribution function may decay as a power law at high luminosity end.  LRGs show that they can be described as being the extremes of a luminosity distribution with an exponentially decaying tail.

1204.0372

Constraints on cosmological parameters from strong gravitational lensing by galaxy clusters

Zieser, Bartelmann

SL observation inferring DE EoS (w): growth of critical lines of lensing clusters with the source redshift (depends on distance-redshift relation).  Devise a numerical methods.  Find no constraints can be derived from observations of individual clusters if no knowledge of the underlying mass distribution is assumed.  Uncertainties improved if a fixed lens model is used for purely geometrical optimization, but the choice of a parametric model may produce strong biases.

1204.0485

Evanescent matter

Peebles

LCDM difficult to reconcile with the evidence that environment has strikingly little effect on the evolution of both ellipticals and pure disk spiral galaxies.  Reconciliation might be aided by adding to LCDM an evanescent component of matter with evolving mass and a fifth force large enough to aid early assembly of more neary isolated protogalaxies.  Present a simple illustration.