Day 297

Thursday.

1209.2413
Submillimeter galaxies in a hierarchical universe: number counts, redshift distribution, and implications for the IMF
Hayward, Narayanan, Keres, Jonsson, Hopkins, Cox, Hernquist

SMGs = rapid SF galaxies; galaxy formation models have difficulty explaining the number counts of SMGs.  Combine semi-empirical models with hydro sims and 3d dust radiative transfer, to predict the number counts of unlensed SMGs.  Stellar mass functions, gas and dust masses, and sizes of galaxies constrained to match observations: can isolate uncertainties related to the dynamical evolution of galaxy mergers and dust radiative transfer.  Number counts and z distribution agree well with observations.  Isolated disc galaxies dominate the faint population; brighter sources are a mix of merger-induced starbursts and galaxy-pair SMGs (30-50% of all SMGs at S_1.1>~0.5 mJy).  Mean redshifts are z~3-3.5 (depends on flux cut); brightest sources tend to be a higher redshifts.  IMF need not be top-heavy for the model to match observation.

1209.2414
Herschel detection of dust emission from UV-luminous star-forming galaxies at 3.3<z<4.3
Lee, Alberts, Atlee, Dey, Pope, Jannuzi, Reddy, Brown

Sample of 1913 Lyman Break Gals candidates over 5.3 deg sq, largest samples of UV-luminous (L>~L*) galaxies at this epoch, bright end of galaxy LF can be measured here.  Divide into 3 bins, stack for average SED of LBGs at FIR.  Have 4e11 Lsun IR luminosities, 60-70% of SF obscured by dust.  FIR SEDs peak at lambda>100um, so dust temperature T=30K, significantly colder than that of local galaxies of comparable IR luminosities.  Observed IR/UV ratio is low (3-4) compared to z~2 LBGs (~7).  Slope of continuum and IR/UV ratio suggest dust properties similar to local starburst galaxies, but galaxies in the highest luminosity bin deviate from the local relation.  Speculate: most UV luminous galaxies at this epoch are being observed in a shirt-lived and young evolutionary phase.

1209.2416
The panchromatic Hubble Andromeda treasury II. tracing the inner M31 halo with blue horizontal branch stars
Willliams, Dalcaonton, Bell, ... Lauer, et al

As the title says.  BHB a good tracer of the stellar halo to smaller galactocentric distances.

1209.2420
Occupation of X-ray selected galaxy groups by X-ray AGN
Allevato, Finoguenov, et al

HOD of X-ray selected AGN in COSMOS at z<1.

1209.2435
Internal gravity waves modulate the apparent misalignment of exoplanets around hot stars
Rogers, Lin, Lau

Propose: observed misalignment between exoplanets and their host hot stars can be explained by angular momentum transport within the host star [misalignment of what?].  Substantial angular momentum transport by internal gravity waves (IGW) generated at the convective-radiative interface.

1209.2451
THe dark energy spectrometer (DESpec): a multi-fiber spectroscopic upgrade of the dark energy camera and survey for the Blanco telescope
Abdalla, ... et al

Describe an initiative to build and use the DESpec: 4000 robotically positioned optical fibers interchangeable with the CCD imager of DECam, with FoV 3.8 sq. deg., operated by CTIO and available for astronomy community.  

1209.2478
Why do breaking indicies of pulsars span over more than 100 millions?
Zhang, Xie

Breaking indicies of 366 pulsars from Hobbs+ (2012) span from -1e8 to +1e8, and significantly correlated with their characteristic ages.  Generate model of B-field evolution, derive analytical expression of the breaking index.  This model incompatible to the previous interpretation that the B-field growth is responsible for the observed small values of brekaing indicies (<3) of young pulsars with characteristic ages of <2e3 yr.  "Instantaneous" breaking index may be different from the "averaged" breaking index.   ...

1209.2482
Testing models of intrinsic brightness variations in type Ia supernovae, and their impact on measuring cosmological parameters
Kessler et al

Introduces an additional systematic uncertainty on w of ~0.02, well below the total uncertainty.  But this number may be sample dependent.

1209.2554
Lensing and dynamics in two simple steps
Agnello, Auger, Evans

Combine Virial theorem with lens equation to get the power-law index of density profile in dearly-type galaxy lenses.  Results rely just on surface brightnesses and LoS kinematics, making deprojection unnecessary.  Apply to 3 known systems.  This method yields a good approximation for the density profile even when the true profiles is a broken power-law, although it has a mild bias toward isothermality.

1209.2591
Elemental abundances of low-mass stars in nearby young associations: AB Doradus, Carina Near, and Ursa Major
Biazzo et al

Present stellar parameters and abundances of 11 elements (Li, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni and Zn) of 13 F6-K2 MS stars in young groups.  Li abundance consistent with their age.  All other elements show solar abundances.  Metallicity distribution of nearby young stars (targets of direct imaging planet-search surveys) is different from that of old, field solar-type stars (radial velocity survey target).