Day 633

Sunday.

1401.5059
Establishing an analogue population for the most distant galaxies
Stanway, Davies

The LBGs at z~3 are more massive, luminous, redder, more extended and at higher metallicities than their z~5 counterparts.  Thus extrapolations from the existing LBA (Lyman break analogue) samples (which match z=3 properties) have limited value for characterizing z>5 galaxies, or inferring properties unobservable at high z.  Present a new pilot sample of 21 compact SF galaxies in the local 0.05<z<0.25 Universe, which are tuned to match the luminosities and SF volume densities observed in z>~5 LBGs.  Analysis of optical emission line indices suggests that these sources have typical metallicities of a few tenths Solar.  Present radio continuum observations of a subset of this sample (13 sources) and determine that their radio fluxes are consistent with those inferred form the UV, precluding the presence of a hazily obscured AGN or significant dusty SF.

1401.5063
The first hypervelocity star from the LAMOST survey
Zheng et al

B-type star with a heliocentric radial velocity about 620 km/s, which projects to a Galactocentric radial velocity component of ~477 km/s.  With a heliocentric distance of ~13 kpc and an apparent magnitude of ~13 mag, it is the nearest and brightest HVS currently known.  With a mass of ~9 Msun, similar to another massive HVS.  The star is clustered on the sky with many other known HVSs, with the position suggesting a possible connection to Galactic center structures.  With the currently poorly-determined proper motion, a Galactic enter origin of this HVS remains consistent with the data at the 2-3 sigma level.  Discuss the potential of the LAMOST survey to discover a large statistical sample of HVSs of different types.

1401.5065
Photometric studies of Abell 1664: the subtle effect a minor merger has on cluster galaxies
Kleiner et al

A substructure ~800 kpc south of cluster core, identified as most likely the remnant core of a merging group which has passed pericenter and responsible for triggering a cold from in the cluster core.  Find there are more asymmetric galaxies in the inner sample (~4 sigma) which is likely due to galaxy-galaxy interactions as the merging group passed through core passage.  The color profiles of the galaxies are found to be consistent wit the morphology-density relation suggesting there is no unique environmental effect in A1664 that has enhanced galaxy transformations.  This study favors the SF of cluster galaxies being quenched well before it is able to interact with the merging group, and demonstrates that a minor cluster merger has little effect on the observable parameters of cluster galaxies such as morphology and color.

1401.5067
Can AGN feedback break the self-similarity of galaxies, groups, and cluster?
Gaspari et al

Use high-res 3d hydrosims to isolate the impact of AGN feedback on the L_X-T_x relation, in the two archetypal and common regimes, self-regulated mechanical feedback and quasar thermal blast.  Find that AGN feedback has severe difficulty in breaking the relation in a consistent way.  The similarity breaking is directly linked to the gas evacuation within R_500, while the central cooling times are inversely proportional to the core density.  Breaking self-similarity implies thus breaking the cool core, morphing all systems to non-cool-core objects, which is in clear contradiction with the observed data populated by several cool-core systems.  Self-regulated feedback, which quenches cooling flows and preserves cool cores, prevents the dramatic evacuation and similarity breaking at any scale; the relation scatter is also limited.  The impulsive thermal blast can weak the core-included LX-TX at T500<1 keV, but substantially empties and overheats the halo, generating a perennial non-cool-core group, as experienced by cosmo sims.  Even with partial evacuation, massive systems remain overheated.  Show the action of purely AGN feedback is to lower the luminosity and heating the gas, perpendicular to the fit.

1401.5073
First gravitational lensing mass estimate of a damped Lyman-alpha galaxy at z=2.2
Grillo, Fynbo


Galaxy at z=2.207 which is a damped Ly-a absorber and a deflector of a quasar at z=2.888.  Impact parameter at 0.8pm0.1 kpc.  QSO likely to be 2.2 mag brighter (or 8 times more luminous) than the median QSO at comparable redshifts.  Describe the total mass distribution of the lens galaxy with a one-component singular isothermal sphere model and contrast the values of the observed and model-predicted magnification factors.  Estimat that the effective velocity dispersion and 2d total mass, projected within a cylinder with radius equal to the impact parameter, are included between 60-170 km/s and 2.1e9-1.8e10 Msun, respectively.  Remark that analysis of this kind are crucial to exploring the relation between the luminous and DM components of galaxies in the high-z universe.