Day 525

Wednesday.

1310.1918
The smooth MgII gas distribution through the interstellar/extra-planar/halo interface
Kacprzak et al

First measurements of MgII absorption systems associated with spectroscopically confirmed z~0.1 SF galaxies at projected distances of D<6kpc.  Data consistent with anti-correlation between rest-frame MgII equivalent width Wr(2796), and impact parameter D, represented by a single log-linear relation derived by Nielsen+ that converges to ~2A at D=0kpc.  Find that the halo gas covering fraction is unity below D~25kpc [but measurements are <6kpc?].  Report that D<6kpc absorbers are consistent with the Wr(2796) distributions of the MW ISM and ISM+halo.  In addition, quasar sight-lines of intermediate z galaxies with 6<D<25 kpc have an EW distribution similar to that of MW halo, implying that beyond ~6kpc, quasar sight-lines are likely probing halo gas and not the ISM.  As inferred by MW and this new data, the gas profiles of galaxies can be fit by a single log-linear Wr(2796)-D relation out to large scales across a variety of gas-phase conditions and is maintained through the halo/extra-planar/ISM interfaces, remarkable considering their kinematic complexity   These low z, small impact parameter absorption systems are the first steps to bridge the gap between quasar absorption-line studies and HI observations of the CGM.  [so did they get any info on the ISM at all?]

1310.1920
Where the world stands still: turnaround as a strong test of \Lambda CDM cosmology
Pavlidou, Tomaras

The maximum possible value of the turnaround radius (of gravitational collapse) in LCDM is 3GM/(Lambda c^2)^{1/3}; discuss the possible use of this prediction as an observational test for LCDM cosmology.

1310.1957
The role of magnetic fields in starburst galaxies as revealed by OH megamesers
BcBride, Quataert, Heiles, Bauermeister

Present estimates of B-field strengths in the interstellar media of SB galaxies derived from measurements of Zeeman splitting associated with OH megamasers.  The results for 8 galaxies with Zeeman detections suggest that the magnetic energy density in the interstellar medium of starburst galaxies is comparable to their hydrostatic gas pressure, as in the MW.  Discuss the significant uncertainties in this conclusion, and possible measurements that could reduce these uncertainties.  Also compare the Zeeman splitting derived B-field estimates to B-field strengths estimated using synchrotron fluxes and assuming that the B-field and CRs have comparable energy densities, known as the "minimum energy" argument. Find that the minimum energy argument systematically underestimates B-fields in SB galaxies, and that the conditions that would be required to produce agreement between the minimum energy estimate and the Zeeman derived estimate of interstellar medium B-fields are implausible.  The conclusion that B-fields in starburst galaxies exceed the minimum energy B-fields is consistent with starburst galaxies adhering to the linearity of the FIR-radio correlation.

1310.2020
The formation of the massive galaxies in the SSA22 z=3.1 protocluster
Kubo et al

Properties of K-band (K_AB<24) selected galaxies in the z=3.09 SSA22 protocluster field studied; 430 galaxies at 2.6<z_ph<3.6 selected as potential members in a 112 arcmin^2 area based on their photoz.  Find that ~20% of the massive galaxies with M*>1e11Msun at photoz~3.1 have colors consistent with those of quiescent galaxies with ages >0.5 Gyr.  This fraction increases to ~50% after correcting for unrelated FG/BG objects.  Find that 30% of the massive galaxies are heavily reddened dust SF galaxies.  Few such quiescent [?] galaxies at similar redshifts are seen in typical survey fields.  An excess surface density of 24 um sources at photoz~3.1 is also observed, implying the presence of dusty SF activity in the protocluster.  Cross-correlation with the X-ray data indicates that the fraction of K-band selected protocluster galaxies hosting AGN is also high compared with the field.  The sky distribution of the quiescent galaxies, the 24 um sources, and the X-ray AGNs show clustering around a density peak of z=3.1 LAEs.  A significant fraction of the massive galaxies have already become quiescent, while the dusty SF is still active in the SSA22 protocluster.  These fiundings indicate that we are witnessing the formation epoch of massive early-type galaxies at the center of predecessors to present-day rich galaxy cluster.

1310.2096
HST absolute proper motions of NGC 6681 (M70) and the Sagittarius dwarf spheroidal galaxy
Massari et al

Temporal baseline of 5.5 years; BG galaxies used to determine the zero point of absolute-motion reference frame.  Proper motion of 6681 is (mu_alpha cos(delta), mu_delta) = (1.58pm0.18, -4.57pm0.16) mas/yr; for Sgr dSph 9-2.54pm0.18, -1.19pm0.16), consistent with previous measurements and with the values predicted by theoretical models.  The absolute proper motion of the Galaxy population in the FoV is (-1.21pm0.27, -4.39pm0.26) mas/yr.  In this study, also use BG Sag dSph stars to determine the rotation of the globular cluster in the plane of the sky and find that 6681 is not rotating significantly; v_rot=0.82 pm 1.02 km/s at a distance of 1 arcmin from the cluster center.

1310.2146
Discovery of the Hot Big Bang: what happened in 1948
Peebles

11 publications in 1948 discussed CMB.  These papers offer a detailed example of the process of development of a new and now very productive line of research, and of the confusion that can attend new ideas.  The confusion in this case left a common misunderstanding of the considerations that motivated the idea of the sea of radiation.