Tuesday, was Xmas yesterday, no posts!
Wednesday, ditto.
Thursday, 106 posts, but no reading.
Friday, read yesterday's posts.
1212.5603
Super-Nyquist astroseismology with the Kepler space telescope
Murphy, Shibahashi, Kurtz
Time stamps are periodically modulated due to variations in light arrival time at the satellite, causing barycentric corrections to the Kepler observations. Consequence: Nyquist aliases are split into multiplets that can be identified by their shape. Real pulsation frequencies are distinguishable from these aliases and their frequencies are completely recoverable, even in the super-Nyquist regime (when the sampling interval is longer than half the pulsation period). Provide an analytical derivation of the phenomenon, alongside demonstrations with simulated and real Kepler data. For Kepler data sets spanning more than one Kepler orbital period (372.5d), there are no Nyquist ambiguities on the determination of pulsation frequencies, which are the fundamental data of astroseismology.
1212.5625
On measuring the CMB temperature at redshift 0.89
Sato, Reid, Menten, Carilli
As the title says, use HC3N(3-2) and (5-4) absorption in the FG galaxy of gravitational-lens magnified radio source. T_rot=5.6p2.5-0.9K; consistent with the temperature of CMB at that z. Absorption peak position of the FG gas is offset from the continuum peak position of the synchrotron radiation, which indicates that the absorbing cloud is covering only part of the emission, rather than the entire core-jet region. Find T_rot between 1.1 and 2.5K, lower than CMB temperature. Previous T_rot measurements could be biased due to unresolved structure.
1212.5640
Discovery of an Halpha emitting disk around the supermassive black hole of M31
Menezes, Steiner, Ricci
Model implies SMBH mass of 5e7Msun; eccentric Ha emitting disk; mass compatible with stellar dynamics results; also consistent with M-sigma relation. Ha emission possibly associated with a gaseous disk; supported by detection of traces of weaker nebular lines in the nuclear region of M31. Cannot exclude the possibility that the Ha emission is at least partially generated by stars.
1212.5641
Galaxy formation: where do we stand?
Conselice
A review of galaxy formation and evolution; focus on basic features of galaxies, and how these observables reveal how galaxies and their stars assemble over cosmic time. Overview of observed properties of galaxies in the nearby universe, and for those at higher redshifts up to z~10. Includes a discussion of the major processes in which galaxies assemble and how these can be observed - including the merger history of galaxies, the gas accretion and SFR. Show that the most massive galaxy mergers and accretion are about equally important in the galaxy formation process between z=1-3, while this likely differs for lower mass systems. Also discuss the mass differential evolution for galaxies, as well as how environment can affect galaxy evolution, although mass is the primary criteria for driving evolution. Measurements of the DM content of galaxies at different epochs as measured through kinematics and clustering. Review how observable of galaxies, and the observed galaxy formation process, compares with predictions from simulations of galaxy formation, finding significant discrepancies in the abundances of massive galaxies and merger history. Conclude by examining prospects for the future using JWST, Euclid, SKA, and the ELTs in addressing outstanding issues.
1212.5642
The nature of the H2-emitting gas in the crab nebula
Richardson et al
The sims that come closest to fitting the observations have the core of Knot 15 almost entirely atomic with the H2 emission coming from just a trace molecular component.
1212.5747
Testing the dark matter origin of the WMAP-Planck haze with radio observations of spiral galaxies
Carlson, Hooper, Linden, Profumo
If DM annihilation produces WMAP haze (recently confirmed by Planck), similar diffuse radio halos should exist around other galaxies with physical properties comparable to the MW. If the radio halo is due to a transient astrophysical mechanism, a similar halo should not exist for all MW-like galaxies. Use radio observations of 66 spiral galaxies to test the DM origin of the haze. While observation cannot rule out a DM origin for the radio haze at this time, find numerous examples (including the Andromeda) where, if DM is indeed the origin of the MW haze, some mechanism must be in place to suppress the corresponding haze of the external galaxy. Point out that Planck will offer opportunities to improve this type of constraint in a highly relevant frequency range and for a potentially larger set of candidate galaxies.
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