Day 479

Thursday.


1307.8121
The SDSS-III APOGEE radial velocity survey of M dwarfs I: description of survey and science goals
Deshpande et al

Obtain high-resolution H-band spectra of more than 1200 M dwarfs; used to measure spectroscopic rotational velocities, radial velocities, physical stellar parameters, and variability of the target stars.  Describe the target selection for this survey and results from the first year of scientific observations based on spectra that is publicly available in the SDSS-III DR10.  Present RVs and vsini [?] of >200 M dwarfs, with vsini precision of ~2 km/s and a measurement floor at vsini = 4 km/s.  Survey significantly increases the number of M dwarfs studied for vsini and RV variability (at ~100-200 m/s) and will advance the target selection for planned RV and photometric searches for low mass exoplanets around M dwarfs, such as HPF, CARMENES, and TESS [lingos not explained...].  Multiple epochs of radial velocity observations enable identification of short period binaries, and AO imaging of a subset of stars enables the detection of possible stellar companions at larger separations.  The high-resolution H-band APOGEE spectra provide the opportunity to measure physical stellar parameters such as effective temperatures and metallicities for many of these stars.  At the culmination of this survey, obtain multi-epoch spectra and RVs for >1400 stars spanning spectral types of M0-L0, providing the largest set of NIR M dwarf spectra at high resolution, and more than doubling the number of known spectroscopic vsini values for M dwarfs.  Furthermore, by modeling telluric lines to correct for small instrumental radial velocity shifts, hope to achieve a relative velocity precision floor of 50 m/s for bright M dwarfs.  Present preliminary results of this telluric modeling technique in this paper.

1307.8152
Measuring cosmic distances with galaxy clusters
Allen, Mantz, Morris, Applegate, Kelly, von der Linden, Rapetti, Schmidt

Two independent ways of using clusters to measure cosmic distances: (1) measurements of the X-ray emitting gas mass fraction (an approximately standard quantity, independent of mass and redshift, for the most massive clusters).  (2) use combined mm and X-ray measurements of cluster pressure profiles.  Review these methods; their current status and the prospects for improvements over the next decade.  For the first technique, which currently provides comparable DE constraints to SNIa studies, improvements of a factor of 6 or more should be readily achievable, together with tight constraints on the mean matter density that are largely independent of the cosmological model assumed.  Realizing this potential will require a coordinated, multiwavelength approach, utilizing new cluster surveys, X-ray, optical and mm facilities, and a continued emphasis on improved hydrodynamical simulations.

1307.8218
Ancient eclipses and long-term drifts in the Earth - Moon system
Vahia, Singh, Seta, Subbarayappa

Identify nine groups of anomalous eclipses between 500 and 1800 AD recorded in parts of India that should have completely missed the subcontinent as per NASA simulations.  Show that the typical correction to the lunar location required to reconcile the anomalous eclipses is relatively small and consistent with fluctuations in the length of day that are observed in recent periods.  Change in Earth's moment of inertia due to differential acceleration of land and water that can account for this discrepancy investigated.  Show that 80% of these discrepancies occur when the Moon is at declinations greater than 10 deg and closer to its major standstill of 28 deg while it spends 46% of the time in this region.  Simulate the differential interaction of the Moon's gravity with landmass and water using finite element method to account for landmass and water mass.  Show that the results of eclipse error are consistent with the estimate of a small differential acceleration when the Moon is over land at high latitudes.  Encounter some examples where the results from simulations studies cannot explain the phenomena.  Propose that dT corrections have to be coupled with some other mechanism possibly a small vertical oscillation in the Moon's rotational plane with a period of the order of a few 100 years to achieve the required adjustment on the Eclipse maps.

1307.8440
The inner kiloparsec of Mrk 273 with Keck Adaptive Optics
Vivian et al

Mrk 273, a late-stage ULIRG merger, hosts a powerful AGN; has X-ray, optical, and MIR imaging and spectroscopic evidence for this.  However, the exact location of the AGN and the nature of the nuclei have been difficult to determine due to dust obscuration and the limited wavelength coverage of available high-res data.  Present NIR integral-field spectra and images of the nuclear region of Mrk 273 taken with OSIRIS and NIRC2 on the Keck II Telescope with laser guide star adaptive optics.  Observe 3 spatially resolved components, and analyze the local molecular and ionized gas emission lines and their kinematics.  Confirm the presence of the hard X-ray AGN in the SW nucleus.  In the North nucleus, find a strongly rotating gas disk whose kinematics indicate a central BH of mass 1e9 Msun.  The H2 emission line shows an increase in velocity dispersion along the minor axis in both directions, and an increased flux with negative velocities in the SE direction; this provides direct evidence for a collimated molecular outflow along the axis of rotation of the disk.  The third spatially distinct component appears to the SE, 640 and 750 pc from the N and SW nuclei, respectively.  This component is faint in continuum emission but shows several strong emission line features, including [Se vi] 1.964 um which traces an extended coronal-line region.  The geometry of the [Si vi] emission combined with shock models and energy arguments suggest that [Si vi] in the SE component must be at least partly ionized by the SW AGN or a putative AGN in the Northern disk, either through photoionization or through shock-heating from strong AGN- and circumnuclear SB-driven outflows.  This lends support to a scenario in which Mrk 273 may be a dual AGN sysytem.