Sloan Fellows

About: Sloan Fellows is a based out in . It is known for research contribution in the topics: Galaxy & Star formation. The organization has 55 authors who have published 253 publications receiving 35008 citations. The organization is also known as: Sloan Fellows.

Cosmic evolution of black holes and spheroids. IV. The M BH - L sph relation

Abstract: From high-resolution images of 23 Seyfert-1 galaxies at z = 0.36 and z = 0.57 obtained with the Near-Infrared Camera and Multi-Object Spectrometer on board the Hubble Space Telescope (HST), we determine host-galaxy morphology, nuclear luminosity, total host-galaxy luminosity, and spheroid luminosity. Keck spectroscopy is used to estimate black hole mass (M BH). We study the cosmic evolution of the M BH-spheroid luminosity (L sph) relation. In combination with our previous work, totaling 40 Seyfert-1 galaxies, the covered range in BH mass is substantially increased, allowing us to determine for the first time intrinsic scatter and correct evolutionary trends for selection effects. We re-analyze archival HST images of 19 local reverberation-mapped active galaxies to match the procedure adopted at intermediate redshift. Correcting spheroid luminosity for passive luminosity evolution and taking into account selection effects, we determine that at fixed present-day V-band spheroid luminosity, M BH/L sph?(1 + z)2.8? 1.2. When including a sample of 44 quasars out to z = 4.5 taken from the literature, with luminosity and BH mass corrected to a self-consistent calibration, we extend the BH mass range to over 2 orders of magnitude, resulting in M BH/L sph (1 + z)1.4? 0.2. The intrinsic scatter of the relation, assumed constant with redshift, is 0.3?? 0.1 dex (<0.6 dex at 95% CL). The evolutionary trend suggests that BH growth precedes spheroid assembly. Interestingly, the M BH-total-host-galaxy-luminosity relation is apparently non-evolving. It hints at either a more fundamental relation or that the spheroid grows by a redistribution of stars. However, the high-z sample does not follow this relation, indicating that major mergers may play the dominant role in growing spheroids above z 1.

Low stellar obliquities in compact multiplanet systems

Abstract: We measure the sky-projected stellar obliquities (λ) in the multiple-transiting planetary systems KOI-94 and Kepler-25, using the Rossiter-McLaughlin effect. In both cases, the host stars are well aligned with the orbital planes of the planets. For KOI-94 we find λ = –11° ± 11°, confirming a recent result by Hirano and coworkers. Kepler-25 was a more challenging case, because the transit depth is unusually small (0.13%). To obtain the obliquity, it was necessary to use prior knowledge of the star's projected rotation rate and apply two different analysis methods to independent wavelength regions of the spectra. The two methods gave consistent results, λ = 7° ± 8° and –0°.5 ± 5°.7. There are now a total of five obliquity measurements for host stars of systems of multiple-transiting planets, all of which are consistent with spin-orbit alignment. This alignment is unlikely to be the result of tidal interactions because of the relatively large orbital distances and low planetary masses in the systems. In this respect, the multiplanet host stars differ from hot-Jupiter host stars, which commonly have large spin-orbit misalignments whenever tidal interactions are weak. In particular, the weak-tide subset of hot-Jupiter hosts has obliquities consistent with an isotropic distribution (p = 0.6), but the multiplanet hosts are incompatible with such a distribution (p ~ 10^(–6)). This suggests that high obliquities are confined to hot-Jupiter systems, and provides further evidence that hot-Jupiter formation involves processes that tilt the planetary orbit.

The Southern Galactic Plane Survey: Polarized Radio Continuum Observations and Analysis

Abstract: The Southern Galactic Plane Survey (SGPS) is a radio survey in the 21 cm H I line and in 1.4 GHz full-polarization continuum, observed with the Australia Telescope Compact Array and the Parkes 64 m single-dish telescope. The survey spans a Galactic longitude of 253° < l < 358° and a latitude of |b| < 15 at a resolution of 100'' and a sensitivity below 1 mJy beam-1. This paper presents interferometer only polarized continuum survey data and describes the data taking, analysis processes, and data products. The primary data products are the four Stokes parameters I, Q, U, and V in 25 overlapping fields of 55 by 3°, from which polarized intensity, polarization angle, and rotation measure are calculated. We describe the effects of missing short spacings, and discuss the importance of the polarized continuum data in the SGPS for studies of fluctuations and turbulence in the ionized interstellar medium and for studying the strength and structure of the Galactic magnetic field.

The Multiplicity of the Hyades and Its Implications for Binary Star Formation and Evolution

Abstract: A 2.2 μm speckle imaging survey of 167 bright (K < 8.5 mag) Hyades members reveals a total of 33 binaries with separations spanning 0044 to 134 and magnitude differences as large as 5.5 mag. Of these binaries, 9 are new detections and an additional 20 are now spatially resolved spectroscopic binaries, providing a sample from which dynamical masses and distances can be obtained. The closest three systems, marginally resolved at Palomar Observatory, were reobserved with the 10 m Keck Telescope in order to determine accurate binary star parameters. Combining the results of this survey with previous radial velocity, optical speckle, and direct-imaging Hyades surveys, the detected multiplicity of the sample is 98 singles, 59 binaries, and 10 triples. A statistical analysis of this sample investigates a variety of multiple star formation and evolution theories. Over the binary separation range 01–107 (5–50 AU), the sensitivity to companion stars is relatively uniform, with ΔKlim = 4 mag, equivalent to a mass ratio qmin = 0.23. Accounting for the inability to detect high flux ratio binaries results in an implied companion star fraction (CSF) of 0.30 ± 0.06 in this separation range. The Hyades CSF is intermediate between the values derived from observations of T Tauri stars (CSFTTS = 0.40 ± 0.08) and solar neighborhood G dwarfs (CSFSN = 0.14 ± 0.03). This result allows for an evolution of the CSF from an initially high value for the pre-main sequence to that found for main-sequence stars. Within the Hyades, the CSF and the mass ratio distribution provide observational tests of binary formation mechanisms. The CSF is independent of the radial distance from the cluster center and the primary star mass. The distribution of mass ratios is best fitted by a power law q-1.3±0.3 and shows no dependence on the primary mass, binary separation, or radial distance from the cluster center. Overall, the Hyades data are consistent with scale-free fragmentation, but inconsistent with capture and disk-assisted capture in small clusters. Without testable predictions, scale-dependent fragmentation and disk fragmentation cannot be assessed with the Hyades data.

AMUSE-Virgo. I. Supermassive Black Holes in Low-Mass Spheroids

Abstract: We present the first results from the AGN Multiwavelength Survey of Early-Type Galaxies in the Virgo Cluster (AMUSE-Virgo). This large program targets 100 early-type galaxies with the Advanced CCD Imaging Spectrometer on board the Chandra X-Ray Observatory and the Multiband Imaging Photometer on board the Spitzer Space Telescope, with the aim of providing an unbiased census of low-level supermassive black hole activity in the local universe. Here we report on the Chandra observations of the first 16 targets, and combine them with results from archival data of another, typically more massive, 16 targets. Pointlike X-ray emission from a position coincident with the optical nucleus is detected in 50% of the galaxies (down to our completeness limit of ~4 × 1038 ergs s−1). Two of the X-ray nuclei are hosted by galaxies (VCC 1178 [N4464] and VCC 1297 [N4486B]) with absolute B magnitudes fainter than –18, where nuclear star clusters are known to become increasingly common. After carefully accounting for possible contamination from low-mass X-ray binaries, we argue that the detected nuclear X-ray sources are most likely powered by low-level accretion on to a supermassive black hole, with a 11% chance contamination in VCC 1178, where a star cluster is barely resolvable in archival Hubble Space Telescope images. Based on black hole mass estimates from the global properties of the host galaxies, all the detected nuclei are highly sub-Eddington, with luminosities in the range –8.4 < log (L0.3–10 keV/LEdd) < − 5.9. The incidence of nuclear X-ray activity increases with the stellar mass M of the host galaxy: only between 3% and 44% of the galaxies with M < 1010 M☉ harbor an X-ray active supermassive black hole. The fraction rises to between 49% and 87% in galaxies with stellar mass above 1010 M☉ (at the 95% confidence level).