Systematic challenges for future gravitational wave measurements of precessing binary black holes

The properties of precessing, coalescing binary black holes are presently inferred through comparison with two approximate models of compact binary coalescence. In this work we show these two models often disagree substantially when binaries have modestly large spins ($a\gtrsim 0.4$) and modest mass ratios ($q\gtrsim 2$). We demonstrate these disagreements using standard figures of merit and the parameters inferred for recent detections of binary black holes. By comparing to numerical relativity, we confirm these disagreements reflect systematic errors. We provide concrete examples to demonstrate that these systematic errors can significantly impact inferences about astrophysically significant binary parameters. For the immediate future, parameter inference for binary black holes should be performed with multiple models (including numerical relativity), and carefully validated by performing inference under controlled circumstances with similar synthetic events.Comment: 12 pages, 9 figure

Quantum fields and "Big Rip" expansion singularities

The effects of quantized conformally invariant massless fields on the evolution of cosmological models containing a ``Big Rip'' future expansion singularity are examined. Quantized scalar, spinor, and vector fields are found to strengthen the accelerating expansion of such models as they approach the expansion singularity.Comment: 7 pages; REVTeX

Transient tunneling effects of resonance doublets in triple barrier systems

Transient tunneling effects in triple barrier systems are investigated by considering a time-dependent solution to the Schr\"{o}dinger equation with a cutoff wave initial condition. We derive a two-level formula for incidence energies $E$ near the first resonance doublet of the system. Based on that expression we find that the probability density along the internal region of the potential, is governed by three oscillation frequencies: one of them refers to the well known Bohr frequency, given in terms of the first and second resonance energies of the doublet, and the two others, represent a coupling with the incidence energy $E$. This allows to manipulate the above frequencies to control the tunneling transient behavior of the probability density in the short-time regim

On the Distribution of Stellar Masses in Gamma-ray Burst Host Galaxies

We analyze Spitzer images of 30 long-duration gamma-ray burst (GRB) host galaxies. We estimate their total stellar masses (M_*) based on the rest-frame K-band luminosities (L_K_(rest)) and constrain their star formation rates (SFRs; not corrected for dust extinction) based on the rest-frame UV continua. Further, we compute a mean M_*/ L_K_(rest) = 0.45 M_☉/L_☉. We find that the hosts are low M_*, star-forming systems. The median M_* in our sample ( = 10^(9.7) M_☉) is lower than that of "field" galaxies (e.g., Gemini Deep Deep Survey). The range spanned by M_* is 10^7 M_☉ < M_* < 10^(11) M_☉, while the range spanned by the dust-uncorrected UV SFR is 10^(–2) M_☉ yr^(–1) < SFR < 10 M_☉ yr^(–1). There is no evidence for intrinsic evolution in the distribution of M_* with redshift. We show that extinction by dust must be present in at least 25% of the GRB hosts in our sample and suggest that this is a way to reconcile our finding of a relatively lower UV-based, specific SFR (φ ≡ SFR/M_*) with previous claims that GRBs have some of the highest φ values. We also examine the effect that the inability to resolve the star-forming regions in the hosts has on φ

Ysovar: The First Sensitive, Wide-area, Mid-infrared Photometric Monitoring of the Orion Nebula Cluster

We present initial results from time-series imaging at infrared wavelengths of 0.9 deg^2 in the Orion Nebula Cluster (ONC). During Fall 2009 we obtained 81 epochs of Spitzer 3.6 and 4.5 μm data over 40 consecutive days. We extracted light curves with ~3% photometric accuracy for ~2000 ONC members ranging from several solar masses down to well below the hydrogen-burning mass limit. For many of the stars, we also have time-series photometry obtained at optical (I_c) and/or near-infrared (JK_s ) wavelengths. Our data set can be mined to determine stellar rotation periods, identify new pre-main-sequence eclipsing binaries, search for new substellar Orion members, and help better determine the frequency of circumstellar disks as a function of stellar mass in the ONC. Our primary focus is the unique ability of 3.6 and 4.5 μm variability information to improve our understanding of inner disk processes and structure in the Class I and II young stellar objects (YSOs). In this paper, we provide a brief overview of the YSOVAR Orion data obtained in Fall 2009 and highlight our light curves for AA-Tau analogs—YSOs with narrow dips in flux, most probably due to disk density structures passing through our line of sight. Detailed follow-up observations are needed in order to better quantify the nature of the obscuring bodies and what this implies for the structure of the inner disks of YSOs

Magnetic Field Probing of an SU(4) Kondo Resonance in a Single Atom Transistor

Semiconductor nano-devices have been scaled to the level that transport can be dominated by a single dopant atom. In the strong coupling case a Kondo effect is observed when one electron is bound to the atom. Here, we report on the spin as well as orbital Kondo ground state. We experimentally as well than theoretically show how we can tune a symmetry transition from a SU(4) ground state, a many body state that forms a spin as well as orbital singlet by virtual exchange with the leads, to a pure SU(2) orbital ground state, as a function of magnetic field. The small size and the s-like orbital symmetry of the ground state of the dopant, make it a model system in which the magnetic field only couples to the spin degree of freedom and allows for observation of this SU(4) to SU(2) transition.Comment: 12 pages, 10 figures, accepted for publication in Physical Review Letter