Nearby Galaxies in the 2micron All Sky Survey I. K-band Luminosity Functions

Differential K-band luminosity functions (LFs) are presented for a complete sample of 1613 nearby bright galaxies segregated by visible morphology. The LF for late-type spirals follows a power law that rises towards low luminosities whereas the LFs for ellipticals, lenticulars and bulge-dominated spirals are peaked and decline toward both higher and lower luminosities. Each morphological type (E, S0, S0/a-Sab, Sb-Sbc, Sc-Scd) contributes approximately equally to the overall K-band luminosity density of galaxies in the local universe. Type averaged bulge/disk ratios are used to subtract the disk component leading to the prediction that the K-band LF for bulges is bimodal with ellipticals dominating the high luminosity peak, comprising 60% of the bulge luminosity density in the local universe with the remaining 40% contributed by lenticulars and the bulges of spirals. Overall, bulges contribute 30% of the galaxy luminosity density at K in the local universe with spiral disks making up the remainder. If bulge luminosities indicate central black hole masses, then our results predict that the black hole mass function is also bimodal.Comment: 49 pages, 9 figures, accepted for publication in the Astrophysical Journal 5/22/0

Low Gain Avalanche Detectors (LGAD) for particle physics and synchrotron applications

A new avalanche silicon detector concept is introduced with a low gain in the region of ten, known as a Low Gain Avalanche Detector, LGAD. The detector's characteristics are simulated via a full process simulation to obtain the required doping profiles which demonstrate the desired operational characteristics of high breakdown voltage (500 V) and a gain of 10 at 200 V reverse bias for X-ray detection. The first low gain avalanche detectors fabricated by Micron Semiconductor Ltd are presented. The doping profiles of the multiplication junctions were measured with SIMS and reproduced by simulating the full fabrication process which enabled further development of the manufacturing process. The detectors are 300 μm thick p-type silicon with a resistivity of 8.5 kΩcm, which fully depletes at 116 V. The current characteristics are presented and demonstrate breakdown voltages in excess of 500 V and a current density of 40 to 100 nAcm−2 before breakdown measured at 20oC. The gain of the LGAD has been measured with a red laser (660 nm) and shown to be between 9 and 12 for an external bias voltage range from 150 V to 300 V

Rotational Doppler Effect in Magnetic Resonance

We compute the shift in the frequency of the spin resonance in a solid that rotates in the field of a circularly polarized electromagnetic wave. Electron spin resonance, nuclear magnetic resonance, and ferromagnetic resonance are considered. We show that contrary to the case of the rotating LC circuit, the shift in the frequency of the spin resonance has strong dependence on the symmetry of the receiver. The shift due to rotation occurs only when rotational symmetry is broken by the anisotropy of the gyromagnetic tensor, by the shape of the body, or by magnetocrystalline anisotropy. General expressions for the resonance frequency and power absorption are derived and implications for experiment are discussed.Comment: 8 pages, 4 figure

The Diverse Infrared Properties of a Complete Sample of Star-Forming Dwarf Galaxies

We present mid-infrared Spitzer Space Telescope observations of a complete sample of star-forming dwarf galaxies selected from the KPNO International Spectroscopic Survey. The galaxies span a wide range in mid-infrared properties. Contrary to expectations, some of the galaxies emit strongly at 8 micron indicating the presence of hot dust and/or PAHs. The ratio of this mid-infrared dust emission to the stellar emission is compared with the galaxies' luminosity, star-formation rate, metallicity, and optical reddening. We find that the strength of the 8.0 micron dust emission to the stellar emission ratio is more strongly correlated with the star-formation rate than it is with the metallicity or the optical reddening in these systems. Nonetheless, there is a correlation between the 8.0 micron luminosity and metallicity. The slope of this luminosity-metallicity correlation is shallower than corresponding ones in the B-band and 3.6 micron. The precise nature of the 8.0 micron emission seen in these galaxies (i.e., PAH versus hot dust or some combination of the two) will require future study, including deep mid-IR spectroscopy.Comment: 14 pages, accepted Ap

Gravitational Self-Force Correction to the Binding Energy of Compact Binary Systems

Using the first law of binary black-hole mechanics, we compute the binding energy E and total angular momentum J of two non-spinning compact objects moving on circular orbits with frequency Omega, at leading order beyond the test-particle approximation. By minimizing E(Omega) we recover the exact frequency shift of the Schwarzschild innermost stable circular orbit induced by the conservative piece of the gravitational self-force. Comparing our results for the coordinate invariant relation E(J) to those recently obtained from numerical simulations of comparable-mass non-spinning black-hole binaries, we find a remarkably good agreement, even in the strong-field regime. Our findings confirm that the domain of validity of perturbative calculations may extend well beyond the extreme mass-ratio limit.Comment: 5 pages, 1 figure; matches the published versio

New measurements of the cosmic infrared background fluctuations in deep Spitzer/IRAC survey data and their cosmological implications

We extend previous measurements of cosmic infrared background (CIB) fluctuations to ~ 1 deg using new data from the Spitzer Extended Deep Survey. Two fields, with depths of ~12 hr/pixel over 3 epochs, are analyzed at 3.6 and 4.5 mic. Maps of the fields were assembled using a self-calibration method uniquely suitable for probing faint diffuse backgrounds. Resolved sources were removed from the maps to a magnitude limit of AB mag ~ 25, as indicated by the level of the remaining shot noise. The maps were then Fourier-transformed and their power spectra were evaluated. Instrumental noise was estimated from the time-differenced data, and subtracting this isolates the spatial fluctuations of the actual sky. The power spectra of the source-subtracted fields remain identical (within the observational uncertainties) for the three epochs indicating that zodiacal light contributes negligibly to the fluctuations. Comparing to 8 mic power spectra shows that Galactic cirrus cannot account for the fluctuations. The signal appears isotropically distributed on the sky as required for an extragalactic origin. The CIB fluctuations continue to diverge to > 10 times those of known galaxy populations on angular scales out to < 1 deg. The low shot noise levels remaining in the diffuse maps indicate that the large scale fluctuations arise from the spatial clustering of faint sources well below the confusion noise. The spatial spectrum of these fluctuations is in reasonable agreement with an origin in populations clustered according to the standard cosmological model (LCDM) at epochs coinciding with the first stars era.Comment: ApJ, to be publishe

The Active Nucleus of IC4970: A Nearby Example of Merger-Induced Cold-Gas Accretion

We present results from Chandra X-ray and Spitzer mid-infrared observations of the interacting galaxy pair NGC6872/IC4970 in the Pavo galaxy group and show that the smaller companion galaxy IC4970 hosts a highly obscured active galactic nucleus (AGN). The 0.5-10 keV X-ray luminosity of the nucleus is variable, increasing by a factor 2.9 to 1.7 x 10^{42} erg/s (bright state) on ~100 ks timescales. The X-ray spectrum of the is heavily absorbed (N_H = 3 x 10^{23} cm^{-2}) for power law models with Gamma = 1.5-2.0 and shows a clear 6.4 keV Fe Kalpha line with equivalent width of 144-195 eV. Limits on the diffuse emission in IC4970 from Chandra X-ray data suggest that the available power from Bondi accretion of hot interstellar gas may be an order of magnitude too small to power the AGN. Spitzer images show that 8 micron nonstellar emission is concentrated in the central 1 kpc of IC4970, consistent with high obscuration in this region. The mid-infrared colors of the nucleus are consistent with those expected for a highly obscured AGN. Taken together these data suggest that the nucleus of IC4970 is a Seyfert 2, triggered and fueled by cold material supplied to the central supermassive black hole as a result of the off-axis collision of IC4970 with the cold-gas rich spiral galaxy NGC6872.Comment: 10 pages, 9 figures, submitted to ApJ, MIR flux conversion error corrected in Table 4, MIR colors and paper text unchange