6,458 research outputs found
Dynamic Normalization for Compact Binary Coalescence Searches in Non-Stationary Noise
The output of gravitational-wave interferometers, such as LIGO and Virgo, can be highly non-stationary. Broadband detector noise can affect the detector sensitivity on the order of tens of seconds. Gravitational-wave transient searches, such as those for colliding black holes, estimate this noise in order to identify gravitational-wave events. During times of non-stationarity we see a higher rate of false events being reported. To accurately separate signal from noise, it is imperative to incorporate the changing detector state into gravitational-wave searches. We develop a new statistic which estimates the variation of the interferometric detector noise. We use this statistic to re-rank candidate events identified during LIGO-Virgo's second observing run by the PyCBC search pipeline. This results in a 7% improvement in the sensitivity volume for low mass binaries, particularly binary neutron stars mergers
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Dissecting the spiral galaxy M83: mid-infrared emission and comparison with other tracers of star formation
We present a detailed mid-infrared study of the nearby, face-on spiral galaxy
M83 based on ISOCAM data. M83 is a unique case study, since a wide variety of
MIR broad-band filters as well as spectra, covering the wavelength range of 4
to 18\mu m, were observed and are presented here. Emission maxima trace the
nuclear and bulge area, star-formation regions at the end of the bar, as well
as the inner spiral arms. The fainter outer spiral arms and interarm regions
are also evident in the MIR map. Spectral imaging of the central 3'x3' (4 kpc x
4 kpc) field allows us to investigate five regions of different environments.
The various MIR components (very small grains, polycyclic aromatic hydrocarbon
(PAH) molecules, ionic lines) are analyzed for different regions throughout the
galaxy. In the total 4\mu m to 18\mu m wavelength range, the PAHs dominate the
luminosity, contributing between 60% in the nuclear and bulge regions and 90%
in the less active, interarm regions. Throughout the galaxy, the underlying
continuum emission from the small grains is always a smaller contribution in
the total MIR wavelength regime, peaking in the nuclear and bulge components.
The implications of using broad-band filters only to characterize the
mid-infrared emission of galaxies, a commonly used ISOCAM observation mode, are
discussed. We present the first quantitative analysis of new H-alpha and 6cm
VLA+Effelsberg radio continuum maps of M83. The distribution of the MIR
emission is compared with that of the CO, HI, R band, H-alpha and 6cm radio. A
striking correlation is found between the intensities in the two mid-infrared
filter bands and the 6cm radio continuum. To explain the tight
mid-infrared-radio correlation we propose the anchoring of magnetic field lines
in the photoionized shells of gas clouds.Comment: 22 pages, 15 figures. Accepted for publication in A&
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