GX 3012 A High Mass Xray Binary 31 Overview

GX 301-2 (4U 1223-62) is a pulsar with a 680 s rotation period, in a 41.5 day eccentric orbit ( 43 ). The mass function is 31.8 Mq, making the minimum companion mass 35 Mq for a 1.4 Mq neutron star. The companion, Wray 977, has a B2 Iae spectral classification ( 39 ). The orbital parameters of GX 301-2, updated with the BATSE observations ( 11 ) are as follows. Porb 41.498days, axsin(i) 368.3 lt-s, eccentricity e 0.462, longitude of periastron w 310 , time of periastron passage T0 MJD48802.79....

Newer Investigatory Approaches 41 Simulated Annealing

Our WD2007 implementation of simulated annealing (SA) is based on the Corana, et al. (1987) simulated annealing algorithm for multimodal and robust optimization as implemented and modified by Goffe, et al. (1994). The implementation also contains a multimodal example from Judge, et al. (1985). Simulated annealing is a function-evaluation based improvement method often used to solve optimization problems. It is capable of escaping local minima and can, in principle, find the global optimium...

The Hard State

In the hard state, the accretion-disk component is either absent or it is modified in the sense of appearing comparatively cool and large. The hard state has been clearly associated with the presence of a steady type of radio jet. Transitions to either the thermal state or an SPL state effectively quench this radio emission. Thus, the presence of the jet is an important defining feature of this state. The definition of the hard state is based on three X-ray conditions (1) f < 0.2, i.e. the...

BNS Astrophysics with GWs

As discussed above, we expect that future GW observations will begin to probe the interesting range of BNS inspiral rates over the next several years when advanced detectors like Advanced LIGO begin running at the anticipated sensitivity, we expect BNS inspirals to be routinely detected, which will give a direct measurement of the true BNS merger rate as well as observed properties (such as the distribution of masses of the companions) of the population. Such constraints on the population of...

References

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Hercules X1 a Low Mass Xray Binary 21 Overview

Eclipse Low Mass Ray Binaries

Her X-1 HZ Her is a low-mass accretion-powered pulsar system exhibiting a great variety of phenomena. This eclipsing system contains a 1.24 second period pulsar in a 1.7 day circular orbit around its optical companion HZ Her. This binary system also displays a longer 35-day cycle that was first discovered as a repeating pattern of High and Low X-ray flux states ( 8 ). A Main High state, lasting about ten days, and Short High state, lasting about five days, are each followed by a ten day long...

Conclusions

Re-examination of global constraints on common envelope evolution leads to the following conclusions Both energy and angular momentum conservation pose strict limits on the outcome of common envelope evolution. Of these two constraints, however, energy conservation is much the more demanding. The recent study of close double white dwarf formation by Nelemans & Tout 35 shows clearly that their progenitors can have lost little orbital energy through their first episodes of mass transfer....

Comparisons among S1 S5 Runs LIGOG06000902Z

LLO' 4km-S1 (2002 SB7) LLO 4km-S2 (2003 0301) LHO 4km-S3 (2001 01 04)7T LHO 4km-S4 (2005 02 26) LLO 4km-S5 (2006 06 04) LIGO I SRD Goal, 4km LLO' 4km-S1 (2002 SB7) LLO 4km-S2 (2003 0301) LHO 4km-S3 (2001 01 04)7T LHO 4km-S4 (2005 02 26) LLO 4km-S5 (2006 06 04) LIGO I SRD Goal, 4km Fig. 3. Interferometer noise in each of the five LIGO science runs. The solid thick black curve is design goal of LIGO. There are two changes of slope indicated by dashed thick black lines. These correspond to changes...

W

Light and radial velocities were fitted with the physical model of Wilson (1979, 1990), with results given in Sect. 2.1. Star spots (hot or cool) were invoked to handle light curve asymmetries. We exploited the benefits of the bandpass-based stellar atmosphere approach outlined in Van Hamme & Wilson (2003). Time instead of phase was used as the independent variable and ephemeris parameters (reference epoch To, period P and the period time rate of change dP dt) were determined as part of the...

Vela X1 GP Vel Results from RXTE Data

Filter Orbital

The binary composed of the 283s X-ray pulsar Vela X-1 and the B0.5Ib supergiant GP Velorum can serve as an example of DDE. The supergiant's optical light curves show essentially ellipsoidal variation that surely must be 2 Of course the actual star-size parameter is a surface potential that can be converted to local or mean Ro a. 3 The situation can be more difficult if the optical star's edge is not sharp, as with atmospheric or wind eclipses. due to dynamical tides driven by the eccentrically...

Matched Filtering and Chi Squared Veto

When the expected signal is known in advance and the noise is Gaussian and stationary, the optimal linear search algorithm is matched filtering 79 . The idea behind matched filtering is to take the signal, and data segments of the same length as the signal, and treat them as members of a vector space. As with any two vectors in a vector space, the degree to which the signal and a data vector overlap is calculated using an inner product. 5 The detectors in Washington are somewhat misaligned with...

N 1R 3DS

With the source position 3 known, equation (9) can be used to compute the distances of closest approach in the lens plane for each of the images. The distances of closest approach (1,2 are then translated into the angular image positions 012. The closest approach distances, the orbital radius and 1 also provide the light travel distances D1,2 which determine the difference in angular orientation of the two beams (i.e. the angle 7). Here it is assumed that the time difference required for the...

Getting to the Bottom of it Software for Eclipsing Binaries Analysis

KM99 provides an overview of existing software. In this section, we comment on four software programs which have seen active developments over the years since then the original Wilson-Devinney program (WD), WD2007 by Josef Kallrath, Bradstreet's Binary Maker, and PHOEBE. 3.1 The BASE Software The Wilson-Devinney Program (WD) This program is continually improved and new versions are produced aperio-dically. Major releases appeared in 1971 (Wilson & Devinney 1971), 1979 (Wilson 1979), 1998,...

Continuum Fitting

Among the several spectral states of accreting black holes, the thermal state ( 4.1) is of particular interest. A feature of this state is that the X-ray spectrum is dominated by a soft blackbody-like component that is emitted by (relatively) cool optically-thick gas, presumed to be located in the accretion disk. A minor nonthermal (power-law) component in the spectrum, possibly from a hot optically thin corona, is energetically unimportant. The thermal state is believed to match very closely...

Recent Infrared Spectroscopic Observations of Cataclysmic Variables

CVs contain three main emitting components, the white dwarf, the secondary star, and the accretion disk (in the weak magnetic systems) or accretion column region (in the polars). In the optical part of the electromagnetic spectrum, the accretion disk or column is often the dominant light source. Thus, studies of the component stars in a CV are limited to UV or shorter wavelengths (for the white dwarf) and the IR for the secondary. Even these non-optical bands are not perfect as the accretion...