16,107 research outputs found

    Determination of mass of IGR J17091-3624 from "Spectro-Temporal" variations during onset-phase of the 2011 outburst

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    The 2011 outburst of the black hole candidate IGR J17091-3624 followed the canonical track of state transitions along with the evolution of Quasi-Periodic Oscillation (QPO) frequencies before it began exhibiting various variability classes similar to GRS 1915+105. We use this canonical evolution of spectral and temporal properties to determine the mass of IGR J17091-3624, using three different methods, viz : Photon Index (Γ\Gamma) - QPO frequency (ν\nu) correlation, QPO frequency (ν\nu) - Time (day) evolution and broadband spectral modelling based on Two Component Advective Flow. We provide a combined mass estimate for the source using a Naive Bayes based joint likelihood approach. This gives a probable mass range of 11.8 M_{\odot} - 13.7 M_{\odot}. Considering each individual estimate and taking the lowermost and uppermost bounds among all three methods, we get a mass range of 8.7 M_{\odot} - 15.6 M_{\odot} with 90% confidence. We discuss the probable implications of our findings in the context of two component accretion flow.Comment: 10 pages, 5 figures (4 in colour), 2 tables. Accepted for publication in Ap

    A new approach to particle based smoothed marginal MAP

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    We present here a new method of finding the MAP state estimator from the weighted particles representation of marginal smoother distribution. This is in contrast to the usual practice, where the particle with the highest weight is selected as the MAP, although the latter is not necessarily the most probable state estimate. The method developed here uses only particles with corresponding filtering and smoothing weights. We apply this estimator for finding the unknown initial state of a dynamical system and addressing the parameter estimation problem

    PT-Symmetric, Quasi-Exactly Solvable matrix Hamiltonians

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    Matrix quasi exactly solvable operators are considered and new conditions are determined to test whether a matrix differential operator possesses one or several finite dimensional invariant vector spaces. New examples of 2×22\times 2-matrix quasi exactly solvable operators are constructed with the emphasis set on PT-symmetric Hamiltonians.Comment: 14 pages, 1 figure, one equation corrected, results adde

    Manifestation of helical edge states as zero-bias magneto-tunneling-conductance peaks in non-centrosymmetric superconductors

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    Helical edge states exist in the mixed spin-singlet and -triplet phase of a noncentrosymmetric superconductor (NCSS) when the pair amplitude (PA) in the negative helicity band, Δ\Delta_-, is smaller than the PA in the positive helicity band, Δ+\Delta_+, i.e., when the PA in the triplet component is more than the same in the singlet component. We numerically determine energies of these edge states as a function of γ=Δ/Δ+\gamma = \Delta_-/\Delta_+. The presence of these edge states is reflected in the tunneling process from a normal metal to an NCSS across a bias energy eVeV: (i) Angle resolved spin conductance (SC) obeying the symmetry gs(ϕ)=gs(ϕ)g_s(\phi) =-g_s(-\phi) shows peaks when the bias energy equals the available quasiparticle edge state energy provided eVΔ|eV| \lesssim \Delta_-. (ii) The total SC, GsG_s, is zero but modulates with eVeV for finite magnetic field HH. (iii) The zero bias peaks of GsG_s and total charge conductance, GcG_c, at finite HH split into two at finite eVeV for moderate HH. (iv) At zero bias, GcG_c and GsG_s increase with HH and show peaks at HγH0|H|\sim \gamma H_0 where H0H_0 is a characteristic field.Comment: minor changes; one figure is adde
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