10,570 research outputs found
Determination of mass of IGR J17091-3624 from "Spectro-Temporal" variations during onset-phase of the 2011 outburst
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 () - QPO frequency ()
correlation, QPO frequency () - 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 - 13.7
M. Considering each individual estimate and taking the lowermost and
uppermost bounds among all three methods, we get a mass range of 8.7
M - 15.6 M 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
Anti-isospectral Transformations, Orthogonal Polynomials and Quasi-Exactly Solvable Problems
We consider the double sinh-Gordon potential which is a quasi-exactly
solvable problem and show that in this case one has two sets of Bender-Dunne
orthogonal polynomials . We study in some detail the various properties of
these polynomials and the corresponding quotient polynomials. In particular, we
show that the weight functions for these polynomials are not always positive.
We also study the orthogonal polynomials of the double sine-Gordon potential
which is related to the double sinh-Gordon case by an anti-isospectral
transformation. Finally we discover a new quasi-exactly solvable problem by
making use of the anti-isospectral transformation.Comment: Revtex, 19 pages, No figur
Incommensurate, helical spin ground states on the Hollandite lattice
We present a model of classical Heisenberg spins on a Hollandite lattice,
which has been developed to describe the magnetic properties of
-MnO and similar compounds. The model has nearest neighbor
interacting spins, however the strength and the sign of spin-spin interactions
is anisotropic and depends on the nature of the bonds. Our analysis shows that
the Hollandite lattice supports four different incommensurate and helical
magnetic ground states depending on the relative strengths and signs of
spin-spin interactions. We show that the incommensurate helical ground states
appear due to the geometrical frustration present in the model. We demonstrate
that each of the four helical incommensurate magnetic phases are continuously
connected to four different collinear antiferromagnetic ground states as the
strength of spin-spin interaction along some bonds is increased. The present
results give support to the presence of helical states that have been
previously suggested experimentally for Hollandite compounds. We provide an
in-depth analysis of the magnetic form factors for each helical phase and
describe how it could be used to identify each of these phases in neutron
diffraction experiments.Comment: 11 pages, 8 figure
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