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Renyi Ma

Publications and source records attributed to Renyi Ma.

29 records · Page 2Linked to original sources
arXiv2012

Modeling the Spectrum of IGR J17177-3656

The correlation between radio and X-ray luminosity in the hard state of black hole X-ray binaries is important for unveiling the relation between the accretion flow and the jets. In this paper, we have modeled the quasi-simultaneous multi-band observations of a recently discovered transient X-ray source, IGR J17177-3656. It is found that the source is probably an outlier following the steep radio/X-ray correlation rather than an outlier in the transition region as suggested by Paizis et al. (2011). It is also found that the multi-band spectrum can be successfully modeled by the luminous hot accretion flow (LHAF) but less likely by the advection dominated accretion flow (ADAF). Our results support the point that LHAF can explain the steep radio/X-ray correlation.

astro-ph.HE↗
arXiv2012

Complex manifolds with generating tangent bundles

Let $M$ be a close complex manifold and $TM$ its holomorphic tangent bundle. We prove that if the global holomorphic sections of tangent bundle generate each fibre, then $M$ is a complex homogeneous manifold. Our proof depends on the complex version of Chow-Rashevskii theorem in Carnot-Caratheodory spaces.

math.AG↗
arXiv2011

Nonthermal Radiation from Type Ia Supernova Remnants

We present calculations of expected continuum emissions from Sedov-Taylor phase Type Ia supernova remnants (SNRs), using the energy spectra of cosmic ray (CR) electrons and protons from nonlinear diffusive shock acceleration (DSA) simulations. A new, general-purpose radiative process code, Cosmicp, was employed to calculate the radiation expected from CR electrons and protons and their secondary products. These radio, X-ray and gamma-ray emissions are generally consistent with current observations of Type Ia SNRs. The emissions from electrons in these models dominate the radio through X-ray bands. Decays of π^0 s from p-p collisions mostly dominate the gamma-ray range, although for a hot, low density ISM case (n_{ISM}=0.003 cm^{-3}), the pion decay contribution is reduced sufficiently to reveal the inverse Compton contribution to TeV gamma-rays. In addition, we present simple scalings for the contributing emission processes to allow a crude exploration of model parameter space, enabling these results to be used more broadly. We also discuss the radial surface brightness profiles expected for these model SNRs in the X-ray and gamma-ray bands.

astro-ph.HE↗
arXiv2008

A simplified global solution for an advection-dominated accretion flow

When we model black hole accretion sources such as active galactic nuclei and black hole X-ray binaries as advection-dominated accretion flows (ADAFs), it is neccesary to use the global solution to the equations rather than the simpler self-similar solution, since the latter is inaccurate in the region near the black hole where most of the radiation is emitted. However, technically, it is a difficult task to calculate the global solution because of the transonic nature of the flow, which makes it a two-point boundary value problem. In this paper we propose a simplified approach for calculating the global ADAF solution. We replace the radial momentum equation by a simple algebraic relation between the angular velocity of the gas and the Keplerian angular velocity, while keeping all other equations unchanged. It is then easy to solve the differential energy equations to obtain an approximate global solution. By adjusting the free parameters, we find that for almost any accretion rate and for $α=0.1-0.3$ we can get good simplified global solutions. The predicted spectra from the approximate solutions are very close to the spectra obtained from the true global solutions.

astro-ph↗
arXiv2004

On Existences Of Periodic Orbits For Hamilton Systems

We prove that either there exists at least one hamilton periodic orbit in a given energy close smooth hypersurface or there exist at least two hamilton periodic orbits in a near-by energy close smooth hypersurface. More general results also hold.

math.SG↗
arXiv2003

J-holomorphic Disks and Lagrangian Squeezing

We define an invariant $l(M,W,ω)$ for Lagrangian submanifold and prove that if the Lagrangian submanifold is embedded in the ball of radius $r_0$, then $l(M,W,Ω)$ must be smaller than $4πt_0^2$. This improves Gromov's Lagrangian embedding theorem.

math.SG↗
arXiv2000

Pre-Lagrangian Submanifolds in Contact Manifolds

In this paper we prove that there does not exists any closed Pre-Lagrangian submanifolds in any closed contact manifolds by using the $J-$holomorphic curves and Gromov's nonlinear Fredholm alternative.

math.DG↗