arXiv subjects

Shifeng Huang

Publications and source records attributed to Shifeng Huang.

21 records · Page 2Linked to original sources

arXiv2021

A possible tidal disruption event candidate in the black hole binary system of OJ 287

The BL Lacertae OJ 287 is a supermassive black holes binary (SMBHB) system with complex physics of its irregular flares. During 2016 October -- 2017 April period, a surprising outburst in the X-ray, UV and optical bands was detected, while no variability was seen in the $γ$-ray light curve. During the outburst, the X-ray light curves were dominated by the soft X-rays, whose peak in the luminosity was $\sim$ $10^{46}\text{erg}~\text{s}^{-1}$ -- more than 10 times higher than the mean level before the outburst -- and a "softer-when-brighter" phenomenon was exhibited. These above phenomena have been reported by some previous works. The hardness ratio showed negligible evolution with flare time and soft X-ray luminosity. Critically, the luminosity of the soft X-rays decayed following a power law of $t^{-5/3}$ which occurs in most tidal disruption events (TDEs), and similar trend can be seen in UV and optical bands during the soft X-ray declining period. Helium and oxygen narrow emission lines are strengthened prominently in the optical spectra of postoutburst epochs, that could be attributed to the surrounding gas appeared due to TDE. We discuss three possible origins of the event, including the jet's precession, the aftereffect of the black hole-disk impaction and the TDE. Our results show that the TDE is the more likely scenario to explain the outburst.

astro-ph.HE↗

arXiv2021

The X-ray outburst of PG 1553+113: A precession effect of two jets in the supermassive black hole binary system

Blazar PG 1553+113 is thought to be a host of supermassive black hole binary (SMBHB) system. A 2.2-year quasi-periodicity in the $γ$-ray light curve was detected, possibly result of jet precession. Motivated by the previous studies based on the $γ$-ray data, we analyzed the X-ray light curve and spectra observed during 2012--2020. The 2.2-year quasi-periodicity might be consistent with the main-flare recurrence in the X-ray light curve. When a weak rebrightening in the $γ$-ray was observed, a corresponding relatively strong brightening in the X-ray light curve can be identified. The "harder-when-brighter" tendency in both X-ray main and weak flares was shown, as well as a weak "softer-when-brighter" behavior for the quiescent state. We explore the possibility that the variability in the X-ray band can be interpreted with two-jet precession scenario. Using the relation between jets and accretion discs, we derive the primary black hole mass $\simeq 3.47\times 10^8M_{\odot}$ and mass of the secondary one $\simeq 1.40\times 10^8M_{\odot}$, and their mass ratio $\sim 0.41$.

astro-ph.HE↗

arXiv2021

Recall and Learn: A Memory-augmented Solver for Math Word Problems

In this article, we tackle the math word problem, namely, automatically answering a mathematical problem according to its textual description. Although recent methods have demonstrated their promising results, most of these methods are based on template-based generation scheme which results in limited generalization capability. To this end, we propose a novel human-like analogical learning method in a recall and learn manner. Our proposed framework is composed of modules of memory, representation, analogy, and reasoning, which are designed to make a new exercise by referring to the exercises learned in the past. Specifically, given a math word problem, the model first retrieves similar questions by a memory module and then encodes the unsolved problem and each retrieved question using a representation module. Moreover, to solve the problem in a way of analogy, an analogy module and a reasoning module with a copy mechanism are proposed to model the interrelationship between the problem and each retrieved question. Extensive experiments on two well-known datasets show the superiority of our proposed algorithm as compared to other state-of-the-art competitors from both overall performance comparison and micro-scope studies.

cs.CL↗