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Unravelling the nature of the dual AGN in the galaxy pair system IRAS 05589+2828 and 2MASX J06021107 + 2828382 期刊论文  OAI收割
Monthly Notices of the Royal Astronomical Society, 2022, 卷号: 516, 期号: 4, 页码: 5270
作者:  Benítez, E.;  Jiménez-Bailón, E.;  Negrete, C. A.;  Ruschel-Dutra, D.;  Rodríguez-Espinosa, J. M.
  |  收藏  |  浏览/下载：27/0  |  提交时间：2023/11/10
Spiral arms in broad-line regions of active galactic nuclei. I. Reverberation and differential interferometric signals of tightly wound cases 期刊论文  OAI收割
ASTRONOMY & ASTROPHYSICS, 2022, 卷号: 666, 页码: A86
作者:  Wang, Jian-Min;  Du, Pu;  Songsheng, Yu-Yang;  Li, Yan-Rong
  |  收藏  |  浏览/下载：7/0  |  提交时间：2023/11/09
The Origin of Radio Emission in Black Hole X-ray Binaries 期刊论文  OAI收割
Galaxies, 2021, 卷号: 9, 期号: 4, 页码: 78
作者:  Liu, Xiang;  Chang, Ning;  Wang, Xin;  Yuan, Qi
  |  收藏  |  浏览/下载：36/0  |  提交时间：2022/06/30
Broadband Multi-wavelength Properties of M87 during the 2017 Event Horizon Telescope Campaign 期刊论文  OAI收割
The Astrophysical Journal, 2021, 卷号: 911, 页码: L11
作者:  Algaba, J. C.;  Anczarski, J.;  Asada, K.;  Baloković, M.;  Chandra, S.
  |  收藏  |  浏览/下载：59/0  |  提交时间：2022/06/30
Synchronous X-ray/Optical QPOs from the Black Hole LMXB MAXI J1820+070 期刊论文  OAI收割
Monthly Notices of the Royal Astronomical Society, 2021
作者:  HXMT
  |  收藏  |  浏览/下载：53/0  |  提交时间：2022/02/08
black hole physics  Low Mass X-ray Binaries  accretion  accretion  discs  stars: individual (MAXI J1820+070)  Astrophysics - High Energy  Astrophysical Phenomena  Abstract: We present high-speed optical photometry from SAAO and SALT on the black hole LMXB MAXI J1820+070 (ASSASN-18ey), some of it simultaneous with NICER, Swift and Insight-HXMT X-ray coverage. We detect optical Quasi-Periodic Oscillations (QPOs) that move to higher frequencies as the outburst progresses, tracking both the frequency and evolution of similar X-ray QPOs previously reported. Correlated X-ray/optical data reveal a complex pattern of lags, including an anti-correlation and a sub-second lag that evolve over the first few weeks of outburst. They also show correlated components separated by a lag equal to the QPO period roughly centered on zero lag, implying that the inter-band variability is strongly and consistently affected by these QPOs at a constant phase lag of roughly ±Ю The synchronisation of X-ray and optical QPOs indicates that they must be produced in regions physically very close to each other  we thus propose that they can be explained by a precessing jet model, based on analogies with V404 Cyg and MAXI J1348-630.  
Periodicity Search on X-Ray Bursts of SGR J1935+2154 Using 8.5 yr of Fermi/GBM Data 期刊论文  OAI收割
The Astrophysical Journal, 2021, 卷号: 923, 页码: L30
作者:  HXMT
  |  收藏  |  浏览/下载：23/0  |  提交时间：2022/02/08
Detection of Flare Multiperiodic Pulsations in Mid-ultraviolet Balmer Continuum, Lyl Hard X-Ray, and Radio Emissions Simultaneously 期刊论文  OAI收割
The Astrophysical Journal, 2021, 卷号: 921, 页码: 179
作者:  HXMT
  |  收藏  |  浏览/下载：29/0  |  提交时间：2022/02/08
Solar flares  Solar oscillations  Solar ultraviolet emission  Solar  x-ray emission  Solar radio emission  1496  1515  1533  1536  1522  Astrophysics - Solar and Stellar Astrophysics  Abstract: Quasi-periodic pulsations (QPPs), which usually appear as temporal pulsations of the total flux, are frequently detected in the light curves of solar/stellar flares. In this study, we present the investigation of nonstationary QPPs with multiple periods during the impulsive phase of a powerful flare on 2017 September 6, which were simultaneously measured by the Hard X-ray Modulation Telescope (Insight-HXMT), as well as the ground-based BLENSW. The multiple periods, detected by applying a wavelet transform and Lomb-Scargle periodogram to the detrended light curves, are found to be ~20-55 s in the Ly`and mid-ultraviolet Balmer continuum emissions during the flare impulsive phase. Similar QPPs with multiple periods are also found in the hard X-ray emission and low-frequency radio emission. Our observations suggest that the flare QPPs could be related to nonthermal electrons accelerated by the repeated energy release process, i.e., triggering of repetitive magnetic reconnection, while the multiple periods might be modulated by the sausage oscillation of hot plasma loops. For the multiperiodic pulsations, other generation mechanisms could not be completely ruled out.  
No pulsed radio emission during a bursting phase of a Galactic magnetar 期刊论文  OAI收割
Nature, 2020, 卷号: 587, 页码: 63-65
作者:  HXMT
  |  收藏  |  浏览/下载：48/0  |  提交时间：2022/02/08
Astrophysics - High Energy Astrophysical Phenomena  Abstract: Fast radio bursts (FRBs) are millisecond-duration radio transients of unknown physical origin observed at extragalactic distances1-3. It has long been speculated that magnetars are the engine powering repeating bursts from FRB sources4-13, but no convincing evidence has been collected so far14. Recently, the Galactic magnetar SRG 1935+2154 entered an active phase by emitting intense soft íray bursts15. One FRB-like event with two peaks (FRB 200428) and a luminosity slightly lower than the faintest extragalactic FRBs was detected from the source, in association with a soft íray/hard-X-ray flare18-21. Here we report an eight-hour targeted radio observational campaign comprising four sessions and assisted by multi-wavelength (optical and hard-X-ray) data. During the third session, 29 soft-íray repeater (SGR) bursts were detected in íray energies. Throughout the observing period, we detected no single dispersed pulsed emission coincident with the arrivals of SGR bursts, but unfortunately we were not observing when the FRB was detected. The non-detection places a fluence upper limit that is eight orders of magnitude lower than the fluence of FRB 200428. Our results suggest that FRB-SGR burst associations are rare. FRBs may be highly relativistic and geometrically beamed, or FRB-like events associated with SGR bursts may have narrow spectra and characteristic frequencies outside the observed band. It is also possible that the physical conditions required to achieve coherent radiation in SGR bursts are difficult to satisfy, and that only under extreme conditions could an FRB be associated with an SGR burst.  
Introducing a special collection of papers in the Journal of High Energy Astrophysics on the Early Results of China's 1st X-ray Astronomy Satellite: Insight-HXMT 期刊论文  OAI收割
Journal of High Energy Astrophysics, 2020, 卷号: 27, 页码: 51-52
作者:  HXMT
  |  收藏  |  浏览/下载：53/0  |  提交时间：2022/02/08
Astrophysics - High Energy Astrophysical Phenomena  Abstract: Insight-HXMT is the first Chinese X-ray astronomical mission, launched successfully on June 15, 2017, from China's Jiuquan Satellite Launch Center. Insight-HXMT was designed to have a broad energy coverage in X-rays, from 1-250 keV, with excellent timing and adequate energy resolution at soft X-rays, and the largest effective area at hard X-rays. This allows, in particular, to observe bright sources like X-ray binaries (XRBs) in their bright/outburst states with high cadence and high statistics at hard and soft X-rays at once. It was then expected that the Insight-HXMT mission will bring us new insights regarding the characteristics of several source classes. Examples include characterizing High-Mass X-ray Binaries (HMXBs) and the outburst evolution of Low-Mass X-ray Binaries (LMXBs). For instance, in HMXB systems, the region around their Alfven radius that is responsible to determine whether accretion or propeller occurs, or the region around the NS magnetic pole where the intense X-rays are supposed to be produced are specially appealing targets of study. For the LMXBs, the evolution the outburst and the properties of the compact objects themselves are obvious priority targets for Insight-HXMT. Due to the broad coverage in energy, Insight-HXMT is specially well suited to study the influence of thermonuclear (type-I) X-ray bursts upon the surrounding environment.  
The braking index of PSR B0540-69 and the associated pulsar wind nebula emission after spin-down rate transition 期刊论文  OAI收割
Monthly Notices of the Royal Astronomical Society, 2020, 卷号: 494, 页码: 1865-1870
作者:  HXMT
  |  收藏  |  浏览/下载：61/0  |  提交时间：2022/02/08
stars: magnetic field  stars: neutron  pulsars: general  Astrophysics  - High Energy Astrophysical Phenomena  Abstract: In 2011 December, PSR B054-69 experienced a spin-down rate transition (SRT), after which the spin-down power of the pulsar increased by $\sim 36{{\ \rm per\ cent}}$. About 1000 d after the SRT, the X-ray luminosity of the associated pulsar wind nebula (PWN) was found to brighten by $32\pm 8{{\ \rm per\ cent}}$. After the SRT, the braking index n of PSR B0540-69 changes from n = 2.12 to 0.03 and then keeps this value for about five years before rising to n = 0.9 in the following years. We find that most of the current models have difficulties in explaining the measured braking index. One exceptive model of the braking index evolution is the increasing dipole magnetic field of PSR B0540-69. We suggest that the field increase may result from some instabilities within the pulsar core that enhance the poloidal component at the price of toroidal component of the magnetic field. The increasing dipole magnetic field will result in the X-ray brightening of the PWN. We fit the PWN X-ray light curve by two models: one assumes a constant magnetic field within the PWN during the brightening and the other assumes an enhanced magnetic field proportional to the energy density of the PWN. It appears that the two models fit the data well, though the later model seems to fit the data a bit better. This provides marginal observational evidence that magnetic field in the PWN is generated by the termination shock. Future high-quality and high-cadence data are required to draw a solid conclusion.