中国科学院机构知识库网格系统: 检索

Two components model for TeV gamma-ray emission from extreme high-energy BL Lac objects 期刊论文 OAI收割
ASTROPHYSICS AND SPACE SCIENCE, 2021, 卷号: 366, 期号: 4, 页码: 11
作者: Dong, Q.; Zheng, Y. G.; Yang CY(杨初源)

|

收藏 | 浏览/下载：36/0 | 提交时间：2021/05/17

gamma-ray emission high-energy radiation mechanisms non-thermal BL Lacertae objects

Bipolar fluorophores based on intramolecular charge-transfer moieties of sulfone for nondoped deep blue solution-processed organic light-emitting diodes 期刊论文 OAI收割
DYES AND PIGMENTS, 2020, 卷号: 176
作者: Cao, Liang; Zhang, Lei; Wei, Qiang; Zhang, Jiasen; Chen, Dongjun

|

收藏 | 浏览/下载：90/0 | 提交时间：2020/12/16

ACTIVATED DELAYED FLUORESCENCE HIGH-EFFICIENCY EXCITED-STATE IRIDIUM(III) COMPLEXES TRIPLET ENERGY CARBAZOLE EMISSION EMITTERS PERFORMANCE DERIVATIVES

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：44/0 | 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 distances^1-3. It has long been speculated that magnetars are the engine powering repeating bursts from FRB sources^4-13, 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 flare^18-21. 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.

Constraining the X-Ray-Infrared Spectral Index of Second-timescale Flares from SGR 1935+2154 with Palomar Gattini-IR 期刊论文 OAI收割
The Astrophysical Journal, 2020, 卷号: 901, 页码: L7
作者: HXMT

|

收藏 | 浏览/下载：24/0 | 提交时间：2022/02/08

Radio transient sources Magnetars Soft gamma-ray repeaters 2008 992 1471 Astrophysics - High Energy Astrophysical Phenomena Astrophysics - Instrumentation and Methods for Astrophysics Abstract: The Galactic magnetar SGR 1935+2154 has been reported to produce the first example of a bright millisecond-duration radio burst (FRB 200428) similar to the cosmological population of fast radio bursts (FRBs). The detection of a coincident bright X-ray burst represents the first observed multiwavelength counterpart of an FRB. However, the search for similar emission at optical wavelengths has been hampered by the high inferred extinction on the line of sight. Here, we present results from the first search for second-timescale emission from the source at near-infrared (NIR) wavelengths using the Palomar Gattini-IR observing system in the J band, enabled by a novel detector readout mode that allows short exposure times of ?0.84 s with 99.9% observing efficiency. With a total observing time of ?12 hr (?47,728 images) during its 2020 outburst, we place median 3Ҡlimits on the second-timescale NIR fluence of ?18 Jy ms (13.1 AB mag). The corresponding extinction-corrected limit is ?125 Jy ms for an estimated extinction of A_J = 2.0 mag. Our observations were sensitive enough to easily detect an NIR counterpart of FRB 200428 if the NIR emission falls on the same power law as observed across its radio to X-ray spectrum. We report nondetection limits from epochs of four simultaneous X-ray bursts detected by the Insight-HXMT and NuSTAR telescopes during our observations. These limits provide the most stringent constraints to date on fluence of flares at 10¹⁴ Hz, and constrain the fluence ratio of the NIR emission to coincident X-ray bursts to R_NIR ? 0.025 (fluence index ?0.35).

An underlying clock in the extreme flip-flop state transitions of the black hole transient Swift J1658.2-4242 期刊论文 OAI收割
Astronomy and Astrophysics, 2020, 卷号: 641, 页码: A101
作者: HXMT

|

收藏 | 浏览/下载：58/0 | 提交时间：2022/02/08

accretion accretion disks black hole physics X-rays: binaries time Astrophysics - High Energy Astrophysical Phenomena Abstract:
Aims: Flip-flops are top-hat-like X-ray flux variations, which have been observed in some transient accreting black hole binary systems, and feature simultaneous changes in the spectral hardness and the power density spectrum (PDS). They occur at a crucial time in the evolution of these systems, when the accretion disc emission starts to dominate over coronal emission. Flip-flops remain a poorly understood phenomenon, so we aim to thoroughly investigate them in a system featuring several such transitions.
Methods: Within the multitude of observations of Swift J1658.2-4242 during its outburst in early 2018, we detected 15 flip-flops, enabling a detailed analysis of their individual properties and the differences between them. We present observations by XMM-Newton, NuSTAR, Astrosat, Swift, Insight-HXMT, INTEGRAL, and ATCA. We analysed their light curves, searched for periodicities, computed their PDSs, and fitted their X-ray spectra, to investigate the source behaviour during flip-flop transitions and how the interval featuring flip-flops differs from the rest of the outburst.
Results: The flip-flops of Swift J1658.2-4242 are of an extreme variety, exhibiting flux differences of up to 77% within 100 s, which is much larger than what has been seen previously. We observed radical changes in the PDS simultaneous with the sharp flux variations, featuring transitions between the quasi-periodic oscillation types C and A, which have never been observed before. Changes in the PDS are delayed, but more rapid than changes in the light curve. Flip-flops occur in two intervals within the outburst, separated by about two weeks in which these phenomena were not seen. Transitions between the two flip-flop states occurred at random integer multiples of a fundamental period of 2.761 ks in the first interval and 2.61 ks in the second. Spectral analysis reveals the high and low flux flip-flop states to be very similar, but distinct from intervals lacking flip-flops. A change of the inner temperature of the accretion disc is responsible for most of the flux difference in the flip-flops. We also highlight the importance of correcting for the influence of the dust scattering halo on the X-ray spectra.

Observation of a red Ce3+ center in SrLu2O4:Ce3+ phosphor and its potential application in temperature sensing 期刊论文 OAI收割
Dalton Transactions, 2019, 卷号: 48, 期号: 16, 页码: 5263-5270
作者: S.Zhang; Z.D.Hao; L.L.Zhang; G.H.Pan; H.J.Wu

|

收藏 | 浏览/下载：24/0 | 提交时间：2020/08/24

up-conversion luminescence,energy-transfer,emitting phosphor,photoluminescence properties,high-efficiency,behavior,thermometry,emission,stability,srsc2o4,Chemistry

Red carbon dots-based phosphors for white light-emitting diodes with color rendering index of 92 期刊论文 OAI收割
Journal of Colloid and Interface Science, 2018, 卷号: 528, 页码: 281-288
作者: Zhai, Y. C.; Wang, Y.; Li, D.; Zhou, D.; Jing, P. T.

|

收藏 | 浏览/下载：16/0 | 提交时间：2019/09/17

Carbon dots Red emission Phosphors White light-emitting diodes High color rendering index graphene quantum dots state photoluminescence fluorescence efficient nanodots energy nanoparticles luminescence origin Chemistry

X-ray emission from 424-MeV/u C ions impacting on selected target 期刊论文 OAI收割
CHINESE PHYSICS B, 2016, 卷号: 25, 页码: 5
作者: Cheng, Rui; Lei, Yu; Sun, Yuan-Bo; Wang, Yu-Yu; Wang, Xing

|

收藏 | 浏览/下载：39/0 | 提交时间：2017/03/24

High Energy Heavy Ions Ion-atom Collisions X-ray Emission

OSCILLATOR STRENGTHS OF VIBRIONIC EXCITATIONS OF NITROGEN DETERMINED BY THE DIPOLE (gamma, gamma) METHOD 期刊论文 OAI收割
ASTROPHYSICAL JOURNAL, 2016, 卷号: 819, 期号: 2, 页码: —
作者: Liu, YW; Kang, X; Xu, LQ; Ni, DD; Yang, K

收藏 | 浏览/下载：125/0 | 提交时间：2016/09/12

EXTREME-ULTRAVIOLET EMISSION ENERGY-LOSS SPECTRUM HIGH-RESOLUTION ELECTRON-IMPACT CROSS-SECTIONS ABSORPTION-SPECTRUM N-2 TRANSITIONS STATE BAND

OSCILLATOR STRENGTH MEASUREMENT FOR THE A(0-6)-X(0), C(0)-X(0), AND E(0)-X(0) TRANSITIONS OF CO BY THE DIPOLE (gamma, gamma) METHOD 期刊论文 OAI收割
ASTROPHYSICAL JOURNAL, 2015, 卷号: 807, 期号: 1, 页码: —
作者: Kang, X; Liu, YW; Xu, LQ; Ni, DD; Yang, K

收藏 | 浏览/下载：210/0 | 提交时间：2016/03/04

EXTREME-ULTRAVIOLET EMISSION POTENTIAL-ENERGY CURVES CARBON-MONOXIDE HIGH-RESOLUTION ELECTRON-IMPACT CROSS-SECTIONS VIBRATIONAL BANDS INTERSTELLAR CO VIBRONIC BANDS 115 NM