scholarly journals Multi-waveband detection of quasi-periodic pulsations in a stellar flare on EK Draconis observed by XMM-Newton

2019 ◽  
Vol 629 ◽  
pp. A147 ◽  
Author(s):  
A.-M. Broomhall ◽  
A. E. L. Thomas ◽  
C. E. Pugh ◽  
J. P. Pye ◽  
S. R. Rosen
Keyword(s):  
Energy Band ◽  
Cross Correlation ◽  
Power Spectra ◽  
High Energy ◽  
Low Energy ◽  
The Sun ◽  
Energy Bands ◽  
X Ray ◽  
High Energy Band ◽  
The Cross

Context. Quasi-periodic pulsations (QPPs) are time variations in the energy emission during a flare that are observed on both the Sun and other stars and thus have the potential to link the physics of solar and stellar flares. Aims. We characterise the QPPs detected in an X-ray flare on the solar analogue, EK Draconis, which was observed by XMM-Newton. Methods. We used wavelet and autocorrelation techniques to identify the QPPs in a detrended version of the flare. We also fitted a model to the flare based on an exponential decay combined with a decaying sinusoid. The flare is examined in multiple energy bands. Results. A statistically significant QPP is observed in the X-ray energy band of 0.2–12.0 keV with a periodicity of 76 ± 2 min. When this energy band is split, a statistically significant QPP is observed in the low-energy band (0.2–1.0 keV) with a periodicity of 73 ± 2 min and in the high-energy band (1.0–12.0 keV) with a periodicity of 82 ± 2 min. When fitting a model to the time series the phases of the signals are also found to be significantly different in the two energy bands (with a difference of 1.8 ± 0.2 rad) and the high-energy band is found to lead the low-energy band. Furthermore, the first peak in the cross-correlation between the detrended residuals of the low- and high-energy bands is offset from zero by more than 3σ (4.1 ± 1.3 min). Both energy bands produce statistically significant regions in the wavelet spectrum, whose periods are consistent with those listed above. However, the peaks are broad in both the wavelet and global power spectra, with the wavelet showing evidence for a drift in period with time, and the difference in period obtained is not significant. The offset in the first peak in the cross-correlation of the detrended residuals of two non-congruent energy bands (0.5−1.0 keV and 4.5−12.0 keV) is found to be even larger (10 ± 2 min). However, the signal-to-noise in the higher of these two energy-bands, covering the range 4.5−12.0 keV, is low. Conclusions. The presence of QPPs similar to those observed on the Sun, and other stars, suggests that the physics of flares on this young solar analogue is similar to the physics of solar flares. It is possible that the differences in the QPPs detected in the two energy bands are seen because each band observes a different plasma structure. However, the phase difference, which differs more significantly between the two energy bands than the period, could also be explained in terms of the Neupert effect. This suggests that QPPs are caused by the modulation of the propagation speeds of charged particles.

scholarly journals Unravelling strong electronic interlayer and intralayer correlations in a transition metal dichalcogenide

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
T. J. Whitcher ◽  
Angga Dito Fauzi ◽  
D. Caozheng ◽  
X. Chi ◽  
A. Syahroni ◽  
...  
Keyword(s):  
Transition Metal ◽  
Near Infrared ◽  
Theoretical Calculations ◽  
High Energy ◽  
Low Energy ◽  
Great Effort ◽  
Energy Bands ◽  
Electronic Correlations ◽  
X Ray ◽  
Wide Range

AbstractElectronic correlations play important roles in driving exotic phenomena in condensed matter physics. They determine low-energy properties through high-energy bands well-beyond optics. Great effort has been made to understand low-energy excitations such as low-energy excitons in transition metal dichalcogenides (TMDCs), however their high-energy bands and interlayer correlation remain mysteries. Herewith, by measuring temperature- and polarization-dependent complex dielectric and loss functions of bulk molybdenum disulphide from near-infrared to soft X-ray, supported with theoretical calculations, we discover unconventional soft X-ray correlated-plasmons with low-loss, and electronic transitions that reduce dimensionality and increase correlations, accompanied with significantly modified low-energy excitons. At room temperature, interlayer electronic correlations, together with the intralayer correlations in the c-axis, are surprisingly strong, yielding a three-dimensional-like system. Upon cooling, wide-range spectral-weight transfer occurs across a few tens of eV and in-plane p–d hybridizations become enhanced, revealing strong Coulomb correlations and electronic anisotropy, yielding a two-dimensional-like system. Our result shows the importance of strong electronic, interlayer and intralayer correlations in determining electronic structure and opens up applications of utilizing TMDCs on plasmonic nanolithrography.

scholarly journals ROSAT X-ray Observations of Pair Mrk474/NGC 5682

1994 ◽  
Vol 159 ◽  
pp. 366-367
Author(s):  
Hongguang Bi
Keyword(s):  
Energy Band ◽  
High Energy ◽  
Optical Observations ◽  
X Ray ◽  
High Energy Band

Like radio and optical observations of AGN/Galaxy pairs (e.g. Carilli, C & van Gorkom, J. 1992, ApJ, 399, 373), X-ray observations of the pairs can reveal absorption at high energy band, and also, possible galactic gaseous X-ray emissions that are very useful in constructing halo models. ROSAT/PSPC X-ray spectra of 4 AGNs in the well-known pairs 3C232/NGC 3067, 3C275.1/NGC 4651, 3C309.1/NGC 5832 and Mrk474/NGC 5682 are reported here. Especially, we have detected an extragalactic HI of NGC 5862 in the Mrk474 spectrum.

A Model of the Soft X-Ray Background as a Blast wave Viewed from Inside

1984 ◽  
Vol 81 ◽  
pp. 297-300
Author(s):  
Richard J. Edgar ◽  
Donald P. Cox
Keyword(s):  
Energy Band ◽  
Thermal Conduction ◽  
Ambient Medium ◽  
External Pressure ◽  
The Sun ◽  
Relative Importance ◽  
Energy Bands ◽  
X Ray ◽  
Band Ratios ◽  
X Ray Background

AbstractThe suggestion that the soft x-ray background arises In part from the Sun being inside a large (R ∼ 100 pc) supernova blastwave is examined by producing models of spherical blastwaves. Such models can produce quantitative fits to both surface brightnesses and energy band ratios (for the lowest energy bands) when t ∼ 105 yr, EO = 5 x 1050 ergs, and nO ≃ 0.004 cm-3.Such models can be generalized by varying the relative importance of such factors as thermal conduction, Coulomb heating of electrons, and external pressure; by allowing the explosions to occur In pre-existing cavities with steep density gradients, or by examining the effects of large obstructions or other anlsotroples in the ambient medium.

scholarly journals Discovery of X-Ray Emission from the Radio SNR G352.7-0.1

1998 ◽  
Vol 188 ◽  
pp. 251-252
Author(s):  
K. Kinugasa ◽  
K. Torii ◽  
H. Tsunemi ◽  
S. Yamauchi ◽  
K. Koyama ◽  
...  
Keyword(s):  
Energy Band ◽  
Galactic Plane ◽  
High Energy ◽  
Resolving Power ◽  
Major Objective ◽  
X Ray ◽  
Imaging Capability ◽  
High Energy Band ◽  
X Ray Imaging

One major objective of our ASCA Galactic Plane Survey Project (AGPSP) is, utilizing the wide and high energy band (up to 10 keV) X-ray imaging capability and the high spectral resolving power of ASCA, to search possible X-ray SNRs in the Galactic inner disk. The observation of the field including G352.7-0.1 reported in this paper, was performed on 1996 March 14 during the first AO4 survey. We report on the X-ray SNR G352.7-0.1 found in AGPSP. G352.7-0.1 is one of the radio SNRs (Green 1996), and is classified as a shell-like SNR with the size of 8' x 6'.

scholarly journals Combination of Dual-Energy X-ray Transmission and Variable Gas-Ejection for the In-Line Automatic Sorting of Many Types of Scrap in One Measurement

2021 ◽  
Vol 11 (10) ◽  
pp. 4349
Author(s):  
Tianzhong Xiong ◽  
Wenhua Ye ◽  
Xiang Xu
Keyword(s):  
High Efficiency ◽  
Nearest Neighbor ◽  
High Energy ◽  
Dual Energy ◽  
Center Of Gravity ◽  
Low Energy ◽  
Identification Accuracy ◽  
Flow Process ◽  
X Ray ◽  
Automatic Sorting

As an important part of pretreatment before recycling, sorting has a great impact on the quality, efficiency, cost and difficulty of recycling. In this paper, dual-energy X-ray transmission (DE-XRT) combined with variable gas-ejection is used to improve the quality and efficiency of in-line automatic sorting of waste non-ferrous metals. A method was proposed to judge the sorting ability, identify the types, and calculate the mass and center-of-gravity coordinates according to the shading of low-energy, the line scan direction coordinate and transparency natural logarithm ratio of low energy to high energy (R_value). The material identification was satisfied by the nearest neighbor algorithm of effective points in the material range to the R_value calibration surface. The flow-process of identification was also presented. Based on the thickness of the calibration surface, the material mass and center-of-gravity coordinates were calculated. The feasibility of controlling material falling points by variable gas-ejection was analyzed. The experimental verification of self-made materials showed that identification accuracy by count basis was 85%, mass and center-of-gravity coordinates calculation errors were both below 5%. The method proposed features high accuracy, high efficiency, and low operation cost and is of great application value even to other solid waste sorting, such as plastics, glass and ceramics.

scholarly journals A study of the cross-correlation and time lag in black hole X-ray binary XTE J1859+226

2017 ◽  
Vol 362 (7) ◽  
Author(s):  
Songpeng Pei ◽  
Guoqiang Ding ◽  
Zhibing Li ◽  
Yajuan Lei ◽  
Rai Yuen ◽  
...  
Keyword(s):  
Black Hole ◽  
Cross Correlation ◽  
Time Lag ◽  
X Ray ◽  
The Cross

scholarly journals Broadband study of blazar 1ES 1959+650 during flaring state in 2016

2018 ◽  
Vol 611 ◽  
pp. A44 ◽  
Author(s):  
S. R. Patel ◽  
A. Shukla ◽  
V. R. Chitnis ◽  
D. Dorner ◽  
K. Mannheim ◽  
...  
Keyword(s):  
High Energy ◽  
Spectral Energy ◽  
Quiescent State ◽  
Energy Bands ◽  
Energy Distributions ◽  
X Ray ◽  
Broadband Emission ◽  
June July ◽  
Power Law Index ◽  
Observation Period

Aims. The nearby TeV blazar 1ES 1959+650 (z = 0.047) was reported to be in flaring state during June–July 2016 by Fermi-LAT, FACT, MAGIC and VERITAS collaborations. We studied the spectral energy distributions (SEDs) in different states of the flare during MJD 57530–57589 using simultaneous multiwaveband data with the aim of understanding the possible broadband emission scenario during the flare. Methods. The UV-optical and X-ray data from UVOT and XRT respectively on board Swift and high energy γ-ray data from Fermi-LAT were used to generate multiwaveband lightcurves as well as to obtain high flux states and quiescent state SEDs. The correlation and lag between different energy bands was quantified using discrete correlation function. The synchrotron self-Compton (SSC) model was used to reproduce the observed SEDs during flaring and quiescent states of the source. Results. A good correlation is seen between X-ray and high energy γ-ray fluxes. The spectral hardening with increase in the flux is seen in X-ray band. The power law index vs. flux plot in γ-ray band indicates the different emission regions for 0.1–3 GeV and 3–300 GeV energy photons. Two zone SSC model satisfactorily fits the observed broadband SEDs. The inner zone is mainly responsible for producing synchrotron peak and high energy γ-ray part of the SED in all states. The second zone is mainly required to produce less variable optical-UV and low energy γ-ray emission. Conclusions. Conventional single zone SSC model does not satisfactorily explain broadband emission during observation period considered. There is an indication of two emission zones in the jet which are responsible for producing broadband emission from optical to high energy γ-rays.

scholarly journals Long-term multiwavelength view of the blazar 1ES 1218+304

2019 ◽  
Vol 489 (4) ◽  
pp. 5076-5086 ◽  
Author(s):  
K K Singh ◽  
B Bisschoff ◽  
B van Soelen ◽  
A Tolamatti ◽  
J P Marais ◽  
...  
Keyword(s):  
High Energy ◽  
Host Galaxy ◽  
Energy Bands ◽  
X Ray ◽  
Very High Energy ◽  
Γ Ray ◽  
Activity State ◽  
Low Activity ◽  
Very High

ABSTRACT In this work, we present a multiwavelength study of the blazar 1ES 1218+304 using near simultaneous observations over 10 yr during the period 2008 September 1 to 2018 August 31 (MJD 54710–58361). We have analysed data from Swift-UVOT, Swift-XRT, and Fermi-LAT to study the long term behaviour of 1ES 1218+304 in different energy bands over the last decade. We have also used the archival data from OVRO, MAXI, and Swift-BAT available during the above period. The near simultaneous data on 1ES 1218+304 suggest that the long term multiwavelength emission from the source is steady and does not show any significant change in the source activity. The optical/UV fluxes are found to be dominated by the host galaxy emission and can be modelled using the pegase code. However, the time averaged X-ray and γ-ray emissions from the source are reproduced using a single zone leptonic model with log-parabolic distribution for the radiating particles. The intrinsic very high energy γ-ray emission during a low activity state of the source is broadly consistent with the predictions of the leptonic model for blazars. We have investigated the physical properties of the jet and the mass of the supermassive black hole at the centre of the host galaxy using long term X-ray observations from the Swift-XRT which is in agreement with the value derived using blackbody approximation of the host galaxy. We also discuss the extreme nature of the source on the basis of X-ray and γ-ray observations.

Epitaxial growth of BaO and SrO with new crystal structures using mass-separated low-energy O+ beams

1993 ◽  
Vol 8 (2) ◽  
pp. 321-323 ◽  
Author(s):  
Ryusuke Kita ◽  
Takashi Hase ◽  
Hiromi Takahashi ◽  
Kenichi Kawaguchi ◽  
Tadataka Morishita
Keyword(s):  
Lattice Constant ◽  
High Energy ◽  
Low Energy ◽  
Diffraction Reflection ◽  
High Energy Electron ◽  
Bulk Crystals ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Cubic Structure

The growth of BaO and SrO on SrTiO3(100) substrates using mass-separated low-energy (50 eV) O+ beams has been studied using x-ray diffraction, reflection high-energy electron diffraction, and high-resolution transmission electron microscopy. It was found that the BaO and SrO films have been epitaxially grown with new structures different from those of corresponding bulk crystals: The BaO films have a cubic structure with a lattice constant of 4.0 Å, and the SrO films have a tetragonal structure with a lattice constant of a = 3.7 Å parallel to the substrate and with c = 4.0 Å normal to the substrate.

scholarly journals Nonthermal processes in microquasars

2010 ◽  
Vol 6 (S275) ◽  
pp. 215-223
Author(s):  
Valentí Bosch-Ramon
Keyword(s):  
Thermal Emission ◽  
High Energy ◽  
Energy Bands ◽  
X Ray ◽  
Radio Jets ◽  
Extended Radio ◽  
Very High Energy ◽  
X Ray Binaries ◽  
Very High ◽  
Negligible Contribution

AbstractMicroquasars are X-ray binaries that show extended radio jets. These jets can accelerate particles up to relativistic energies that produce non-thermal emission from radio to TeV, and could also make a non-negligible contribution to the galactic CRs in some energy ranges. The orbital motion and compactness of these sources allow the study of high-energy astrophysical phenomena in extreme conditions that change in accessible timescales. In this work, I briefly discuss the production of broadband non-thermal emission in microquasars, putting special emphasis on the high- and the very high-energy bands.

Sign in / Sign up

Export Citation Format

Share Document