scholarly journals X-ray, UV, and optical time delays in the bright Seyfert galaxy Ark 120 with co-ordinated Swift and ground-based observations

2020 ◽  
Vol 494 (1) ◽  
pp. 1165-1179
Author(s):  
A P Lobban ◽  
S Zola ◽  
U Pajdosz-Śmierciak ◽  
V Braito ◽  
E Nardini ◽  
...  
Keyword(s):  
Time Delays ◽  
Seyfert Galaxy ◽  
Optical Observations ◽  
X Ray ◽  
Cross Correlation Analysis ◽  
All Optical ◽  
Wavelength Emission ◽  
Optical Time ◽  
Robotic Telescope ◽  
Short Time

ABSTRACT We report on the results of a multiwavelength monitoring campaign of the bright, nearby Seyfert galaxy Ark 120, using a ∼50-d observing programme with Swift and a ∼4-month co-ordinated ground-based observing campaign, pre-dominantly using the Skynet Robotic Telescope Network. We find Ark 120 to be variable at all optical, UV, and X-ray wavelengths, with the variability observed to be well correlated between wavelength bands on short time-scales. We perform cross-correlation analysis across all available wavelength bands, detecting time delays between emission in the X-ray band and the Swift V, B, and UVW1 bands. In each case, we find that the longer wavelength emission is delayed with respect to the shorter wavelength emission. Within our measurement uncertainties, the time delays are consistent with the τ ∼ λ4/3 relation, as predicted by a disc reprocessing scenario. The measured lag centroids are τcent = 11.90 ± 7.33, 10.80 ± 4.08, and 10.60 ± 2.87 d between the X-ray and V, B, and UVW1 bands, respectively. These time delays are longer than those expected from standard accretion theory and, as such, Ark 120 may be another example of an active galaxy whose accretion disc appears to exist on a larger scale than predicted by the standard thin-disc model. Additionally, we detect further inter-band time delays: most notably between the ground-based I and B bands (τcent = 3.46 ± 0.86 d), and between both the Swift XRT and UVW1 bands and the I band (τcent = 12.34 ± 4.83 and 2.69 ± 2.05 d, respectively), highlighting the importance of co-ordinated ground-based optical observations.

scholarly journals Optical/X-ray correlations during the V404 Cygni June 2015 outburst

2018 ◽  
Vol 620 ◽  
pp. A110 ◽  
Author(s):  
J. Alfonso-Garzón ◽  
C. Sánchez-Fernández ◽  
P. A. Charles ◽  
J. M. Mas-Hesse ◽  
P. Gandhi ◽  
...  
Keyword(s):  
Time Delays ◽  
Cross Correlation ◽  
Light Curves ◽  
Synchrotron Emission ◽  
X Rays ◽  
X Ray ◽  
Physical Mechanisms ◽  
Cross Correlation Analysis ◽  
All Optical ◽  
Negative Time

Context. We present a multiwavelength analysis of the simultaneous optical and X-ray light curves of the microquasar V404 Cyg during the June 2015 outburst. Aims. We have performed a comprehensive analysis of all the INTEGRAL/IBIS, JEM–X, and OMC observations during the brightest epoch of the outburst, along with complementary NuSTAR, AAVSO, and VSNET data, to examine the timing relationship between the simultaneous optical and X-ray light curves, in order to understand the emission mechanisms and physical locations. Methods. We have identified all optical flares that have simultaneous X-ray observations, and performed a cross-correlation analysis to estimate the time delays between the optical and soft and hard X-ray emission. We also compared the evolution of the optical and X-ray emission with the hardness ratios. Results. We have identified several types of behaviour during the outburst. On many occasions, the optical flares occur simultaneously with X-ray flares, but at other times, positive and negative time delays between the optical and X-ray emission are measured. Conclusions. We conclude that the observed optical variability is driven by different physical mechanisms, including reprocessing of X-rays in the accretion disc and/or the companion star, interaction of the jet ejections with surrounding material or with previously ejected blobs, and synchrotron emission from the jet.

scholarly journals Modeling time delays in the X-ray spectrum of the Seyfert galaxy MCG-6-30-15

2007 ◽  
Vol 466 (3) ◽  
pp. 865-873 ◽  
Author(s):  
R. W. Goosmann ◽  
B. Czerny ◽  
V. Karas ◽  
G. Ponti
Keyword(s):  
Time Delays ◽  
Seyfert Galaxy ◽  
X Ray

scholarly journals Correlation and time delays of the X-ray and optical emission of the Seyfert Galaxy NGC 3783

2009 ◽  
Vol 397 (4) ◽  
pp. 2004-2014 ◽  
Author(s):  
P. Arévalo ◽  
P. Uttley ◽  
P. Lira ◽  
E. Breedt ◽  
I. M. McHardy ◽  
...  
Keyword(s):  
Time Delays ◽  
Seyfert Galaxy ◽  
Optical Emission ◽  
X Ray

Recent Optical Observations of the X-Ray Source H0139-68; an AM-Herculis Type Binary System

1982 ◽  
Vol 4 (4) ◽  
pp. 425-428
Author(s):  
A.J. Pickles ◽  
N. Visvanathan
Keyword(s):  
Binary System ◽  
Low Energy ◽  
Optical Observations ◽  
Short Time Scale ◽  
Optical Identification ◽  
Time Resolved ◽  
X Ray ◽  
Short Time ◽  
Energy Detectors ◽  
Optical Spectrophotometry

The soft X-ray source HO 139-68 was originally detected with the low energy detectors of the HEAO A-2 experiment, and confirmed by later IPC observations (Agarwal et al. 1981). The X-ray observations show flux variations in the 0.15 – 0.4 keV band of a factor of two, or timescales of a few hours, with evidence for short time-scale flickering. Following communication of the source position to us by Agarwal and Riegler, we obtained time-resolved optical spectrophotometry of a star close to the X-ray position, using the IDPCA on the MSO 1.9m telescope. The spectrophotometry and later polarisation observations confirm the optical identification and that the source is an AM-Herculis type binary system, with a late type dwarf secondary overflowing its Roche lobe in a magnetically constrained funnel onto a magnetic white dwarf (WD) primary (Visvanathan and Pickles 1982).

The puzzling afterglow of GRB 050721: a rebrightening seen in the optical but not in the X-ray

2007 ◽  
Vol 365 (1854) ◽  
pp. 1235-1240 ◽  
Author(s):  
L. Angelo Antonelli ◽  
Vincenzo Testa ◽  
Patrizia Romano ◽  
Dafne Guetta ◽  
Ken'ichi Torii ◽  
...  
Keyword(s):  
Density Profile ◽  
Gamma Ray ◽  
Matter Density ◽  
Optical Observations ◽  
Large Telescope ◽  
X Ray ◽  
Very Large Telescope ◽  
Robotic Telescope ◽  
Inner Region ◽  
First Time

We present here the analysis of the early and late multiwavelength afterglow emission, as observed by Swift a small robotic telescope and very large telescope (VLT). We compare early observations with late afterglow observations obtained with Swift and the VLT and we observe an intense rebrightening in the optical band at about 1 day after the burst, which is not present in the X-ray band. The lack of detection in X-ray of such a strong rebrightening at lower energies may be described with a variable external density profile. In such a scenario, the combined X-ray and optical observations allow us to derive that the matter density located at ∼10 17  cm from the burst is approximately a factor of 10 higher than in the inner region. This is the first time in which a rebrightening has been observed in the optical afterglow of a gamma-ray burst that is clearly absent in the X-ray afterglow.

Application of Cross-correlation Analysis Method for Measurement of the Fluid Flow Rate Based on X-ray Radiation

2019 ◽  
Vol 11 (1) ◽  
pp. 01025-1-01025-5 ◽  
Author(s):  
N. A. Borodulya ◽  
◽  
R. O. Rezaev ◽  
S. G. Chistyakov ◽  
E. I. Smirnova ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Correlation Analysis ◽  
Flow Rate ◽  
Cross Correlation ◽  
Fluid Flow Rate ◽  
Analysis Method ◽  
X Ray ◽  
Cross Correlation Analysis ◽  
Correlation Analysis Method

scholarly journals X-Ray Determination of the Black-Hole Mass in Cygnus X-1

1998 ◽  
Vol 188 ◽  
pp. 388-389
Author(s):  
A. Kubota ◽  
K. Makishima ◽  
T. Dotani ◽  
H. Inoue ◽  
K. Mitsuda ◽  
...  
Keyword(s):  
Black Hole ◽  
Compact Object ◽  
Optical Observations ◽  
Black Hole Mass ◽  
X Ray ◽  
Upper Limit ◽  
Supergiant Star ◽  
X Ray Binaries ◽  
Two Bodies

About 10 X-ray binaries in our Galaxy and LMC/SMC are considered to contain black hole candidates (BHCs). Among these objects, Cyg X-1 was identified as the first BHC, and it has led BHCs for more than 25 years(Oda 1977, Liang and Nolan 1984). It is a binary system composed of normal blue supergiant star and the X-ray emitting compact object. The orbital kinematics derived from optical observations indicates that the compact object is heavier than ~ 4.8 M⊙ (Herrero 1995), which well exceeds the upper limit mass for a neutron star(Kalogora 1996), where we assume the system consists of only two bodies. This has been the basis for BHC of Cyg X-1.

New optical observations of 2S 0921-630 and its relation to other X-ray binaries

1981 ◽  
Vol 30 (1-4) ◽  
pp. 365-366
Author(s):  
C. Chevalier ◽  
S. A. Ilovaisky
Keyword(s):  
Optical Observations ◽  
X Ray ◽  
X Ray Binaries

Development of WC-Fe3Al Composites by Spark Plasma Sintering Process

2016 ◽  
Vol 881 ◽  
pp. 307-312
Author(s):  
Luis Antonio C. Ybarra ◽  
Afonso Chimanski ◽  
Sergio Gama ◽  
Ricardo A.G. da Silva ◽  
Izabel Fernanda Machado ◽  
...  
Keyword(s):  
Spark Plasma Sintering ◽  
Zinc Stearate ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Plasma Sintering ◽  
Al Composite ◽  
Spark Plasma ◽  
Short Time ◽  
Vibration Mill

Tungsten carbide (WC) based composites are usually produced with cobalt, but this binder has the inconvenience of shortage, unstable price and potential carcinogenicity. The objective of this study was to develop WC composite with intermetallic Fe3Al matrix. Powders of WC, iron and aluminum, with composition WC-10 wt% Fe3Al, and 0.5 wt% zinc stearate were milled in a vibration mill for 6 h and sintered in a SPS (spark plasma sintering) furnace at 1150 °C for 8 min under pressure of 30 MPa. Measured density and microstructure analysis showed that the composite had significant densification during the (low-temperature, short time) sintering, and X-ray diffraction analysis showed the formation of intermetallic Fe3Al. Analysis by Vickers indentation resulted in hardness of 11.2 GPa and fracture toughness of 24.6 MPa.m1/2, showing the feasibility of producing dense WC-Fe3Al composite with high mechanical properties using the SPS technique.

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