scholarly journals Complex optical/UV and X-ray variability in Seyfert 1 galaxy Mrk 509

2021 ◽  
Vol 38 ◽  
Author(s):  
Neeraj Kumari ◽  
Main Pal ◽  
Sachindra Naik ◽  
Arghajit Jana ◽  
Gaurava K. Jaisawal ◽  
...  
Keyword(s):  
Accretion Disk ◽  
Timing Analysis ◽  
Optical Emission ◽  
Light Curves ◽  
Thermal Component ◽  
X Ray ◽  
Uv Emission ◽  
Average Spectrum ◽  
Entire Duration ◽  
Using Data

Abstract We performed a detailed spectral and timing analysis of a Seyfert 1 galaxy Mrk 509 using data from the Neil Gehrels Swift observatory that spanned over $\sim$ 13 years between 2006 and 2019. To study the variability properties from the optical/UV to X-ray emission, we used a total of 275 pointed observations in this work. The average spectrum over the entire duration exhibits a strong soft X-ray excess above the power law continuum. The soft X-ray excess is well described by two thermal components with temperatures of kT $_{\rm BB1}\sim$ 120 eV and kT $_{\rm BB2}\sim$ 460 eV. The warm thermal component is likely due to the presence of an optically thick and warm Comptonizing plasma in the inner accretion disk. The fractional variability amplitude is found to be decreasing with increasing wavelength, i.e., from the soft X-ray to UV/optical emission. However, the hard X-ray (2–8 keV) emission shows very low variability. The strength of the correlation within the UV and the optical bands (0.95–0.99) is found to be stronger than the correlation between the UV/optical and X-ray bands (0.40–0.53). These results clearly suggest that the emitting regions of the X-ray and UV/optical emission are likely distinct or partly interacting. Having removed the slow variations in the light curves, we find that the lag spectrum is well described by the 4/3 rule for the standard Shakura–Sunyaev accretion disk when we omit X-ray lags. All these results suggest that the real disk is complex, and the UV emission is likely reprocessed in the accretion disk to give X-ray and optical emission.

scholarly journals X-Ray Observations Of Stellar Flares

1983 ◽  
Vol 71 ◽  
pp. 255-272 ◽  
Author(s):  
Bernhard M. Haisch
Keyword(s):  
Optical Emission ◽  
Light Curves ◽  
Data Set ◽  
Time Resolved ◽  
X Ray ◽  
Uv Emission ◽  
Stellar Flares ◽  
History Of ◽  
Relationship Of ◽  
Lower Limits

ABSTRACTThe history of stellar X-ray flare observations prior to EINSTEIN is reviewed. X-ray light curves as measured by the IPC are then presented for all time resolved flare events discovered as of July 1982 in the EINSTEIN data set. These light curves are analyzed in terms of solar-like loop models to derive densities, temperatures, loop lengths, magnetic field strength lower limits, etc. The failure of the model to adequately represent the observations in the case of the YZ CMi flares is discussed. The relationship of X-ray to optical emission and X-ray to UV emission is considered from both an observational and a theoretical viewpoint. It is concluded that the characterization of a flare by a single, time averaged ratio, Lx /Lopt , is not physically significant.

scholarly journals A tale of two periods: determination of the orbital ephemeris of the super-Eddington pulsar NGC 7793 P13

2018 ◽  
Vol 616 ◽  
pp. A186 ◽  
Author(s):  
F. Fürst ◽  
D. J. Walton ◽  
M. Heida ◽  
F. A. Harrison ◽  
D. Barret ◽  
...  
Keyword(s):  
Accretion Disk ◽  
Orbital Period ◽  
Timing Analysis ◽  
X Ray ◽  
System Parameters ◽  
Orbital Resonance ◽  
Photometric Period ◽  
Orbital Periods ◽  
Analyze Data

We present a timing analysis of multiple XMM-Newton and NuSTAR observations of the ultra-luminous pulsar NGC 7793 P13 spread over its 65 d variability period. We use the measured pulse periods to determine the orbital ephemeris, confirm a long orbital period with Porb = 63.9+0.5−0.6 d, and find an eccentricity of e ≤ 0.15. The orbital signature is imprinted on top of a secular spin-up, which seems to get faster as the source becomes brighter. We also analyze data from dense monitoring of the source with Swift and find an optical photometric period of 63.9 ± 0.5 d and an X-ray flux period of 66.8 ± 0.4 d. The optical period is consistent with the orbital period, while the X-ray flux period is significantly longer. We discuss possible reasons for this discrepancy, which could be due to a super-orbital period caused by a precessing accretion disk or an orbital resonance. We put the orbital period of P13 into context with the orbital periods implied for two other ultra-luminous pulsars, M82 X-2 and NGC 5907 ULX, and discuss possible implications for the system parameters.

scholarly journals Non-Linear Resonances in Accretion Disks and QPOs

2004 ◽  
Vol 194 ◽  
pp. 128-129
Author(s):  
Włodek Kluźniak
Keyword(s):  
Black Holes ◽  
Neutron Stars ◽  
Accretion Disk ◽  
Accretion Disks ◽  
High Frequency ◽  
Light Curves ◽  
X Ray ◽  
Non Linear ◽  
Low Mass ◽  
X Ray Binaries

AbstractNon-linear oscillations in the accretion disk are favored as an explanation of high-frequency QPOs observed in the light curves of low-mass X-ray binaries containing neutron stars, black holes, or white dwarfs.

scholarly journals Timing Analysis with INTEGRAL: Comparing Different Reconstruction Algorithms

10.14311/1312 ◽  
2011 ◽  
Vol 51 (1) ◽  
Author(s):  
V. Grinberg ◽  
I. Kreykenbohm ◽  
F. Fürst ◽  
J. Wilms ◽  
K. Pottschmidt ◽  
...  
Keyword(s):  
Image Reconstruction ◽  
Time Resolution ◽  
Timing Analysis ◽  
Light Curves ◽  
X Rays ◽  
Reconstruction Algorithms ◽  
X Ray ◽  
Coded Mask

INTEGRAL is one of the few instruments capable of detecting X-rays above 20 keV. It is therefore in principle well suited for studying X-ray variability in this regime. Because INTEGRAL uses coded mask instruments for imaging, the reconstruction of light curves of X-ray sources is highly non-trivial. We present results from a comparison of two commonly employed algorithms, which primarily measure flux from mask deconvolution (ii_lc_extract) and from calculating the pixel illuminated fraction (ii_light). Both methods agree well for timescales above about 10 s, the highest time resolution for which image reconstruction is possible. For higher time resolution, ii light produces meaningful results, although the overall variance of the lightcurves is not preserved.

scholarly journals 4 Years of Radio to X-ray Observations of 3C 273

1989 ◽  
Vol 134 ◽  
pp. 112-113
Author(s):  
T.J.-L. Courvoisier ◽  
E. I. Robson ◽  
A. Blecha ◽  
P. Bouchet
Keyword(s):  
Near Infrared ◽  
Optical Emission ◽  
Light Curves ◽  
Physical Parameters ◽  
List Type ◽  
Type Number ◽  
Rapid Variability ◽  
X Ray ◽  
Model Independent ◽  
Ir Emission

The quasar 3C273 has been repeatedly observed at radio, mm, IR, optical, UV and X-ray frequencies since December 1983. A complex pattern of continuum variations has been discovered, which can be used to provide model independent physical parameters, and to constrain different models. The main features revealed by our set of observations are: (i)A flux decrease by 40% in the 2–10 kev flux in 20 days in early 1984 (Courvoisier et al. 1987).(ii)Differences between the X-ray light curves at 0.5 keV and 2–10 keV.(iii)A drop in the mm to mid-IR emission by factors 2–4 in early 1986, while the near infrared flux remained stable (Robson et al. 1986).(iv)A decrease in the ultraviolet intensity of ∼40% in about 6 months in 1987 (Ulrich, Courvoisier and Wamsteker 1988).(v)Rapid variability in the infrared and optical emission on timescales as short as one day in 1988 (Courvoisier et al. 1988 and Robson, Courvoisier and Bouchet this conference).

scholarly journals X-ray dips and a complex UV/X-ray cross-correlation function in the black hole candidate MAXI J1820+070

2019 ◽  
Vol 488 (1) ◽  
pp. L18-L23 ◽  
Author(s):  
J J E Kajava ◽  
S E Motta ◽  
A Sanna ◽  
A Veledina ◽  
M Del Santo ◽  
...  
Keyword(s):  
Black Hole ◽  
Correlation Function ◽  
Cross Correlation ◽  
Timing Analysis ◽  
Cross Correlation Function ◽  
X Rays ◽  
X Ray ◽  
Black Hole Candidate ◽  
Uv Emission ◽  
Partial Covering

ABSTRACT MAXI J1820+070, a black hole candidate first detected in early 2018 March, was observed by XMM–Newton during the outburst rise. In this letter we report on the spectral and timing analysis of the XMM–Newton X-ray and UV data, as well as contemporaneous X-ray data from the Swift satellite. The X-ray spectrum is well described by a hard thermal Comptonization continuum. The XMM–Newton X-ray light curve shows a pronounced dipping interval, and spectral analysis indicates that it is caused by a moderately ionized partial covering absorber. The XMM–Newton/OM U-filter data do not reveal any signs of the 17 h orbital modulation that was seen later on during the outburst decay. The UV/X-ray cross-correlation function shows a complex shape, with a peak at positive lags of about 4 s and a precognition dip at negative lags, which is absent during the X-ray dipping episode. Such shape could arise if the UV emission comes partially from synchrotron self-Compton emission near the black hole, as well as from reprocessing of the X-rays in the colder accretion disc further out.

scholarly journals Long-Term X-ray Variability of Circinus X-1 as Observed by the RXTE All Sky Monitor

2003 ◽  
Vol 214 ◽  
pp. 218-219
Author(s):  
Junfeng Wang ◽  
W. N. Brandt
Keyword(s):  
Timing Analysis ◽  
Period Change ◽  
Light Curves ◽  
Data Set ◽  
X Ray ◽  
Low Mass ◽  
Sky Monitor ◽  
Radio Band ◽  
Over Time

The luminous low mass X-ray binary Cir X-1 has been observed nearly continuously for about 5 years by the X-ray All Sky Monitor on board the RXTE satellite. We carried out a timing analysis on Cir X-1 with the RXTE data. We define the period from the X-ray data, comparing the period change over time with the best current ephemeris. with folded light curves of entire data set, characteristics of the system like long-term lightcurve changes, behavior of flares and dips and super-Eddington accretion were obtained. We also checked and identified the secondary flaring reported in radio band with X-ray data.

scholarly journals Multiwavelength power-spectrum analysis of NGC 5548

2020 ◽  
Vol 499 (2) ◽  
pp. 1998-2006
Author(s):  
C Panagiotou ◽  
I E Papadakis ◽  
E S Kammoun ◽  
M Dovčiak
Keyword(s):  
Power Spectrum ◽  
Time Lag ◽  
Optical Emission ◽  
X Rays ◽  
Short Term ◽  
X Ray ◽  
Uv Emission ◽  
Accretion Rates ◽  
Measured Time ◽  
Ngc 5548

ABSTRACT NGC 5548 was recently monitored intensively from NIR to X-rays as part of the STORM campaign. Its disc emission was found to lag behind the observed X-rays, while the measured time lag was increasing with wavelength. These results are consistent with the assumption that short-term variability in AGN emission is driven by the X-ray illumination of the accretion disc. In this work, we studied the power spectrum of UV/optical and X-ray emission of NGC 5548, using the data of the STORM campaign as well as previous Swift data, in order to investigate the relation between the UV/optical and X-ray variability and to examine its consistency with the above picture. We demonstrate that even the power spectrum results are compatible with a standard disc being illuminated by X-rays, with low accretion rates, but the details are not entirely consistent with the results from the modelling of the ‘τ versus λ’ relation. The differences indicate that the inner disc might be covered by a ‘warm corona’ which does not allow the detection of UV/optical emission from the inner disc. Finally, we found strong evidence that the UV emission of NGC 5548 is not stationary.

scholarly journals OPTICAL EMISSION OF THE ULTRALUMINOUS X-RAY SOURCE NGC 5408 X-1: DONOR STAR OR IRRADIATED ACCRETION DISK?

2012 ◽  
Vol 745 (2) ◽  
pp. 123 ◽  
Author(s):  
F. Grisé ◽  
P. Kaaret ◽  
S. Corbel ◽  
H. Feng ◽  
D. Cseh ◽  
...  
Keyword(s):  
Accretion Disk ◽  
Optical Emission ◽  
X Ray

scholarly journals Low-frequency X-ray timing with Gaussian processes and reverberation in the radio-loud AGN 3C 120

2019 ◽  
Vol 489 (2) ◽  
pp. 1957-1972 ◽  
Author(s):  
D R Wilkins
Keyword(s):  
Black Holes ◽  
Gaussian Processes ◽  
Timing Analysis ◽  
Low Frequency ◽  
Low Earth Orbit ◽  
Time Lags ◽  
Energy Bands ◽  
X Ray ◽  
Using Data ◽  
3C 120

ABSTRACT A framework is developed to perform Fourier-domain timing analysis on X-ray light curves with gaps, employing Gaussian processes to model the probability distribution underlying the observed time series from which continuous samples can be drawn. A technique is developed to measure X-ray reverberation from the inner regions of accretion discs around black holes in the low-frequency components of the variability, on time-scales longer than can be probed employing standard Fourier techniques. This enables X-ray reverberation experiments to be performed using data from satellites in low-Earth orbit such as NICER, NuSTAR, and the proposed X-ray timing mission STROBE-X, and enables long time-scale reverberation around higher mass active galactic nuclei (AGNs) to be measured by combining observations. Gaussian processes are applied to observations of the broad line radio galaxy 3C 120 spanning two orbits with XMM–Newton to measure the relative time lags of successive X-ray energy bands. The lag–energy spectrum between 5 × 10−6 and 3 × 10−5 Hz, estimated using Gaussian processes, reveals X-ray reverberation from the inner accretion disc for the first time in this radio-loud AGN. Time lags in the relativistically broadened iron K line are significantly detected. The core of the line lags behind the continuum by (3800 ± 1500) s, suggesting a scale height of the corona of (13 ± 8) rg above the disc. The ability to compare the structure of coronae in radio-loud AGNs to their radio-quiet counterparts will yield important insight into the mechanisms by which black holes are able to launch jets.

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