The X-ray variability of the Seyfert~1 galaxy MCG-6-30-15 from long ASCA and RXTE observations

Abstract

We present an analysis of the long RXTE observation of the Seyfert~1 galaxy MCG-6-30-15, taken in July 1997. Our results show that the behaviour is complicated. We find clear evidence from colour ratios and direct spectral fitting that changes to the intrinsic photon index are taking place. Spectral hardening is evident during periods of diminished intensity; in particular, a general trend for harder spectra is seen in the period following the hardest RXTE flare. Flux-correlated studies further show that the 3-10 keV photon index steepens while that in the 10-20 keV band, flattens with flux. The largest changes come from the spectral index below 10keV; however, changes in the intrinsic power law slope, and reflection both contribute in varying degrees to the overall spectral variability. We find that the iron line flux is consistent with being constant over large time intervals on the order of days (although the ASCA and RXTE spectra show that $F_{K\alpha }$ changes on shorter time intervals of order < 10ks), and equivalent width which anticorrelates with the continuum flux, and reflection fraction. Flux-correlated studies point at possible ionization signatures, while detailed spectral analysis of short time intervals surrounding flare events hint tentatively at observed spectral responses to the flare. We present a simple model for partial ionization where the bulk of the variability comes from within 6r_g. Temporal analysis further provides evidence for possible time (< 1000s) and phase (phi~0.6 rad) lags. Finally, we report an apparent break in the power density spectrum (~ 4-5 x 10^{-6}Hz) and a possible 33 hr period. Estimates for the mass of the black hole in MCG-6-30-15 are discussed in the context of spectral and temporal findings.

19 pages, 38 figures total (19 figure captions), accepted for publication in MNRAS July 2000

References in corpus (4)

• Simultaneous EUVE/ASCA/RXTE Observations of NGC 5548
• First Constraints on Iron Abundance versus Reflection Fraction from the Seyfert~1 Galaxy MCG--6-30-15
• On the lack of X-ray iron line reverberation in MCG-6-30-15: Implications for the black hole mass and accretion disk structure
• Implications of the X-ray Variability for the Mass of MCG-6-30-15

Cited by in corpus (75)

• Constraining Black Hole Spin Via X-ray Spectroscopy
• The ROSAT Brightest Cluster Sample (BCS) - IV. The extended sample
• A long hard look at MCG-6-30-15 with XMM-Newton
• Imaging Optically-Thin Hot Spots Near the Black Hole Horizon of Sgr A* at Radio and Near-Infrared Wavelengths
• MCG-6-30-15: Long Timescale X-Ray Variability, Black Hole Mass and AGN High States
• Imaging Bright Spots in the Accretion Flow Near the Black Hole Horizon of Sgr A*
• A long, hard look at MCG-6-30-15 with XMM-Newton II: detailed EPIC analysis and modelling
• Suzaku observations of the hard X-ray variability of MCG-6-30-15: the effects of strong gravity around a Kerr black hole
• Accretion disc coronae as magnetic reservoirs
• Seyfert galaxies in the local Universe (z$\le$ 0.1): the average X-ray spectrum as seen by $BeppoSAX$
• Long-Term X-ray Spectral Variability in Seyfert 1 Galaxies
• The Fragmentation of Pre-enriched Primordial Objects
• The broad band spectral variability of MCG-6-30-15 observed by NuSTAR and XMM-Newton
• Evidence for Rapid Iron K_alpha Line Flux Variability in MCG--6-30-15
• The nature of X-ray spectral variability in Seyfert Galaxies
• A Chandra HETGS Spectral Study of the Iron K Bandpass in MCG-6-30-15: A Narrow View of the Broad Iron Line
• Can a Dusty Warm Absorber Model Reproduce the Soft X-ray Spectra of MCG-6-30-15 and Mrk 766?
• Relativistic spectral features from X-ray illuminated spots and the measure of the black hole mass in AGN
• Mapping the inner regions of MCG-6-30-15 with XMM-Newton
• The continuum variability of MCG--6-30-15: A detailed analysis of the long 1999 ASCA observation
• Light bending scenario for accreting black holes in X-ray polarimetry
• Towards precision tests of general relativity with black hole X-ray reflection spectroscopy
• Wavelet Analysis of AGN X-Ray Time Series: A QPO in 3C 273?
• Broad-Band Spectral Energy Distributions of Active Galactic Nuclei from an Accretion Disk with Advective Coronal Flow
• A two-component ionized reflection model of MCG--6-30-15
• The shape of the relativistic iron K-alpha line from MCG6--6-30-15 measured with the Chandra HETGS and RXTE
• Quasi-Periodic Oscillation in Seyfert galaxies: Significance levels. The Case of Mrk 766
• Iron-line and continuum flux variations in the RXTE spectra of the black-hole candidate XTE J1650-500
• On the deep minimum state in the Seyfert galaxy MCG-6-30-15
• Confirmation of a correlation between the X-ray luminosity and spectral slope of AGNs in the Chandra Deep Fields
• The X-ray variability of the Narrow-Line Seyfert 1 galaxy IRAS 13224-3809 from an XMM-Newton observation
• The soft X-ray absorption lines of the Seyfert 1 galaxy MCG--6-30-15
• X-ray spectral variability of the Seyfert galaxy NGC 4051
• Magnetic fields in AGNs and microquasars
• Chandra Observations of the Cloverleaf Quasar H 1413+117: A Unique Laboratory for Microlensing Studies of a Lobal Quasar
• A New Spin on an Old Black Hole: NuSTAR Spectroscopy of EXO 1846-031
• Cross-spectral analysis of the X-ray variability of Mrk 421
• Long Term Spectral Variability of Seyfert Galaxies from RXTE Color-Flux Diagrams
• IZw1 observed with XMM-Newton: Low-energy spectral complexity, iron lines, and hard X-ray flares
• Understanding Spectral Variability and Time Lags in Accreting Black Holes
• Reflected Iron Line From a Source Above a Kerr Black Hole Accretion Disc
• A softer look at MCG--6-30-15 with XMM-Newton
• On time-dependent X-ray reflection by photoionized accretion disks: implication for Fe K-alpha line reverberation studies of AGN
• On the hard X-ray spectra of radio-loud active galaxies
• Impact of reverberation in flared accretion discs on temporal characteristics of X-ray binaries
• The K-alpha complex of He-like iron with dielectronic satellites
• Detecting X-ray QPOs in Active Galaxies
• The response of the Fe Kαline to changes in the X-ray illumination of accretion discs
• Exact solution for the Green's function describing time-dependent thermal Comptonization
• An Extreme Ultraviolet Explorer Atlas of Seyfert Galaxy Light Curves: Search for Periodicity
• The effects of relativistic bulk motion of X-ray flares in the corona on the iron Kalpha line in Seyfert 1 galaxies
• Impact of the disk thickness on X-ray reflection spectroscopy measurements
• A long hard look at MCG-6-30-15 with XMM-Newton and BeppoSAX
• Estimation of relativistic accretion disk parameters from iron line emission
• A Single Intrinsic Luminosity Function for Both Type-I and Type-II Active Galactic Nuclei
• RXTE and BeppoSAX Observations of MCG -5-23-16: Reflection From Distant Cold Material
• Testing General Relativity with High-Resolution Imaging of Sgr A*
• New method for black-hole spin measurement based on flux variation from an infalling gas ring
• Reprocessed emission line profiles from dense clouds in geometrically thick accretion engines
• Search for traversable wormholes in active galactic nuclei using X-ray data
• Constraining the Johannsen deformation parameter ${\epsilon }_3$ with black hole X-ray data
• Testing a model of variability of X-ray reprocessing features in Active Galactic Nuclei
• Constraining the KRZ deformation parameters I: limits from supermassive black hole X-ray data
• Short Timescale Correlations Between Line and Continuum Fluxes in Cygnus X-1
• The iron $K_{\alpha }$ lines as a tool for magnetic field estimations in non-flat accretion flows
• Fourier-Resolved Spectroscopy of AGN using XMM-Newton data: I. The 3-10 keV band results
• Chandra Observations of the NLS1 RX J2217.9-5941
• Relativistic ionized accretion disc models of MCG--6-30-15
• Does the Iron K${}_{\alpha }$ Line of Active Galactic Nuclei Arise from the Cerenkov Line-like Radiation?
• Exploring the X-ray spectral variability of MCG-6-30-15 with XMM-Newton
• Theory of disk accretion onto supermassive black holes
• Atomic X-ray Spectroscopy of Accreting Black Holes
• Swift Observations of the highly X-ray variable Narrow Line Seyfert 1 galaxy RX J0148.3-2758
• Inferring the coronal flaring patterns in AGN from reverberation maps
• The Spin and Orientation of the Black Hole in XTE J1908$+$094