Relativistic iron K X-ray Reverberation in NGC 4151

Recent X-ray observations have enabled the study of reverberation delays in AGN for the first time. All the detections so far are in sources with a strong soft excess, and the measured delay is between the hard (1-3 keV) direct continuum and the soft excess (0.5-1 keV), interpreted as the reflection continuum smeared by relativistic effects. There is however an inherent ambiguity in identifying and studying the details of the lines in the soft excess. Here we report the first detection of reverberation in the iron K band in any AGN. Using XMM-Newton observations of NGC 4151, we find delays of order 2000 s on time-scales of 10e5 s between the 5-6 keV band and 2-3 and 7-8 keV bands, with a broad lag profile resembling a relativistically-broadened iron line. The peak of the lag spectra shifts to lower energies at higher frequencies, consistent with the red wing of the line being emitted at smaller radii, as expected from reflection off the inner accretion disk. This is a first detection of a broad iron line using timing studies.Comment: final version, corrected small typo

Discovery of high-frequency iron K lags in Ark 564 and Mrk 335

We use archival XMM-Newton observations of Ark 564 and Mrk 335 to calculate the frequency dependent time-lags for these two well-studied sources. We discover high-frequency Fe K lags in both sources, indicating that the red wing of the line precedes the rest frame energy by roughly 100 s and 150 s for Ark 564 and Mrk 335, respectively. Including these two new sources, Fe K reverberation lags have been observed in seven Seyfert galaxies. We examine the low-frequency lag-energy spectrum, which is smooth, and shows no feature of reverberation, as would be expected if the low-frequency lags were produced by distant reflection off circumnuclear material. The clear differences in the low and high frequency lag-energy spectra indicate that the lags are produced by two distinct physical processes. Finally, we find that the amplitude of the Fe K lag scales with black hole mass for these seven sources, consistent with a relativistic reflection model where the lag is the light travel delay associated with reflection of continuum photons off the inner disc.Comment: 10 pages, 12 figures, accepted for publication in MNRA

The Closest Look at 1H0707-495: X-ray Reverberation Lags with 1.3 Ms of Data

Reverberation lags in AGN were first discovered in the NLS1 galaxy, 1H0707-495. We present a follow-up analysis using 1.3 Ms of data, which allows for the closest ever look at the reverberation signature of this remarkable source. We confirm previous findings of a hard lag of ~100 seconds at frequencies v ~ [0.5 - 4] e-4 Hz, and a soft lag of ~30 seconds at higher frequencies, v ~ [0.6 - 3] e-3 Hz. These two frequency domains clearly show different energy dependences in their lag spectra. We also find evidence for a signature from the broad Fe K line in the high frequency lag spectrum. We use Monte Carlo simulations to show how the lag and coherence measurements respond to the addition of Poisson noise and to dilution by other components. With our better understanding of these effects on the lag, we show that the lag-energy spectra can be modelled with a scenario in which low frequency hard lags are produced by a compact corona responding to accretion rate fluctuations propagating through an optically thick accretion disc, and the high frequency soft lags are produced by short light-travel delay associated with reflection of coronal power-law photons off the disc.Comment: 11 pages, 10 figures. Accepted for publication in MNRA

X-ray Lags in PDS 456 Revealed by Suzaku Observations

X-ray reverberation lags from the vicinity of supermassive black holes have been detected in almost 30 AGN. The soft lag, which is the time delay between the hard and soft X-ray light curves, is usually interpreted as the time difference between the direct and reflected emission, but is alternatively suggested to arise from the direct and scattering emission from distant clouds. By analysing the archival Suzaku observations totalling an exposure time of ~ 770 ks, we discover a soft lag of $10\pm3.4$ ks at $9.58\times10^{-6}$ Hz in the luminous quasar PDS 456, which is the longest soft lag and lowest Fourier frequency reported to date. In this study, we use the maximum likelihood method to deal with non-continuous nature of the Suzaku light curves. The result follows the mass-scaling relation for soft lags, which further supports that soft lags originate from the innermost areas of AGN and hence are best interpreted by the reflection scenario. Spectral analysis has been performed in this work and we find no evidence of clumpy partial-covering absorbers. The spectrum can be explained by a self-consistent relativistic reflection model with warm absorbers, and spectral variations over epochs can be accounted for by the change of the continuum, and of column density and ionization states of the warm absorbers.Comment: accepted for publication in MNRA

Long XMM observation of the Narrow-Line Seyfert 1 galaxy IRAS13224-3809: rapid variability, high spin and a soft lag

Results are presented from a 500ks long XMM-Newton observation of the Narrow-Line Seyfert 1 galaxy IRAS13224-3809. The source is rapidly variable on timescales down to a few 100s. The spectrum shows strong broad Fe-K and L emission features which are interpreted as arising from reflection from the inner parts of an accretion disc around a rapidly spinning black hole. Assuming a power-law emissivity for the reflected flux and that the innermost radius corresponds to the innermost stable circular orbit, the black hole spin is measured to be 0.988 with a statistical precision better than one per cent. Systematic uncertainties are discussed. A soft X-ray lag of 100s confirms this scenario. The bulk of the power-law continuum source is located at a radius of 2-3 gravitational radii.Comment: 7 pages, 14 figures, submitted to MNRA

Identificação da época de coleta do óleo-resina de copaíba (Copaifera spp.) no município de Moju, PA.

No processo de extração do óleo-resina de copaíba não é considerada a época mais apropriada do ano, normalmente o coletor extrai em qualquer época não levando em consideração fatores climáticos como a preciptação pluviométrica, que na região amazônica está diretamente relacionada com a produção de várias culturas. A presença de substâncias químicas em uma determinada espécie pode estar ligada a fatores climáticos. Considerando a presença desses compostos químicos nas espécies de copaíba e a falta de informações na literatura consultada sobre a época mais indicada para extração do óleo, o presente trabalho teve como objetivo identificar a época mais adequada para coleta do óleo para o município de Mojú, PA, através da quantificação e qualificação do óleo correlacionados com a preciptação pluviométrica. Amostras de óleo-resina de Copaifera duckei, Copaifera martii e Copaifera reticulata foram coletadas no Campo Experimental do Mojú da Embrapa Amazônia Oriental, localizado no município de Mojú, PA. O período de coleta foi de setembro de 2003 a agosto de 2004. Nos meses de setembro e outubro ocorreram as maiores produções de óleo para a espécie C. reticulata e de setembro a novembro para a espécie C. duckei, coincidindo com o período de menor preciptação pluviométrica. A menor produção de óleo ocorreu no período de janeiro a maio de 2004, principalmente para as espécies C. reticulata e C. duckei, coincidindo com o período mais chuvoso. As espécies C. duckei e C. r eticulata, produziram respectivamente, um óleo-resina de aspecto líquido e de coloração vermelho intenso e amarelo claro. Enquanto, a C. martii produziu um óleo-resina denso de coloração marrom. A concentração do sesquiterpeno, b-bisaboleno na C. duckei foi superior a do b-cariofileno em todos os meses do ano, ocorrendo variações nos percentuais das substâncias independentes do período de chuvas. Na C. reticulata, a concentração do sesquiterpeno, b-cariofileno foi superior a do b-bisaboleno independente do período de preciptação pluviométrica. A concentração do sesquiterpeno a-copaeno na C. martii, foi superior ao D-cadineno e apresentou variações nos percentuais das substâncias, independentes do período de chuvas

Observations of MCG-5-23-16 with Suzaku, XMM-Newton and NuSTAR: Disk tomography and Compton hump reverberation

MCG-5-23-16 is one of the first AGN where relativistic reverberation in the iron K line originating in the vicinity of the supermassive black hole was found, based on a short XMM-Newton observation. In this work, we present the results from long X-ray observations using Suzaku, XMM-Newton and NuSTAR designed to map the emission region using X-ray reverberation. A relativistic iron line is detected in the lag spectra on three different time-scales, allowing the emission from different regions around the black hole to be separated. Using NuSTAR coverage of energies above 10 keV reveals a lag between these energies and the primary continuum, which is detected for the first time in an AGN. This lag is a result of the Compton reflection hump responding to changes in the primary source in a manner similar to the response of the relativistic iron K line.Comment: Accepted for Publication in Ap

Discovery of fe Kα X-Ray reverberation around the black holes in MCG-5-23-16 and NGC 7314

Several X-ray observations have recently revealed the presence of reverberation time delays between spectral components in AGN. Most of the observed lags are between the power-law Comptonization component, seen directly, and the soft excess produced by reflection in the vicinity of the black hole. NGC 4151 was the first object to show these lags in the iron K band. Here, we report the discovery of reverberation lags in the Fe K band in two other sources: MCG-5-23-16 and NGC 7314. In both objects, the 6-7 keV band, where the Fe K line peaks, lags the bands at lower and higher energies with a time delay of ~ 1 kilo-seconds. These lags are unlikely to be due to the narrow Fe K line. They are fully consistent with reverberation of the relativistically-broadened iron K line. The measured lags, their time-scale and spectral modeling, indicate that most of the radiation is emitted at ~ 5 and 24 gravitational radii for MCG-5-23-16 and NGC 7314 respectively