The $BeppoSAX$ archive is currently the largest reservoir of high sensitivity simultaneous soft and hard-X ray data of Seyfert galaxies. From this database all the Seyfert galaxies (105 objects of which 43 are type I and 62 are type II) with redshift lower than 0.1 have been selected and analyzed in a homogeneous way (Dadina 2007). The X-ray data so collected allow to infer the average spectral properties of nearby Seyfert galaxies included in the original sample and, most notably: the photon index ($Γ$$\sim$1.8), the high-energy cut-off (Ec$\sim$290 keV), and the relative amount of reflection (R$\sim$1.0). The data have been also used to test some assumptions of the unified scheme for the AGN. The distributions of the isotropic indicators (photon index, relative amount of reflection, high-energy cut-off and narrow FeK$α$ energy centroid) are similar in type I and type II objects while the absorbing column and the iron line equivalent width significantly differ between the two classes of active galactic nuclei. Confirming previous results, the narrow FeK$α$ line is consistent, in Seyfert 2, with being produced in the same matter responsible for the observed obscuration. These results, thus, support the basic picture of the unified model. Moreover, the presence of a X-ray Baldwin effect in Seyfert 1 has been here measured using the 20-100 keV luminosity (EW$\propto$L(20-100)$^{-0.22\pm0.05}$). Finally, the possible presence of a correlation between the photon index and the amount of reflection is confirmed thus indicating thermal Comptonization as the most likely origin of the high energy emission for the active galactic nuclei included in the original sample.
The contributions that BeppoSAX is expected to give and, after one and a half year of operation, has already given to our knowledge of both type 1 and type 2 Seyfert galaxies are outlined and reviewed.
We present new results from BeppoSAX observations of reflection-dominated Seyfert galaxies, and namely: 1) the Compton-thick Seyfert 2s NGC1068 and Circinus Galaxy; 2) the Seyfert 1 NGC4051, whose nucleus was observed on May 1998 to have switched off, leaving only a residual reflection component as an echo of its past activity. Our main focus in this paper is on the soft X-ray continuum properties and on the X-ray line spectroscopy.
Results are presented for the first year of observations of a selected sample of Narrow-Line Seyfert 1 galaxies (Ton S 180, RE J1034+396, Ark 564) obtained with the imaging instruments onboard BeppoSAX. These are the first simultaneous broad band (0.1--10 keV) spectra so far obtained for this class of objects.
We report on the first spectrum up to 10 keV of the bright narrow-line Seyfert 1 galaxy Ton S 180, obtained with the imaging instruments onboard BeppoSAX. This is the first observed source in a sample of a dozen narrow-line Seyfert 1 galaxies in the BeppoSAX Core Program. We also present and discuss a high quality optical spectrum taken at the 1.5 m telescope at La Silla two months before the BeppoSAX observation. The X-ray spectrum shows a clear hardening above about 2 keV, where a power law with Gamma = 2.3 plus an iron line provide a good description of the data. This slope is significantly…
The Seyfert 2 galaxy NGC 2110 has been observed with BeppoSAX between 0.5 and 150 keV. The high energy instrument onboard, PDS, has succeeded in measuring for the first time the spectrum of this source in the 13-150 keV range. The PDS spectrum, having a photon index Gamma~1.86 is fully compatible with that expected from a Seyfert 1 nucleus. In the framework of unified models, the harder (Gamma~1.67) 2-10 keV spectrum is well explained assuming the presence of a complex partial + total absorber (Nh~30x10^22 cm^-2 x25% + Nh~4x10^22 cm^-2 x100%). The high column density of this complex absorber i…
We test accurate models of Comptonisation spectra over BeppoSAX observations of Seyfert galaxies focusing on the long look at NGC 5548. The hot plasma temperature derived with these models is significantly higher than that obtained fitting the same data with a power law plus high energy cut off model for the continuum. This is due to the fact that in anisotropic geometries Comptonisation spectra show "intrinsic" curvature which moves the fitted high energy cut-off to higher energies. We also show preliminary results of our analysis of a sample of 5 other Seyfert galaxies.
We report on BeppoSAX broad band (0.1-100 keV) observations of bright Seyfert 2 galaxies and discuss the results in the framework of the unified theory of AGNs. The data are used to probe Nh distribution in type 2 objects and to identify heavily absorbed (10^24 <= Nh <= 10^25 cm^-2) sources, which are particularly bright in hard X-rays. They also provide, for the first time, high energy spectral data on Seyfert 2s and tight constraints on the shape of their intrinsic power law continuum. These results confirm the basic expectations of the unified theory and indicate where the INTEGRAL mission …
We report the detection in the X rays of two weak Seyfert2's (NGC3393 and NGC4941) with the Italian-Dutch satellite BeppoSAX. These are among the first sources observed in a sample of 12 Seyfert2's which are being studied within the BeppoSAX core program, in an effort to probe the putative torus at high X-ray energies, calibrate an isotropic luminosity indicator for absorbed nuclei, and determine the distribution of torus thicknesses, Nh. Both a Compton thick spectrum, with a reflected power law and a large equivalent width iron line, and a Compton thin spectrum, with the intrinsic power law t…
The operational conditions found by $BeppoSAX$ in observing nearby (z$\leq$0.1) Seyferts were reproduced for $Simbol$-$X$ in order to simulate a realistic final database of the mission. The results indicate that, even in the worst conditions, the $Simbol$-$X$ archive of pointings will allow to fully characterize the high-energy spectrum of nearby Seyferts and, most importantly, to obtain solid results on R and Ec (fundamental to model the cosmic X-Ray background, CXB). The measurement of the inclination angle of the accretion disk will be possible for $\sim$15 objects allowing to directly test…
We present a study of the hard X-ray spectrum (>15 keV) of different classes of Seyfert galaxies observed with BeppoSAX/PDS. Using hard X-ray data, we avoid absorption effects modifying the Seyfert emission and have direct access to the central engine of these sources. The aim of this study is first to characterize the general properties of the hard X-ray spectrum of Seyfert 1, 1.5 and 2 galaxies and secondly to compare their intrinsic emission to test unified models according to which all the classes have the same nucleus. We compute the average spectrum of 14 Sy 1, 9 Sy 1.5 and 22 Sy 2 galax…
We report optical, radio and X-ray observations of the Narrow-Line Seyfert 1 galaxy RX J1702.5+3247. The soft (0.1-2 keV) X-ray flux, measured by BeppoSAX, is characterized by strong variability on short time scales (< 500 sec). The most extreme amplitude variations require a radiative efficiency exceeding the maximum for a Kerr black hole, implying the presence of relativistic effects. A comparison with archival ROSAT data reveals long term temporal and spectral variability. The 0.1-10 keV spectrum is equally well fitted either by an ionized reflection disk model, or by a broken power law plu…
We present preliminary results of the spectral analysis of a large sample of Seyfert galaxies observed by BeppoSAX. The only selection criterium was a sufficiently large S/N ratio (>10) in the PDS band (12-200 keV) to allow good detection up to the highest energy. The resulting sample is composed of 28 objects (17 Seyfert 1, 11 Seyfert 2) and 50 observations. Our main effort here is to adopt Comptonization models to fit the different spectra on a truly broad band basis (0.1-200 keV). We use two distinct disc-corona configurations, an anisotropic slab and an isotropic spherical one. We discuss …
We present the results of two observations of the bright Seyfert 1 galaxy NGC 3516, obtained with BeppoSAX in 1996 November and 1997 March. Useful signal is detected between 0.2 and 60 keV, allowing for the first time the simultaneous observation of all main spectral features. The source was brighter by a factor 2 at the second epoch of observation. Both spectra present a strong Fe Kalpha line, and a reflection hump at high energy. An absorption edge at 0.8 keV is visible in the later spectrum, but not in the earlier one, indicating that this feature is strongly variable.
We used high quality BeppoSAX data of 6 Seyfert galaxies to test realistic thermal Comptonization models. Our main effort was to adopt a Comptonization model taking into account the anisotropy of the soft photon field. The best fit parameter values of the temperature and optical depth of the corona and of the reflection normalization obtained fitting this class of models to the data are substantially different from those derived fitting the same data with the power law + cut--off model commonly used. The two models also provide different trends and correlation between the physical parameters, …
The BeppoSAX observations of the bright Narrow-Line Seyfert 1 galaxy Ark 564 are presented along with a high quality optical spectrum taken at the 1.5m telescope at La Silla. The 0.1-10 keV X-ray spectrum is characterized by a strong soft component which is best described by blackbody-like emission with a temperature of about 160 eV. At higher energies a steep (Gamma = 2.4) power-law tail is present. There is evidence of an ionized reflector in the form of an iron line and edge. We do not find significant evidence of soft X-ray features if the spectrum is modelled with a two component continuu…
We selected a sample of eight bright unobscured (at least at the iron line energy) Seyfert Galaxies observed simultaneously by XMM-Newton and BeppoSAX, taking advantage of the complementary characteristics of the two missions. The main results of our analysis can be summarized as follows: narrow neutral iron lines are confirmed to be an ubiquitous component in Seyfert spectra; none of the analyzed sources shows unambiguously a broad relativistic iron line; all the sources of our sample (with a single exception) show the presence of a Compton reflection component; emission lines from ionized ir…
The broad band 0.1-200 keV spectra of a sample of 5 Seyfert 2 galaxies (NGC 7172, Mkn 3, NGC 2110, NGC 4507 and NGC 7674) have been measured within the first year of the $BeppoSAX$ Core program. All sources have been detected up to \~ 100 keV and their spectral characteristics derived with good accuracy. Although the results obtained from the detailed analysis of individual sources indicate some ``source-by-source'' differences, we show in the following that all spectra are consistent, at least qualitatively, with what expected from a ``0th-order'' version of unified models. Indeed, a simple t…
The Seyfert 2 galaxy NGC 7674 has been observed within the BeppoSAX Core Programme with the onboard narrow field instruments between 0.1 and 100 keV. The broad-band spectrum shows four most relevant spectral components: a) a soft excess below ~2 keV; b) a prominent (EW~1 keV) Fe line; c) a flat (Gamma~1.1) 2-10 keV continuum; d) a 4.5sigma detection above 13 keV. The flat power law spectrum can be very well explained within the current AGN unified models assuming a steep (Gamma~2) intrinsic spectrum scattered by warm gas for the low energy band and totally reflected by optically thick cold mat…
We have studied the average 3-200 keV spectra of Seyfert galaxies of type 1 and 2, using data obtained with BeppoSAX. The average Seyfert 1 spectrum is well-fitted by a power law continuum with photon spectral index Gamma~1.9, a Compton reflection component R~0.6-1 (depending on the inclination angle between the line of sight and the reflecting material) and a high-energy cutoff at around 200 keV; there is also an iron line at 6.4 keV characterized by an equivalent width of 120 eV. Seyfert 2's on the other hand show stronger neutral absorption (NH=3-4 x 10^{22} atoms cm-2) as expected but are …
IC 4329A is the brightest known Seyfert galaxy in hard (~2-30 keV) X-rays and is likely to be representative of Seyfert 1 galaxies as a class. A recent 100 ks BeppoSAX observation (Perola et al. 1999) clearly confirmed the presence of a warm absorber, a reflection component (R~0.6), and a high-energy cut-off in the power law at Ec~270 keV. Its richness in spectral features, combined with its large flux (~1.6 x 10**-10 erg/cm2s between 2-10 keV), make this target ideal for multiple observations (in particular with BeppoSAX) to search for spectral variations. Results obtained from 3 follow-up ob…
We investigate the X-ray spectra of the type-2 Seyfert galaxies NGC 7172 and ESO 103-G35, using BeppoSAX observations, separated by approximately one year. We find that the X-ray spectra of both NGC 7172 and ESO 103-G35 can be well fitted using a power-law model with an Fe K emission line at 6.4 keV. We did not find any statistically significant evidence for the existence of a reflection component in the X-ray spectra of these two galaxies. The continuum flux has decreased by a factor of approximately two during this period, in both objects. However, the spectral index as well as the absorptio…
From the spectral analysis of a broadband (0.1-200 keV) BeppoSAX observation of the Seyfert 1 galaxy IC 4329A, the main results obtained are: a) the amount of reflection, together with the intensity of the iron K line, indicate a geometry with a solid angle substantially less than 2pi; b) the power law is affected by a cut off with e-folding energy about 270 keV, the fourth individual object so far where this property has been firmly detected; c) two absorption features at about 0.7 and 1 keV are found, the first corresponding to a blend of O vi and O vii, the other to a combination of FeL and…
We report broad band (0.1-200 keV) X-ray observations, made by BeppoSAX, of a sample of bright Seyfert 2 galaxies: NGC7172, NGC2110, NGC4507, Mkn 3 and NGC7674. These spectra provide a better understanding of the effects of X-ray reprocessing by cold material in the source and allow to put tighter constraints on the various spectral parameters involved. In particular, the data are used to determine, with less ambiguities than in the past, the shape of the intrinsic continuum emission by means of the high energy data. Within the small sample both Compton thin and Compton thick sources are found…
We present the analysis of 31 observations of 20 bright Compton thin Seyfert 2s, in the 0.1-200 keV band, performed with the BeppoSAX satellite. The sample consists of all Seyfert 2s in the BeppoSAX public archive, with a 2-10 keV flux higher than 5x10^(-12) erg/cm^2/s. The good statistics available and the broad energy band permit a detailed study of the main continuum components of these sources, i.e. the primary power-law, the reflected component, the soft emission and the high-energy cut-off. The main results of our analysis are: (1) the 3-200 keV intrinsic power-law has a mean photon inde…
Results from BeppoSAX observations of Compton--thick Seyfert 2 galaxies are summarized and reviewed, and their general properties derived and discussed. In five out of the seven observed sources, the nucleus is directly visible at high X-ray energies, where the photons penetrate absorbers with column densities in the range 1.1-4.3x10^{24} cm-2 (in the other two sources, NGC 1068 and NGC 7674, the nucleus is instead totally obscured at all energies, implying even larger column densities). In most sources there is unambiguous evidence of a reflection component from optically thick, cold matter, …
BeppoSAX observed the Seyfert 1 galaxy NGC 3783 for ~ 5 days from 1998 June 6 to 1998 June 10. The average flux during the observation was F(2-10 keV) ~ 6 X 10^{-11} erg cm^-2 s^-1. The long exposure provided a very high quality spectrum that exhibits all the typical features of Seyfert 1s. The high energy cut-off of the intrinsic continuum, at E_c=340+560/-107 keV, was detected for the first time in this object. During the observation the source showed modest flux variations (~ 20% in 2-10 keV) and spectral variability that can be completely explained by a change of the intrinsic slope ΔΓ~ 0.…
In the present work we report the BeppoSAX serendipitous discovery of the type 2 AGN 1SAXJ2234.8-2541 in the MECS field of view when pointing at the Seyfert 2 galaxy NGC7314. The source is optical identified with the bright (m_B=14.40) galaxy ESO533-G50 at redshift z=0.026. The source is clearly detected at energies above 4 keV but barely visible below this energy implying heavy obscuration intrinsic to the source. Spectral analysis indicates a column density of the order of 2-3 x 10^(23) cm^-2$ and a power law photon index compatible with values often seen in active galaxies. These X-ray char…
A new BeppoSAX broad-band (0.6-150 keV) spectrum of the Seyfert 2 galaxy Mkn 3 is presented. The spectrum provides a direct measurement of a large, neutral column of gas with Nh~10**24 cm**-2 in the source direction. The source, as bright as 3C 273 above 10 keV, has a steep (Gamma~1.8) spectrum without any evidence of a high-energy cutoff up to at least 150 keV. At lower energies, the data are best modeled with the addition of an unabsorbed reflection component. Combining these data with previous Ginga and ASCA observations, the Fe K$_α$ and reflection continuum indicate that the reprocessed e…
We present the results of BeppoSAX AO1 Core Program observations of 3C~273 performed in Jan. 1997 and compare them in detail with data obtained during the satellite Science Verification Phase (SVP), in Jul. 1996. Though a power law is an acceptable representation of the data in the whole 0.1-200 keV range, there is indication of a steepening of the spectrum as the energy increases. Our data mark a difference with respect to the SVP data, where a steeper power law below 0.5 keV, an absorption feature at 0.6 keV, and a more prominent fluorescence iron line have been found. The weakening of cold/…
We have used realistic Comptonization models to fit high quality BeppoSAX data of 6 Seyfert galaxies. Our main effort was to adopt a Comptonization model taking into account the anisotropy of the soft photon field. The most important consequence is a reduction of the first scattering order, which produces a break (the so-called anisotropy break) in the outgoing spectra. The physical parameters of the hot corona (i.e. the temperature and optical depth) obtained fitting this class of models to broad band X-ray spectra are substantially different from those derived fitting the same data with the …
BeppoSAX observations of Broad Line Radio Galaxies (BLRGs) have shown that they have a considerable variety of spectral properties and important differences with respect to their radio-quiet counter-part Seyfert 1s. In radio galaxies the soft photons are often absorbed by cold material. In contrast, in Seyfert 1s the soft photons are generally absorbed by warm gas. The iron lines, always detected in Seyfert 1s, are not always present in BLRGs and generally are weak. In addition, small iron line equivalent widths seem to correspond to weak reflection components in radio galaxies. The emerging p…
In this work we present the first of two papers devoted to the study of the X-ray spectral characteristics of Seyfert 1 galaxies in the Piccinotti sample. In particular we analyse here the BeppoSAX broad band (0.1-100 keV) data of 4 objects which, despite their X-ray brightness, have been historically poorly studied due to their late identification with an AGN; these are H0111-149 (MKN1152), H0235-525 (ESO198-G24), H0557-385 (IRAS F05563-3820) and H1846-786 (IRAS F18389-7834). We have assumed for all the sources a baseline model which includes a power law with an exponential cut-off plus a ref…
In the present work we report the BeppoSAX observation of the Seyfert 1.9 galaxy NGC 526A in the band 0.1-150 keV. The high energy instrument onboard, PDS, has succeeded in measuring for the first time the spectrum of this source in the 13-150 keV range. The combined analysis of all Narrow Field Instruments provides a power law spectral index of ~ 1.6 and confirms the flat spectral nature of this source. Although NGC 526A varies strongly in the 2-10 keV over period of months/years, its spectral shape remains constant over these timescales. An Fe K-alpha line, characterized by a complex structu…
A sample of nine bright Seyfert 1 and NELG type galaxies, observed with BeppoSAX, is analyzed to assess on a truly broad band basis (0.1-200 keV) the issue of the spectral contributions of Compton reflection and iron line fluorescence from circumnuclear gas. The empirical description adopted for the direct continuum is the commonly used power law with an exponential cut-off. The most direct test of the theoretical predictions, namely that the equivalent width of the line, Walpha, and the strength R of the reflection relative to the direct continuum are closely related to each other, gives a su…
We present BeppoSAX observations of the Seyfert 1.8 galaxy NGC1365 in the 0.1--100 keV range. The source was 6 times brighter than during an ASCA observation 3 years earlier. The 4--10 keV flux is highly variable during the BeppoSAX observation, while the soft (0.1-4 keV) emission is constant within the errors. Both a cold and a warm reflector and a cold absorber are required to explain the observed spectrum. The comparison between ASCA and BeppoSAX spectra strongly suggests that the circumnuclear material has a more complex structure than a simple homogeneous torus, with quite different absor…
We discuss BeppoSAX observations and archive ASCA data of NGC 7679, a nearby, nearly face-on SB0 galaxy in which starburst and AGN activities coexist. The X-ray observations reveal a bright (L_{0.1-50 keV} \sim 2.9 \times 10^{43} erg s^{-1}) and variable source having a minimum observed doubling/halving time scale of \sim 10 - 20 ksec. A simple power law with photon index of Γ\sim 1.75 and small absorption (N_H < 4\times 10^{20} cm^{-2}) can reproduce the NGC 7679 spectrum from 0.1 up to 50 keV. These X-ray properties are unambiguous signs of Seyfert 1 activity in the nucleus of NGC 7679. The …
High energy emission has been discovered serendipitously by the BeppoSAX/PDS telescope in the ~1.3 degree field of view around the Piccinotti source H0917-074. A re-pointing of BeppoSAX/NFI has allowed the association of this emission with the Seyfert 2 galaxy MCG-1-24-12 which lies within the original HEAO1/A2 error box of H0917-074. This is the first PDS serendipitous discovery of a Seyfert 2 galaxy and the first detection of MCG-1-24-12 in the X-ray domain. The measured 2-10 keV flux of MCG-1-24-12 is ~1 x 10^(-11) erg cm^(-2) s^(-1) compatible with the Piccinotti HEAO-1/A2 observation. Thi…
We present a X-ray spectroscopic study of the bright Compton-thick Seyfert 2s NGC1068 and the Circinus Galaxy, performed with BeppoSAX. Matt et al. (1997 and 1998) interpreted the spectrum above 4 keV as the superposition of Compton reflection and warm plasma scattering of the nuclear radiation. When this continuum is extrapolated downwards to 0.1 keV, further components arise. The NGC1068 spectrum is rich in emission lines, mainly due to K-alpha transitions of He-like elements from oxygen to iron, plus a K-alpha fluorescent line from neutral iron. If the ionized lines originate in the warm sc…
Recent results on the X-ray spectrum and variability of Seyfert 1 galaxies are reviewed. New spectral results from BeppoSAX observations are also presented and briefly discussed.
We report the spectral analysis of a long XMM-Newton observation of the well-studied, moderate luminosity Broad Line Seyfert 1 galaxy NGC 5548. The source was at an historically average brightness and we find the hard (3-10 keV) spectrum can be well fitted by a power law of photon index gamma ~ 1.75, together with reflection. The only feature in the hard X-ray spectrum is a narrow emission line near 6.4 keV, with an equivalent width of ~ 60 eV. The energy and strength of this line is consistent with fluorescence from `neutral' iron distant from the central continuum source. We find no evidence…
We test accurate models of Comptonization spectra over the high quality data of the BeppoSAX long look at NGC 5548, allowing for different geometries of the scattering region, different temperatures of the input soft photon field and different viewing angles. We find that the BeppoSAX data are well represented by a plane parallel or hemispherical corona viewed at an inclination angle of 30$^{\circ}$. For both geometries the best fit temperature of the soft photons is close to 15$^{+3}_{-9}$ eV. The corresponding best fit values of the hot plasma temperature and optical depth are $kT_{\rm e}\si…
An XMM-Newton observation of the luminous Seyfert 1 galaxy 1H 0419-577 is presented. We find that the spectrum is well fitted by a power law of canonical slope (gamma ~ 1.9) and 3 blackbody components (to model the strong soft excess). The XMM data are compared and contrasted with observations by ROSAT in 1992 and by ASCA and BeppoSAX in 1996. We find that the overall X-ray spectrum has changed substantially over the period, and suggest that the changes are driven by the soft X-ray component. When bright, as in our XMM-Newton observation, it appears that the enhanced soft flux cools the Compto…
We report the transition to an active state of the nucleus in the Seyfert 1.9 galaxy NGC 2992, discovered by means of new hard X-ray data. While the 2-10 keV flux declined by a factor of ~ 20 from 1978 to 1994, two recent BeppoSAX observations in 1997 and in 1998 caught the nuclear emission raising back to the same level of activity observed in 1978. In both BeppoSAX observations the X-ray spectrum of the source is well represented by a power law with spectral index Gamma ~ 1.7, absorbed by a column density of N_H ~ 10^{22} cm^{-2} and characterized by a prominent iron Kαline. While in the sec…
The Narrow Line Seyfert 1 galaxy Mrk 766 has been observed by BeppoSAX on May 1997. The source was fairly variable, both in flux and spectrum, during the observation. The variability is the largest around 2 keV, possibly due to variations in the warm absorber properties. An oxygen line is clearly detected, at least in the first part of the observation. An edge around 7.5 keV, coupled with the lack of any detectable iron line, suggests either reprocessing of the primary X-rays by a mildly ionized disc or absorption by a further, thicker and more ionized material.
The Seyfert 2 Galaxy NGC 7172 was observed twice by BeppoSAX narrow field instruments approximately one year apart. As found in previous observations, the source is variable on short time scales (hours) by a factor of $\sim$30%, confirming the presence of a type 1 nucleus at the center. A strong flux variability (by a factor of 2) on a longer time scale was observed between the two observations. Indeed, in November 1997, the lowest flux ever recorded was detected by BeppoSAX. The broad band spectra obtained with the BeppoSAX narrow field instruments show marginal evidence of a reflection compo…
A systematic analysis of a large sample of radio-loud Active Galactic Nuclei available in the BeppoSAX public archive has been performed. The sample includes 3 Narrow Line Radio Galaxies (NLRG), 10 Broad Line Radio Galaxies (BLRG), 6 Steep Spectrum Radio Quasars (SSRQ), and 16 Flat Spectrum Radio Quasars (FSRQ). According to the unified models, these classes correspond to objects with increasing viewing angles. As expected, the presence of a non-thermal beamed component emerges clearly in FSRQ. This class shows in fact a featureless continuum (with the exception of 3C273), and a significantly …
We report our analysis of X-ray spectra of the Seyfert galaxy IRAS 18325-5926 (=Fairall 49) obtained from various X-ray observatories prior to XMM-Newton, including new results from two RXTE and one BeppoSAX observations. A relatively steep continuum slope (photon-index of ~2.2) in the 2-15 keV band is confirmed. The continuum spectrum observed with the BeppoSAX PDS shows a possible roll-over at energies above 30 keV, indicating a Comptonizing corona cooler than in other Seyfert nuclei. The X-ray spectrum above 2 keV is best explained with a model including reflection from a highly ionized dis…
We present a comprehensive study of the spectrum of the narrow-line Seyfert 1 galaxy RE J1034+396, summarizing the information obtained from the optical to X-rays with observations from the William Herschel 4.2m Telescope (WHT), the Hubble Space Telescope, the Extreme UltraViolet Explorer, ROSAT, ASCA and BeppoSAX. The BeppoSAX spectra reveal a soft component which is well-represented by two blackbodies with kT of about 60 eV and 160 eV, mimicking that expected from a hot, optically-thick accretion disc around a low-mass black hole. This is borne out by our modeling of the optical to X-ray nuc…
Although a strong similarity between radio galaxies and Seyferts has been pointed out with ASCA, some radio galaxies do not seem to fit very well the cold thin accretion disk model proposed for radio quiet AGN. The BeppoSAX observations of 3C390.3 and Centaurus A show that cold material responsible for the photon reprocessing is present in these sources but not necessarily near to the primary X-ray source. The featureless spectrum of the broad line radio galaxy 3C111 indicates the absence of cold material near the X-ray source or, alternatively, the presence of a strong jet X-ray component.
We briefly review BeppoSAX observations of X-ray bright radio-galaxies. Their X-ray spectra are quite varied, and perhaps surprisingly, any similarity between radio-loud AGN and Seyfert galaxies is the exception rather than the rule. When detected, reprocessing features (iron line and reflection) are generally weak, suggesting two possible scenarios: either: (1) non-thermal (jet?) radiation dilutes the X-ray emission from the disk in radio-loud objects, or (2) the solid angle subtended by the X-ray reprocessing material is smaller in radio-loud than in radio-quiet AGN due to different characte…
We report on the first detection above ~10 keV of the archetypal Compton-thick Seyfert 2 galaxy NGC 1068. This detection, obtained with the PDS instrument onboard BeppoSAX in the 20-100 keV range, confirms the hardness of the X--ray spectrum above a few keV (as indicated by ASCA observations and supports models envisaging a mixture of both neutral and ionized reflections of an otherwise invisible nuclear continuum, the neutral reflection component being the dominant one in hard X-rays.
We present the results obtained with BeppoSAX observations of the three Composite Seyfert/star-forming galaxies: IRAS 20051-1117, IRAS 04392-0123 and IRAS 01072+4954. These sources belong to an enigmatic class of X-ray sources detected in the ROSAT All-Sky Survey (Moran et al. 1996) which is composed of 6 low redshift galaxies. Their optical spectra are dominated by the features of HII galaxies while their X-ray luminosities (< 10^{42} ergs/s) are typical of Seyfert galaxies. IRAS 20051-1117 shows a 2-10 keV spectrum well described by a power-law with photon index = 1.9 and low intrinsic absor…
We report on soft X-ray observations of the Seyfert 1 galaxy MCG-6-30-15 with the Low and Medium Energy Concentrator Spectrometers on board BeppoSAX. The time averaged 0.1-4 keV spectrum shows evidence for a complex warm absorber. K-edges of highly ionized oxygen (O vii and O viii) can only partly describe the soft X-ray spectrum below 2 keV. A spectral variability study reveales large and rapid changes in absorption at the energy of the O viii K-edge and in the continuum shape and count rate. These fluctuations are not simply correlated.
In this work we present the observation of the Mkn 463 field performed with the MECS instrument on-board BeppoSAX in the 1.8-10.5 keV band. The Mkn 463 field is an example of an extragalactic field crowded with absorbed X-ray sources: apart from the Seyfert 2 galaxy Mkn 463 and the well known QSO PG 1352+183 (the only object showing no absorption), two other objects are detected with a column density in excess to the galactic value. The first 1SAX J1353.9+1820 is a red QSO from the BeppoSAX High Energy Large Area Survey (HELLAS). The second 1SAX J1355.4+1815 is optically unidentified, but its …
The Seyfert 2 galaxy Mrk 1210 was found to exhibit a flat hard X-ray component by ASCA, although ASCA could not distinguish whether it is an absorbed direct component or a reflected one. We then observed Mrk 1210 with BeppoSAX, and found that the X-ray spectral properties are quite different from those of ASCA, as have been confirmed with XMM-Newton; the flux is significantly higher than that in the ASCA observation, and a clear absorption cut-off appears below 5 keV. A bright hard X-ray emission is detected up to 100 keV. The reflection component is necessary to describe the BeppoSAX PDS spec…
We present Bepposax observations of the starburst/Seyfert composite galaxy Mrk609. This enigmatic object has an optical spectrum dominated by the features of starburst galaxies, yet its X-ray luminosity (6.3$\times10^{42}$\lunits) is typical of an AGN. The X-ray spectrum of Mrk609 can be parameterised by a single power-law model with a photon index $Γ\sim1.6\pm0.1$ and no evidence for significant absorption above the Galactic value. Long term variability in both the 0.1-2 keV and 2-10 keV energy bands is detected, again suggesting that the X-ray emission is dominated by an AGN. The observed br…
We have made BeppoSAX observations of the Seyfert 2/1.9 galaxy ESO103-G35, which contains a nuclear maser source and is known to be heavily absorbed in the X-rays. Analysis of the X-ray spectra observed by SAX in October 1996 and 1997 yields a spectral index 0.74+/-0.07, typical of Seyfert galaxies and consistent with earlier observations of this source. The strong, soft X-ray absorption has column density 1.79E(23)/cm^2, again consistent with earlier results. The best fitting spectrum is that of a power law with a high energy cutoff at 29+/-10 keV, a cold, marginally resolved Fe Kalpha line w…
