1,082 research outputs found
Multiwavelength campaign on Mrk 509: testing realistic comptonization models
Mrk 509 was observed by XMM-Newton and INTEGRAL in October/November 2009, with one observation every four days for a total of ten observations. Each observation has been fitted with a realistic thermal Comptonization model for the continuum emission. Prompted by the correlation between the UV and soft X-ray flux, we used a thermal Comptonization component for the soft X-ray excess. The UV to X-ray/gamma-ray emission of Mrk 509 can be well fitted by these components, pointing to the existence of a hot (kT ⌠100 keV), optically-thin (Ï âŒ 0.5) corona producing the primary continuum. In contrast, the soft X-ray component requires a warm (kT ⌠1 keV), optically-thick (Ï âŒ 10-20) plasma. Estimates of the amplification ratio for this warm plasma support a configuration relatively close to the âtheoreticalâ configuration of a slab corona above a passive disk. This plasma could be the warm upper layer of the accretion disk. In contrast, the hot corona has a more photon-starved geometry. The high temperature (⌠100 eV) of the soft-photon field entering and cooling it favors a localization of the hot corona in the inner flow. This soft-photon field could be part of the comptonized emission produced by the warm plasma
Multiwavelength campaign on Mrk 509 XII. Broad band spectral analysis
(Abridged) The simultaneous UV to X-rays/gamma rays data obtained during the
multi-wavelength XMM/INTEGRAL campaign on the Seyfert 1 Mrk 509 are used in
this paper and tested against physically motivated broad band models. Each
observation has been fitted with a realistic thermal comptonisation model for
the continuum emission. Prompted by the correlation between the UV and soft
X-ray flux, we use a thermal comptonisation component for the soft X-ray
excess. The UV to X-rays/gamma-rays emission of Mrk 509 can be well fitted by
these components. The presence of a relatively hard high-energy spectrum points
to the existence of a hot (kT~100 keV), optically-thin (tau~0.5) corona
producing the primary continuum. On the contrary, the soft X-ray component
requires a warm (kT~1 keV), optically-thick (tau~15) plasma. Estimates of the
amplification ratio for this warm plasma support a configuration close to the
"theoretical" configuration of a slab corona above a passive disk. An
interesting consequence is the weak luminosity-dependence of its emission, a
possible explanation of the roughly constant spectral shape of the soft X-ray
excess seen in AGNs. The temperature (~ 3 eV) and flux of the soft-photon field
entering and cooling the warm plasma suggests that it covers the accretion disk
down to a transition radius of 10-20 . This plasma could be the
warm upper layer of the accretion disk. On the contrary the hot corona has a
more photon-starved geometry. The high temperature ( 100 eV) of the
soft-photon field entering and cooling it favors a localization of the hot
corona in the inner flow. This soft-photon field could be part of the
comptonised emission produced by the warm plasma. In this framework, the change
in the geometry (i.e. ) could explain most of the observed flux and
spectral variability.Comment: 19 pages, 14 figures. Accepted for publication in A&
A long hard look at MCG-6-30-15 with XMM-Newton and BeppoSAX
We summarise the primary results from a 320 ks observation of the bright
Seyfert 1 galaxy MCG-6-30-15 with XMM-Newton and Beppo-SAX.Comment: 4 pages, 6 figures. Proc. of the meeting: "The Restless High-Energy
Universe" (Amsterdam, The Netherlands), E.P.J. van den Heuvel, J.J.M. in 't
Zand, and R.A.M.J. Wijers Ed
Neutron density distributions from antiprotonic 208Pb and 209Bi atoms
The X-ray cascade from antiprotonic atoms was studied for 208Pb and 209Bi.
Widths and shifts of the levels due to the strong interaction were determined.
Using modern antiproton-nucleus optical potentials the neutron densities in the
nuclear periphery were deduced. Assuming two parameter Fermi distributions
(2pF) describing the proton and neutron densities the neutron rms radii were
deduced for both nuclei. The difference of neutron and proton rms radii /\r_np
equal to 0.16 +-(0.02)_{stat} +- (0.04)_{syst} fm for 208Pb and 0.14 +-
(0.04)_{stat} +- (0.04)_{syst} fm for 209Bi were determined and the assigned
systematic errors are discussed. The /\r_np values and the deduced shapes of
the neutron distributions are compared with mean field model calculations.Comment: 22 pages, 8 tables, 15 figure
Multiwavelength campaign on Mrk 509. I. Variability and spectral energy distribution
(Abridged) Active galactic nuclei show a wealth of interesting physical
processes, some of which are poorly understood. We want to address a number of
open questions, including the location and physics of the outflow from AGN, the
nature of the continuum emission, the geometry and physical state of the X-ray
broad emission line region, the Fe-K line complex, the metal abundances of the
nucleus and finally the interstellar medium of our own Galaxy. We study one of
the best targets for these aims, the Seyfert 1 galaxy Mrk 509 with a
multiwavelength campaign using five satellites (XMM-Newton, INTEGRAL, Chandra,
HST and Swift) and two ground-based facilities (WHT and PAIRITEL). Our
observations cover more than five decades in frequency, from 2 um to 200 keV.
The combination of high-resolution spectroscopy and time variability allows us
to disentangle and study the different components. Our campaign covers 100 days
from September to December 2009, and is centred on a simultaneous set of deep
XMM-Newton and INTEGRAL observations with regular time intervals, spanning
seven weeks. We obtain a continuous light curve in the X-ray and UV band,
showing a strong, up to 60% flux increase in the soft X-ray band during the
three weeks in the middle of our deepest monitoring campaign, and which is
correlated with an enhancement of the UV flux. This allows us to study the time
evolution of the continuum and the outflow. By stacking the observations, we
have also obtained one of the best X-ray and UV spectra of a Seyfert galaxy
ever obtained. In this paper we also study the effects of the spectral energy
distribution (SED) that we obtained on the photo-ionisation equilibrium. Thanks
to our broad-band coverage, uncertainties on the SED do not strongly affect the
determination of this equilibrium.Comment: 10 pages, 5 figures, 2 tables. Accepted for publication in Astronomy
& Astrophysic
2003--2005 INTEGRAL and XMM-Newton observations of 3C 273
The aim of this paper is to study the evolution of the broadband spectrum of
one of the brightest and nearest quasars 3C 273.
We analyze the data obtained during quasi-simultaneous INTEGRAL and XMM
monitoring of the blazar 3C 273 in 2003--2005 in the UV, X-ray and soft
gamma-ray bands and study the results in the context of the long-term evolution
of the source.
The 0.2-100 keV spectrum of the source is well fitted by a combination of a
soft cut-off power law and a hard power law. No improvement of the fit is
achieved if one replaces the soft cut-off power law by either a blackbody, or a
disk reflection model. During the observation period the source has reached the
historically softest state in the hard X-ray domain with a photon index
. Comparing our data with available archived X-ray data
from previous years, we find a secular evolution of the source toward softer
X-ray emission (the photon index has increased by
over the last thirty years). We argue that existing theoretical models have to
be significantly modified to account for the observed spectral evolution of the
source.Comment: 11 pages, accepted to A&
Concentration of electric dipole strength below the neutron separation energy in N = 82 nuclei
The semi-magic nuclei Ba-138, Ce-140, and Sm-144 have been investigated in
photon scattering experiments up to an excitation energy of about 10 MeV. The
distribution of the electric dipole strength shows a resonance like structure
at energies between 5.5 and 8 MeV exhausting up to 1% of the isovector E1
Energy Weighted Sum Rule.Comment: 10 pages, 3 figure
Crab: the standard X-ray candle with all (modern) X-ray satellites
Various X-ray satellites have used the Crab as a standard candle to perform
their calibrations in the past. The calibration of XMM-Newton, however, is
independent of the Crab nebula, because this object has not been used to adjust
spectral calibration issues. In 2004 a number of special observations were
performed to measure the spectral parameters and the absolute flux of the Crab
with XMM-Newtons EPIC-pn CCD camera. We describe the results of the campaign in
detail and compare them with data of four current missions (Integral, Swift,
Chandra, RXTE) and numerous previous missions (ROSAT, EXOSAT, Beppo-SAX, ASCA,
Ginga, Einstein, Mir-HEXE).Comment: 12 pages, 7 figure
Professional excellence: the necessary convergence of psychological variables
O estudo da excelĂȘncia humana assume essencialmente dois enfoques, um deles acentuando as variĂĄveis psicolĂłgicas dos indivĂduos e outro enfatizando as aquisiçÔes decorrentes da prĂĄtica ou treino deliberado. Neste artigo procurou-se integrar tais estudos, propondo que o surgimento e a manutenção da excelĂȘncia pressupĂ”em uma constelação de variĂĄveis psicolĂłgicas que vĂŁo para alĂ©m da alta capacidade intelectual. Mais concretamente, descreveu-se um conjunto de variĂĄveis cognitivas, motivacionais e de personalidade, assumidas como relevantes na excelĂȘncia profissional em diferentes ĂĄreas de desempenho e de conhecimento. No seio das variĂĄveis cognitivas e, fazendo uma ponte com as variĂĄveis de personalidade, destaca-se o papel da criatividade para a excelĂȘncia, reconhecendo a sua particular relevĂąncia em algumas ĂĄreas de realização profissional.The study of human excellence can be described based on two main approaches focusing either on individuals' psychological variables or on acquisitions by training or deliberate practice. The purpose of this study is to integrate these models based on the assumption that the emergence and maintenance of excellence requires a constellation of fundamental psychological variables that transcend intellectual capacity. More specifically, a set of cognitive, motivational, and personality variables that are considered important for professional excellence in different levels of performance and areas of knowledge were described. Among the cognitive variables and their association with personality variables, it is worth mentioning the significant role of creativity in the pursuit of excellence, recognizing its relevance to specific areas of professional performance.(undefined
Strong interaction and E2 effect in even- A antiprotonic Te atoms
The x-ray cascade from antiprotonic atoms was studied for Te-122, Te-124, Te-126, Te-128, and Te-130. Widths and shifts due to the strong interaction were deduced for several levels. The E2 nuclear resonance effect was observed in all investigated nuclei. In Te-130 the E2 resonance allowed to determine level widths and shifts of the LS-split deeply bound (n,l)=(6,5) state, otherwise unobservable. The measured level widths and shifts, corrected for the E2-resonance effect, were used to investigate the nucleon density in the nuclear periphery. The deduced neutron distributions are compared with results of the previously introduced radiochemical method and with Hartree-Fock-Bogoliubov model calculations
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