publicationDate stringlengths 1 2.79k | title stringlengths 1 36.5k ⌀ | abstract stringlengths 1 37.3k ⌀ | id stringlengths 9 47 |
|---|---|---|---|
1998-08-27 | Iron Opacity and the Pulsar of Supernova 1987A | Neutron stars formed in Type II supernovae are likely to be initially
obscured by late-time fallback. Although much of the late-time fallback is
quickly accreted via neutrino cooling, some material remains on the neutron
star, forming an atmosphere which slowly accretes through photon emission. In
this paper, we derive... | 9808309v1 |
1998-10-28 | Reprocessing and Variable Cold Absorption in the Broad-Line Radio Galaxy 3C390.3 | A BeppoSAX observation of the BLRG 3C390.3 is reported. For the first time,
both the 6.4 keV iron line and a strong reflection hump, produced by the
illumination of the primary X-ray emission on cold matter, are detected in this
source. The 0.1-100 keV continuum is modeled by an absorbed power law (\Gamma~
1.8) reflect... | 9810450v1 |
1998-11-16 | A Comparison of Metal Enrichment Histories in Rich Clusters and Individual Luminous Elliptical Galaxies | Hot, X-ray emitting gaseous halos around massive elliptical galaxies are a
result of both stellar mass loss and inflow toward the overdensity from which
giant ellipticals and their associated galaxy groups formed. The metal
abundance in this gas contains important information about early star formation
and past superno... | 9811258v1 |
1999-01-09 | Constraining the Role of SN Ia and SN II in Galaxy Groups by Spatially Resolved Analysis of ROSAT and ASCA Observations | We present the results of modelling the distribution of gas properties in the
galaxy groups HCG51, HCG62 and NGC5044, and in the poor cluster AWM7, using
both ASCA SIS and ROSAT data. The spectral quality of the ASCA data allows the
radial distribution in the abundances of several elements to be resolved. In
all system... | 9901100v1 |
1999-01-16 | Concave Accretion Discs and X-ray Reprocessing | Spectra of Seyfert Is are commonly modelled as emission from an X-ray
illuminated flat accretion disc orbiting a central black hole. This provides
both a reprocessed and direct component of the X-ray emission as required by
observations of individual objects and possibly a fraction of the cosmological
X-ray background.... | 9901216v2 |
1999-03-30 | The complex 0.1-200 keV spectrum of the Seyfert 1 Galaxy NGC4593 | We report on the first observation of the Seyfert 1 galaxy NGC4593 in the
0.1-200 keV band, performed with the BeppoSAX observatory. Its spectral
components are for the first time simultaneously measured: a power-law with
photon spectral index ~1.9; the Compton-reflection of the primary power-law; a
moderately broad (>... | 9903449v1 |
1999-06-23 | Iron line signatures in X-ray afterglows of GRB by BeppoSAX | We report the possible detection (99.3% of statistical significance) of
redshifted Fe iron line emission in the X-ray afterglow of Gamma-ray burst
GRB970508 observed by BeppoSAX. Its energy is consistent with the redshift of
the putative host galaxy determined from optical spectroscopy. In contrast to
the fairly clean ... | 9906363v1 |
1999-07-09 | Simultaneous EUVE/ASCA/RXTE Observations of NGC 5548 | We present simultaneous observations by EUVE, ASCA, and RXTE of the type~1
Seyfert galaxy NGC 5548. These data indicate that variations in the EUV
emission (at $\sim 0.2 $keV) appear to lead similar modulations in higher
energy ($\ga 1 $keV) X-rays by $\sim$10--30 ks. This is contrary to popular
models which attribute ... | 9907114v1 |
1999-07-14 | The properties of the relativistic iron K-line in NGC 3516 | We present an analysis of the relativistic iron K-alpha line in the Seyfert 1
galaxy NGC 3516, based on a continuous, five-day ASCA observation. The broad
profile which has been found in several other AGN is confirmed in NGC 3516 with
unprecedented signal-to-noise ratio. Disk-line models with either a Kerr or
Schwarzsc... | 9907193v1 |
1999-09-01 | Evidence for Doppler-Shifted Iron Emission Lines in Black Hole Candidate 4U 1630-47 | We report the first detection of a pair of correlated emission lines in the
X-ray spectrum of black hole candidate 4U 1630-47 during its 1996 outburst,
based on RXTE observations of the source. At the peak plateau of the outburst,
the emission lines are detected, centered mostly at $\sim$5.7 keV and $\sim$7.7
keV, resp... | 9909023v1 |
1999-11-10 | Nucleosynthesis and Clump Formation in a Core Collapse Supernova | High-resolution two-dimensional simulations were performed for the first five
minutes of the evolution of a core collapse supernova explosion in a 15 solar
mass blue supergiant progenitor. The computations start shortly after bounce
and include neutrino-matter interactions by using a light-bulb approximation
for the ne... | 9911183v2 |
1999-12-07 | BeppoSAX uncovers a type-2 QSO in the hyperluminous infrared galaxy IRAS 09104+4109 | We studied with BeppoSAX the infrared luminous galaxy IRAS 09104+4109 over a
very wide X-ray band from 0.1 to 80 keV. Our observations indicate the
dominance of a thermal component at energies below 8 keV, which we attribute to
the free-free emission from the intracluster (IC) plasma surrounding the
source. Above 10 ke... | 9912127v1 |
1999-12-25 | Global Relationships among Physical Properties of Galaxy Cluster Cores | Using X-ray data, we investigate interrelations between gas density rho_0,
virial density rho_vir, core radius R, temperature T, entropy S_gas, and metal
abundance Z in the core region of clusters of galaxies. First, we confirm that
fundamental relations among rho_0, R, and T found by Fujita and Takahara are
reproduced... | 9912515v1 |
2000-01-15 | Helium Emission in the Type Ic SN 1999cq | We present the first unambiguous detection of helium emission lines in
spectra of Type Ic supernovae (SNe Ic). The presence of He I lines, with full
width at half maximum ~ 2000 km/s, and the distinct absence of any other
intermediate-width emission (e.g., Halpha), implies that the ejecta of SN Ic
1999cq are interactin... | 0001270v1 |
2000-01-18 | WWhat Heavy Elements in Clusters of Galaxies Tell About Clusters and Galaxies | Clusters of galaxies allow a direct estimate of the metallicity and metal
production yield on the largest scale so far. The ratio of the total iron mass
in the ICM to the total optical luminosity of the cluster (the iron
mass-to-light-ratio) is the same for all clusters which ICM is hotter than
$\sim 2$ keV, and the el... | 0001312v1 |
2000-02-01 | The relativistic iron line profile in the Seyfert 1 Galaxy IC4329a | We present simultaneous ASCA and RXTE data on the bright Seyfert 1 galaxy
IC4329a. The iron line is significantly broadened, but not to the extent
expected from an accretion disk which extends down to the last stable orbit
around a black hole. We marginally detect a narrow line component, presumably
from the molecular ... | 0002023v1 |
2000-02-02 | Stellar Iron Abundances at the Galactic Center | We present measurements of [Fe/H] for six M supergiant stars and three giant
stars within 0.5 pc of the Galactic Center (GC) and one M supergiant star
within 30 pc of the GC. The results are based on high-resolution (lambda /
Delta lambda =40,000) K-band spectra, taken with CSHELL at the NASA Infrared
Telescope Facilit... | 0002062v1 |
2000-02-23 | ISO spectroscopy of circumstellar dust in the Herbig Ae systems AB Aur and HD 163296 | Using both the Short- and Long-wavelength Spectrometers on board the Infrared
Space Observatory (ISO), we have obtained infrared spectra of the Herbig Ae
systems AB Aur and HD 163296. In addition, we obtained ground-based N band
images of HD 163296. Our results can be summarized as follows: (1) The main
dust components... | 0002440v1 |
2000-06-05 | Iron K line Variability in the Low-Luminosity AGN NGC 4579 | We present results of new ASCA observations of the low-luminosity AGN (LLAGN)
NGC 4579 obtained on 1998 December 18 and 28, and we report on detection of
variability of an iron K emission line. The X-ray luminosities in the 2--10 keV
band for the two observations are nearly identical (LX $\approx$
2$\times10^{41}$ ergs... | 0006055v1 |
2000-06-30 | Chemical abundances in seven red giants of NGC 2360 and NGC 2447 | Chemical abundances of about fifteen elements from oxygen to europium are
measured in seven red giants of the two open clusters NGC 2360 and NGC 2447.
The effective temperatures of the giants are determined spectroscopically by
taking advantage of their known masses (~2 Mo in NGC 2360 and ~3 Mo in NGC
2447) and bolomet... | 0006442v1 |
2000-07-24 | Iron K line emission in AGN: observations | Iron K-alpha lines are key diagnostics of the central regions of AGN. Their
profiles indicate that they are formed deep in the potential well of the
central black hole, where extreme broadening and red shift occur. The profiles
are most easily reproducible in an accretion disk: the lack of significant
emission blue-war... | 0007356v1 |
2000-08-01 | Atomic data from the Iron Project XLV. Relativistic transition probabilities for carbon-like Ar XIII and Fe XXI using Breit-Pauli R-matrix method | The Breit-Pauli R-matrix method developed under the Iron Project has been
used to obtain extensive sets of oscillator strengths and transition
probabilities for dipole allowed and intercombination fine structure
transitions in carbon like ions, Ar XIII and Fe XXI. The complete set consists
of 1274 fine structure bound ... | 0008032v1 |
2000-09-17 | Reprocessed emission line profiles from dense clouds in geometrically thick accretion engines | The central engines of active galactic nuclei (AGN) contain cold, dense
material as well as hot X-ray emitting gas. The standard paradigm for the
engine geometry is a cold thin disc sandwiched between hot X-ray coronae.
Strong support for this geometry in Seyferts comes from the study of
fluorescent iron line profiles,... | 0009263v2 |
2000-09-20 | ASCA Observations of the Twin Supernova Remnants in the Large Magellanic Cloud, DEM L316 | We report results from an ASCA X-ray study of DEM L316, an emission nebula in
the Large Magellanic Cloud (LMC) consisting of two closely-spaced supernova
remnants (SNRs). The SIS image shows separate X-ray sources located at the
positions of the two radio- and optically-emitting SNR shells, 0547$-$69.7A and
0547$-$69.7... | 0009318v1 |
2000-09-20 | Matter in Strong Magnetic Fields | The properties of matter are significantly modified by strong magnetic
fields, $B>>2.35\times 10^9$ Gauss ($1 G =10^{-4} Tesla$), as are typically
found on the surfaces of neutron stars. In such strong magnetic fields, the
Coulomb force on an electron acts as a small perturbation compared to the
magnetic force. The str... | 0009333v2 |
2000-10-13 | Evidence for Rapid Iron K_alpha Line Flux Variability in MCG--6-30-15 | This paper employs direct spectral fitting of individual orbital data in
order to measure rapid X-ray iron K_alpha line and continuum spectral slope
variations in Seyfert 1 galaxies with unprecedented temporal resolution.
Application of this technique to a long RXTE observation of MCG--6-30-15
indicates that the line f... | 0010274v1 |
2000-10-18 | The first XMM-Newton spectrum of a high redshift quasar - PKS 0537-286 | We present XMM-Newton observations of the high redshift z=3.104, radio-loud
quasar PKS 0537-286. The EPIC CCD cameras provide the highest signal-to-noise
spectrum of a high-z quasar to date. The EPIC observations show that PKS
0537-286 is extremely X-ray luminous (Lx=2x10^47 erg/s), with an unusually hard
X-ray spectru... | 0010367v1 |
2000-12-14 | Discovery of a Transient Absorption Edge in the X-ray Spectrum of GRB 990705 | We report the discovery of a transient equivalent hydrogen column density
with an absorption edge at ~3.8 kiloelectron volts in the spectrum of the
prompt x-ray emission of gamma-ray burst (GRB) 990705. This feature can be
satisfactorily modeled with a photoelectric absorption by a medium located at a
redshift of ~0.86... | 0012318v1 |
2001-01-12 | Accretion and emission processes in AGN | The UV-X continuum, the X-ray spectral features, and the variability in these
bands provide powerful tools for studying the innermost regions of AGNs from
which we gain an insight into the accretion process. In this chapter the
discussion focusses on luminous AGN, i.e. Seyfert galaxies and quasars. The
standard accreti... | 0101203v2 |
2001-03-06 | A Simple Model for r-Process Scatter and Halo Evolution | Recent observations of heavy elements produced by rapid neutron capture
(r-process) in the halo have shown a striking and unexpected behavior: within a
single star, the relative abundances of r-process elements heavier than Eu are
the same as the same as those of solar system matter, while across stars with
similar met... | 0103083v1 |
2001-03-26 | Weak Reprocessed Features in the Broad Line Radio Galaxy 3C382 | We present a detailed X-ray study of the Broad Line Radio Galaxy 3C382,
observed with the BeppoSAX satellite in a very bright state. The continuum
emission is well modeled with a power law that steepens at high energies, with
an e-folding energy of about 120 keV. At soft energies a clear excess of
emission is detected,... | 0103413v1 |
2001-03-29 | Abundances in Stars from the Red Giant Branch Tip to the Near Main Sequence in M71: II. Iron Abundance | We present [Ffe/H] abundance results that involve a sample of stars with a
wide range in luminosity from luminous giants to stars near the turnoff in a
globular cluster. Our sample of 25 stars in M71 includes 10 giant stars more
luminous than the RHB, 3 horizontal branch stars, 9 giant stars less luminous
than the RHB,... | 0103494v2 |
2001-04-04 | X-Ray Probing of the Central Regions of Clusters of Galaxies | Results of ASCA X-ray study of central regions of medium-richness clusters of
galaxies are summarized, emphasizing differences between cD and non-cD
clusters. The intra-cluster medium (ICM) is likely to consist of two (hot and
cool) phases within $\sim 100$ kpc of a cD galaxy, where the ICM metallicity is
also enhanced... | 0104079v1 |
2001-06-01 | X-Ray Spectroscopy of II Pegasi: Coronal Temperature Structure, Abundances, and Variability | We have obtained high resolution X-ray spectra of the coronally active
binary, II Pegasi (HD 224085), covering the wavelength range of 1.5-25
Angstroms. For the first half of our 44 ksec observation, the source was in a
quiescent state with constant X-ray flux, after which it flared, reaching twice
the quiescent flux i... | 0106007v1 |
2001-06-28 | On a possible GRB-supernova time sequence | The data from the Chandra satellite on the iron emission lines in the
afterglow of GRB 991216 are used to give further support for the EMBH theory,
which links the origin of the energy of GRBs to the extractable energy of
electromagnetic black holes (EMBHs), leading to an interpretation of the
GRB-supernova correlation... | 0106534v1 |
2001-07-09 | BeppoSAX observations of Mrk 841 and Mrk335 | We present and discuss BeppoSAX observations of Mrk841 and Mrk335, two
Seyfert 1 galaxies in which previous observations have established the presence
of soft excesses. We confirm the soft excess in both sources, even if for
Mrk~841 a warm absorber provides a fit almost as good as the one with a true
excess. As far as ... | 0107151v1 |
2001-07-20 | On the GRB progenitors: possible consequences for supernovae connection with gamma-ray bursts | Unique data on $BVRI$ light curves of the optical transient (OT) of GRB
970508 obtained with the 6-m telescope have been interpreted in the framework
of the idea of a straightforward link between supernovae (SNe) and long
duration gamma-ray bursts (GRBs). The effect must be maximum in the $I_{c}$
band as for OT GRB 970... | 0107399v1 |
2001-07-25 | The X-ray emission of the Intermediate Polar V709 Cas | We present RXTE and BeppoSAX observations of the Intermediate Polar V709 Cas
acquired in 1997 and 1998 respectively. The X-ray emission from 0.1 to 30keV is
dominated by the strong pulsation at the rotational period of the white dwarf
(312.8s) with no sign of orbital or sideband periodicity, thus confirming
previous RO... | 0107480v1 |
2001-08-15 | Boron Abundances in Main Sequence B-type Stars: A Test of Rotational Depletion during Main Sequence Evolution | Boron abundances have been derived for seven main sequence B-type stars from
HST STIS spectra around the B III 2066 A line. In two stars, boron appears to
be undepleted with respect to the presumed initial abundance. In one star,
boron is detectable but it is clearly depleted. In the other four stars, boron
is undetect... | 0108263v1 |
2001-09-20 | An XMM-Newton observation of the extreme Narrow Line Seyfert 1 Galaxy, Mrk 359 | We present XMM-Newton observations of Mrk 359, the first Narrow Line Seyfert
1 galaxy discovered. Even among NLS1s, Mrk 359 is an extreme case with
extraordinarily narrow optical emission lines. The XMM-Newton data show that
Mrk 359 has a significant soft X-ray excess which displays only weak absorption
and emission fe... | 0109346v1 |
2001-11-21 | Detection of an Iron Emission Feature from the Lensed BAL QSO H1413+117 at z=2.56 | We present the X-ray energy spectrum of the lensed BAL QSO H1413+117 (the
Cloverleaf) at z=2.56 observed with the Chandra X-ray observatory. We detected
293 photons in a 40 ks Advanced CCD Imaging Spectrometer (ACIS-S) observation.
The X-ray image consists of four lensed image components, thus the photons are
from the ... | 0111410v1 |
2001-11-30 | Deep inside the core of Abell 1795: the Chandra view | We present X-ray spatial and spectral analysis of the Chandra data from the
central 400 kpc (H0 = 50 km/s/Mpc) of the cluster of galaxies Abell 1795. The
plasma temperature rises outwards by a factor of 3, whereas the iron abundance
decreases by a factor of 4. The spatial distribution of Oxygen, Neon, Sulphur,
Silicon ... | 0111586v1 |
2001-12-01 | Production of neutrons, neutrinos and gamma-rays by a very fast pulsar in the Galactic Center region | We consider the possibility that the excess of cosmic rays near $\sim
10^{18}$ eV, reported by the AGASA and SUGAR groups from the direction of the
Galactic Center, is caused by a young, very fast pulsar in the high density
medium. The pulsar accelerates iron nuclei to energies $\sim 10^{20}$ eV, as
postulated by the G... | 0112008v1 |
2001-12-02 | Asymmetric Supernovae from Magneto-Centrifugal Jets | Strong toroidal magnetic fields generated in stellar collapse can generate
magneto-centrifugal jets in analogy to those found in simulations of black hole
accretion and explain why all core collapse supernovae are found to be
substantially asymmetric and predominantly bi-polar. We describe two phases:
the initial LeBla... | 0112020v1 |
2002-03-04 | X-ray Sources and Star Formation Activity in the Sgr B2 Cloud Observed with Chandra | We report the X-ray population study in the giant molecular cloud Sagittarius
B2 (SgrB2). More than a dozen of X-ray cloud members (and candidates) are
discovered with Chandra. Two bright X-ray sources are located near Sgr B2 Main,
the most copious complex of the ultra compact HII sources. The X-ray spectra
are fitted ... | 0203035v1 |
2002-04-08 | X-Ray Resonance Opacity of Oxygen and Iron in AGN MCG--6-30-15 | Theoretical differential oscillator strengths related to monochromatic
opacity due to K- and L-shell absorption from oxygen and iron ions are directly
compared with the Chandra and Xmm-Newton spectra of Seyfert~1 galaxy
MCG--6-30-15. We compute the highly resolved continuum with resonances due to O
I - VI and Fe XVI. I... | 0204116v2 |
2002-05-02 | History of Milky Way Dwarf Spheroidal Galaxies Imprinted on Abundance Patterns of Neutron-Capture Elements | Stellar abundance pattern of neutron-capture elements such as barium is used
as a powerful tool to infer how star formation proceeded in dwarf spheroidal
(dSph) galaxies. It is found that the abundance correlation of barium with iron
in stars belonging to dSph galaxies orbiting the Milky Way, i.e., Draco,
Sextans, and ... | 0205013v1 |
2002-06-06 | Predicted FeII Emission-Line Strengths from Active Galactic Nuclei | We present theoretical FeII emission line strengths for physical conditions
typical of Active Galactic Nuclei with Broad-Line Regions. The FeII line
strengths were computed with a precise treatment of radiative transfer using
extensive and accurate atomic data from the Iron Project. Excitation mechanisms
for the FeII e... | 0206096v1 |
2002-07-10 | The Iron Project and Non-LTE stellar modeling | Latest developments in theoretical computations since the international
Opacity Project (OP), under the new the Iron Project (IP) and extensions, are
described for applications to a variety of objects such as stellar atmospheres,
nebulae, and active galactic nuclei. The primary atomic processes are: electron
impact exc... | 0207223v1 |
2002-08-06 | The Magnetorotational Instability in Core Collapse Supernova Explosions | We investigate the action of the magnetorotational instability (MRI) in the
context of iron-core collapse. Exponential growth of the field on the rotation
time scale by the MRI will dominate the linear growth process of field line
"wrapping" with the same characteristic time. We examine a variety of initial
rotation st... | 0208128v2 |
2002-09-12 | Integrated Spectroscopy of Bulge Globular Clusters and Fields I. The Data Base and Comparison of Individual Lick Indices in Clusters and Bulge | We present a comprehensive spectroscopic study of the integrated light of
metal-rich Galactic globular clusters and the stellar population in the
Galactic bulge. We measure line indices which are defined by the Lick standard
system and compare index strengths of the clusters and Galactic bulge. Both
metal-rich globular... | 0209238v1 |
2002-09-12 | The Spiral Structure of the Milky Way, Cosmic Rays, and Ice Age Epochs on Earth | The short term variability of the Galactic cosmic ray flux (CRF) reaching
Earth has been previously associated with variations in the global low altitude
cloud cover. This CRF variability arises from changes in the solar wind
strength. However, cosmic ray variability also arises intrinsically from
variable activity of ... | 0209252v1 |
2002-11-07 | Gamma-Ray Bursts in Pulsar Wind Bubbles: Putting the Pieces Together | We present the main observational features expected for GRBs that occur
inside pulsar wind bubbles (PWBs). This is the most natural outcome of
supranova model where initially a supernova explosion takes place, leaving a
supra-massive NS, which loses its rotational energy over a time t_sd and
collapses to a BH, triggeri... | 0211136v1 |
2002-11-20 | Magnetic Field in Supernovae | A relatively modest value of the initial rotation of the iron core, a period
of ~ 6-31 s, will give a very rapidly rotating protoneutron star and hence
strong differential rotation with respect to the infalling matter. Under these
conditions, a seed field is expected to be amplified by the MRI and to grow
exponentially... | 0211458v1 |
2002-12-27 | Iron is not Depleted in High-Ionization Nuclear Emission-Line Regions of Active Galactic Nuclei | In order to examine whether or not high-ionization nuclear emission-line
regions (HINERs) in narrow-line regions of active galactic nuclei are dusty, we
focus on two high-ionization forbidden emission lines, [Fe VII]6087 and [Ne
V]3426. We perform photoionization model calculations to investigate possible
dependences o... | 0212546v1 |
2003-02-26 | Atomic data from the Iron Project. LIII. Relativistic allowed and forbidden transition probabilities for Fe XVII | An extensive set of fine structure levels and corresponding transition
probabilities for allowed and forbidden transitions in Fe XVII is presented. A
total of 490 bound energy levels of Fe XVII of total angular momenta 0 <= J <=
7 of even and odd parities with 2 <= n <= 10, 0 <= l <= 8, 0 <= L <= 8, and
singlet and tri... | 0302561v1 |
2003-04-08 | BeppoSAX average spectra of Seyfert galaxies | 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 o... | 0304133v1 |
2003-04-26 | Hot HB stars in globular clusters - Physical parameters and consequences for theory. VI. The second parameter pair M 3 and M 13 | We present the results of spectroscopic analyses of hot horizontal branch
(HB) stars in M 13 and M 3, which form a famous ``second parameter'' pair. From
the spectra and Stroemgren photometry we derived -- for the first time in M 13
-- atmospheric parameters (effective temperature and surface gravity). For
stars with S... | 0304475v1 |
2003-05-24 | A New Population of Old Stars | We report the results of a coherent study of three chemically anomalous
metal-poor ([Fe/H] ~ -2) stars. These objects exhibit unusually low abundances
of Mg, Si, Ca (alpha-elements) and Sr, Y, and Ba (neutron-capture elements).
Our analyses confirm and expand upon earlier reports of atypical abundances in
BD+80~245, G4... | 0305479v1 |
2003-06-26 | An intense and broad FeKalpha line observed in the X-ray luminous quasar Q0056-363 with XMM-Newton | We present an XMM-Newton observation of the radio-quiet quasar Q0056-363
(z=0.162). This is the first time that this quasar is observed in the hard
X-ray range (above 2 keV). We find that Q0056-363 is a powerful X-ray quasar,
with a 0.3-12 keV unabsorbed luminosity of about 1.2 x 10^45 erg s-1 with the
largest part (~6... | 0306550v1 |
2003-08-05 | The hard X-ray view of the low-luminosity blazar in the radio galaxy NGC6251 | We present results from a BeppoSAX (July 2001) observation of the FRI radio
galaxy NGC6251, together with a re-analysis of archival ASCA (October 1994) and
Chandra (September 2000) data. The weak detection above 10 keV and the lack of
iron fluorescent K-alpha emission lines in the BeppoSAX spectrum rule out that
the bu... | 0308076v3 |
2003-08-11 | The XMM/BeppoSAX observation of Mkn 841 | Mkn 841 has been observed simultaneously by XMM and BeppoSAX in January 2001.
Due to operational contingency, the 30ks XMM observation was split into two
parts, separated by about 15 hours. We first report the presence of a narrow
iron line which appears to be rapidly variable between the two pointings,
requiring a non... | 0308176v1 |
2003-09-15 | The X-ray spectra of the flaring and quiescent states of AT Microscopii observed by XMM-Newton | The X-ray spectrum of the late-type M-dwarf binary AT Mic (dM4.5e+dM4.5e) is
observed in the wavelength range 1 - 40 Angstrom by means of rgs and epic-mos
on board XMM-Newton. During the exposure a flare occured. We have performed a
3-temperature fit and a DEM-modeling to the flaring and quiescent part of the
spectrum.... | 0309383v1 |
2003-09-16 | Timing and spectral studies of LMC X-4 in high and low states with Beppo-SAX: Detection of pulsations in the soft spectral component | We report here detailed timing and spectral analysis of two Beppo-SAX
observations of the binary X-ray pulsar LMC X-4 carried out during the low and
high states of its 30.5 days long super-orbital period. Timing analysis clearly
shows 13.5 s X-ray pulsations in the high state of the super-orbital period
which allows us... | 0309431v1 |
2003-09-19 | The photospheric abundances of active binaries II. Atmospheric parameters and abundance patterns for 6 single-lined RS CVn systems | Photospheric parameters and abundances are presented for a sample of
single-lined chromospherically active binaries from a differential LTE analysis
of high-resolution spectra. Abundances have been derived for 13 chemical
species, including several key elements such as Li, Mg, and Ca. Two methods
have been used. The ef... | 0309535v1 |
2003-10-09 | BeppoSAX observations of Seyfert 1s in the Piccinotti sample I: poorly studied sources | 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 du... | 0310248v1 |
2003-10-22 | A Method for energy estimation and mass composition determination of primary cosmic rays at Chacaltaya observation level based on atmospheric Cerenkov light technique | A new method for energy and mass composition estimation of primary cosmic ray
radiation based on atmospheric Cerenkov light flux in extensive air showers
(EAS) analysis is proposed. The Cerenkov light flux in EAS initiated by primary
protons and iron nuclei is simulated with CORSIKA 5.62 code for Chacaltaya
observation... | 0310651v2 |
2003-11-20 | A long, hard look at MCG-6-30-15 with XMM-Newton II: detailed EPIC analysis and modelling | The bright Seyfert 1 galaxy MCG-6-30-15 has provided some of the best
evidence to date for the existence of supermassive black holes in active
galactic nuclei. Observations with ASCA revealed an X-ray iron line profile
shaped by strong Doppler and gravitational effects. In this paper the shape of
the iron line, its var... | 0311473v1 |
2004-01-09 | Theoretical FeI/II/III Emission-Line Strengths from Active Galactic Nuclei with Broad-Line Regions | We present theoretical iron emission line strengths for physical conditions
typical of Active Galactic Nuclei with Broad-Line Regions. The non-local
thermodynamic equilibrium (NLTE) models include a new and extensive treatment
of radiative transfer in the FeIII ion, complementing the FeII emission line
strengths predic... | 0401168v1 |
2004-01-20 | Nitrogen abundances in Planet-harbouring stars | We present a detailed spectroscopic analysis of nitrogen abundances in 91
solar-type stars, 66 with and 25 without known planetary mass companions. All
comparison sample stars and 28 planet hosts were analysed by spectral synthesis
of the near-UV NH band at 3360 \AA observed at high resolution with the
VLT/UVES,while t... | 0401396v1 |
2004-02-09 | The Toroidal Iron Atmosphere of a Protoneutron Star: Numerical Solution | A numerical method presented by Imshennik et al. (2002) is used to solve the
two dimensional axisymmetric hydrodynamic problem on the formation of a
toroidal atmosphere during the collapse of an iron stellar core and outer
stellar layers. An evolutionary model from Boyes et al. (1999) with a total
mass of $25M_{\odot}$... | 0402191v1 |
2004-02-10 | Discovery of Soft Spectral Component and Transient 22.7s Quasi Periodic Oscillations of SAX J2103.5+4545 | XMM-Newton observed SAX J2103.5+4545 on January 6, 2003, while RXTE was
monitoring the source. Using RXTE-PCA dataset between December 3, 2002 and
January 29, 2003, the spin period and average spin-up rate during the
XMM-Newton observations were found to be $354.7940\pm0.0008$ s and
$(7.4\pm0.9)\times10^{-13}$Hz s$^{-1... | 0402221v2 |
2004-02-13 | The high energy X-ray tail of Eta Car revealed by BeppoSAX | We report on the June 2000 long (100 ks) BeppoSAX exposure that has unveiled
above 10 keV a new very high energy component of the X-ray spectrum of Eta Car
extending to at least 50 keV. We find that the 2-150 keV spectrum is best
reproduced by a thermal + non-thermal model. The thermal component dominates
the 2-10 keV ... | 0402329v1 |
2004-03-03 | XMM-Newton Observations of NGC 507: Super-solar Metal Abundances in the Hot ISM | We present the results of the X-ray XMM-Newton observations of NGC 507, a
dominant elliptical galaxy in a small group of galaxies, and report
'super-solar' metal abundances of both Fe and a-elements in the hot ISM of this
galaxy. We find Z_Fe = 2-3 times solar inside the D25 ellipse of NGC 507. This
is the highest Z_Fe... | 0403105v2 |
2004-03-10 | Far-UV Spectroscopic Analyses of Four Central Stars of Planetary Nebulae | We analyze the Far-UV/UV spectra of four central stars of planetary nebulae
with strong wind features -- NGC 2371, Abell 78, IC 4776 and NGC 1535, and
derive their photospheric and wind parameters by modeling high-resolution FUSE
(Far-Ultraviolet Spectroscopic Explorer) data in the Far-UV and HST-STIS and
IUE data in t... | 0403262v1 |
2004-04-15 | Iron abundances from high-resolution spectroscopy of the open clusters NGC 2506, NGC 6134, and IC 4651 | This is the first of a series of papers devoted to derive the metallicity of
old open clusters in order to study the time evolution of the chemical
abundance gradient in the Galactic disk. We present detailed iron abundances
from high resolution (R~40000) spectra of several red clump and bright giant
stars in the open ... | 0404298v1 |
2004-05-19 | Where Did The Moon Come From? | The current standard theory of the origin of the Moon is that the Earth was
hit by a giant impactor the size of Mars causing ejection of iron poor impactor
mantle debris that coalesced to form the Moon. But where did this Mars-sized
impactor come from? Isotopic evidence suggests that it came from 1AU radius in
the sola... | 0405372v2 |
2004-05-27 | High resolution X-ray spectra of quasars | Past X-ray observations by ASCA suggest that warm absorbers (O VII and O VIII
edges) are apparently rare in high luminosity AGNs (quasars) while they are
more common in low luminosity AGNs (Seyferts). However, this could be a
selection effect if high luminosity AGNs have mostly narrow absorption lines
(with no strong b... | 0405563v1 |
2004-06-11 | Intracluster Stars and the Chemical Enrichment of the Intracluster Medium | We explore the contribution of intracluster stars (ICS) to the chemical
enrichment history of the intracluster medium (ICM). In contrast to scenarios
in which all the metals originate in cluster galaxies and are then transported
into the ICM, intracluster stars enrich the ICM in situ, thereby contributing
100% of their... | 0406291v2 |
2004-07-19 | The Origin of Fe II Emission in AGN | We used a very large set of models of broad emission line (BEL) clouds in AGN
to investigate the formation of the observed Fe II emission lines. We show that
photoionized BEL clouds cannot produce both the observed shape and observed
equivalent width of the 2200-2800A Fe II UV bump unless there is considerable
velocity... | 0407404v1 |
2004-07-29 | A Study of the Composition of Ultra High Energy Cosmic Rays Using the High Resolution Fly's Eye | The composition of Ultra High Energy Cosmic Rays (UHECR) is measured with the
High Resolution Fly's Eye cosmic ray observatory (HiRes) data using the Xmax
technique. Data were collected in stereo between 1999 November and 2001
September. The data are reconstructed with well-determined geometry.
Measurements of the atmo... | 0407622v3 |
2004-08-27 | The metal enrichment of the intracluster medium in hierarchical galaxy formation models | We investigate the metal enrichment of the intracluster medium (ICM) in the
framework of hierarchical models of galaxy formation. We calculate the
formation and evolution of galaxies and clusters using a semi-analytical model
which includes the effects of flows of gas and metals both into and out of
galaxies. For the f... | 0408529v2 |
2004-09-02 | Orbital Phase Spectroscopy of GX 301--2 with RXTE-PCA | We have investigated the orbital phase dependence of the X-ray spectrum of
the High Mass X-ray Binary pulsar GX 301--2. Here we present the results from a
spectral analysis of two sets of observations of GX 301--2 with the Rossi X-ray
Timing Explorer (RXTE). Of particular interest are the variations of the
absorption c... | 0409056v1 |
2004-09-17 | Presupernova Evolution of Differentially Rotating Massive Stars Including Magnetic Fields | As a massive star evolves through multiple stages of nuclear burning on its
way to becoming a supernova, a complex, differentially rotating structure is
set up. Angular momentum is transported by a variety of classic instabilities,
and also by magnetic torques from fields generated by the differential
rotation. We pres... | 0409422v1 |
2004-11-12 | An XMM-Newton Observation of the Seyfert 2 Galaxy NGC 6300. I. The Nucleus | We present results from a half-day observation by XMM-Newton of the nucleus
of the nearby Seyfert 2 galaxy NGC 6300. The X-ray spectrum of the nucleus
consists of a heavily absorbed hard component dominating the 3--10 keV band and
a soft component seen in the 0.2--2 keV band. In the hard band, the spectrum is
well fitt... | 0411328v1 |
2004-11-18 | An XMM-Newton view of the cluster of galaxies Abell 85 | We have observed the cluster of galaxies Abell 85 with XMM-Newton. These data
have allowed us to confirm in a previous paper the existence of the extended 4
Mpc filament detected by the ROSAT PSPC in the neighbourhood of this cluster,
and to determine an X-ray temperature of about about 2 keV. We now present a
thorough... | 0411527v1 |
2004-11-22 | The iron $K_α$-line as a tool for an evaluation of black hole parameters | Recent X-ray observations of microquasars and Seyfert galaxies reveal broad
emission lines in their spectra, which can arise in the innermost parts of
accretion disks. Simulations indicate that at low inclination angle the line is
measured by a distant observer as characteristic two-peak profile. However, at
high incli... | 0411611v1 |
2004-12-03 | How do Uncertainties in the Surface Chemical Abundances of the Sun Affect the Predicted Solar Neutrino Fluxes? | We show that uncertainties in the values of the surface heavy element
abundances of the Sun are the largest source of the theoretical uncertainty in
calculating the p-p, pep, 8B, 13N, 15O, and 17F solar neutrino fluxes. We
evaluate for the first time the sensitivity (partial derivative) of each solar
neutrino flux with... | 0412096v2 |
2004-12-09 | Unusual X-ray transients in the Galactic Centre | We report the discovery in the Galactic Centre region of two hard X-ray
sources, designated as XMM J174457-2850.3 and XMM J174544-2913.0, which
exhibited flux variations in the 2--10 keV band in excess of a factor of 100 in
observations spanning roughly a year. In both cases the observed hydrogen
column density is cons... | 0412236v1 |
2005-01-26 | The XMM-Newton view of PG quasars: II. Properties of the Fe K-alpha line | The properties of the fluorescence Fe K-alpha emission lines of a sample of
38 quasars (QSOs) observed with XMM-Newton are studied. These objects are
included in the optically selected sample from the Palomar-Green (PG) Bright
Quasar Survey with an X-ray luminosity 1.3E43<L(2-10 keV)<5.1E45 ergs/s and
z<1.72. For each ... | 0501587v1 |
2005-02-13 | Neural Networks as a Composition Diagnostic for Ultra-high Energy Cosmic Rays | We analyze here the possibility of studying mass composition in the Auger
data sample using neural networks as a diagnostic tool. Extensive air showers
were simulated using the AIRES code, for the two hadronic interaction models in
current use: QGSJet and Sibyll. Both, photon and hadron primaries were
simulated and use... | 0502255v1 |
2005-03-01 | Nucleosynthetic signatures of the first stars | The chemically most primitive stars provide constraints on the nature of the
first stellar objects that formed in the Universe; elements other than
hydrogen, helium and traces of lithium within these objects were generated by
nucleosynthesis in the very first stars. The relative abundances of elements in
the surviving ... | 0503021v2 |
2005-04-14 | Iron abundances derived from RR Lyrae light curves and low-dispersion spectroscopy | With the aid of the All Sky Automated Survey (ASAS) database on the Galactic
field, we compare the iron abundances of fundamental mode RR Lyrae stars
derived from the Fourier parameters with those obtained from low-dispersion
spectroscopy. We show from a set of 79 stars, distinct from the original
calibrating sample of... | 0504327v1 |
2005-04-21 | Sulphur abundances in Terzan 7 | We present here the first measurements of sulphur abundances in extragalactic
stars. We make use of high resolution spectra, obtained with UVES at the ESO
8.2 m Kueyen telescope, of three giants of the Globular Cluster Terzan 7, which
belongs to the Sagittarius dwarf galaxy. We measure the sulphur abundances
using the ... | 0504463v1 |
2005-08-02 | Charge Exchange Spectra of Hydrogenic and He-like Iron | We present H-like Fe XXVI and He-like Fe XXV charge-exchange spectra
resulting from collisions of highly charged iron with N2 gas at an energy of 10
eV/amu in an electron beam ion trap. Although individual high-n emission lines
are not resolved in our measurements, we observe that the most likely level for
Fe25+ --> Fe... | 0508078v1 |
2005-08-05 | The Radiative Transport of Dust in Primordial Galaxies and Second-Generation Star Formation | We investigate the radiative transport of dust in primordial galaxies in the
presence of the UV radiation field from the first metal-free stars. We find
that dust created in the first supernova (SN) explosions can be driven through
the interior of the SN remnant to accumulate in the SN shells, where
second-generation s... | 0508163v2 |
2005-08-24 | XMM-Newton spectroscopy of high-redshift QSOs | XMM-Newton observations of 29 high redshift (z>2) quasars, including seven
radio-quiet, 16 radio-loud and six Broad Absorption Line (BAL) objects, are
presented; due to the high redshifts, the rest-frame energy bands extend up to
\~30-70 keV. Over 2-10 keV, the quasars can be well fitted in each case by a
simple power-... | 0508524v1 |
2005-09-22 | The new record holder for the most iron-poor star: HE 1327-2326, a dwarf or subgiant with [Fe/H]=-5.4 | We describe the discovery of HE 1327-2326, a dwarf or subgiant with
[Fe/H]}=-5.4. The star was found in a sample of bright metal-poor stars
selected from the Hamburg/ESO survey. Its abundance pattern is characterized by
very high C and N abundances. The detection of Sr which is overabundant by a
factor of 10 as compare... | 0509658v1 |
2005-10-05 | IGR J16393-4643: a new heavily-obscured X-ray pulsar | An analysis of the high-energy emission from IGR J16393-4643 (=AX
J1639.0-4642) is presented using data from INTEGRAL and XMM-Newton. The source
is persistent in the 20-40 keV band at an average flux of 5.1x10^-11
ergs/cm2/s, with variations in intensity by at least an order of magnitude. A
pulse period of 912.0+/-0.1 ... | 0510112v2 |
2006-02-03 | On the origin of the Fe K-alpha line cores in Active Galactic Nuclei | X-ray observations with Chandra and XMM-Newton have shown that there are
relatively narrow cores to the iron K-alpha emission lines in active galactic
nuclei (AGN). Plausible origins for this core emission include the outer
regions of an accretion disk, a pc-scale molecular torus, and the optical
broad-line region (BLR... | 0602081v1 |
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