18385480
Rapidly variable Fe K$\alpha$ line in NGC 4051
We present a detailed analysis on the variability of the Fe K emission line in NGC 4051 using ASCA data. Through simple Gaussian line fits, we find not only obvious Fe K line variability with no significant difference in the X-ray continuum flux between two ASCA observations which were separated by $\sim$ 440 days, but also rapid variability of Fe K line on time scales $\sim 10^4$ s within the second observation. During the second observation, the line is strong (EW = 733$^{+206}_{-219}$ eV) and broad ($\sigma = 0.96^{+0.49}_{-0.35}$ keV) when the source is brightest, and become weaker (EW = 165$^{+87}_{-86}$ eV) and narrower ($\sigma<0.09$ keV) whilst the source is weakest. The equivalent width of Fe K line correlates positively with the continuum flux, which shows an opposite trend with another Seyfert 1 galaxy MCG --6-30-15.
17167816
Two-Current-Sheet Reconnection Model of Interdependent Flare and Coronal Mass Ejection
Time-dependent resistive magnetohydrodynamic simulations are carried out to study a flux rope eruption caused by magnetic reconnection with implication in coexistent flare-CME (coronal mass ejection) events. An early result obtained in a recent analysis of double catastrophe of a flux rope system is used as the initial condition, in which an isolated flux rope coexists with two current sheets: a vertical one below and a transverse one above the flux rope. The flux rope erupts when reconnection takes place in the current sheets, and the flux rope dynamics depends on the reconnection sequence in the two current sheets. Three cases are discussed: reconnection occurs (1) simultaneously in the two current sheets, (2) first in the transverse one and then in the vertical one, and (3) in an order opposite that of case 2. Such a two-current-sheet reconnection exhibits characteristics of both magnetic breakout for CME initiation and the standard flare model. We argue that both breakout-like and tether-cutting reconnections could be important for CME eruptions and associated surface activities.
17200560
Ionized ultraviolet and soft X-ray absorption in the low-redshift active galactic nucleus PG 1126−041
We present here the analysis of ultraviolet spectra from IUE and an X-ray spectrum from ROSAT PSPC observations of the X-ray-weak, far-infrared-loud AGN, PG 1126−041 (Mrk 1298). The first UV spectra taken in 1992 June, simultaneously with ROSAT, show strong absorption lines of N v, C iv and Si iv, extending over a velocity range from −1000 to −5000 km s−1 with respect to the corresponding line centre. Our analysis shows that the broad emission-line region (BELR) is, at least partially, covered by the material causing these absorption lines. In the IUE spectrum taken in 1995 January, the continuum was a factor of 2 brighter and the UV absorption lines are found to be considerably weaker than in 1992, but little variation in the emission-line fluxes is found. With UV spectral indices of αUV≃1.82 and 1.46 for the 1992 and 1995 data, the far-UV spectrum is steep. Based on the emission-line ratios and the broad-band spectral energy distribution, we argue that the steepness of the UV spectrum is unlikely to be caused by reddening. 
 
 
 
The soft X-ray emission in the ROSAT band is weak. A simple power-law model yields a very poor fit with a UV-to-X-ray spectral index αUVX=2.3. Highly ionized (warm) absorption is suggested by the ROSAT data. After correcting for a warm absorber, the optical to X-ray spectral slope is close to the average of αUVX≃1.67 for radio-quiet quasars. 
 
 
 
From photoionization calculations we find the following results. (1) A single-zone absorption model cannot explain simultaneously the UV absorption lines and the ionized X-ray absorption if metal abundances are solar. Furthermore, in order to be consistent with the equivalent width of the observed Lyα absorption line, the turbulent velocity of the warm absorber must be less than 190 km s−1, which imposes serious constraints on a disc wind model. (2) The UV absorption lines and their variability cannot be explained by a single-zone model with solar abundances and the large variability in the absorption lines suggests that C iv and N v absorption lines are not severely saturated. (3) The absorption of the ionizing continuum by warm material strongly affects the emission-line spectrum.
12993780
Measurement of CC interactions produced by ${}^8$B solar neutrinos at SNO
1458695
The X-Ray Absorber in Broad Absorption Line Quasars
Recent observations of Broad Absorption Line (BAL) quasars demonstrated that the soft X-ray emission of these objects is extremely weak, and convincing evidence for very strong absorption by a high column density (~1023.5 cm-2) was obtained for PG 1411+442, even though it is one of the few BAL QSOs strongly detected in soft X-rays. This paper examines the ionization status and geometry of the X-ray absorber by combining the properties of the UV lines with the X-ray continuum absorption. We show that the gas has to have large column densities in ions of major UV absorption lines, such as C IV, N V, O VI, and Ne VIII, in order to have sufficient opacity around 0.2-0.35 keV. The UV absorption lines have to be saturated if the X-ray absorber intersects the line of sight to the UV continuum emission region. A uniformly covering UV and X-ray absorption model can be constructed for PG 1411+442, but in some other soft X-ray-detected BAL QSOs, such as PG 1001+054, the observed line optical depth is much lower than expected from the X-ray-absorbing material. We propose a scheme in which a substantial fraction of the line of sight to the continuum source may be covered by either an optically thick flow or clouds in a narrow velocity range, but in which the total covering factor of either the whole flow or all clouds is close to unity. The absorber can contribute significantly to the extremely highly ionized emission lines, such as O VI λλ1032/1037 and Ne VIII λλ770/780, if it covers a substantial fraction of solid angle and if the density is higher than 108 cm-3. However, it has very little impact on the medium- and low-ionization UV lines such as N V and C IV. The profiles of Ne VIII and O VI lines may be indicators for the kinematics of the X-ray absorber in QSOs. The observed Ne VIII line profiles in QSOs suggest that the velocity of the gas projected onto our line of sight is similar to that seen in the outflows of the UV BALs.
16824048
How Saturated Are Absorption Lines in the Broad Absorption Line Quasar PG 1411+442?
Recently, convincing evidence was found for extremely large X-ray absorption by column densities greater than 1023 cm-2 in broad absorption line quasars. One consequence of this is that any soft X-ray emission from these QSOs would be the scattered light or leaked light from partially covering absorbing material. A detection of the unabsorbed soft X-ray and absorbed hard X-ray component will allow us to determine the total column density as well as the effective covering factor of the absorbing material, which are difficult to obtain from the UV absorption lines. Brinkmann et al. recently showed that both the unabsorbed and absorbed components are detected in the nearby very bright broad absorption line quasar PG 1411+442. In this Letter, we make a further analysis of the broadband X-ray spectrum and the UV spectrum from the Hubble Space Telescope and demonstrate that broad absorption lines are completely saturated at the bottom of absorption troughs.
43759506
Bounds on the CP asymmetry in b --> sgamma decays.
We have measured the CP asymmetry A(CP) identical with[gamma(b-->sgamma)-gammab-->sgamma)]/[gamma(b-->sgamma)+gamma(b-->sgamma)] to be A(CP) = (-0.079+/-0.108+/-0.022) (1.0+/-0.030), implying that, at 90% confidence level, A(CP) lies between -0.27 and +0.10. These limits rule out some extreme non-standard-model predictions, but are consistent with most, as well as with the standard model.
15380121
A Puzzling X-Ray Source Found in the Chandra Deep Field-South
In this Letter, we report the detection of an extremely strong X-ray emission line in the 940 ks Chandra ACIS-I spectrum of CXOCDFS J033225.3-274219. The source was identified as a type 1 active galactic nucleus at a redshift of z = 1.617, with a 2.0-10.0 keV rest-frame X-ray luminosity of ~1044 ergs s-1. The emission line was detected at 6.2 keV, with an equivalent width (EW) of 4.4 keV; both quantities refer to the observed frame. In the rest frame, the line is at 16.2 keV with an EW of 11.5 keV. An X-ray emission line at a similar energy (~17 keV, in the rest frame) in PKS 2149-306 was discovered before using ASCA data. We reject the possibility that the line is due to a statistical or instrumental artifact. The line is most likely due to blueshifted Fe K emission from an relativistic outflow, probably an inner X-ray jet, with velocities of the order of ~0.6c-0.7c. Other possible explanations are also discussed.
39289464
HLS Turn-by-Turn System and its Application
Measurement principles and analysis of Turn-by-Turn beam position monitor system at Hefei Light Source (HLS) are presented in this paper. In emphases, several typical applications are presented here, which include the commissioning of upgraded injection system on HLS storage, monitoring of transientν transientν transientν transientν transientν transientν transientν transientν transientν transientν and damping time of storage ring, beam instability in injection, as well as experiments of low frequency feedback system. Precise analyses of experimental results offer some conclusions, which are consistent with theoretical expectations. The system plays an important role in study of beam instability and improvement of machine performance.
119283371
EXSdetect: an end-to-end software for extended source detection in X-ray images: application to Swift-XRT data
Aims. We present a stand-alone software (named EXSdetect) for the detection of extended sources in X-ray images. Our goal is to provide a flexible tool capable of detecting extended source s down to the lowest flux levels attainable within instrument al limitations, while maintaining robust photometry, high completeness, and low contamination, regardless of source morphology. EXSdetect was developed mainly to exploit the ever-increasing wealth of archival X-ray data, but is also ideally suited to explore the scientific capabilities of future X-ray facilities, with a strong focu s on investigations of distant groups and clusters of galaxi es. Methods. EXSdetect combines a fast Voronoi tessellation code with a friends-of-friends algorithm and an automated deblending procedure. The values of key parameters are matched to fundamental telescope properties such as angular resolution and instrumental background. In addition, the software is designed to permit extensive tests of its performance via simulations of a wide range of observational scenarios. Results. We applied EXSdetect to simulated data fields modeled to real istically represent the Swift X-ray Cluster Survey (SXCS ), which is based on archival data obtained by the X-ray telescope onboard the Swift satellite. We achieve more than 90% completeness for extended sources comprising at least 80 photons in the 0.5‐2 keV band, a limit that corresponds to 10 14 erg cm 2 s 1 for the deepest SXCS fields. This detection limit is comparable to th e one attained by the most sensitive cluster surveys conducted with much larger X-ray telescopes. While evaluating the performance of EXSdetect, we also explored the impact of improved angular resolution and discuss the ideal properties of the next generation of X-ray survey missions.
18156072
The Unique Rapid Variabilities of the Iron Kα Line Profiles in NGC 4151
We present a detailed analysis of iron Kα line variabilities in NGC 4151 using long ASCA observation data obtained in 1995 May. Despite the relatively small amplitude variations in the continuum flux, the iron Kα line flux and profile show dramatic variations. Particularly, the line profile changes from a single peak to what appears to be double peaks and back in timescales of a few times 104 s. The apparently double-peaked profiles can be well interpreted as line emission from a Keplerian ring around a massive black hole. An absorption line at around 5.9 keV is also marginally detected. We discuss current Fe K line models, but none of them can well explain the observed line and continuum variations.