29,220 research outputs found

    Viscous timescale in high mass X-ray binaries

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    Context: Low mass X-ray binaries were found to have very low frequency breaks in their power density spectra below which the power density spectra are nearly in white noise structure and at higher frequencies they approximately follow the Pνν1.3P_\nu \propto \nu^{-1.3} law. Aims: In 2005, Gilfanov and Arefiev studied X-ray variability of persistent LMXBs in the 10810110^{-8}-10^{-1} Hz frequency range and To determine whether high mass X-ray binary power density spectra have similar properties and the findings for low mass X-ray binaries are also valid for high mass binaries, we analyzed the time series of high mass X-ray binary sources produced by All Sky Monitor of Rossi X-ray Timing Explorer. Method: We obtained the power density spectra of the high mass X-ray binaries using the cosine transform of autocorrelation function. Results: We identified break frequencies for seven sources, namely OAO 1657-415, SS 433, Vela X-1, SMC X-1, 4U 1700-377, GX 301-2, and LMC X-1. The normalized break frequencies with respect to the orbital frequency (fbreak/forbitf_{break}/f_{orbit}) for sources OAO 1657-415, SS 433, SMC X-1 and LMC X-1 are consistent with those of Roche lobe overflow systems. The other high mass X-ray binary systems, Vela X-1, GX 301-2, and 4U 1700-377, however, have larger break frequency ratios, fbreak/forbf_{break}/f_{orb} , which are indicative of short viscous times. These are all wind-accreting sources and the stellar winds in the systems allow the formation of only short radius discs. Consequently, we qualitatively distinguished the Roche lobe overflow binaries from the wind accreting system by comparing their normalized break frequencies.Comment: 9 pages, 5 figures, accepted by A&

    A blowout jet associated with one obvious extreme-ultraviolet wave and one complicated coronal mass ejection event

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    In this paper, we present a detailed analysis of a coronal blowout jet eruption which was associated with an obvious extreme-ultraviolet (EUV) wave and one complicated coronal mass ejection (CME) event based on the multi-wavelength and multi-view-angle observations from {\sl Solar Dynamics Observatory} and {\sl Solar Terrestrial Relations Observatory}. It is found that the triggering of the blowout jet was due to the emergence and cancellation of magnetic fluxes on the photosphere. During the rising stage of the jet, the EUV wave appeared just ahead of the jet top, lasting about 4 minutes and at a speed of 458 - \speed{762}. In addition, obvious dark material is observed along the EUV jet body, which confirms the observation of a mini-filament eruption at the jet base in the chromosphere. Interestingly, two distinct but overlapped CME structures can be observed in corona together with the eruption of the blowout jet. One is in narrow jet-shape, while the other one is in bubble-shape. The jet-shaped component was unambiguously related with the outwardly running jet itself, while the bubble-like one might either be produced due to the reconstruction of the high coronal fields or by the internal reconnection during the mini-filament ejection according to the double-CME blowout jet model firstly proposed by Shen et al. (2012b), suggesting more observational evidence should be supplied to clear the current ambiguity based on large samples of blowout jets in future studies.Comment: APJ, Accepted October 19, 201

    Covariant calculation of mesonic baryon decays

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    We present covariant predictions for pi and eta decay modes of N and Delta resonances from relativistic constituent-quark models based on one-gluon-exchange and Goldstone-boson-exchange dynamics. The results are calculated within the point-form approach to Poincare-invariant relativistic quantum mechanics applying a spectator-model decay operator. The direct predictions of the constituent-quark models for covariant pi and eta decay widths show a behaviour completely different from previous ones calculated in nonrelativistic or so-called semirelativistic approaches. It is found that the present theoretical results agree with experiment only in a few cases but otherwise always remain smaller than the experimental data (as compiled by the Particle Data Group). Possible reasons for this behaviour are discussed with regard to the quality of both the quark-model wave functions and the mesonic decay operator.Comment: 10 pages, 2 figures, accepted for publication in Phys. Rev.

    Polarization of Broad Absorption Line QSOs I. A Spectropolarimetric Atlas

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    We present a spectropolarimetric survey of 36 broad absorption line quasi-stellar objects (BAL QSOs). The continuum, absorption trough, and emission line polarization of BAL QSOs yield clues about their structure. We confirm that BAL QSOs are in general more highly polarized than non-BAL QSOs, consistent with a more equatorial viewing direction for the former than the latter. We have identified two new highly-polarized QSOs in our sample (1232+1325 and 1333+2840). The polarization rises weakly to the blue in most objects, perhaps due to scattering and absorption by dust particles. We find that a polarization increase in the BAL troughs is a general property of polarized BAL QSOs, indicating an excess of scattered light relative to direct light, and consistent with the unification of BAL QSOs and non-BAL QSOs. We have also discovered evidence of resonantly scattered photons in the red wing of the C IV broad emission lines of a few objects. In most cases, the broad emission lines have lower polarization and a different position angle than the continuum. The polarization characteristics of low-ionization BAL QSOs are similar to those of high-ionization BAL QSOs, suggesting a similar BAL wind geometry.Comment: 39 pages, 6 figures (20 .gif files), accepted for publication in The Astrophysical Journal Supplement

    Vector meson-vector meson interaction in a hidden gauge unitary approach

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    The formalism developed recently to study vector meson--vector meson interaction, and applied to the case of ρρ\rho\rho, is extended to study the interaction of the nonet of vector mesons among themselves. The interaction leads to poles of the scattering matrix corresponding to bound states or resonances. We show that 11 states (either bound or resonant) get dynamically generated in nine strangeness-isospin-spin channels. Five of them can be identified with those reported in the PDG, i.e., the f0(1370)f_0(1370), f0(1710)f_0(1710), f2(1270)f_2(1270), f2(1525)f'_2(1525), and K2(1430)K^*_2(1430). The masses of the latter three tensor states have been used to fine-tune the free parameters of the unitary approach, i.e., the subtraction constants in evaluating the vector meson -vector meson loop functions in the dimensional regularization scheme. The branching ratios of these five dynamically generated states are found to be consistent with data. The existence of the other six states should be taken as predictions to be tested by future experiments.Comment: typos corrected; more discussions; one of the appendix rearrange

    The Volatility Trend of Protosolar and Terrestrial Elemental Abundances

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    We present new estimates of protosolar elemental abundances based on an improved combination of solar photospheric abundances and CI chondritic abundances. These new estimates indicate CI chondrites and solar abundances are consistent for 60 elements. We compare our new protosolar abundances with our recent estimates of bulk Earth composition (normalized to aluminium), thereby quantifying the devolatilization in going from the solar nebula to the formation of the Earth. The quantification yields a linear trend log(f)=αlog(TC)+β\log(f) = \alpha\log(T_C) + \beta, where ff is the Earth-to-Sun abundance ratio and TCT_C is the 50%\% condensation temperature of elements. The best fit coefficients are: α=3.676±0.142\alpha = 3.676\pm 0.142 and β=11.556±0.436\beta = -11.556\pm 0.436. The quantification of these parameters constrains models of devolatilization processes. For example, the coefficients α\alpha and β\beta determine a critical devolatilization temperature for the Earth TD(E)=1391±15T_{\mathrm{D}}(\mathrm{E}) = 1391 \pm 15 K. The terrestrial abundances of elements with TC<TD(E)T_{C} < T_{\mathrm{D}}(\mathrm{E}) are depleted compared with solar abundances, whereas the terrestrial abundances of elements with TC>TD(E)T_{C} > T_{\mathrm{D}}(\mathrm{E}) are indistinguishable from solar abundances. The terrestrial abundance of Hg (TCT_C = 252 K) appears anomalously high under the assumption that solar and CI chondrite Hg abundances are identical. To resolve this anomaly, we propose that CI chondrites have been depleted in Hg relative to the Sun by a factor of 13±713\pm7. We use the best-fit volatility trend to derive the fractional distribution of carbon and oxygen between volatile and refractory components (fvolf_\mathrm{vol}, freff_\mathrm{ref}). We find (0.91±0.080.91\pm 0.08, 0.09±0.080.09 \pm 0.08) for carbon and (0.80±0.040.80 \pm 0.04, 0.20±0.040.20 \pm 0.04) for oxygen.Comment: Accepted for publication in Icarus. 28 pages, 12 figures, 5 tables. Compared to v1, the results and conclusion are the same, while discussion of results and implications is expanded considerabl
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