ترغب بنشر مسار تعليمي؟ اضغط هنا

Effect of the reverse shock on the parameters of the observed X-Ray emission during the 1998 outburst of CI Cam

226   0   0.0 ( 0 )
 نشر من قبل Ekaterina Filippova
 تاريخ النشر 2009
  مجال البحث فيزياء
والبحث باللغة English




اسأل ChatGPT حول البحث

Based on the model of interaction between spherically symmetrical expanding matter and the external medium, we have estimated the parameters of the matter heated by the shock that was produced in the envelope ejected by the explosion of a classical nova during its interaction with the stellar wind from the optical companion. Using this model, we have shown that the matter ejected during the outburst in the system CI Cam had no steep velocity gradients and that the reverse shock could heat the ejected matter only to a temperature of ~0.1 keV. Therefore, this matter did not contribute to the mean temperature and luminosity of the system observed in the energy range 3-20 keV.

قيم البحث

اقرأ أيضاً

This paper reports on the X-ray emission evolution of the ultra-luminous Galactic X-ray pulsar, Swift J0243.6+6124, during the 2017-2018 giant outburst observed by the MAXI GSC. The 2-30 keV light curve and the energy spectra confirm that the luminos ity $L_mathrm{X}$ reached $2.5times 10^{39}$ erg s$^{-1}$, 10 times higher than the Eddington limit. When the source was luminous with $L_mathrm{X}gtrsim 0.9times 10^{38}$ erg s$^{-1}$, it exhibited a negative correlation on a hardness-intensity diagram. However, two hardness ratios, a soft color ($=$ 4-10 keV / 2-4 keV) and a hard color ($=$ 10-20 keV / 4-10 keV), showed somewhat different behavior across a characteristic luminosity of $L_mathrm{c}simeq 5times 10^{38}$ erg s$^{-1}$. The soft color changed more than the hard color when $L_mathrm{X} < L_mathrm{c}$, whereas the opposite was observed above $L_mathrm{c}$. The spectral change above $L_mathrm{c}$ was represented by a broad enhanced feature at $sim 6$ keV. The pulse profiles made a transition from a single-peak to a double-peak one as the source brightened across $L_mathrm{c}$. These spectral and pulse-shape properties can be interpreted by a scenario that the accretion columns on the neutron star surface, producing the Comptonized X-ray emission, gradually became taller as $L_mathrm{X}$ increased. The broad 6 keV enhancement could be a result of cyclotron-resonance absorption at $sim 10$ keV, corresponding to a surface magnetic field $B_mathrm{s}simeq 1.1times 10^{12}$ G. The spin-frequency derivatives calculated with the Fermi GBM data showed a smooth correlation with $L_mathrm{X}$ up to the outburst peak, and its linear coefficient is comparable to those of X-ray binary pulsars whose $B_mathrm{s}$ are $(1-8)times 10^{12}$ G. These results suggest that $B_mathrm{s}$ of Swift J0243.6$+$6124 is a few times $10^{12}$ G.
We present the results of observations of XTE J0421+560 X-ray transient with Rossi X-ray Timing Explorer in the beginning of April 1998. Lightcurve, obtained by ASM all-sky monitor, shows unusually fast decrease in the objects luminosity. Spectra fro m series of observations by PCA and HEXTE experiments were studied in detail. Two emission line regions with energies around 6.5 keV and around 8 keV have been mentioned in the spectra. The possibility of generation of the observed emission in relativistic plasma jet has been discussed. Some analogy is found with known Galactic jet source SS433.
We use a parent sample of 118 gamma-ray burst (GRB) afterglows, with known redshift and host galaxy extinction, to separate afterglows with and without signatures of dominant reverse-shock emission and to determine which physical conditions lead to a prominent reverse-shock emission. We identify 10 GRBs with reverse shock signatures - GRBs 990123, 021004, 021211, 060908, 061126, 080319B, 081007, 090102, 090424 and 130427A. By modeling their optical afterglows with reverse and forward shock analytic light curves and using Monte Carlo simulations, we estimate the parameter space of the physical quantities describing the ejecta and circumburst medium. We find that physical properties cover a wide parameter space and do not seem to cluster around any preferential values. Comparing the rest-frame optical, X-ray and high-energy properties of the larger sample of non-RS-dominated GRBs, we show that the early-time ($<$ 1ks) optical spectral luminosity, X-ray afterglow luminosity and $gamma$-ray energy output of our reverse-shock dominated sample do not differ significantly from the general population at early times. However, the GRBs with dominant reverse shock emission have fainter than average optical forward-shock emission at late time ($>$ 10 ks). We find that GRBs with an identifiable reverse shock component show high magnetization parameter $R_{mathrm{B}} = varepsilon_{rm B,r}/varepsilon_{rm B,f} sim 2 - 10^4$. Our results are in agreement with the mildly magnetized baryonic jet model of GRBs.
58 - E. V. Filippova 2009
We have computed a spherically symmetric model for the interaction of matter ejected during the outburst of a classical nova with the stellar wind from its optical component.This model is used to describe the intense X-ray outburst (the peak 3-20 keV flux was ~2 Crab) of the binary system CI Camelopardalis in 1998. According to our model, the stellar wind from the optical component heated by a strong shock wave produced when matter is ejected from the white dwarf as the result of a thermonuclear explosion on its surface is the emission source in the standard X-ray band. Comparison of the calculated and observed time dependences of the mean radiation temperature and luminosity of the binary system during its outburst has yielded very important characteristics of the explosion.We have been able to measure the velocity of the ejected matter immediately after the onset of the explosion for the first time: it follows from our model that the ejected matter had a velocity of ~2700 km/s even on 0.1-0.5 day after the outburst onset and it flew with such a velocity for the first 1-1.5 day under an external force, possibly, the radiation pressure from the white dwarf. Subsequently, the matter probably became transparent and began to decelerate. The time dependence of the mean radiation temperature at late expansion phases has allowed us to estimate the mass of the ejected matter, ~10^{-7}-10^{-6} Msun. The mass loss rate in the stellar wind required to explain the observed peak luminosity of the binary system during its outburst has been estimated to be dM/dt ~(1-2)x10^{-6} Msun/yr.
42 - L. Boirin 2002
We have observed the X-ray transient XTE J0421+56 in quiescence with XMM-Newton. The observed spectrum is highly unusual being dominated by an emission feature at ~6.5 keV. The spectrum can be fit using a partially covered power-law and Gaussian line model, in which the emission is almost completely covered (covering fraction of 0.98_{-0.06}^{+0.02}) by neutral material and is strongly absorbed with an N_H of (5_{-2}^{+3}) x 10^{23} atom cm^{-2}. This absorption is local and not interstellar. The Gaussian has a centroid energy of 6.4 +/- 0.1 keV, a width < 0.28 keV and an equivalent width of 940 ^{+650}_{-460} eV. It can be interpreted as fluorescent emission line from iron. Using this model and assuming XTE J0421+56 is at a distance of 5 kpc, its 0.5-10 keV luminosity is 3.5 x 10^{33} erg s^{-1}. The Optical Monitor onboard XMM-Newton indicates a V magnitude of 11.86 +/- 0.03. The spectra of X-ray transients in quiescence are normally modeled using advection dominated accretion flows, power-laws, or by the thermal emission from a neutron star surface. The strongly locally absorbed X-ray emission from XTE J0421+56 is therefore highly unusual and could result from the compact object being embedded within a dense circumstellar wind emitted from the supergiant B[e] companion star. The uncovered and unabsorbed component observed below 5 keV could be due either to X-ray emission from the supergiant B[e] star itself, or to the scattering of high-energy X-ray photons in a wind or ionized corona, such as observed in some low-mass X-ray binary systems.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا