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Register a new userThe XMM Newton spectra of the 2012 outburst of the black-hole candidate 4U 1630-47 revisited
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Recent XMM-Newton observations of the black-hole candidate 4U 1630-47 during the 2012 outburst revealed three relativistically Doppler-shifted emission lines that were interpreted as arising from baryonic matter in the jet of this source. Here we reanalyse those data and find an alternative model that, with less free parameters than the model with Doppler-shifted emission lines, fits the data well. In our model we allow the abundance of S and Fe in the interstellar material along the line of sight to the source to be non solar. Among other things, this significantly impacts the emission predicted by the model at around 7.1 keV, where the edge of neutral Fe appears, and renders the lines unnecessary. The fits to all the 2012 XMM-Newton observations of this source require a moderately broad emission line at around 7 keV plus several absorption lines and edges due to highly ionised Fe and Ni, which reveal the presence of a highly-ionised absorber close to the source. Finally, our model also fits well the observations in which the lines were detected when we apply the most recent calibration files, whereas the model with the three Doppler-shifted emission lines does not.
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Accreting black holes are known to power relativistic jets, both in stellar-mass binary systems and at the centres of galaxies. The power carried away by the jets, and hence the feedback they provide to their surroundings, depends strongly on their composition. Jets containing a baryonic component should carry significantly more energy than electron-positron jets. While energetic considerations and circular polarisation measurements have provided conflicting circumstantial evidence for the presence or absence of baryons, the only system in which baryons have been unequivocally detected in the jets is the X-ray binary SS 433. Here we report the detection of Doppler-shifted X-ray emission lines from a more typical black hole candidate X-ray binary, 4U1630-47, coincident with the reappearance of radio emission from the jets of the source. We argue that these lines arise in a jet with velocity 0.66c, thereby establishing the presence of baryons in the jet. Such baryonic jets are more likely to be powered by the accretion disc rather than the spin of the black hole, and if the baryons can be accelerated to relativistic speeds, should be strong sources of gamma rays and neutrino emission.
We report the results from an X-ray and near-infrared observation of the Galactic black hole binary 4U 1630--47 in the very high state, performed with {it Suzaku} and IRSF around the peak of the 2012 September-October outburst. The X-ray spectrum is approximated by a steep power law, with photon index of 3.2, identifying the source as being in the very high state. A more detailed fit shows that the X-ray continuum is well described by a multi-color disc, together with thermal and non-thermal Comptonization. The inner disc appears slightly truncated by comparison with a previous high/soft state of this source, even taking into account energetic coupling between the disc and corona, although there are uncertainties due to the dust scattering correction. The near-infrared fluxes are higher than the extrapolated disc model, showing that there is a contribution from irradiation in the outer disk and/or the companion star at these wavelengths. Our X-ray spectra do not show the Doppler shifted iron emission lines indicating a baryonic jet which were seen four days previously in an XMM-Newton observation, despite the source being in a similar state. There are also no significant absorption lines from highly ionized irons as are seen in the previous high/soft state data. We show that the increased source luminosity is not enough on its own to make the wind so highly ionized as to be undetectable. This shows that the disc wind has changed in terms of its launch radius and/or density compared to the high/soft state.
We present the analysis of six {it Chandra} X-ray high-resolution observations of the black hole low-mass X-ray binary 4U~1630-47 taken during its 2012-2013 outburst. {rm Fe}~{sc XXVI} K$alpha$, K$beta$, {rm Fe}~{sc XXV} K$alpha$, K$beta$ and {rm Ca}~{sc XX} K$alpha$ blueshifted absorption lines were identified in the first four observations, which correspond to soft accretion states. The remaining observations, associated to intermediate and possibly hard accretion states, do not show significant absorption features down to equivalent width of 1 eV for both {rm Fe}~{sc XXVI} and {rm Fe}~{sc XXV}. We inferred wind launching radii between $1.2- 2.0$ ($10^{12}$ cm$/n$)$ times 10^{11}$~cm and column densities $N({rm H})> 10^{23}$ cm$^{-2}$. In the first four observations we found that thermal pressure is likely to be the dominant launching mechanism for the wind, although such conclusions depend on the assumed density. We used the spectral energy distributions obtained from our continuum modeling to compute thermal stability curves for all observations using the {sc xstar} photoionization code. We found that the absence of lines in the transitional state cannot be attributed to an evolution of the plasma caused by thermal instabilities derived from the change in the continuum spectrum. In contrast, the disappearance of the wind could indicate an acceleration of the flow or that the plasma has been exhausted during the soft state.
We present the analysis of X-ray observations of the black hole binary 4U~1630$-$47 using relativistic reflection spectroscopy. We use archival data from the RXTE, Swift, and NuSTAR observatories, taken during different outbursts of the source between $1998$ and $2015$. Our modeling includes two relatively new advances in modern reflection codes: high-density disks, and returning thermal disk radiation. Accretion disks around stellar-mass black holes are expected to have densities well above the standard value assumed in traditional reflection models (i.e., $n_{rm e}sim10^{15}~{rm cm^{-3}}$). New high-density reflection models have important implications in the determination of disk truncation (i.e., the disk inner radius). This is because one must retain self-consistency in the irradiating flux and corresponding disk ionization state, which is a function of disk density and system geometry. We find the disk density is $n_{rm e}ge10^{20}~{rm cm^{-3}}$ across all spectral states. This density, combined with our constraints on the ionization state of the material, implies an irradiating flux impinging on the disk that is consistent with the expected theoretical estimates. Returning thermal disk radiation -- the fraction of disk photons which bend back to the disk producing additional reflection components -- is expected predominantly in the soft state. We show that returning radiation models indeed provide a better fit to the soft state data, reinforcing previous results which show that in the soft state the irradiating continuum may be blackbody emission from the disk itself.
We report on the analysis of the data collected by Swift, INTEGRAL and RXTE of the Black Hole Candidate (BHC) 4U 1630-47 during 3 consecutive outbursts occurred in 2006, 2008 and 2010, respectively. We show that, although a similar spectral and temporal behaviour in the energy range between 2-10 keV, these 3 outbursts present pronounced differences above 20 keV. In fact, the 2010 outburst extends at high energies without any detectable cut-off until 150-200 keV, while the other two previous outbursts, occurred on 2006 and 2008, are not detected at all above 20 keV. Moreover, the 2008 outburst does not show any detectable hard state in its final phases and even during the 2010 outburst, the final hard state shows some peculiarities rarely observed in other BHC. We also investigate on the peculiar huge variation of 4U 1630-47 hydrogen column density (N$_{H}$) reported in the literature using the Swift/XRT data. In fact this instrument is one of the most suitable for this purpose thanks to its lower energy coverage.
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