9 research outputs found
Soft X-ray emission lines in the X-ray binary Swift J1858.6-0814 observed with XMM-Newton-RGS: disc atmosphere or wind?
We find soft X-ray emission lines from the X-ray binary Swift J1858.6-0814 in
data from XMM-Newton-RGS: N VII, O VII and O VIII, as well as notable residuals
short of a detection at Ne IX and other higher ionisation transitions. These
could be associated with the disc atmosphere, as in accretion disc corona
sources, or with a wind, as has been detected in Swift J1858.6-0814 in emission
lines at optical wavelengths. Indeed, the N VII line is redshifted, consistent
with being the emitting component of a P-Cygni profile. We find that the
emitting plasma has an ionisation parameter and a
density cm. From this, we infer that the emitting
plasma must be within cm of the ionising source,
for a neutron star, and from the
line width that it is at least away
( cm). We compare this with known classes of
emission line regions in other X-ray binaries and active galactic nuclei.Comment: 10 pages, 7 figures, MNRAS accepte
A NuSTAR view of SS433: Precessional evolution of the jet-disk system
SS433 is a Galactic microquasar with powerful outflows (double jet, accretion disk and winds) with well known orbital, precessional and nutational period. In this work we characterise different outflow parameters throughout the precessional cycle of the system. We analyse 10 NuSTAR ( keV) observations of 30~ks that span 1.5 precessional cycles. We extract averaged spectra and model them using a combination of a double thermal jet model (bjet) and pure neutral and relativistic reflection (xillverCp and relxilllpCp) over an accretion disk. We find an average jet bulk velocity of with an opening angle of 6~degrees. Eastern jet kinetic power ranges from 1 to ~erg/s, with base "coronal" temperatures ranging between 14 and 18 keV. Nickel to iron abundances remain constant at 9 (within 1). The western to eastern jet flux ratio becomes on intermediate phases, about 35% of the total precessional orbit. The keV total unabsorbed luminosity of the jet and disk ranges from 2 to 20 10~erg/s, with the disk reflection component contributing mainly to the hard keV excess and the stationary 6.7 keV ionized Fe line complex. At low opening angles we find that the jet expands sideways following an adiabatic expansion of a gas with temperature . Finally, the central source and lower parts of the jet could be hidden by an optically thick region of and size ~cm1700~ for $M_{BH}=3~M_{\odot}
A NuSTAR view of SS433: Precessional evolution of the jet-disk system
SS433 is a Galactic microquasar with powerful outflows (double jet, accretion disk and winds) with well known orbital, precessional and nutational period. In this work we characterise different outflow parameters throughout the precessional cycle of the system. We analyse 10 NuSTAR ( keV) observations of 30~ks that span 1.5 precessional cycles. We extract averaged spectra and model them using a combination of a double thermal jet model (bjet) and pure neutral and relativistic reflection (xillverCp and relxilllpCp) over an accretion disk. We find an average jet bulk velocity of with an opening angle of 6~degrees. Eastern jet kinetic power ranges from 1 to ~erg/s, with base "coronal" temperatures ranging between 14 and 18 keV. Nickel to iron abundances remain constant at 9 (within 1). The western to eastern jet flux ratio becomes on intermediate phases, about 35% of the total precessional orbit. The keV total unabsorbed luminosity of the jet and disk ranges from 2 to 20 10~erg/s, with the disk reflection component contributing mainly to the hard keV excess and the stationary 6.7 keV ionized Fe line complex. At low opening angles we find that the jet expands sideways following an adiabatic expansion of a gas with temperature . Finally, the central source and lower parts of the jet could be hidden by an optically thick region of and size ~cm1700~ for $M_{BH}=3~M_{\odot}
A NuSTAR view of SS433: Precessional evolution of the jet-disk system
SS433 is a Galactic microquasar with powerful outflows (double jet, accretion disk and winds) with well known orbital, precessional and nutational period. In this work we characterise different outflow parameters throughout the precessional cycle of the system. We analyse 10 NuSTAR ( keV) observations of 30~ks that span 1.5 precessional cycles. We extract averaged spectra and model them using a combination of a double thermal jet model (bjet) and pure neutral and relativistic reflection (xillverCp and relxilllpCp) over an accretion disk. We find an average jet bulk velocity of with an opening angle of 6~degrees. Eastern jet kinetic power ranges from 1 to ~erg/s, with base "coronal" temperatures ranging between 14 and 18 keV. Nickel to iron abundances remain constant at 9 (within 1). The western to eastern jet flux ratio becomes on intermediate phases, about 35% of the total precessional orbit. The keV total unabsorbed luminosity of the jet and disk ranges from 2 to 20 10~erg/s, with the disk reflection component contributing mainly to the hard keV excess and the stationary 6.7 keV ionized Fe line complex. At low opening angles we find that the jet expands sideways following an adiabatic expansion of a gas with temperature . Finally, the central source and lower parts of the jet could be hidden by an optically thick region of and size ~cm1700~ for $M_{BH}=3~M_{\odot}
The variable radio counterpart of Swift J1858.6-0814
Swift J1858.6-0814 is a transient neutron star X-ray binary discovered in 2018 October. Multiwavelength follow-up observations across the electromagnetic spectrum revealed many interesting properties, such as erratic flaring on minute time-scales and evidence for wind outflows at both X-ray and optical wavelengths, strong and variable local absorption, and an anomalously hard X-ray spectrum. Here, we report on a detailed radio observing campaign consisting of one observation at 5.5/9âGHz with the Australia Telescope Compact Array, and nine observations at 4.5/7.5âGHz with the Karl G. Jansky Very Large Array. A radio counterpart with a flat to inverted radio spectrum is detected in all observations, consistent with a compact jet being launched from the system. Swift J1858.6-0814 is highly variable at radio wavelengths in most observations, showing significant variability when imaged on 3-to-5-min time-scales and changing up to factors of 8 within 20âmin. The periods of brightest radio emission are not associated with steep radio spectra, implying they do not originate from the launching of discrete ejecta. We find that the radio variability is similarly unlikely to have a geometric origin, be due to scintillation, or be causally related to the observed X-ray flaring. Instead, we find that it is consistent with being driven by variations in the accretion flow propagating down the compact jet. We compare the radio properties of SwiftJ1858.6-0814 with those of Eddington-limited X-ray binaries with similar X-ray and optical characteristics, but fail to find a match in radio variability, spectrum, and luminosity
The variable radio counterpart of <i>Swift </i>J1858.6-0814
Swift J1858.6-0814 is a transient neutron star X-ray binary discovered in 2018 October. Multiwavelength follow-up observations across the electromagnetic spectrum revealed many interesting properties, such as erratic flaring on minute time-scales and evidence for wind outflows at both X-ray and optical wavelengths, strong and variable local absorption, and an anomalously hard X-ray spectrum. Here, we report on a detailed radio observing campaign consisting of one observation at 5.5/9 GHz with the Australia Telescope Compact Array, and nine observations at 4.5/7.5 GHz with the Karl G. Jansky Very Large Array. A radio counterpart with a flat to inverted radio spectrum is detected in all observations, consistent with a compact jet being launched from the system. Swift J1858.6-0814 is highly variable at radio wavelengths in most observations, showing significant variability when imaged on 3-to-5-min time-scales and changing up to factors of 8 within 20 min. The periods of brightest radio emission are not associated with steep radio spectra, implying they do not originate from the launching of discrete ejecta. We find that the radio variability is similarly unlikely to have a geometric origin, be due to scintillation, or be causally related to the observed X-ray flaring. Instead, we find that it is consistent with being driven by variations in the accretion flow propagating down the compact jet. We compare the radio properties of Swift J1858.6-0814 with those of Eddington-limited X-ray binaries with similar X-ray and optical characteristics, but fail to find a match in radio variability, spectrum, and luminosity.</p