scholarly journals Looking through the photoionisation wake: Vela X−1 at φorb ≈ 0.75 with Chandra/HETG

2021 ◽  
Vol 648 ◽  
pp. A105
Author(s):  
R. Amato ◽  
V. Grinberg ◽  
N. Hell ◽  
S. Bianchi ◽  
C. Pinto ◽  
...  
Keyword(s):  
Compact Object ◽  
High Resolution Spectroscopy ◽  
Plasma Parameters ◽  
Plasma Properties ◽  
X Ray ◽  
Block Algorithm ◽  
Orbital Phase ◽  
Blind Search ◽  
Multi Phase ◽  
First Time

Context. The supergiant X-ray binary Vela X−1 represents one of the best astrophysical sources to investigate the wind environment of an O/B star irradiated by an accreting neutron star. Previous studies and hydrodynamic simulations of the system have revealed a clumpy environment and the presence of two wakes: an accretion wake surrounding the compact object and a photoionisation wake trailing it along the orbit. Aims. Our goal is to conduct, for the first time, high-resolution spectroscopy on Chandra/HETGS data at the orbital phase φorb ≈ 0.75, when the line of sight is crossing the photoionisation wake. We aim to conduct plasma diagnostics, inferring the structure and the geometry of the wind. Methods. We performed a blind search employing a Bayesian block algorithm to find discrete spectral features and identify them thanks to the most recent laboratory results or through atomic databases. Plasma properties were inferred both with empirical techniques and with photoionisation models within CLOUDY and SPEX. Results. We detect and identify five narrow radiative recombination continua (Mg XI-XII, Ne IX-X, O VIII) and several emission lines from Fe, S, Si, Mg, Ne, Al, and Na, including four He-like triplets (S XV, Si XIII, Mg XI, and Ne IX). Photoionisation models reproduce the overall spectrum well, except for the near-neutral fluorescence lines of Fe, S, and Si. Conclusions. We conclude that the plasma is mainly photoionised, but more than one component is most likely present, which is consistent with a multi-phase plasma scenario, where denser and colder clumps of matter are embedded in the hot, photoionised wind of the companion star. Simulations with the future X-ray satellites Athena and XRISM show that a few hundred seconds of exposure is sufficient to disentangle the lines of the Fe Kα doublet and the He-like Fe XXV, improving, in general, the determination of the plasma parameters.

scholarly journals The Nature of the Compact Object in the Hard X-Ray Source 4U2206+54

2004 ◽  
Vol 194 ◽  
pp. 208-208
Author(s):  
J. M. Torrejón ◽  
I. Kreykenbohni ◽  
A. Orr ◽  
L. Titarchuk ◽  
I. Negueruela
Keyword(s):  
Neutron Star ◽  
Accretion Disk ◽  
Compact Object ◽  
High Energy ◽  
Energy Data ◽  
X Ray ◽  
Hot Plasma ◽  
Cyclotron Line ◽  
First Time

We present an analysis of archival RXTE and BeppoSAX data of the X-ray source 4U2206+54. For the first time, high energy data (≥ 30 keV) is analyzed. The data is well described by comptonization models in which seed photons with temperatures between 1.1 keV arid 1.5 keV are comptonized by a hot plasma at 50 keV thereby producing a hard tail which extends up to 100 keV. From luminosity arguments it is shown that the area of the soft photons source must be small (r ≈ 1 km) and that the presence of an accretion disk in this system is unlikely. Here we report on the possible existence of a cyclotron line around 30 keV . The presence of a neutron star in the system is strongly favored by the available data.

scholarly journals Deep XMM-Newton observations of the northern disc of M31

2020 ◽  
Vol 637 ◽  
pp. A12
Author(s):  
Patrick J. Kavanagh ◽  
Manami Sasaki ◽  
Dieter Breitschwerdt ◽  
Miguel A. de Avillez ◽  
Miroslav D. Filipović ◽  
...  
Keyword(s):  
Massive Stars ◽  
Low Density ◽  
Plasma Properties ◽  
X Ray ◽  
Star Forming ◽  
Hot Gas ◽  
Grand Design ◽  
Multi Wavelength ◽  
Multi Phase ◽  
Extended Emission

Aims. We use new deep XMM-Newton observations of the northern disc of M31 to trace the hot interstellar medium (ISM) in unprecedented detail and to characterise the physical properties of the X-ray emitting plasmas. Methods. We used all XMM-Newton data up to and including our new observations to produce the most detailed image yet of the hot ISM plasma in a grand design spiral galaxy such as our own. We compared the X-ray morphology to multi-wavelength studies in the literature to set it in the context of the multi-phase ISM. We performed spectral analyses on the extended emission using our new observations as they offer sufficient depth and count statistics to constrain the plasma properties. Data from the Panchromatic Hubble Andromeda Treasury were used to estimate the energy injected by massive stars and their supernovae. We compared these results to the hot gas properties. Results. The brightest emission regions were found to be correlated with populations of massive stars, notably in the 10 kpc star-forming ring. The plasma temperatures in the ring regions are ~0.2 up to ~0.6 keV. We suggest this emission is hot ISM heated in massive stellar clusters and superbubbles. We derived X-ray luminosities, densities, and pressures for the gas in each region. We also found large extended emission filling low density gaps in the dust morphology of the northern disc, notably between the 5 and 10 kpc star-forming rings. We propose that the hot gas was heated and expelled into the gaps by the populations of massive stars in the rings. Conclusions. It is clear that the massive stellar populations are responsible for heating the ISM to X-ray emitting temperatures, filling their surroundings, and possibly driving the hot gas into the low density regions. Overall, the morphology and spectra of the hot gas in the northern disc of M31 is similar to other galaxy discs.

scholarly journals Asteroseismology of massive stars with the MOST satellite

2009 ◽  
Vol 5 (H15) ◽  
pp. 366-366
Author(s):  
Anthony F. J. Moffat ◽  
Keyword(s):  
Massive Stars ◽  
Period Range ◽  
Optical Photometry ◽  
X Ray ◽  
Ob Stars ◽  
Stellar Oscillations ◽  
Rotation Periods ◽  
Minute Period ◽  
Orbital Phase ◽  
First Time

AbstractSince 2003 the MOST (Microvariability and Oscillations of STars) microsatellite has obtained typically a month of non-stop, minute-of-time resolution, high-precision, single-broadband optical photometry for each of a significant number of Galactic OB and WR stars. Numerous p- and g-modes were clearly detected in several OB stars, including discovery of g-modes for the first time in a blue supergiant (Saio et al. 2006). True rotation periods were found for some SPBe pulsators (Cameron et al. 2008). Many O stars are remarkably quiet. Five presumably single WR stars have been observed so far, each interesting in its own way. In particular, the cool WR stars WR123 (WN8) and WR103 (WC9d) both show mostly short-lived, multimode oscillations with most of the Fourier power occurring on a day or longer timescale (Moffat et al. 2008a). WR123 also revealed a fairly stable 10-hour periodicity (Lefèvre et al. 2005). All of these oscillations probably arise in the stellar cores. WR111 (WC5) shows no (coherent) oscillations above the detection limit of 0.05 mmag in the 10-minute period range predicted for strange-mode pulsations at a level of 2 mmag (Moffat et al. 2008b). WR110 (WN5-6 and a stronger-than-average X-ray source) and WR124 (WN8h, i.e. in contrast with the previously observed, hydrogen-free WR123 of otherwise similar subtype), both strongly variable with MOST, are currently being analyzed. The next target just observed (late-June to early Aug 2009) is the 30-day eclipsing binary CV Ser = WR113 (WC8d + O8-9IV). Besides stellar oscillations, we will also search for orbital-phase dependent, stochastic variability in CV Ser as wind clumps in the WR component's dense wind pass in front of the O-star.

scholarly journals Collimated radiation in SS 433

2019 ◽  
Vol 624 ◽  
pp. A127 ◽  
Author(s):  
Idel Waisberg ◽  
Jason Dexter ◽  
Pierre Olivier-Petrucci ◽  
Guillaume Dubus ◽  
Karine Perraut
Keyword(s):  
Spectral Synthesis ◽  
Spectral Energy Distribution ◽  
Compact Object ◽  
Spectral Energy ◽  
X Ray ◽  
Ss 433 ◽  
Heating Mechanism ◽  
Ionization Balance ◽  
First Time ◽  
Optical Bullets

Context. The microquasar SS 433 is well known for its precessing, relativistic, and highly collimated baryonic jets, which manifest in its optical spectrum as pairs of hydrogen and helium emission lines moving with large Doppler shifts. Depending on their heating mechanism, the optical jet bullets may serve as a probe of the collimated radiation coming from the inner region close to the compact object, and which is not directly visible to observers on Earth. Aims. We aim to better understand the baryonic jet phenomenon in SS 433, in particular the properties of the optical bullets and their interaction with the ionizing collimated radiation. Methods. The optical interferometer VLTI/GRAVITY has allowed us to spatially resolve the optical jets in SS 433 for the first time. We present here the second such observation taken over three nights in July 2017. In addition, we used the X-shooter spectrograph at VLT to study the optical bullets in SS 433 in detail. Over the full wavelength range 0.3−2.5 μm, we identified up to twenty pairs of jet lines observed simultaneously, which we modeled with the spectral synthesis code Cloudy. Results. GRAVITY reveals elongated exponential-like radial spatial profiles for the optical jets on scales ≲1−10 mas, suggestive of a heating mechanism acting throughout a long portion of the jet and naturally explained by photoionization by the collimated radiation. We also spatially resolve the movement of the optical bullets for the first time, detecting more extended jet components corresponding to previous ejections. Cloudy photoionization models can explain the spatial intensity profiles measured with GRAVITY and the emission line ratios from X-shooter, and constrain the properties of the optical bullets and the ionizing radiation. We find that the latter must peak in the UV with an isotropic luminosity (as inferred by a face-on observer) ∼1041 erg s−1. Provided that the X-ray spectral energy distribution is sufficiently hard, the collimated X-ray luminosity could still be high enough so that the face-on observer would see SS 433 as ultraluminous X-ray source and it would still be compatible with the H/He/He+ ionization balance of the optical bullets. The kinetic power in the optical jets is constrained to 2−20 × 1038 erg s−1, and the extinction in the optical jets to AV = 6.7 ± 0.1. We suggest there may be substantial AV ≳ 1 and structured circumstellar extinction in SS 433, likely arising from dust formed in equatorial outflows.

scholarly journals The evolving jet spectrum of the neutron star X-ray binary Aql X-1 in transitional states during its 2016 outburst

2018 ◽  
Vol 616 ◽  
pp. A23 ◽  
Author(s):  
M. Díaz Trigo ◽  
D. Altamirano ◽  
T. Dinçer ◽  
J. C. A. Miller-Jones ◽  
D. M. Russell ◽  
...  
Keyword(s):  
Neutron Star ◽  
Flux Density ◽  
Compact Object ◽  
State Transitions ◽  
X Ray ◽  
Spectral Break ◽  
Soft State ◽  
Internal Properties ◽  
Star Surface ◽  
First Time

We report on quasi-simultaneous observations from radio to X-ray frequencies of the neutron star X-ray binary Aql X-1 over accretion state transitions during its 2016 outburst. All the observations show radio to millimetre spectra consistent with emission from a jet, with a spectral break from optically thick to optically thin synchrotron emission that decreases from ~100 GHz to <5.5 GHz during the transition from a hard to a soft accretion state. The 5.5 GHz radio flux density as the source reaches the soft state, 0.82 ± 0.03 mJy, is the highest recorded to date for this source. During the decay of the outburst, the jet spectral break is detected again at a frequency of ~30–100 GHz. The flux density is 0.75 ± 0.03 mJy at 97.5 GHz at this stage. This is the first time that a change in the frequency of the jet break of a neutron star X-ray binary has been measured, indicating that the processes at play in black holes are also present in neutron stars, supporting the idea that the internal properties of the jet rely most critically on the conditions of the accretion disc and corona around the compact object, rather than the black hole mass or spin or the neutron star surface or magnetic field.

scholarly journals XMM–Newton campaign on ultraluminous X-ray source NGC 1313 X-1: wind versus state variability

2020 ◽  
Vol 492 (4) ◽  
pp. 4646-4665 ◽  
Author(s):  
C Pinto ◽  
D J Walton ◽  
E Kara ◽  
M L Parker ◽  
R Soria ◽  
...  
Keyword(s):  
Accretion Rate ◽  
Compact Object ◽  
Accretion Disc ◽  
Emission Lines ◽  
Time Variability ◽  
Strong Emission ◽  
X Ray ◽  
First Time ◽  
Eddington Limit ◽  
Absorption Features

ABSTRACT Most ultraluminous X-ray sources (ULXs) are thought to be powered by neutron stars and black holes accreting beyond the Eddington limit. If the compact object is a black hole or a neutron star with a magnetic field ≲1012 G, the accretion disc is expected to thicken and launch powerful winds driven by radiation pressure. Evidence of such winds has been found in ULXs through the high-resolution spectrometers onboardXMM–Newton, but several unknowns remain, such as the geometry and launching mechanism of these winds. In order to better understand ULX winds and their link to the accretion regime, we have undertaken a major campaign with XMM–Newton to study the ULX NGC 1313 X-1, which is known to exhibit strong emission and absorption features from a mildly relativistic wind. The new observations show clear changes in the wind with a significantly weakened fast component (0.2c) and the rise of a new wind phase which is cooler and slower (0.06–0.08c). We also detect for the first time variability in the emission lines which indicates an origin within the accretion disc or in the wind. We describe the variability of the wind in the framework of variable super-Eddington accretion rate and discuss a possible geometry for the accretion disc.

scholarly journals High resolution X-ray spectroscopy of Supergiant HMXB 4U1700−37 during the compact object eclipse.

2020 ◽  
Author(s):  
M Martínez-Chicharro ◽  
V Grinberg ◽  
J M Torrejón ◽  
N Schulz ◽  
L Oskinova ◽  
...  
Keyword(s):  
High Resolution ◽  
Emission Line ◽  
Density Ratio ◽  
Compact Object ◽  
High Energy ◽  
High Resolution Spectroscopy ◽  
High Mass ◽  
X Ray ◽  
Radial Segregation ◽  
Cold Wind

Abstract We present an analysis of the first observation of the iconic High Mass X-ray Binary 4U 1700−37 with the Chandra High Energy Transmission Gratings during an X-ray eclipse. The goal of the observation was to study the structure/physical conditions in the clumpy stellar wind through high resolution spectroscopy. We find that: a) emission line brightness from K shell transitions, corresponding to near neutral species, directly correlates with continuum illumination. However, these lines do not greatly diminish during eclipse. This is readily explained if fluorescence Kα emission comes from the bulk of the wind. b) The highly ionised Fe xxv and Fe xxvi Lyα diminish during eclipse. Thus, they must be produced in the vicinity of the compact object where log ξ &gt; 3. c) to describe the emission line spectrum, the sum of two self consistent photo ionisation models with low ionisation (log ξ ∼ −1) and high ionisation (log ξ ∼ 2.4) is required. From their emission measures, the clump-to-interclump density ratio can be estimated to be nc/ni ∼ 300. To fit the complex He-like Si xiii profile, the plasma requires a broadening with vbulk ∼ 840 km s−1. Reproducing the observed r ≈ f line fluxes requires the addition of a third collisionally ionised plasma. d) Emission lines widths appear unresolved at the hetg gratings resolution with exception of Silicon. There is no clear radial segregation between (quasi)neutral and ionised species, consistent with cold wind clumps interspersed in a hot rarefied interclump medium.

scholarly journals High-resolution X-ray spectroscopy of the stellar wind in Vela X-1 during a flare

2020 ◽  
Vol 641 ◽  
pp. A144 ◽  
Author(s):  
M. Lomaeva ◽  
V. Grinberg ◽  
M. Guainazzi ◽  
N. Hell ◽  
S. Bianchi ◽  
...  
Keyword(s):  
High Resolution ◽  
Stellar Wind ◽  
Emission Lines ◽  
High Mass ◽  
Time Resolved ◽  
X Ray ◽  
Multi Phase ◽  
Resonant Transitions ◽  
First Time ◽  
Charged Ions

Context. We present a ~130 ks observation of the prototypical wind-accreting, high-mass X-ray binary Vela X-1 collected with XMM-Newton at orbital phases between 0.12 and 0.28. A strong flare took place during the observation that allows us to investigate the reaction of the clumpy stellar wind to the increased X-ray irradiation. Aims. To examine the wind’s reaction to the flare, we performed both time-averaged and time-resolved analyses of the RGS spectrum and examined potential spectral changes. Methods. We focused on the high-resolution XMM-Newton RGS spectra and divided the observation into pre-flare, flare, and post-flare phases. We modeled the time-averaged and time-resolved spectra with phenomenological components and with the self-consistent photoionization models calculated via CLOUDY and XSTAR in the pre-flare phase, where strong emission lines due to resonant transitions of highly ionized ions are seen. Results. In the spectra, we find emission lines corresponding to K-shell transitions in highly charged ions of oxygen, neon, magnesium, and silicon as well as radiative recombination continua (RRC) of oxygen. Additionally, we observe potential absorption lines of magnesium at a lower ionization stage and features identified as iron L lines. The CLOUDY and XSTAR photoionization models provide contradictory results, either pointing towards uncertainties in theory or possibly a more complex multi-phase plasma, or both. Conclusions. We are able to demonstrate the existence of a plethora of variable narrow features, including the firm detection of oxygen lines and RRC that RGS enables to observe in this source for the first time. We show that Vela X-1 is an ideal source for future high-resolution missions, such as XRISM and Athena.

Diphosphinoazine Rhodium(I) and Iridium(I) Complexes

2006 ◽  
Vol 71 (2) ◽  
pp. 197-206 ◽  
Author(s):  
Martin Pošta ◽  
Jan Čermák ◽  
Pavel Vojtíšek ◽  
Ivana Císařová
Keyword(s):  
Rhodium Complexes ◽  
Iridium Complexes ◽  
X Ray ◽  
First Time

The first rhodium complexes of diphosphinoazines [{RhCl(1,2-η:5,6-η-CH=CHCH2CH2CH=CHCH2CH2)}2 {μ-R2PCH2C(But)=NN=C(But)CH2PR2] (R = Ph, Cy, Pri) were prepared by cleavage of the bridge in chloro(cycloocta-1,5-diene)rhodium(I) dimer, the analogous iridium(I) complexes were also prepared for the first time. The X-ray structures of isostructural rhodium and iridium complexes with bis(dicyclohexylphosphino)pinacoloneazine were determined. Diphosphinoazine ligands in the complexes remained in (Z,Z) configuration bridging two RhCl(C8H12) units.

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