- ID:
- ivo://CDS.VizieR/J/A+A/575/L6
- Title:
- Optical observations of LS I +61 303
- Short Name:
- J/A+A/575/L6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The gamma-ray binary LS I +61 303 is composed of a Be star and a compact companion orbiting in an eccentric orbit. Variable flux modulated with the orbital period of ~26.5d has been detected from radio to very high-energy gamma-rays. In addition, the system presents a superorbital variability of the phase and amplitude of the radio outbursts with a period of ~4.6yr. We present optical photometric observations of LS I +61 303 spanning ~1.5yr (table 1) and contemporaneous H-alpha equivalent width (EW) data (table 2). The optical photometry shows, for the first time, that the known orbital modulation suffers a positive orbital phase shift and an increase in flux for data obtained 1-yr apart. The orbital modulation of the EW presents, for the first time, a positive orbital phase shift. These orbital phase shifts of the thermal indicators are in line with the observed behavior for nonthermal indicators, such as X-ray or radio emission. This shows that there is a strong coupling between the thermal and nonthermal emission processes in the gamma-ray binary LS I +61 303.
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- ID:
- ivo://CDS.VizieR/J/A+A/561/A137
- Title:
- Optical spectra of IGR J21343+4738
- Short Name:
- J/A+A/561/A137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Present X-ray missions are regularly discovering new X-ray and gamma-ray sources. The identification of their counterparts at other wavelengths allows us to determine their nature. The main goal of this work is to determine the properties of the optical counterpart to the INTEGRAL source IGR J21343+4738, and to study its long-term optical variability. Although its nature as a Be/X-ray binary has been suggested, little is known about its physical parameters. We have been monitoring IGR J21343+4738 since 2009 in the optical band. We present BVRI optical photometric and spectroscopic observations covering the wavelength band 4000-7500{AA}. The photometric data allowed us to derive the colour excess E(B-V) and estimate the distance. The blue-end spectra were used to determine the spectral type of the optical companion, while the spectra around the Halpha line allowed us to study the long-term structural changes in the circumstellar disc.
- ID:
- ivo://CDS.VizieR/J/ApJ/866/83
- Title:
- Opt/NIR obs. of 1FGLJ1417.7-4407 neutron star bin.
- Short Name:
- J/ApJ/866/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Fermi {gamma}-ray source 1FGL J1417.7-4407 (J1417) is a compact X-ray binary with a neutron star primary and a red giant companion in a ~5.4 days orbit. This initial conclusion, based on optical and X-ray data, was confirmed when a 2.66ms radio pulsar was found at the same location (and with the same orbital properties) as the optical/X-ray source. However, these initial studies found conflicting evidence about the accretion state and other properties of the binary. We present new optical, radio, and X-ray observations of J1417 that allow us to better understand this unusual system. We show that one of the main pieces of evidence previously put forward for an accretion disk-the complex morphology of the persistent H{alpha} emission line-can be better explained by the presence of a strong, magnetically driven stellar wind from the secondary and its interaction with the pulsar wind. The radio spectral index derived from VLA/ATCA observations is broadly consistent with that expected from a millisecond pulsar, further disfavoring an accretion disk scenario. X-ray observations show evidence for a double-peaked orbital light curve, similar to that observed in some redback millisecond pulsar binaries and likely due to an intrabinary shock. Refined optical light-curve fitting gives a distance of 3.1+/-0.6kpc, confirmed by a Gaia DR2 parallax measurement. At this distance the X-ray luminosity of J1417 is (1.0_-0.3_^+0.4^)x10^33^erg/s, which is more luminous than all known redback systems in the rotational-powered pulsar state, perhaps due to the wind from the giant companion. The unusual phenomenology of this system and its differing evolutionary path from redback millisecond pulsar binaries points to a new eclipsing pulsar "spider" subclass that is a possible progenitor of normal field millisecond pulsar binaries.
- ID:
- ivo://CDS.VizieR/J/MNRAS/431/L107
- Title:
- Outbursts of GX339-4 at 5.5 and 9.0GHz fluxes
- Short Name:
- J/MNRAS/431/L107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Galactic black hole binaries produce powerful outflows which emit over almost the entire electromagnetic spectrum. Here, we report the first detection with the Herschel observatory of a variable far-infrared source associated with the compact jets of the black hole transient GX 339-4 during the decay of its recent 2010-2011 outburst, after the transition to the hard state. We also outline the results of very sensitive radio observations conducted with the Australia Telescope Compact Array, along with a series of near-infrared, optical (OIR) and X-ray observations, allowing for the first time the re-ignition of the compact jets to be observed over a wide range of wavelengths. The compact jets first turn on at radio frequencies with an optically thin spectrum that later evolves to an optically thick synchrotron emission. An OIR reflare is observed about 10d after the onset of radio and hard X-ray emission, likely reflecting the necessary time to build up enough density, as well as to have acceleration (e.g. through shocks) along an extended region in the jets. The Herschel measurements are consistent with an extrapolation of the radio inverted power-law spectrum, but they highlight a more complex radio to OIR spectral energy distribution for the jets.
- ID:
- ivo://CDS.VizieR/J/A+A/642/A208
- Title:
- Oxygen K-edge cross sections
- Short Name:
- J/A+A/642/A208
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Interstellar dust permeates our Galaxy and plays an important role in many physical processes in the diffuse and dense regions of the interstellar medium (ISM). High-resolution X-ray spectroscopy, coupled with modelling based on laboratory dust measurements, provides a unique probe for investigating the interstellar dust properties along our line of sight towards Galactic X-ray sources. Here, we focus on the oxygen content of the ISM through its absorption features in the X-ray spectra. To model the dust features, we perform a laboratory experiment using the electron microscope facility located at the University of Cadiz in Spain, where we acquire new laboratory data in the oxygen K-edge. We study 18 dust samples of silicates and oxides with different chemical compositions. The laboratory measurements are adopted for our astronomical data analysis. We carry out a case study on the X-ray spectrum of the bright low-mass X-ray binary Cygnus X-2, observed by XMM-Newton. We determine different temperature phases of the ISM and parameterise oxygen in both gas (neutral and ionised) and dust form. We find Solar abundances of oxygen along the line of sight towards the source. Due to both the relatively low depletion of oxygen into dust form and the shape of the oxygen cross section profiles, it is challenging to determine the precise chemistry of interstellar dust. However, silicates provide an acceptable fit. Finally, we discuss the systematic discrepancies in the atomic (gaseous phase) data of the oxygen edge spectral region using different X-ray atomic databases as well as consider future prospects for studying the ISM with the Arcus concept mission.
- ID:
- ivo://CDS.VizieR/J/AJ/151/104
- Title:
- Photometry and spectroscopy of LS V+44 17
- Short Name:
- J/AJ/151/104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the spectroscopic and photometric observations on the Be/X-ray binary RX J0440.9+4431 from 2001 to 2014. The short-term and long-term variability of the H{alpha} line profile indicates that one-armed global oscillations existed in the circumstellar disk. Several positive and negative correlations between the V-band brightness and the H{alpha} intensity were found from the long-term photometric and spectroscopic observations. We suggest that the monotonic increase of the V-band brightness and the H{alpha} brightness between our 2005 and 2007 observations might be the result of a continuous mass ejection from the central Be star, while the negative correlation in 2007-2010 should be caused by the cessation of mass loss from the Be star just before the decline in V-band brightness began (around our 2007 observations). With the extension of the ejection material, the largest circumstellar disk during the last two decades has been observed in our 2010 observations with an equivalent width of approximately -12.88{AA}, which corresponds to a circumstellar disk with a size of 12.9 times the radius of the central Be star. Three consecutive X-ray outbursts peaking around MJD 55293, 55444, and 55591 might be connected with the largest circumstellar disk around the Be star. We also use the orbital motion of the neutron star as a probe to constrain the structure of the circumstellar disk and estimate the eccentricity of the binary system to be >=0.4. After three years of the H{alpha} intensity decline after the X-ray outbursts, a new circumstellar disk was being formed around the Be star after our 2013 observations.
- ID:
- ivo://CDS.VizieR/J/AJ/146/135
- Title:
- Physical parameters of 29 M31 globular clusters
- Short Name:
- J/AJ/146/135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Andromeda galaxy, M31, has several times the number of globular clusters found in the Milky Way. It contains a correspondingly larger number of low-mass X-ray binaries (LMXBs) associated with globular clusters, and as such can be used to investigate the cluster properties that lead to X-ray binary formation. The best tracer of the spatial structure of M31 globulars is the high-resolution imaging available from the Hubble Space Telescope (HST), and we have used HST data to derive structural parameters for 29 LMXB-hosting M31 globular clusters. These measurements are combined with structural parameters from the literature for a total of 41 (of 50 known) LMXB clusters and a comparison sample of 65 non-LMXB clusters. Structural parameters measured in blue bandpasses are found to be slightly different (smaller core radii and higher concentrations) than those measured in red bandpasses; this difference is enhanced in LMXB clusters and could be related to stellar population differences. Clusters with LMXBs show higher collision rates for their mass compared to clusters without LMXBs, and collision rates estimated at the core radius show larger offsets than rates estimated at the half-light radius. These results are consistent with the dynamical formation scenario for LMXBs. A logistic regression analysis finds that, as expected, the probability of a cluster hosting an LMXB increases with increasing collision rate and proximity to the galaxy center. The same analysis finds that probability of a cluster hosting an LMXB decreases with increasing cluster mass at a fixed collision rate, although we caution that this could be due to sample selection effects. Metallicity is found to be a less important predictor of LMXB probability than collision rate, mass, or distance, even though LMXB clusters have a higher metallicity on average. This may be due to the interaction of location and metallicity: a sample of M31 LMXBs with a greater range in galactocentric distance would likely contain more metal-poor clusters and make it possible to disentangle the two effects.
- ID:
- ivo://CDS.VizieR/J/MNRAS/496/L96
- Title:
- Polarization of LMXB MAXI J1820+070
- Short Name:
- J/MNRAS/496/L96
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the first complete polarimetric dataset of the entire outburst of a low-mass black hole X-ray binary system and discuss the constraints for geometry and radiative mechanisms it imposes. During the decaying hard state, when the optical flux is dominated by the non-thermal component, the observed polarization is consistent with the interstellar values in all filters. During the soft state, the intrinsic polarization of the source is small, ~0.15 per cent in B and V filters, and is likely produced in the irradiated disc. A much higher polarization, reaching ~0.5 per cent in V and R filters, at position angle of ~25{deg} observed in the rising hard state coincides in time with the detection of winds in the system. This angle coincides with the position angle of the jet. The detected optical polarization is best explained by scattering of the non-thermal (hot flow or jet base) radiation in an equatorial wind.
- ID:
- ivo://CDS.VizieR/J/A+A/584/A122
- Title:
- Precessing jets of 1E1740.7-2942
- Short Name:
- J/A+A/584/A122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The source 1E 1740.7-2942 is believed to be one of the two prototypical microquasars towards the Galactic center region whose X-ray states strongly resemble those of Cygnus X-1. Yet, the bipolar radio jets of 1E 1740.7-2942 are very reminiscent of a radio galaxy. The true nature of the object has thus remained an open question for nearly a quarter of a century. Our main goal here is to confirm the Galactic membership of 1E 1740.7-2942 by searching for morphological changes of its extended radio jets in human timescales. This work was triggered as a result of recent positive detection of fast structural changes in the large-scale jets of the very similar source GRS 1758-258. We carried out an in-depth exploration of the Very Large Array public archives and fully recalibrated all 1E 1740.7-2942 extended data sets in the C configuration of the array. We obtained and analyzed matching beam radio maps for five epochs, covering years 1992, 1993, 1994, 1997 and 2000, with an angular resolution of a few arcseconds.
- ID:
- ivo://CDS.VizieR/J/A+A/342/736
- Title:
- Pre-eclipse dip of Her X-1
- Short Name:
- J/A+A/342/736
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on a pre-eclipse dip of the X-ray binary pulsar Her X-1 observed by the Rossi X-ray Timing Explorer (RXTE) in 1996 July. The energy spectra in the 3-18keV range can be described by the sum of two power-laws, one of which is modified by photoelectric absorption and by Thomson scattering in cold material, plus an iron emission line at 6.7keV. We present the evolution of the spectral parameters with a temporal resolution of 16s and show that the varying flux and spectrum can be interpreted solely by a time varying column density. The data do not appear to require non-solar abundances in the absorbing material, although a slight over-abundance of the metals cannot be ruled out. We also find that the lightcurve is characterized by symmetric substructures which can be successfully modeled by Gaussian profiles. The recurrence time of these substructures is on a timescale of a few minutes.
