- ID:
- ivo://CDS.VizieR/J/ApJ/728/9
- Title:
- Quasi-periodic oscillations from XTE J1701-462
- Short Name:
- J/ApJ/728/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the quality factor and root mean square (rms) amplitude of the lower kilohertz quasi-periodic brightness variations (kHz QPOs) from XTE J1701-462, a unique X-ray source which was observed in both the so-called Z and atoll states. Correcting for the frequency drift of the QPO, we show that, as in all sources for which such a correction can be applied, the quality factor and rms amplitude drops sharply above a critical frequency. For XTE J1701-462, this frequency is estimated to be ~800Hz, where the quality factor reaches a maximum of ~200 (e.g., a value consistent with the one observed from more classical systems, such as 4U 1636-536). Such a drop has been interpreted as the signature of the innermost stable circular orbit, and that interpretation is consistent with the observations we report here. The kHz QPOs in the Z state are much less coherent and lower amplitude than they are in the atoll state. We argue that the change of the QPO properties between the two source states is related to the change of the scale height of the accretion disk; a prediction of the toy model proposed by Barret et al. As a by-product of our analysis, we also increased the significance of the upper kHz QPO detected in the atoll phase up to 4.8{sigma} (single trial significance) and show that the frequency separation (266.5+/-13.1Hz) is comparable with the one measured from simultaneous twin QPOs in the Z phase.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/150/170
- Title:
- Radial velocities of 7 cataclysmic binaries
- Short Name:
- J/AJ/150/170
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From a set of 13 cataclysmic binaries that were discovered in the Swift Burst Alert Telescope (BAT) survey, we conducted time-resolved optical spectroscopy and/or time-series photometry of 11, with the goal of measuring their orbital periods and searching for spin periods. Seven of the objects in this study are new optical identifications. Orbital periods are found for seven targets, ranging from 81 minutes to 20.4hr. PBC J0706.7+0327 is an AM Herculis star (polar) based on its emission-line variations and large amplitude photometric modulation on the same period. Swift J2341.0+7645 may be a polar, although the evidence here is less secure. Coherent pulsations are detected from two objects, Swift J0503.7-2819 (975s) and Swift J0614.0+1709 (1412s and 1530s, spin and beat periods, respectively), indicating that they are probable intermediate polars (DQ Herculis stars). For two other stars, longer spin periods are tentatively suggested. We also present the discovery of a 2.00hr X-ray modulation from RX J2015.6+3711, possibly a contributor to Swift J2015.9+3715, and likely a polar.
- ID:
- ivo://CDS.VizieR/J/ApJ/698/514
- Title:
- Radial velocities of LSI+61 303 and LS 5039
- Short Name:
- J/ApJ/698/514
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- LS I +61 303 and LS 5039 are two of only a handful of known high-mass X-ray binaries (HMXBs) that exhibit very high energy emission in the MeV-TeV range, and these "{gamma}-ray binaries" are of renewed interest due to the recent launch of the Fermi Gamma-ray Space Telescope. Here we present new radial velocities of both systems based on recent red and blue optical spectra. Both systems have somewhat discrepant orbital solutions available in the literature, and our new measurements result in improved orbital elements and resolve the disagreements. The improved geometry of each orbit will aid in studies of the high-energy emission region near each source.
- ID:
- ivo://CDS.VizieR/J/AJ/155/247
- Title:
- Radial velocities of 6 X-ray cataclysmic binaries
- Short Name:
- J/AJ/155/247
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We conducted time-resolved optical spectroscopy and/or time-series photometry of 15 cataclysmic binaries that were discovered in hard X-ray surveys by the Swift Burst Alert Telescope and the International Gamma-Ray Astrophysics Laboratory, with the goal of measuring their orbital periods and searching for spin periods. Four of the objects in this study are new optical identifications: Swift J0535.2+2830, Swift J2006.4+3645, IGR J21095+4322, and Swift J2116.5+5336. Coherent pulsations are detected from three objects for the first time, Swift J0535.2+2830 (1523 s), 2PBC J1911.4+1412 (747 s), and 1SWXRT J230642.7+550817 (464 s), indicating that they are intermediate polars (IPs). We find two new eclipsing systems in time-series photometry: 2PBC J0658.0-1746, a polar with a period of 2.38 hr, and Swift J2116.5+5336, a disk system that has an eclipse period of 6.56 hr. Exact or approximate spectroscopic orbital periods are found for six additional targets. Of note is the long 4.637-day orbit for Swift J0623.9-0939, which is revealed by the radial velocities of the photospheric absorption lines of the secondary star. We also discover a 12.76 hr orbital period for RX J2015.6+3711, which confirms that the previously detected 2.00 hr X-ray period from this star is the spin period of an IP, as inferred by Coti Zelati et al. (2016MNRAS.456.1913C). These results support the conclusion that hard X-ray selection favors magnetic CVs, with IPs outnumbering polars.
- ID:
- ivo://CDS.VizieR/J/ApJ/716/L109
- Title:
- Radio and X-ray observations of Aql X-1
- Short Name:
- J/ApJ/716/L109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The 2009 November outburst of the neutron star X-ray binary Aquila X-1 (Aql X-1) was observed with unprecedented radio coverage and simultaneous pointed X-ray observations, tracing the radio emission around the full X-ray hysteresis loop of the outburst for the first time. We use these data to discuss the disk-jet coupling, finding the radio emission to be consistent with being triggered at state transitions, both from the hard to the soft spectral state and vice versa. Our data appear to confirm previous suggestions of radio quenching in the soft state above a threshold X-ray luminosity of ~10% of the Eddington luminosity. We also present the first detections of Aql X-1 with very long baseline interferometry, showing that any extended emission is relatively diffuse and consistent with steady jets rather than arising from discrete, compact knots. In all cases where multi-frequency data were available, the source radio spectrum is consistent with being flat or slightly inverted, suggesting that the internal shock mechanism that is believed to produce optically thin transient radio ejecta in black hole X-ray binaries is not active in Aql X-1.
- ID:
- ivo://CDS.VizieR/J/AZh/78/922
- Title:
- Radio emission of SS433
- Short Name:
- J/AZh/78/922
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Two daily sets monitoring data of the galactic X-ray binary SS 433 (V1343 Aql) obtained on the RATAN-600 radio telescope (117 days in 1997 and 120 days in 1999) show variations in its quiescent radio emission with a period of 6.05 days at six frequencies from 0.96 to 22GHz.
- ID:
- ivo://CDS.VizieR/J/MNRAS/406/307
- Title:
- Radio variations of Cygnus X-3
- Short Name:
- J/MNRAS/406/307
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cygnus X-3 is one of the brightest X-ray and radio sources in the Galaxy and is well known for its erratic behaviour in X-rays as well as in the radio, occasionally producing major radio flares associated with relativistic ejections. However, even after many years of observations in various wavelength bands Cyg X-3 still eludes clear physical understanding. Studying different emission bands simultaneously in microquasars has proved to be a fruitful approach towards understanding these systems, especially by shedding light on the accretion disc/jet connection. We continue this legacy by constructing a hardness-intensity diagram (HID) from archival Rossi X-ray Timing Explorer data and linking simultaneous radio observations to it. We find that surprisingly Cyg X-3 sketches a similar shape in the HID to that seen in other transient black hole X-ray binaries during outburst but with distinct differences.
- ID:
- ivo://CDS.VizieR/J/A+A/587/A102
- Title:
- 1RXSJ180408.9-342058 spectrum
- Short Name:
- J/A+A/587/A102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed near-infrared/optical/UV study of the transient low-mass X-ray binary 1RXS J180408.9-342058 performed during its 2015 outburst, which is aimed at determining the nature of its companion star. We obtained three optical spectra (R~1000) at the 2.1m San Pedro Martir Observatory telescope (Mexico). We performed optical and NIR photometric observations with both the REM telescope and the New Technology Telescope (NTT) in La Silla. We obtained optical and UV observations from the Swift archive. Finally, we performed optical polarimetry of the source using the EFOSC2 instrument mounted on the NTT.
- ID:
- ivo://CDS.VizieR/J/ApJ/822/60
- Title:
- RXTE observations of GRS 1915+105
- Short Name:
- J/ApJ/822/60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the X-ray spectral behavior within the steady states of GRS1915+105. Our work is based on the full data set of the source obtained using the Proportional Counter Array (PCA) on the Rossi X-ray Timing Explorer (RXTE) and 15GHz radio data obtained using the Ryle Telescope. The steady observations within the X-ray data set naturally separated into two regions in the color-color diagram and we refer to these regions as steady-soft and steady-hard. GRS1915+105 displays significant curvature in the coronal component in both the soft and hard data within the RXTE/PCA bandpass. A majority of the steady-soft observations displays a roughly constant inner disk radius (R_in_), while the steady-hard observations display an evolving disk truncation which is correlated to the mass accretion rate through the disk. The disk flux and coronal flux are strongly correlated in steady-hard observations and very weakly correlated in the steady-soft observations. Within the steady-hard observations, we observe two particular circumstances when there are correlations between the coronal X-ray flux and the radio flux with log slopes {eta}~0.68+/-0.35 and {eta}~1.12+/-0.13. They are consistent with the upper and lower tracks of Gallo et al. (2012MNRAS.423..590G), respectively. A comparison of the model parameters to the state definitions shows that almost all of the steady-soft observations match the criteria of either a thermal or steep power-law state, while a large portion of the steady-hard observations match the hard-state criteria when the disk fraction constraint is neglected.
- ID:
- ivo://CDS.VizieR/J/ApJ/738/128
- Title:
- RXTE observations of 4U 1728-34
- Short Name:
- J/ApJ/738/128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the spectral properties observed in X-rays from neutron star X-ray binary 4U 1728-34 during transitions between the low- and high-luminosity states when the electron temperature kT_e_ of the Compton cloud monotonically decreases from 15 to 2.5keV. We analyze the transition episodes from this source observed with BeppoSAX and RXTE satellites. We find that the X-ray broadband energy spectra of 4U 1728-34 during all spectral states can be modeled by a combination of a thermal (blackbody-like) component, a Comptonized component (which we herein denote as COMPTB), and a Gaussian component. Spectral analysis using this model provides evidence that the photon power-law index {Gamma} is almost constant ({Gamma}=1.99+/-0.02) when kT_e_ changes from 15 to 2.5keV during these spectral transitions.
