ORCID Profile
0000-0002-4622-796X
Current Organisation
University of the Chinese Academy of Sciences
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Publisher: Oxford University Press (OUP)
Date: 21-03-2004
Publisher: Oxford University Press (OUP)
Date: 09-01-2018
DOI: 10.1093/MNRAS/STY014
Publisher: American Astronomical Society
Date: 10-2022
Abstract: We present detailed timing and spectral analyses of the transient X-ray pulsar RX J0209.6−7427 in the Small Magellanic Cloud during its 2019 giant outburst. With a better known distance than most galactic X-ray pulsars, its peak luminosity is determined to be (1.11 ± 0.06) × 10 39 erg s −1 it is thus a bona fide pulsating ultraluminous X-ray source (PULX). Owing to the broad energy band of Insight-HXMT, its pulsed X-ray emission was detected from 1 keV up to the 130–180 keV band, which is the highest energy emission detected from any PULXs outside the Milky Way. This allows us to conclude that its main pulsed X-ray emission is from the fan beam of the accretion column, and its luminosity is thus intrinsic. We also estimate its magnetic field of (4.8–8.6) × 10 12 or (1.7–2.2) × 10 13 G, from its spin evolution or transition in the accretion column structure during the outburst we suggest that the two values of the magnetic field strength correspond to the dipole and multipole magnetic fields of the neutron star, similar to the recent discovery in the Galactic PULX Swift J0243.6+6124. Therefore, the nature of the neutron star and its ULX emission can be understood within the current theoretical frame of accreting neutron stars. This may have implications for understanding the nature of those farther away extragalactic PULXs.
Publisher: Oxford University Press (OUP)
Date: 02-2009
Publisher: American Astronomical Society
Date: 03-2022
Abstract: The symbiotic X-ray binary Sct X-1 was suggested to be the first known neutron star accreting from a red supergiant companion. Although known for nearly 50 yr, detailed characterization of the donor remains lacking, particularly due to the extremely high reddening toward the source ( A V ≳ 25 mag). Here, we present (i) improved localization of the counterpart using Gaia and Chandra observations, (ii) the first broadband infrared spectrum (≈1–5 μ m R ≈ 2000) obtained with SpeX on the NASA Infrared Telescope Facility, and (iii) the J -band light curve from the Palomar Gattini-IR survey. The infrared spectrum is characterized by (i) deep water absorption features (H 2 O index ≈ 40%), (ii) strong TiO, VO, and CO features, and (iii) weak/absent CN lines. We show that these features are inconsistent with known red supergiants but suggest an M8-9 III–type O-rich Mira donor star. We report the discovery of large- litude (Δ J ≈ 3.5 mag) periodic photometric variability, suggesting a pulsation period of 621 ± 36 (systematic) ± 8 (statistical) days, which we use to constrain the donor to be a relatively luminous Mira ( M K = −8.6 ± 0.3 mag) at a distance of 3.6 − 0.7 + 0.8 kpc. Comparing these characteristics to recent models, we find the donor to be consistent with a ≈3–5 M ⊙ star at an age of ≈0.1–0.3 Gyr. Together, we show that Sct X-1 was previously misclassified as an evolved high-mass X-ray binary instead, it is an intermediate-mass system with the first confirmed Mira donor in an X-ray binary. We discuss the implications of Mira donors in symbiotic X-ray binaries and highlight the potential of wide-field infrared time-domain surveys and broadband infrared spectroscopy to unveil their demographics.
Publisher: American Astronomical Society
Date: 05-10-2012
Publisher: Oxford University Press (OUP)
Date: 06-02-2023
Abstract: We present a high time resolution, multifrequency linear polarization analysis of very large array (VLA) radio observations during some of the brightest radio flaring (${\\sim } 1 \\,{\\rm Jy}\\,$) activity of the 2015 outburst of V404 Cygni. The VLA simultaneously captured the radio evolution in two bands (each with two 1 GHz base-bands), recorded at 5/7 GHz and 21/26 GHz , allowing for a broadband polarimetric analysis. Given the source’s high flux densities, we were able to measure polarization on time-scales of ${\\sim }13\\,$ min, constituting one of the highest temporal resolution radio polarimetric studies of a black hole X-ray binary outburst to date. Across all base-bands, we detect variable, weakly linearly polarized emission (${\\lt } 1{{ \\rm per\\ cent}}$) with a single, bright peak in the time-resolved polarization fraction, consistent with an origin in an evolving, dynamic jet component. We applied two independent polarimetric methods to extract the intrinsic electric vector position angles and rotation measures from the 5 and 7 GHz base-band data and detected a variable intrinsic polarization angle, indicative of a rapidly evolving local environment or a complex magnetic field geometry. Comparisons to the simultaneous, spatially-resolved observations taken with the Very Long Baseline Array at 15.6 GHz , do not show a significant connection between the jet ejections and the polarization state.
Publisher: American Astronomical Society
Date: 29-04-2013
Publisher: Oxford University Press (OUP)
Date: 03-09-2010
Publisher: Oxford University Press (OUP)
Date: 28-12-2015
Publisher: American Astronomical Society
Date: 30-08-2013
Publisher: EDP Sciences
Date: 11-2001
Publisher: Oxford University Press (OUP)
Date: 23-08-2004
Publisher: AIP
Date: 2010
DOI: 10.1063/1.3475162
Publisher: American Astronomical Society
Date: 08-2021
Publisher: Oxford University Press (OUP)
Date: 30-05-2013
DOI: 10.1093/MNRAS/STT767
Publisher: American Astronomical Society
Date: 20-03-2006
DOI: 10.1086/499935
Publisher: Oxford University Press (OUP)
Date: 16-10-2018
Publisher: Oxford University Press (OUP)
Date: 21-12-2019
Publisher: American Astronomical Society
Date: 20-03-2006
DOI: 10.1086/499934
Publisher: EDP Sciences
Date: 2001
Publisher: American Astronomical Society
Date: 10-1997
DOI: 10.1086/304631
Publisher: American Astronomical Society
Date: 03-2022
Abstract: We present a spectral study of the black hole candidate MAXI J1348−630 during its 2019 outburst, based on monitoring observations with Insight-HXMT and Swift. Throughout the outburst, the spectra are well fitted with power-law plus disk-blackbody components. In the soft-intermediate and soft states, we observed the canonical relation L ∝ T in 4 between disk luminosity L and peak color temperature T in , with a constant inner radius R in (traditionally identified with the innermost stable circular orbit). At other stages of the outburst cycle, the behavior is more unusual, inconsistent with the canonical outburst evolution of black hole transients. In particular, during the hard rise, the apparent inner radius is smaller than in the soft state (and increasing), and the peak color temperature is higher (and decreasing). This anomalous behavior is found even when we model the spectra with self-consistent Comptonization models, which take into account the upscattering of photons from the disk component into the power-law component. To explain both anomalous trends at the same time, we suggest that the hardening factor for the inner-disk emission was larger than the canonical value of ≈1.7 at the beginning of the outburst. A more physical trend of radii and temperature evolution requires a hardening factor evolving from ≈3.5 at the beginning of the hard state to ≈1.7 in the hard-intermediate state. This could be evidence that the inner disk was in the process of condensing from the hot, optically thin medium and had not yet reached a sufficiently high optical depth for its emission spectrum to be described by the standard optically thick disk solution.
Publisher: American Astronomical Society
Date: 20-05-2014
Publisher: Oxford University Press (OUP)
Date: 24-02-2022
Abstract: We have studied the unusual time variability of an ultraluminous X-ray source in M 101, 4XMM J140314.2 + 541806 (henceforth, J1403), using Chandra and XMM-Newton data. Over the last two decades, J1403 has shown short-duration outbursts with an X-ray luminosity ∼1–3 × 1039 erg s−1, and longer intervals at luminosities ∼0.5–1 × 1038 erg s−1. The bimodal behaviour and fast outburst evolution (sometimes only a few days) are more consistent with an accretor ropeller scenario for a neutron star than with the canonical outburst cycles of stellar-mass black holes. If this scenario is correct, the luminosities in the accretor and propeller states suggest a fast spin (P ≈ 5 ms) and a low surface magnetic field (B ∼ 1010 G), despite our identification of J1403 as a high-mass X-ray binary. The most striking property of J1403 is the presence of strong ∼600-s quasi-periodic oscillations (QPOs), mostly around frequencies of ≈1.3–1.8 mHz, found at several epochs during the ultraluminous regime. We illustrate the properties of such QPOs, in particular their frequency and litude changes between and within observations, with a variety of techniques (Fast Fourier Transforms, Lomb–Scargle periodograms, weighted wavelet Z-transform analysis). The QPO frequency range & mHz is an almost unexplored regime in X-ray binaries and ultraluminous X-ray sources. We compare our findings with the (few) ex les of very low frequency variability found in other accreting sources, and discuss possible explanations (Lense–Thirring precession of the inner flow or outflow radiation pressure limit-cycle instability marginally stable He burning on the neutron star surface).
Publisher: American Astronomical Society
Date: 18-02-2015
Publisher: Springer Science and Business Media LLC
Date: 11-2005
Publisher: Oxford University Press (OUP)
Date: 17-07-2006
Publisher: American Astronomical Society
Date: 16-09-2015
Publisher: Springer Science and Business Media LLC
Date: 07-2010
DOI: 10.1038/NATURE09168
Abstract: Black-hole accretion states near or above the Eddington luminosity (the point at which radiation force outwards overcomes gravity) are still poorly known because of the rarity of such sources. Ultraluminous X-ray sources are the most luminous class of black hole (L(X) approximately 10(40) erg s(-1)) located outside the nuclei of active galaxies. They are likely to be accreting at super-Eddington rates, if they are powered by black holes with masses less than 100 solar masses. They are often associated with shock-ionized nebulae, though with no evidence of collimated jets. Microquasars with steady jets are much less luminous. Here we report that the large nebula S26 (ref. 4) in the nearby galaxy NGC 7793 is powered by a black hole with a pair of collimated jets. It is similar to the famous Galactic source SS433 (ref. 5), but twice as large and a few times more powerful. We determine a mechanical power of around a few 10(40) erg s(-1). The jets therefore seem 10(4) times more energetic than the X-ray emission from the core. S26 has the structure of a Fanaroff-Riley type II (FRII-type) active galaxy: X-ray and optical core, X-ray hot spots, radio lobes and an optical and X-ray cocoon. It is a microquasar where most of the jet power is dissipated in thermal particles in the lobes rather than relativistic electrons.
Publisher: American Astronomical Society
Date: 10-03-1998
DOI: 10.1086/311225
Publisher: American Astronomical Society
Date: 09-08-2012
Publisher: Oxford University Press (OUP)
Date: 24-12-2015
Publisher: American Geophysical Union (AGU)
Date: 2005
DOI: 10.1029/2004GL021497
Publisher: American Astronomical Society
Date: 25-04-2012
Publisher: Oxford University Press (OUP)
Date: 2005
Publisher: Oxford University Press (OUP)
Date: 21-08-2007
Publisher: American Astronomical Society
Date: 31-01-2019
Publisher: Wiley
Date: 04-2011
Publisher: Oxford University Press (OUP)
Date: 21-03-2012
Publisher: American Astronomical Society
Date: 03-02-2010
Publisher: Cambridge University Press (CUP)
Date: 2013
DOI: 10.1017/PAS.2013.003
Abstract: We re-examine the long-standing problem of the date of the Cassiopeia A supernova (SN), in view of recent claims that it might be the 1630 ‘noon-star’ seen at the birth of King Charles II. We do not support this identification, based on the expected brightness of a Type-IIb SN (too faint to be seen in daylight), the extrapolated motion of the ejecta (inconsistent with a date earlier than 1650), the lack of any scientific follow-up observations, the lack of any mention of it in Asian archives. The origin of the 1630 noon-star event (if real) remains a mystery there was a bright comet in 1630 June but no evidence to determine whether or not it was visible in daylight. Instead, we present French reports about a fourth-magnitude star discovered by Cassini in Cassiopeia in or shortly before 1671, which was not seen before or since. The brightness is consistent with what we expect for the Cas A SN the date is consistent with the extrapolated motion of the ejecta. We argue that this source could be the long-sought SN.
Publisher: EDP Sciences
Date: 24-02-2003
Publisher: Oxford University Press (OUP)
Date: 06-04-2018
DOI: 10.1093/MNRAS/STY872
Publisher: EDP Sciences
Date: 07-2004
Publisher: Oxford University Press (OUP)
Date: 16-03-2011
Publisher: Oxford University Press (OUP)
Date: 21-10-1999
Publisher: American Astronomical Society
Date: 30-11-2015
Publisher: American Astronomical Society
Date: 10-08-2000
DOI: 10.1086/309194
Publisher: American Astronomical Society
Date: 07-02-2017
Publisher: Springer Science and Business Media LLC
Date: 09-08-2007
Publisher: Oxford University Press (OUP)
Date: 17-05-2017
Publisher: American Astronomical Society
Date: 11-2021
Abstract: We present optical and infrared (IR) light curves of NaSt1, also known as Wolf–Rayet 122, with observations from Palomar Gattini-IR (PGIR), the Zwicky Transient Facility (ZTF), the Katzman Automatic Imaging Telescope, the Asteroid Terrestrial-impact Last Alert System, and the All-Sky Automated Survey for Supernovae (ASAS-SN). We identify a P = 309.7 ± 0.7 day photometric period from the optical and IR light curves that reveal periodic, sinusoidal variability between 2014 July and 2021 July. We also present historical IR light curves taken between 1983 July and 1989 May, which show variability consistent with the period of the present-day light curves. In the past, NaSt1 was brighter in the J band with larger variability litudes than the present-day PGIR values, suggesting that NaSt1 exhibits variability on longer (≳decade) timescales. Sinusoidal fits to the recent optical and IR light curves show that the litude of NaSt1's variability differs at various wavelengths and also reveal significant phase offsets of 17.0 ± 2.5 day between the ZTF r and PGIR J light curves. We interpret the 310 day photometric period from NaSt1 as the orbital period of an enshrouded massive binary. We suggest that the photometric variability of NaSt1 may arise from variations in the line-of-sight optical depth toward circumstellar optical/IR-emitting regions throughout its orbit due to colliding-wind dust formation. We speculate that past mass transfer in NaSt1 may have been triggered by Roche-lobe overflow (RLOF) during an eruptive phase of an Ofpe/WN9 star. Lastly, we argue that NaSt1 is no longer undergoing RLOF mass transfer.
Publisher: Oxford University Press (OUP)
Date: 11-03-2009
Publisher: Oxford University Press (OUP)
Date: 03-2008
Publisher: Oxford University Press (OUP)
Date: 30-06-2015
Publisher: Oxford University Press (OUP)
Date: 26-02-2021
Abstract: We studied the apparent galaxy pair NGC 1232/NGC 1232A with Chandra, looking for evidence of interactions and collisions. We report that there is no cloud of diffuse emission in NGC 1232, contrary to previous claims in the literature. Instead, we find that the small ‘companion’ galaxy NGC 1232A contains three ultraluminous X-ray sources with peak 0.3–10 keV luminosities above 1040 erg s−1 (assuming a cosmological distance of ≈93 Mpc for this galaxy). For its mass, morphology, metal abundance, and bright ULX population, NGC 1232A is analogous to the more nearby late-type spiral NGC 1313.
Publisher: American Astronomical Society
Date: 08-2022
Abstract: We present the discovery and multiwavelength characterization of SRGA J181414.6-225604, a Galactic hard X-ray transient discovered during the ongoing SRG/ART-XC sky survey. Using data from the Palomar Gattini-IR survey, we identify a spatially and temporally coincident variable infrared (IR) source, IRAS 18111-2257, and classify it as a very-late-type (M7–M8), long-period (1502 ± 24 days), and luminous ( M K ≈ −9.9 ± 0.2) O-rich Mira donor star located at a distance of ≈14.6 +2.9 −2.3 kpc. Combining multicolor photometric data over the last ≈25 yr, we show that the IR counterpart underwent a recent (starting ≈800 days before the X-ray flare) enhanced mass-loss (reaching ≈2.1 × 10 −5 M ⊙ yr −1 ) episode, resulting in an expanding dust shell obscuring the underlying star. Multi-epoch follow-up observations from Swift, NICER, and NuSTAR reveal a ≈200 day long X-ray outburst reaching a peak luminosity of L X ≈ 2.5 × 10 36 erg s −1 , characterized by a heavily absorbed ( N H ≈ 6 × 10 22 cm −2 ) X-ray spectrum consistent with an optically thick Comptonized plasma. The X-ray spectral and timing behavior suggest the presence of clumpy wind accretion, together with a dense ionized nebula overabundant in silicate material surrounding the compact object. Together, we show that SRGA J181414.6-225604 is a new symbiotic X-ray binary in outburst, triggered by an intense dust-formation episode of a highly evolved donor. Our results offer the first direct confirmation for the speculated connection between enhanced late-stage donor mass loss and the active lifetimes of symbiotic X-ray binaries.
Publisher: American Astronomical Society
Date: 12-2021
Abstract: Galaxies can grow through their mutual gravitational attraction and subsequent union. While orbiting a regular high-surface-brightness galaxy, the body of a low-mass galaxy can be stripped away. However, the stellar heart of the infalling galaxy, if represented by a tightly bound nuclear star cluster, is more resilient. From archival Hubble Space Telescope images, we have discovered a red, tidally stretched star cluster positioned ∼5″ (∼400 pc in projection) from, and pointing toward the center of, the post-merger spiral galaxy NGC 4424. The star cluster, which we refer to as “Nikhuli,” has a near-infrared luminosity of (6.88 ± 1.85) × 10 6 L ⊙, F 160 W and likely represents the nucleus of a captured/wedded galaxy. Moreover, from our Chandra X-ray Observatory image, Nikhuli is seen to contain a high-energy X-ray point source, with L 0.5 − 8 keV = 6.31 − 3.77 + 7.50 × 10 38 erg s −1 (90% confidence). We argue that this is more likely to be an active massive black hole than an X-ray binary. Lacking an outward-pointing comet-like appearance, the stellar structure of Nikhuli favors infall rather than the ejection from a gravitational-wave recoil event. A minor merger with a low-mass early-type galaxy may have sown a massive black hole, aided an X-shaped pseudobulge, and be sewing a small bulge. The stellar mass and the velocity dispersion of NGC 4424 predict a central black hole of (0.6–1.0) × 10 5 M ⊙ , similar to the expected intermediate-mass black hole in Nikhuli, and suggestive of a black hole supply mechanism for bulgeless late-type galaxies. We may potentially be witnessing black hole seeding by capture and sinking, with a nuclear star cluster the delivery vehicle.
Publisher: American Astronomical Society
Date: 19-09-2019
Publisher: EDP Sciences
Date: 2001
Publisher: American Astronomical Society
Date: 10-06-2002
DOI: 10.1086/341445
Publisher: Oxford University Press (OUP)
Date: 21-11-1999
Publisher: American Astronomical Society
Date: 30-04-2021
Abstract: The nova rate in the Milky Way remains largely uncertain, despite its vital importance in constraining models of Galactic chemical evolution as well as understanding progenitor channels for Type Ia supernovae. The rate has been previously estimated to be in the range of ≈10–300 yr −1 , either based on extrapolations from a handful of very bright optical novae or the nova rates in nearby galaxies both methods are subject to debatable assumptions. The total discovery rate of optical novae remains much smaller (≈5–10 yr −1 ) than these estimates, even with the advent of all-sky optical time-domain surveys. Here, we present a systematic s le of 12 spectroscopically confirmed Galactic novae detected in the first 17 months of Palomar Gattini-IR (PGIR), a wide-field near-infrared time-domain survey. Operating in the J band (≈1.2 μ m), which is significantly less affected by dust extinction compared to optical bands, the extinction distribution of the PGIR s le is highly skewed to a large extinction values ( % of events obscured by A V ≳ 5 mag). Using recent estimates for the distribution of Galactic mass and dust, we show that the extinction distribution of the PGIR s le is commensurate with dust models. The PGIR extinction distribution is inconsistent with that reported in previous optical searches (null-hypothesis probability .01%), suggesting that a large population of highly obscured novae have been systematically missed in previous optical searches. We perform the first quantitative simulation of a 3 π time-domain survey to estimate the Galactic nova rate using PGIR, and derive a rate of ≈ 43.7 − 8.7 + 19.5 yr −1 . Our results suggest that all-sky near-infrared time-domain surveys are well poised to uncover the Galactic nova population.
Publisher: American Astronomical Society
Date: 09-2008
DOI: 10.1086/587776
Publisher: Elsevier BV
Date: 11-2011
Publisher: Oxford University Press (OUP)
Date: 15-11-2013
Publisher: EDP Sciences
Date: 11-08-2009
Publisher: EDP Sciences
Date: 2001
Publisher: American Astronomical Society
Date: 11-06-2009
Publisher: EDP Sciences
Date: 10-2003
Publisher: American Astronomical Society
Date: 20-07-2007
DOI: 10.1086/518237
Publisher: EDP Sciences
Date: 04-2020
DOI: 10.1051/0004-6361/201834647
Abstract: We present the spectral and timing evolution of the persistent black hole X-ray binary GRS 1758−258 based on almost 12 years of observations using the Rossi X-ray Timing Explorer Proportional Counter Array. While the source was predominantly found in the hard state during this time, it entered the thermally dominated soft state seven times. In the soft state GRS 1758−258 shows a strong decline in flux above 3 keV rather than the pivoting flux around 10 keV more commonly shown by black hole transients. In its 3–20 keV hardness intensity diagram, GRS 1758−258 shows a hysteresis of hard and soft state fluxes typical for transient sources in outburst. The RXTE-PCA and RXTE-ASM long-term light curves do not show any orbital modulations in the range of 2–30 d. However, in the dynamic power spectra significant peaks drift between 18.47 and 18.04 d for the PCA data, while less significant signatures between 19 d and 20 d are seen for the ASM data as well as for the Swift /BAT data. We discuss different models for the hysteresis behavior during state transitions as well as possibilities for the origin of the long term variation in the context of a warped accretion disk.
Publisher: Oxford University Press (OUP)
Date: 10-2010
Publisher: American Astronomical Society
Date: 02-04-2014
Publisher: Oxford University Press (OUP)
Date: 09-12-2020
Abstract: Some ultraluminous X-ray sources (ULXs) are surrounded by collisionally ionized bubbles, larger and more energetic than supernova remnants: they are evidence of the powerful outflows associated with super-Eddington X-ray sources. We illustrate the most recent addition to this class: a huge (350 pc × 220 pc in diameter) bubble around a ULX in NGC 5585. We modelled the X-ray properties of the ULX (a broadened-disc source with LX ≈ 2–4 × 1039 erg s−1) from Chandra and XMM–Newton, and identified its likely optical counterpart in Hubble Space Telescope images. We used the Large Binocular Telescope to study the optical emission from the ionized bubble. We show that the line emission spectrum is indicative of collisional ionization. We refine the method for inferring the shock velocity from the width of the optical lines. We derive an average shock velocity ≈125 km s−1, which corresponds to a dynamical age of ∼600 000 yr for the bubble, and an average mechanical power Pw ∼ 1040 erg s−1 thus, the mechanical power is a few times higher than the current photon luminosity. With Very Large Array observations, we discovered and resolved a powerful radio bubble with the same size as the optical bubble, and a 1.4-GHz luminosity ∼1035 erg s−1, at the upper end of the luminosity range for this type of source. We explain why ULX bubbles tend to become more radio luminous as they expand while radio supernova remnants tend to fade.
Publisher: Oxford University Press (OUP)
Date: 06-2006
Publisher: Oxford University Press (OUP)
Date: 04-05-2011
Publisher: Oxford University Press (OUP)
Date: 22-03-2022
Abstract: We studied the 2018 outburst of the black hole transient H 1743 − 322 with a series of Insight-HXMT, NICER, and NuSTAR observations, covering the 1–120 keV band. With our broad-band X-ray spectral modelling, we confirm that the source remained in the low/hard state throughout the month-long outburst, although it became marginally softer at peak flux. We detected Type-C quasi-periodic oscillations (QPOs) and followed the evolution of their properties. The QPO frequency increased from ∼0.1 to ∼0.4 Hz during the rising phase of the outburst and decreased again in the decline. Continuum X-ray flux, power-law photon index, QPO frequency, and QPO root-mean-square litude were positively correlated. The QPO litude was slightly higher in the soft X-ray band (typical values of 12–16 per cent, compared with 8–10 per cent in the hard band). Our spectral-timing results shed light on the initial rising phase in the low/hard state, which has rarely been monitored with such high cadence, time resolution, and broad-band coverage. Combining spectral and timing properties, we find that ‘failed’ (hard state only) and ‘successful’ outbursts follow the same initial evolutionary track, although the former class of outburst never reaches the threshold for a transition to softer (thermally dominated) accretion regimes.
Publisher: Cambridge University Press (CUP)
Date: 1999
DOI: 10.1071/AS99147
Abstract: We conducted spectroscopic and photometric observations of the optical companion of the X-ray transient RX J0117·6–7330 in the Small Magellanic Cloud, during a quiescent state. The primary star is identified as a B0·5 IIIe with a mass M * = (18 ± 2) M ⨀ and bolometric magnitude M bol = –7·4 ± 0·2. The main spectral features are strong Hα emission, Hβ and Hγ emission cores with absorption wings, and narrow He I and O II absorption lines. Equivalent widths and full widths at half maximum of the main lines are listed. The average systemic velocity over our observing run is v r = (184 ± 4) km s −1 measurements over a longer period of time are needed to determine the binary period and the K velocity of the primary. We determine a projected rotational velocity v sin i = (145 ± 10) km s −1 for the Be star if we assume a true rotational velocity at the equator v = (400 ± 50) km s −1 , we deduce that the inclination angle of the system is i = (21 ± 3) deg.
Publisher: Oxford University Press (OUP)
Date: 11-04-2007
Publisher: EDP Sciences
Date: 17-12-2003
Publisher: Oxford University Press (OUP)
Date: 17-01-2012
Publisher: EDP Sciences
Date: 17-08-2004
Publisher: International Academy Publishing (IAP)
Date: 06-2015
Publisher: EDP Sciences
Date: 12-08-2004
Publisher: EDP Sciences
Date: 03-2002
Publisher: EDP Sciences
Date: 05-2014
Publisher: Oxford University Press (OUP)
Date: 15-03-2017
DOI: 10.1093/MNRAS/STX641
Publisher: American Astronomical Society
Date: 26-08-2009
Publisher: Oxford University Press (OUP)
Date: 21-10-2011
Publisher: American Astronomical Society
Date: 12-2022
Abstract: Pulsating ultraluminous X-ray sources (PULXs) are accreting pulsars with apparent X-ray luminosity exceeding 10 39 erg s −1 . We perform Monte Carlo simulations to investigate whether a high collimation effect (or strong beaming effect) is dominant in the presence of accretion outflows, for the fan beam emission of the accretion column of the neutron stars in PULXs. We show that the three nearby PULXs (RX J0209.6−7427, Swift J0243.6+6124, and SMC X-3), namely, the Three Musketeers here, have their main pulsed emission not strongly collimated even if strong outflows exist. This conclusion can be extended to the current s le of extragalactic PULXs, if accretion outflows are commonly produced from them. This means that the observed high luminosity of PULXs is indeed intrinsic, which can be used to infer the existence of very strong surface magnetic fields of ∼10 13–14 G, possibly multipole fields. However, if strong outflows are launched from the accretion disks in PULXs as a consequence of disk spherization by radiation pressure, regular dipole magnetic fields of ∼10 12 G may be required, comparable to that of the Three Musketeers, which have experienced large luminosity changes from well below their Eddington limit (2 × 10 38 erg s −1 for an NS) to super-Eddington and whose maximum luminosity fills the luminosity gap between Galactic pulsars and extragalactic PULXs.
Publisher: Wiley
Date: 04-2011
Publisher: EDP Sciences
Date: 27-05-2008
Publisher: Oxford University Press (OUP)
Date: 07-02-2014
Publisher: Oxford University Press (OUP)
Date: 29-01-2022
Abstract: We present an analysis of the ultraluminous X-ray source (ULX) population in 75 Virgo cluster late-type galaxies, including all those with a star formation rate ≳1 M⊙ yr−1 and a representative s le of the less star forming ones. This study is based on 110 observations obtained over 20 yr with the Chandra X-ray Observatory Advanced Camera for Imaging Spectroscopy. As part of a Large Chandra Program, new observations were obtained for 52 of these 75 galaxies. The data are complete to a sensitivity of ≈1039 erg s−1, with a typical detection limit of ≈3 × 1038 erg s−1 for the majority of the sources. The catalogue contains about 80 ULXs (0.3–10 keV luminosity & erg s−1), and provides their location, observed flux, de-absorbed luminosity, and (for the 25 most luminous ones) simple X-ray spectral properties. We discuss the ULX luminosity function in relation to the mass and star formation rate of the s le galaxies. We show that recent models of low-mass plus high-mass X-ray binary populations (scaling with stellar mass and star formation rate, respectively) are mostly consistent with our observational results. We tentatively identify the most luminous X-ray source in the s le (a source in IC 3322A with LX ≈ 6 × 1040 erg s−1) as a recent supernova or its young remnant. The properties of the s le galaxies (morphologies, stellar masses, star formation rates, total X-ray luminosities from their point-source population) are also summarized.
Publisher: American Astronomical Society
Date: 14-10-2011
Publisher: American Astronomical Society
Date: 18-02-2016
Publisher: Oxford University Press (OUP)
Date: 07-2015
Publisher: Wiley
Date: 04-2011
Publisher: EDP Sciences
Date: 11-2013
Publisher: American Astronomical Society
Date: 30-09-2019
Publisher: Oxford University Press (OUP)
Date: 11-04-2017
DOI: 10.1093/MNRAS/STX888
Publisher: Springer Science and Business Media LLC
Date: 08-10-2014
DOI: 10.1038/NATURE13730
Abstract: Most ultraluminous X-ray sources have a typical set of properties not seen in Galactic stellar-mass black holes. They have luminosities of more than 3 × 10(39) ergs per second, unusually soft X-ray components (with a typical temperature of less than about 0.3 kiloelectronvolts) and a characteristic downturn in their spectra above about 5 kiloelectronvolts. Such puzzling properties have been interpreted either as evidence of intermediate-mass black holes or as emission from stellar-mass black holes accreting above their Eddington limit, analogous to some Galactic black holes at peak luminosity. Recently, a very soft X-ray spectrum was observed in a rare and transient stellar-mass black hole. Here we report that the X-ray source P13 in the galaxy NGC 7793 is in a binary system with a period of about 64 days and exhibits all three canonical properties of ultraluminous sources. By modelling the strong optical and ultraviolet modulations arising from X-ray heating of the B9Ia donor star, we constrain the black hole mass to be less than 15 solar masses. Our results demonstrate that in P13, soft thermal emission and spectral curvature are indeed signatures of supercritical accretion. By analogy, ultraluminous X-ray sources with similar X-ray spectra and luminosities of up to a few times 10(40) ergs per second can be explained by supercritical accretion onto massive stellar-mass black holes.
Publisher: Oxford University Press (OUP)
Date: 04-03-2017
DOI: 10.1093/MNRAS/STX526
Publisher: Oxford University Press (OUP)
Date: 04-2010
Publisher: Oxford University Press (OUP)
Date: 10-05-2012
Publisher: EDP Sciences
Date: 16-07-2004
Publisher: American Astronomical Society
Date: 07-1996
DOI: 10.1086/177403
Publisher: American Astronomical Society
Date: 02-2002
DOI: 10.1086/324328
Publisher: American Astronomical Society
Date: 22-08-2023
Abstract: We present the results of our study of the luminous ( L X ≈ 10 39 erg s −1 ) X-ray binary CXOU J121538.2+361921 in NGC 4214, the high-mass X-ray binary with the shortest known orbital period. Using Chandra data, we confirm the ≈13,000 s (3.6 hr) eclipse period, and an eclipse duration of ≈2000 s. From this, we estimate a mass ratio M 2 / M 1 ≳ 3 and a stellar density ρ ≈ 6 g cm −3 , which implies that the donor must be a Wolf–Rayet or a stripped helium star. The eclipse egress is consistently much slower than the ingress. This can be explained by denser gas located either in front of the compact object (as expected for a bow shock) or trailing the donor star (as expected for a shadow wind, launched from the shaded side of the donor). There is no change in X-ray spectral shape with changing flux during the egress, which suggests either variable partial covering of the X-ray source by opaque clumps or, more likely, a gray opacity dominated by electron scattering in a highly ionized medium. We identify the optical counterpart from Hubble images. Photometry blueward of ∼5500 Å indicates a bright ( M B ≈ −3.6 ± 0.3 mag, for a range of plausible extinctions), hot ( T ≈ 90,000 ± 30,000 K) emitter, consistent with the Wolf–Rayet scenario. There is also a bright ( M I ≈ −5.2 mag), cool ( T ≈ 2700 ± 300 K) component consistent with an irradiated circumbinary disk or with a chance projection of an unrelated asymptotic giant branch star along the same line of sight.
Publisher: Oxford University Press (OUP)
Date: 28-10-2014
Publisher: American Astronomical Society
Date: 24-05-2019
Publisher: American Astronomical Society
Date: 08-04-2009
Publisher: American Astronomical Society
Date: 10-2007
DOI: 10.1086/520710
Publisher: American Astronomical Society
Date: 26-10-2021
Publisher: American Astronomical Society
Date: 10-2007
DOI: 10.1086/520711
Publisher: Oxford University Press (OUP)
Date: 05-01-2023
Abstract: Owing to their quiet evolutionary histories, nearby dwarf galaxies (stellar masses $M_\\star \\lesssim 3 \\times 10^9 \\, \\mathrm{M}_\\odot$) have the potential to teach us about the mechanism(s) that ‘seeded’ the growth of supermassive black holes, and also how the first stellar mass black holes formed and interacted with their environments. Here, we present high spatial resolution observations of three dwarf galaxies in the X-ray (Chandra), the optical/near-infrared (Hubble Space Telescope), and the radio (Karl G. Jansky Very Large Array). These three galaxies were previously identified as hosting candidate active galactic nuclei on the basis of lower resolution X-ray imaging. With our new observations, we find that X-ray sources in two galaxies (SDSS J121326.01+543631.6 and SDSS J122111.29+173819.1) are off-nuclear and lack corresponding radio emission, implying they are likely luminous X-ray binaries. The third galaxy (Mrk 1434) contains two X-ray sources (each with LX ≈ 1040 erg s−1) separated by 2.8 arcsec, has a low metallicity [12 + log(O/H) = 7.8], and emits nebular He ii λ4686 line emission. The northern source has spatially coincident point-like radio emission at 9.0 GHz and extended radio emission at 5.5 GHz. We discuss X-ray binary interpretations (where an ultraluminous X-ray source blows a ‘radio bubble’) and active galactic nucleus interpretations (where an $\\approx 4\\times 10^5 \\, \\mathrm{M}_\\odot$ black hole launches a jet). In either case, we find that the He ii emission cannot be photoionized by the X-ray source, unless the source was ≈30–90 times more luminous several hundred years ago.
Publisher: American Astronomical Society
Date: 23-01-2018
Publisher: American Astronomical Society
Date: 06-2022
Abstract: We study the spectral evolution of the black hole candidate EXO 1846−031 during its 2019 outburst, in the 1–150 keV band, with the Hard X-ray Modulation Telescope. The continuum spectrum is well modeled with an absorbed disk-blackbody plus cutoff power law, in the hard, intermediate, and soft states. In addition, we detect an ≈6.6 keV Fe emission line in the hard intermediate state. Throughout the soft intermediate and soft states, the fitted inner disk radius remains almost constant we suggest that it has settled at the innermost stable circular orbit (ISCO). However, in the hard and hard intermediate states, the apparent inner radius was unphysically small (smaller than the ISCO), even after accounting for the Compton scattering of some of the disk photons by the corona in the fit. We argue that this is the result of a high hardening factor, f col ≈ 2.0–2.7, in the early phases of the outburst evolution, well above the canonical value of 1.7 suitable for a steady disk. We suggest that the inner disk radius was already close to the ISCO in the low/hard state. Furthermore, we propose that this high value of the hardening factor in the relatively hard state was probably caused by the additional illuminating of the coronal irradiation onto the disk. Additionally, we estimate the spin parameter using the continuum-fitting method, over a range of plausible black hole masses and distances. We compare our results with the spin measured using the reflection-fitting method and find that the inconsistency of the two results is partly caused by different choices of f col .
Publisher: American Astronomical Society
Date: 21-05-2014
Publisher: Oxford University Press (OUP)
Date: 11-07-2022
Abstract: We revisit various sets of published results from X-ray and optical studies of the Galactic black hole (BH) candidate MAXI J0637-430, which went into outburst in 2019. Combining the previously reported values of peak outburst luminosity, best-fitting radii of inner and outer accretion disc, viewing angle, exponential decay time-scale, and peak-to-peak separation of the He II λ4686 disc emission line, we improve the constraints on the system parameters. We estimate a heliocentric distance d ≈ (8.7 ± 2.3) kpc, a projected Galactocentric distance R ≈ (13.2 ± 1.8) kpc and a height |z| ≈ (3.1 ± 0.8) kpc from the Galactic plane. It is the currently known Milky Way BH candidate located farthest from the Galactic Centre. We infer a BH mass M1 ≈ (5.1 ± 1.6)M⊙, a spin parameter a* ≲ 0.25, a donor star mass M2 ≈ (0.25 ± 0.07)M⊙, a peak Eddington ratio λ ≈ 0.17 ± 0.11 and a binary period $P_{\rm orb} \approx 2.2^{+0.8}_{-0.6}$ hr. This is the shortest period measured or estimated so far for any Galactic BH X-ray binary. If the donor star is a main-sequence dwarf, such a period corresponds to the evolutionary stage where orbital shrinking is driven by gravitational radiation and the star has regained contact with its Roche lobe (low end of the period gap). The three Galactic BHs with the shortest period (≲3 hr) are also those with the highest vertical distance from the Galactic plane (≳2 kpc). This is probably because binaries with higher binding energies can survive faster natal kicks.
Publisher: Oxford University Press (OUP)
Date: 11-11-2006
Publisher: EDP Sciences
Date: 13-11-2006
Publisher: Oxford University Press (OUP)
Date: 17-12-2018
Publisher: American Astronomical Society
Date: 19-04-2013
Publisher: Oxford University Press (OUP)
Date: 2005
Publisher: Oxford University Press (OUP)
Date: 21-10-2006
Publisher: American Astronomical Society
Date: 12-2021
Abstract: Building upon three late-type galaxies in the Virgo cluster with both a predicted black hole mass of less than ∼10 5 M ⊙ and a centrally located X-ray point source, we reveal 11 more such galaxies, more than tripling the number of active intermediate-mass black hole candidates among this population. Moreover, this amounts to a ∼36 ± 8% X-ray detection rate (despite the sometimes high, X-ray-absorbing, H i column densities), compared to just 10 ± 5% for (the largely H i -free) dwarf early-type galaxies in the Virgo cluster. The expected contribution of X-ray binaries from the galaxies’ inner field stars is negligible. Moreover, given that both the spiral and dwarf galaxies contain nuclear star clusters, the above inequality appears to disfavor X-ray binaries in nuclear star clusters. The higher occupation, or rather detection, fraction among the spiral galaxies may instead reflect an enhanced cool gas/fuel supply and Eddington ratio. Indeed, four of the 11 new X-ray detections are associated with known LINERs or LINER/H ii composites. For all (four) of the new detections for which the X-ray flux was strong enough to establish the spectral energy distribution in the Chandra band, it is consistent with power-law spectra. Furthermore, the X-ray emission from the source with the highest flux (NGC 4197: L X ≈ 10 40 erg s −1 ) suggests a non-stellar-mass black hole if the X-ray spectrum corresponds to the “low/hard state”. Follow-up observations to further probe the black hole masses, and prospects for spatially resolving the gravitational spheres of influence around intermediate-mass black holes, are reviewed in some detail.
Publisher: Oxford University Press (OUP)
Date: 28-04-2017
Publisher: Oxford University Press (OUP)
Date: 19-02-2018
DOI: 10.1093/MNRAS/STY390
Publisher: American Astronomical Society
Date: 04-10-2019
Publisher: Oxford University Press (OUP)
Date: 18-08-2022
Abstract: We present the results of a search for associated 21 cm H i absorption at redshift 0.42 & z & 1.00 in radio-loud galaxies from three Galaxy And Mass Assembly (GAMA) survey fields. These observations were carried out as part of a pilot survey for the Australian SKA Pathfinder (ASKAP) First Large Absorption Survey in H i (FLASH). From a s le of 326 radio sources with 855.5 MHz peak flux density above 10 mJy, we detected two associated H i absorption systems, in SDSS J090331+010847 at z = 0.522 and SDSS J113622+004852 at z = 0.563. Both galaxies are massive (stellar mass $\\gt 10^{11}\\, \\mathrm{M}_\\odot$) and have optical spectra characteristic of luminous red galaxies, though spectral energy distribution fitting implies that SDSS J113622+004852 contains a dust-obscured starburst with star formation rate ∼69 M⊙ yr−1. The H i absorption lines have a high optical depth, with τpk of 1.77 ± 0.16 for SDSS J090331+010847 (the highest value for any z & 0.1 associated system found to date) and 0.14 ± 0.01 for SDSS J113622+004852. In the redshift range probed by our ASKAP observations, the detection rate for associated H i absorption lines (with τpk & 0.1 and at least 3σ significance) is $2.9_{-2.6}^{+9.7}$ per cent. Although the current s le is small, this rate is consistent with a trend seen in other studies for a lower detection rate of associated 21 cm H i absorption systems at higher redshift. We also searched for OH absorption lines at 0.67 & z & 1.34, but no detection was made in the 145 radio sources searched.
Publisher: Oxford University Press (OUP)
Date: 2004
Publisher: American Astronomical Society
Date: 04-2021
Abstract: We are undertaking the first systematic infrared (IR) census of R Coronae Borealis (RCB) stars in the Milky Way, beginning with IR light curves from the Palomar Gattini IR (PGIR) survey. The PGIR is a 30 cm J -band telescope with a 25 deg 2 camera that is surveying 18,000 deg 2 of the northern sky ( δ −28°) at a cadence of 2 days. We present PGIR light curves for 922 RCB candidates selected from a mid-IR color-based catalog. Of these 922, 149 are promising RCB candidates, as they show pulsations or declines similar to RCB stars. The majority of the candidates that are not RCB stars are either long-period variables (LPVs) or RV Tauri stars. We identify IR color-based criteria to better distinguish between RCB stars and LPVs. As part of a pilot spectroscopic run, we obtain NIR spectra for 26 of the 149 promising candidates and spectroscopically confirm 11 new RCB stars. We detect strong He i λ 10830 features in the spectra of all RCB stars, likely originating within high-velocity (200–400 km s −1 ) winds in their atmospheres. Nine of these RCB stars show 12 C 16 O and 12 C 18 O molecular absorption features, suggesting that they are formed through a white dwarf merger. We detect quasiperiodic pulsations in the light curves of five RCB stars. The periods range between 30 and 125 days and likely originate from the strange-mode instability in these stars. Our pilot run results motivate a dedicated IR spectroscopic c aign to classify all RCB candidates.
Publisher: Elsevier BV
Date: 06-2007
Publisher: Oxford University Press (OUP)
Date: 31-01-2014
Publisher: American Astronomical Society
Date: 26-10-2016
Publisher: American Astronomical Society
Date: 14-01-2020
Publisher: Oxford University Press (OUP)
Date: 28-04-2015
DOI: 10.1093/MNRAS/STV723
Publisher: Oxford University Press (OUP)
Date: 11-01-2001
Publisher: American Astronomical Society
Date: 20-08-2008
DOI: 10.1086/589995
Publisher: Oxford University Press (OUP)
Date: 14-12-2015
Publisher: Oxford University Press (OUP)
Date: 09-2005
Publisher: American Astronomical Society
Date: 20-08-2006
DOI: 10.1086/504680
Publisher: FapUNIFESP (SciELO)
Date: 2021
Publisher: American Astronomical Society
Date: 28-08-2020
Publisher: FapUNIFESP (SciELO)
Date: 2021
Publisher: Oxford University Press (OUP)
Date: 05-02-2018
DOI: 10.1093/MNRAS/STY284
Publisher: Oxford University Press (OUP)
Date: 2002
Publisher: Oxford University Press (OUP)
Date: 06-07-2017
Publisher: American Association for the Advancement of Science (AAAS)
Date: 21-03-2014
Abstract: A mass-accreting black hole in steady-state cannot produce more radiative energy than its gravity can counterbalance, achieving what is known as the Eddington limit. However, mass accretion can also be converted into kinetic energy via mechanical outflow. Using x-ray observations, Soria et al. (p. 1330 , published online 27 February see the Perspective by King and the cover) identified a compact shock-ionized radio/optical nebula in spiral galaxy M83, powered by a black hole, inferred that the black hole emits a spherical wind that exceeds the Eddington limit tenfold and succeeded in estimating it's mass in the range of 5 to 15 solar masses. It is possible that rapidly accreting black holes have greater influence on their host galaxy than once appreciated.
Publisher: World Scientific Publishing Company
Date: 05-2006
Publisher: Oxford University Press (OUP)
Date: 11-09-2006
Publisher: American Astronomical Society
Date: 06-2023
Abstract: We report observations of the optical counterpart of the long gamma-ray burst GRB 221009A. Due to the extreme rarity of being both nearby ( z = 0.151) and highly energetic ( E γ ,iso ≥ 10 54 erg), GRB 221009A offers a unique opportunity to probe the connection between massive star core collapse and relativistic jet formation across a very broad range of γ -ray properties. Adopting a phenomenological power-law model for the afterglow and host galaxy estimates from high-resolution Hubble Space Telescope imaging, we use Bayesian model comparison techniques to determine the likelihood of an associated supernova (SN) contributing excess flux to the optical light curve. Though not conclusive, we find moderate evidence ( K Bayes = 10 1.2 ) for the presence of an additional component arising from an associated SN, SN 2022xiw, and find that it must be substantially fainter ( % as bright at the 99% confidence interval) than SN 1998bw. Given the large and uncertain line-of-sight extinction, we attempt to constrain the SN parameters ( M Ni , M ej , and E KE ) under several different assumptions with respect to the host galaxy’s extinction. We find properties that are broadly consistent with previous GRB-associated SNe: M Ni = 0.05–0.25 M ⊙ , M ej = 3.5–11.1 M ⊙ , and E KE = (1.6–5.2) × 10 52 erg. We note that these properties are weakly constrained due to the faintness of the SN with respect to the afterglow and host emission, but we do find a robust upper limit on M Ni of M Ni 0.36 M ⊙ . Given the tremendous range in isotropic gamma-ray energy release exhibited by GRBs (seven orders of magnitude), the SN emission appears to be decoupled from the central engine in these systems.
Publisher: Elsevier BV
Date: 08-2008
Publisher: American Astronomical Society
Date: 06-2022
Abstract: We present a detailed study of the evolution of the Galactic black hole transient GRS 1716−249 during its 2016–2017 outburst at optical (Las Cumbres Observatory), mid-infrared (Very Large Telescope), near-infrared (Rapid Eye Mount telescope), and ultraviolet (the Neil Gehrels Swift Observatory Ultraviolet/Optical Telescope) wavelengths, along with archival radio and X-ray data. We show that the optical/near-infrared and UV emission of the source mainly originates from a multi-temperature accretion disk, while the mid-infrared and radio emission are dominated by synchrotron emission from a compact jet. The optical/UV flux density is correlated with the X-ray emission when the source is in the hard state, consistent with an X-ray irradiated accretion disk with an additional contribution from the viscous disk during the outburst fade. We find evidence for a weak, but highly variable jet component at mid-infrared wavelengths. We also report the long-term optical light curve of the source and find that the quiescent i ′ -band magnitude is 21.39 ± 0.15 mag. Furthermore, we discuss how previous estimates of the system parameters of the source are based on various incorrect assumptions, and so are likely to be inaccurate. By comparing our GRS 1716−249 data set to those of other outbursting black hole X-ray binaries, we find that while GRS 1716−249 shows similar X-ray behavior, it is noticeably optically fainter, if the literature distance of 2.4 kpc is adopted. Using several lines of reasoning, we argue that the source distance is further than previously assumed in the literature, likely within 4–17 kpc, with a most likely range of ∼4–8 kpc.
Publisher: American Astronomical Society
Date: 22-01-2015
Publisher: American Astronomical Society
Date: 15-04-2009
Publisher: American Astronomical Society
Date: 10-02-2014
Publisher: American Astronomical Society
Date: 18-09-2020
Publisher: Oxford University Press (OUP)
Date: 30-03-2023
Abstract: Tracking the motions of transient jets launched by low-mass X-ray binaries (LMXBs) is critical for determining the moment of jet ejection, and identifying any corresponding signatures in the accretion flow. However, these jets are often highly variable and can travel across the resolution element of an image within a single observation, violating a fundamental assumption of aperture synthesis. We present a novel approach in which we directly fit a single time-dependent model to the full set of interferometer visibilities, where we explicitly parametrize the motion and flux density variability of the emission components, to minimize the number of free parameters in the fit, while leveraging information from the full observation. This technique allows us to detect and characterize faint, fast-moving sources, for which the standard time binning technique is inadequate. We validate our technique with synthetic observations, before applying it to three Very Long Baseline Array (VLBA) observations of the black hole candidate LMXB MAXI J1803−298 during its 2021 outburst. We measured the proper motion of a discrete jet component to be 1.37 ± 0.14 mas h−1, and thus we infer an ejection date of MJD $59348.08_{-0.06}^{+0.05}$, which occurs just after the peak of a radio flare observed by the Australia Telescope Compact Array (ATCA) and the Atacama Large Millimeter/Sub-Millimeter Array (ALMA), while MAXI J1803−298 was in the intermediate state. Further development of these new VLBI analysis techniques will lead to more precise measurements of jet ejection dates, which, combined with dense, simultaneous multiwavelength monitoring, will allow for clearer identification of jet ejection signatures in the accretion flow.
Publisher: Oxford University Press (OUP)
Date: 14-11-2012
DOI: 10.1093/MNRAS/STS220
Publisher: Oxford University Press (OUP)
Date: 10-2003
Publisher: American Astronomical Society
Date: 15-04-2009
Location: United Kingdom of Great Britain and Northern Ireland
Location: United States of America
Start Date: Start date not available
End Date: End date not available
Funder: Australian Research Council
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