Rapid Burster Research Articles

Time lags in QPO sources

The observations and interpretation of the time lags between hard and soft X-ray spectral bands that were recently discovered in QPO sources are reviewed. The time lags occurring in the fast QPO (quasi-periodic oscillations) associated with the “horizontal branch” X-ray spectral state probably can be satisfactorily explained by inverse Compton scattering of the X-rays in a hot cloud around the source. However, for the time lags that have been seen in the slow QPO associated with the “normal branch” spectral state and in the Rapid Burster, alternative models may be preferable.

Rapid optical flaring in MXB 1735-444 and an optical burst from GX 17+2

view Abstract Citations (7) References (15) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Rapid Optical Flaring in MXB 1735-444 and an Optical Burst from GX 17+2 Imamura, James N. ; Steiman-Cameron, Thomas Y. ; Middleditch, John Abstract The results of high-speed white-light photometry of five low-mass X-ray binaries (LMXB), including MXB 1735-444 (V926 Sco), are reported. It is found that MXB 1735-444 was in a previously unreported state. It showed rapid optical flaring on time scales of 10 s or less to about 20 minutes over the course of a 2 hr observation. During the bursts, the optical luminosity increased by up to a factor of five; the average optical luminosity of MXB 1735-444 was about 2 x 10 to the 34th ergs/s at these times. Qualitatively similar long type II X-ray bursts have been observed from the rapid burster, MXB 1730-335, and long X-ray bursts of undetermined type have been observed from GX 17+2 (4U 1813-14). The detection of an optical burst from the source GX 17+2 is also reported. Optical bursts have not been previously reported in this object. Publication: The Astrophysical Journal Pub Date: September 1987 DOI: 10.1086/184973 Bibcode: 1987ApJ...320L..41I Keywords: Neutron Stars; Stellar Flares; Stellar Spectrophotometry; X Ray Binaries; X Ray Sources; Eddington Approximation; Light Curve; Astrophysics; STARS: BINARIES; STARS: NEUTRON; X-RAYS: BURSTS; X-RAYS: SOURCES full text sources ADS | data products SIMBAD (7)

Quasi-Periodic Oscillations: The Rapid Burster (MXB 1730-335): Models vs. Observations - A Brief Review

The salient features of quasi-periodic oscillations (QPO) observed in type 2 bursts and in the persistent emission from the Rapid Burster are discussed. In addition, a brief review is given of the models that have recently been proposed to explain high-frequency QPO observed in several bright low-mass X-ray binaries. We do not yet know the mechanism(s) of the QPO, not even whether they are magnetospheric in origin. However, some of the proposed ideas could well be relevant to the various rather complex aspects of the QPO. It is likely that more than one mechanism is at work.

Recent Results from the Japanese X‐Ray Astronomy Satellites

Observations of neutron stars and their environments, and the emission and absorption of iron, obtained with the Hakucho and Tenma satellites, are examined. The characteristics of X-ray bursts, neutron stars, and accretion disks, in particular spectra, color and effective temperatures, blackbody temperature and radius, the emissivity factor, and the Eddington limit luminosity, are discussed. Consideration is given to the rapid burster discovered by Lewin et al. (1976) and potential blackhole sources. 43 references.

X-ray spectra of various bursts from the rapid burster

About 20 type-I bursts and 3000 type-II bursts were observed with Tenma and Hakucho in 1983. Spectral evolutions were analyzed for both types of bursts and results are presented.

Accretion Disk Instabilities

In this article we discuss two instabilities of stationary accretion disks which lead to an understanding of observed light variations in accretion disk systems, the dwarf novae and the rapid burster MXB 17030-335. The accretion disks in these systems avoid instability at the cost of stationarity and perform stable cycles in which sudden changes of the accretion flow lead to corresponding, often dramatic, variations of their accretion luminosity.Figure 1 shows a light curve of U Geminorum. It was discovered In 1855 by J.R. Hind and has become a prototype of the dwarf novae. In these systems an extended time of quiescence of up to several weeks Is followed by a short outburst of a few days during which the luminosity rises by a factor of 30 to 100. The dwarf novae belong to the cataclysmic variables. They are all close binaries In which a white dwarf primary is orbited by a Roche lobe-filling low mass secondary. Through the inner Lagrangian point mass flows over from the secondary and forms a luminious accretion disk around the white dwarf. In the case of the dwarf novae this disk has temperatures below about 10000K in Its outer region. It will be discussed how partial lonizatlon and convection then affect the vertical structure of the disk such that the stationary flow becomes unstable.Fig. 1. Light curve of the dwarf nova U Geminorum. Abszissa in days С [2])

Timescale-invariant profile of the type II bursts from the Rapid Burster

The Rapid Burster is a unique X-ray source which produces rapidly repetitive X-ray bursts. Each rapid burst shows a characteristic structure in its decay part comprising successive peaks. We have now discovered that the structure of each individual burst shows a nearly identical profile except for the timescale, which differs largely from burst to burst; the profile of the decay is timescale invariant. This invariance holds over a wide range of timescales to at least a factor of 30. Furthermore, we have found that the heights of successive peaks as well as the intervals between them decrease with time according to a common arithmetic rule.

The rapid burster activity observed from tenma

The Japanese X-ray astronomy satellite Hakucho and Tenma observed the activity of the rapid burster MXB 1730-335 in 1979 and 1983. In the first observation from 8 to 22 August 1979, the activity began with rapidly repetitive type II bursts which are similar to those observed earlier. Then the energy per burst quickly increased and evolved to exhibit a long flat top or roughly trapezoidal shape. In the last phase, burst size became smaller and the activity returned to the short type II burst mode. In the second observation from 5 to 31 August 1983, the burster started to emit a train of bursts which aparently resemble to type I bursts with quasi-periodical occurrence of 74 ∼ 90 minutes. In the second phase, there appeared long type II bursts of trapezoidal profiles and exotic long bursts. In the last phase, about 3000 rapidly repetitive short type II bursts were observed. The bursts with shortest intervals exhibited almost periodic features of 16 sec. The type II bursts in both observation evolved to the size E of ∼ 6 × 10 40 erg that is one order larger than ever observed. They were long bursts ( τ ≦ 600 s) of flat topped (trapezoidal) shape and those of exotic profiles. Those type II bursts exhibited some kinds of quasi-periodicities, which implies the vibrations or instabilities of the mass accretion onto the neutron stars. The type I bursts were often observed with/without type II bursts.

No IR burst during a type I X-ray burst from the rapid burster (MXB1730–335)

The rapid X-ray burster, MXB1730–335, discovered by Lewin et al.1 and identified2 with the compact globular cluster Liller 1, produces thousands of X-ray bursts a day when in an active phase. The X-ray bursts have thermal spectra and can be classified into two types by their spectral evolution during burst decay (see ref. 3 and refs therein). Type I bursts normally occur at intervals of hours or days, their spectra soften during decay and their behaviour can be accounted for well by a thermonuclear flash in accreted material on a neutron star. Type I bursts are produced by all other bursters. Type II bursts are unique to the rapid burster, occur at intervals from a few seconds up to 10 min and their spectra do not soften during burst decay. Type II bursts are probably caused by an instability of the accretion flow onto the neutron star. We report here the absence of an IR burst during a type I X-ray burst from MXB1730–335. The upper limit on the IR luminosity during the X-ray burst is 70 times smaller than those of reported IR bursts from this object. This seems to rule out a connection between type I X-ray bursts and the reported IR bursts.

X-ray, radio, and infrared observations of the 'rapid burster' /MXB 1730-335/ during 1979 and 1980

view Abstract Citations (7) References (29) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS X-ray, radio, and infrared observations of the "rapid burster" (MXB 1730-335) during 1979 and 1980. Lawrence, A. ; Cominsky, L. ; Lewin, W. H. G. ; Oda, M. ; Ogawara, Y. ; Inoue, H. ; Koyama, K. ; Makishima, K. ; Matsuoka, M. ; Murakami, T. ; Ohashi, T. ; Shibazaki, N. ; Tanaka, Y. ; Kondo, I. ; Hayakawa, S. ; Kunieda, H. ; Makino, F. ; Masai, K. ; Nagase, F. ; Tawara, Y. ; Miyamoto, S. ; Tsunemi, H. ; Yamashita, K. ; Daishido, T. ; Oka, R. ; Ohkawa, T. ; Maruyama, T. ; Yokoyama, T. ; Nicholson, G. ; Balonek, T. ; Dent, W. A. ; Glass, I. S. ; Carter, B. S. ; Jones, A. W. ; Selby, M. J. ; Martinez Roger, C. ; Sanchez Magro, C. ; Giles, A. B. ; Duldig, M. ; Pramesh Rao, A. ; Venugopal, V. R. ; Haynes, R. F. ; Jauncey, D. L. ; Okuda, H. ; Sato, S. ; Kobayashi, Y. ; Jugaku, J. ; Backman, D. ; Pogge, R. ; Hodge, P. E. and 2 more Abstract The paper reports partially simultaneous observations of the 'rapid burster' (MXB 1730-335) at X-ray, infrared, and radio wavelengths, covering several hundred hours during 1979 and 1980. None of the authors of this report saw any infrared or radio bursts. On several occasions an absence of infrared bursting was observed during X-ray bursting. On one occasion an absence of X-ray bursting was observed during a radio burst (4.1 GHz) reported by Calla et al. (1979). To date, radio bursts (a total of at least a dozen) have been reported only by Calla et al. (1980). Considering these and other observations summarized here, the reported radio bursts are either unreal or do not bear a simple relation to the X-ray bursts from the 'rapid burster'. The status of the reported infrared bursts also remain ambiguous. Limits to the brightness of any persistent radio source at the position of MXB 1730-335, limits to persistent X-ray emission during an extended X-ray quiet phase, and a measurement of the infrared polarization in the direction of the X-ray source are also reported. Publication: The Astrophysical Journal Pub Date: April 1983 DOI: 10.1086/160868 Bibcode: 1983ApJ...267..301L Keywords: Astronomical Spectroscopy; Infrared Astronomy; Radio Sources (Astronomy); Variable Stars; X Ray Sources; Brightness Distribution; Bursts; Polarization Characteristics; Temporal Distribution; Astrophysics full text sources ADS | data products SIMBAD (1)

A model of rapid burster MXB 1730-335

A model of rapid burster MXB 1730-335, the source of type II X-ray burst is proposed, based on the Rayleigh-Taylor instability due to interaction of relativistic electrons produced by the rapid rotation of a highly magnetized neutron star, and the infalling accreted matter through the magnetic funnel at the poles. Conclusions are made that type II X-ray burster may be a constant source of cosmic rays and such a mechanism may be the progenitor of some forms of nebulae.Permanent address: Imphal College, Imphal, Manipur.

High‐energy astrophysics

The european X-ray observatory (EXOSAT), which was launched in 1983 and which finished operations in April 1986, has brought a rich harvest of results in the period 1984–1987, surveyed here. The EXOSAT payload consisted of three sets of instruments : two low energy imaging telescopes (LE:E<2 KeV), a medium-energy experiment (ME:E=l-50KeV) and a gas scintillation proportional counter (GSPC:E=2-20KeV). Over most of the energy range covered, EXOSAT was not more sensitive than its predecessor, the american EINSTEIN satellite. But the EINSTEIN satellite is far from having exhausted the treasures of the X-ray sky. And EXOSAT, thanks to its elliptical 90-hour orbit, had the extra advantage of being able to make long, continuous observations of interesting objects, lasting up to 72 hours. Thus, EXOSAT was very well suited for variability studies, and many of its most important findings are in this area. EXOSAT observations sample a wide range of astrophysical sources : X-ray binaries, cataclysmic variables and active stars ; supernova remnants and the interstellar medium ; active galactic nuclei, and clusters of galaxies. Among the highlights, let us mention : the detection of quasi-periodic oscillations (QPO) in seven well known X-ray sources, starting with the galactic bulge source GX 5-1, and including Sco X-l, the brightest X-ray source in the sky, Cyg X2 and the Rapid Burster. The 38 majority of the QPO sources are very luminous (>1038 erg/sec), and the oscillations are strong (5% rms variation in flux), persistent (> 10 cycles), and take place at high frequency (5-50 Hz). Other characteristics of the QPO, however, such as their relation to the source intensity or the spectral shape, vary widely from source to source. QPO sources are believed to be binary systems containing a neutron star, and the models proposed generally involve interactions between the accretion disk and the neutron star magnetosphere. the mapping out of the X-ray galactic ridge in the 2–6 KeV band. The “ridge” is a disk of radius 10 to 12 Kpsec and a height of a few hundred parsecs ; its total luminosity is 1038 erg/sec. the detailed observations of active galactic nuclei (AGN), revealing, in some cases, the presence of a soft X-ray component, in the .05-1 KeV range. Long terra monitoring of AGN allowed to study their variability on timescales from minutes to years. For NGC 4151, the flux in the 2-10 KeV band can vary by a factor 2 over periods of six months, while the soft component remains constant. A possible interpretation is that the soft component originates in a hot intercloud medium in the narrow-line region, while the hard X-ray flux is emitted by regions surrounding the nucleus. EXOSAT observations indicate that rapid variability, on time scales of the order of an hour, is frequent in AGNs.

Discovery of 0.5-s oscillations in long flat top bursts from the Rapid Burster

We report here a search for periodic emission of X rays from MXB1730–335 (the Rapid Burster, which is the most unusual X-ray burst source1 out of about 30 other bursters) during the long flat top bursts2. Two events from the 63 bursts showed clear peaks in the frequency power spectra at ∼0.5 s in period. However, this is unlikely to be a pulsar period, because the periods of these two bursts are different.

An auroral precipitation model for the rapid X-ray burster

It is suggested that rotating magnetospheres can be separated into two catgories according to their rotation speeds. Fast rotators such as pulsars, and perhaps Jupiter, are dominated by gravitational and centrifugal effects and have flattened, distended magnetopheres. The dominant forces in slowly rotating magnetospheres: of which the Earth is an example: are gravitational, electric, and magnetic. Because the outer regions of slowly rotating magnetospheres are subject mainly to electric and magnetic forces, magnetospheric substorms and other types of unstable behavior are expected to occur frequently. It is proposed that the rapid X-ray burster may be a slow rotator, whose magnetospheric activity should resemble the Earth's. Moreover, if all X-ray bursters were slow rotators there should be few X-ray bursters that are also pulsars: in accord with the observational data. The proposed relaxation oscillator that turns the rapid bursters on-and-off has a terrestrial analog in pulsating aurorae. Repeated bursts of particle precipitation ( e.g., pulsating aurorae) from a magnetospheric trapping region are expected when particle injection in a substorm results in saturation of the trapping region with more matter than it can contain in equilibrium. Saturation leads to rapid growth of plasma waves, which are turned off again when the resonantmore » particles are removed by precipitation. If there is a continual source of ''accreting'' matter of sufficient strength, the wave growth and precipitation episodes repeat semiregular intervals, leading to ''pulsations'' or ''bursts'' of radiation when the precipitating particles are stopped in the atmosphere. The predicted repitition periods for the rapid burster: in the range 8 to 24 s: are within the uncertainties of the calculation. It is argued that a saturation-resonant interaction-wave growth-precipitation model fits the observations better than models based on hydromagnetic instabilities.« less

Thermonuclear Processes on Accreting Neutron Stars

The observed properties of X-ray burst sources have recently been reviewed by Lewin and Clark (1980) and Lewin and Joss (1980). About thirty-five such sources are presently known, and they have a spatial distribution reminiscent of stellar Population II (see Figure 1). The salient features of these sources include burst rise times of ≲ls, decay time scales of ~3–100 s, peak luminosities of ~1039 ergs per burst, spectra that can generally be well fitted by blackbody emission from a surface with a constant effective radius of ~10 km and a peak temperature of ~3 × 107 K, and “tails” of softer X-ray emission that may persist for several minutes after the burst maximum. Profiles of bursts from some typical burst sources are shown in Figure 2. The intervals between bursts from a given source may be regular or erratic and are typically in the range of ~104−105 s; many sources undergo burst-inactive phases that can last for weeks or months. Most burst sources are also sources of persistent X-ray emission, and the ratio of average persistent luminosity to time-averaged burst luminosity is typically ~102 during burst-active phases. (The properties of the “Rapid Burster,” MXB1730-335, are different from those of all other known burst sources and will be discussed separately in §VI below.) There are few correlations among the burst flux, burst intervals, and persistent X-ray flux from any given source, and the detailed burst shapes vary from one source to another and often vary with time in a given source.

X-ray bursters and the x-ray sources of the galactic bulge

An attempt is made to distill from observational and theoretical information on the galactic bulge X-ray sources in general, and on the X-ray burst sources in particular, those aspects which seem to have the greatest relevance to the understanding of these sources. Galactic bulge sources appear to be collapsed objects of roughly solar mass, in most cases neutron stars, which are accreting matter from low-mass stellar companions. Type I bursts seem to result from thermonuclear flashes in the surface layers of some of these neutron stars, while the type II bursts from the Rapid Burster are almost certainly due to an instability in the accretion flow onto a neutron star. It is concluded that the studies cited offer a new and powerful observational handle on the fundamental properties of neutron stars and of the interacting binary systems in which they are often contained.

A model of the rapid burster

A new burst mode of MXB 1730 - 335, the rapid burster, as discovered by Hakucho in August 1979, is characterized by a train of long X-ray bursts whose behaviour is dictated by the accretion rate. In this mode the burst luminosity reaches the Eddington limit, so that the X-ray pressure controls the accretion from a reservoir in the magnetopause and accretion columns in the polar regions explain general features of the rapid burster observed in August 1979.

The very long type II X-ray bursts from the rapid burster

Two very long type II bursts (greater than 200 sec) from the rapid burster (MXB 1730-335) have been observed on Mar. 3, 1979 UT. Similar long bursts were observed about five months later, in August 1979, by the Japanese satellite Hakucho. This new burst mode is possibly related to the early stage of the turn-on. In this paper, results of the analysis of the bursts from the rapid burster as observed by the SAS 3 X-ray observatory during Mar. 3-5, 1979 are presented.

Simultaneous IR and X-ray burst observation of Ser X-1

It has been suggested1,2 that the very bright IR bursts1,3 observed from the Rapid Burster (MXB 1730–335) are due to Type I X-ray bursts4. When the bright IR bursts were detected, unfortunately there was no simultaneous X-ray coverage. Therefore, it is not known whether the IR bursts are associated with Type I or Type II bursts or with neither one. The suggestion1,2 is only based on the low recurrence rate of the IR bursts. If the suggestion is correct, similar bright IR bursts may, in general, accompany Type I X-ray bursts1,2. This paper investigates this possibility for one specific case. During the 1977 coordinated worldwide burst watch5, simultaneous X-ray and IR observations were made. On UT June 17, 00 h 00 min 25s, a Type I X-ray burst was observed, which was almost certainly emitted by Ser X-l (MXB 1837 + 05, 4U1837 + 04) (ref. 6). Simultaneous IR observations failed to detect any bursts. We report here on these observations.

No IR burst from the X-ray rapid burster MXB1730–335

The X-ray rapid burster MXB1730–335, discovered by Lewin et al.1 has been identified with a compact globular cluster embedded in the midst of the galactic plane and named2 Liller 1. It has an extremely large interstellar extinction (Av = 11 mag) from which Liller2 and Kleinmann et al.4 derived its distance as 10 kpc. Kulkarni et al.3 detected IR bursts in the globular cluster, six times during their 2.5 h observing time on 4–5 April 1979 using a 1-m telescope at Kavalur3. The burst power emitted in H-band was estimated to be 1.6–2.3 × 1030 W. Stimulated by this report, we monitored MXB1730 – 335 using a multi-band IR photometer for about 10 h during April and August 1979. In the latter period, although the X-ray bursts were very active, no coincident IR and X-ray burst could be detected. We show here that this conflicts with previous results by Kulkarni et al.3 and Jones et al.5.