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High resolution X-ray spectra of classical and recurrent novae in outburst have opened a new window into the nova phenomenon, allowing to observe both the hydrogen burning white dwarf (WD) with only a very thin atmosphere on top, and violent phenomena occurring in the ejecta. By means of these spectra, the mass and chemical composition of the WD can be estimated and insight is obtained into the mass ejection process. I present here the cases of two Magellanic Clouds novae, the recurrent LMC 2009a, and SMC 2016a, the most luminous nova observed in the Clouds. The bolometric and X-ray luminosity of LMC 2009a peaked at only about 10% of the Eddington luminosity; our interpretation is that the WD was partially obscured, probably by the accretion disk, or by large clumps in the ejecta. SMC 2016a instead reached super-Eddington luminosity and was observed at or above the Eddington level for about 6 months. The WD was more massive than 1.2 M ⊙ in both novae, but the short recurrence time and the (inferred) much higher accretion rate caused a less energetic outburst in LMC 2009a. While the SMC 2016a spectrum is dominated by the characteristic continuum and features of the WD atmosphere, the LMC 2009a spectrum is much more complex and has an overlap of absorption and emission features. The main contribution to the continuum in both novae originated in the WD atmosphere, but the spectral features of N LMC 2009a were produced also in different regions, and most likely were due to more than one mechanism.

The evidences for the influence of thermonuclear (type-I) X-ray bursts upon the surrounding environments in neutron star low-mass X-ray binaries (LMXB) were detected previously via spectral and timing analyses. Benefitting from a broad energy coverage of Insight-HXMT, we analyze one photospheric radius expansion (PRE) burst, and find an emission excess at soft X-rays. Our spectral analysis shows that, such an excess is not likely relevant to the disk reflection induced by the burst emission and can be attributed to an enhanced pre-burst/persistent emission. We find that the burst and enhanced persistent emissions sum up to exceed Eddington luminosity by ∼ 40 percentages. We speculate that the enhanced emission is from a region beyond the PRE radius, or through the Comptonization of the corona.

I analyze the evolution of the features which occurred on the timescale of weeks in the very long (∼600 d) X-ray outburst of the neutron star low-mass X-ray binary XTE J1701-462. I used RXTE/ASM (1.5–12 keV) and Swift/BAT (15–50 keV) observations for a time-series analysis of the long-term variations. I utilized the means (usually one-day) of intensity I to increase the signal-to-noise ratio. I applied weighted wavelet Z-transform to investigate the cyclic modulation of I. Using the combined data from both satellites, I also calculated the hardness ratio HR = I(15–50 keV)/I(1.5–12 keV) and investigated its evolution throughout the outburst. Despite the largely different profiles of the light curves in the ASM and the BAT bands especially in the first fourth of the outburst, the profiles of the measures of their scatter (the σ resASM and the σ resBAT curves) display mutual similarities. Both the σ resASM and σ resBAT curves achieved their maxima in the primary peak of the light curve which was present only in the ASM band. The formation of the quasi-periodic variations occurred and their approximate cycle-length P C was decided already in the surrounding of this peak when the bolometric luminosity was close to or even exceeding the Eddington limit. The modulation with P C is present in some time segments only in the ASM band, while the intensity variations are always chaotic in the BAT band. Using the results of spectroscopy of Lin et al., I suggests that only multicolor disk, dominant in the ASM band, was involved in this cycle. The existence of this cycle did not depend on the exact type of the Z, so it was independent of the exact conditions in the inner disk region. The length of P C displayed a large and gradual increase from ∼ 16 to ∼ 26 days with the progress of the outburst. Using models of Foulkes et al., I interpret these variations as a superorbital cycle, caused by tilting and warping of the irradiated disk.

On the basis of Kang et al.’s semi-analytical model of galaxy formation and evolution, the joint formation and evolution of galaxies and their central massive black holes are studied. It is assumed that the activity of quasars is caused by merging of galaxies. Via the introduction of the mass accretion rate of black holes, the bolometric luminosity function of quasars with the redshifts in the region of 0

In this paper, we collect the redshift, bolometric luminosity, the full- width at half maximum of the H β emission line, the monochromatic luminosity at 5100 A and the radio loudness for the sample of 117 quasars, including 20 radio-quiet quasars (RQQs) and 97 radio-loud quasars (RLQs). With the reverberation mapping method we calculate the black hole mass and Eddington ratio for this sample, as well as the radio luminosity from the total 5 GHz flux density. By analyzing the correlations among them, we obtain the following conclusions: (1) The black hole mass has weak correlations with the bolometric luminosity, radio loudness and radio luminosity for the RQQs, and has strong correlations with the bolometric luminosity, radio loudness and radio luminosity for the RLQs; (2) For the RQQs, the bolometric luminosity has weak correlations with the radio luminosity and 5 100 A monochromatic luminosity, and for the RLQs, the bolometric luminosity has strong correlations with the radio luminosity and 5 100 A monochromatic luminosity; (3) The RQQs and RLQs differ in the distributions of the black hole mass, emission line width and Eddington ratio. Based on these results, we suggest: the difference of emission line width between RQQs and RLQs is probably caused by the difference of black hole mass; the fundamental difference between RQQs and RLQs is caused by the difference of their intrinsic physical nature; the black hole mass, black hole spin, Eddington ratio, and host galaxy morphology are the important parameters to explain the origin of radio loudness and the double-peaked distribution; and the radio jet is closely related with the accretion rate of disk.

We analyze the intensity modulation in the final, very broad peak of the main outburst of the neutron star low-mass X-ray binary KS 1731-260. We use ASM/ RXTE observations for a time-series analysis of the long-term variations. We also investigate the X-ray color (hardness ratio) changes in the 1.5–12 keV band. The modulation with the mean cycle-length of 37 days is transient and is detected only in several time segments. It underwent significant variations of both the cycle-length and the amplitude. This cycle cannot be caused by transitions of the outer disk region between the hot and cool state that gave rise to the subsequent series of the echo outbursts. Because of its high X-ray luminosity ( L X ≈ 0.1 of the Eddington luminosity), KS 1731-260 is a promising candidate for having its accretion disk tilted and warped. The properties of the modulation can therefore be explained as due to variable (multimodal), but still detectable superorbital periods caused by a disk precession with mode switching and unstable warps. We find that a variable L X is not the sole parameter that governs the presence of the cycle. Variable absorption of X-rays cannot be dominant in producing the modulation of the ASM flux during the cycle. Variations of the stream impact on the tilted and warped disk, hence affecting the mass flow in the inner disk region, consequently the emission components, are a promising mechanism for the observed cycle. In this scenario, the true cycle-length can be twice as long because of the double-wave profile.

In this paper, we have used optical intra-day variability archive data to calculate the central black hole masses and Eddington luminosities for nine blazars: 3C 66A, AO 0235+164, S5 0716+714, PKS 0735+178, OJ 287, 1215+303, 1216−010, 1308+326, PKS 1510−089, Mrk 501 and BL Lac using intra-day variability timescales and periodicity (if present). The calculated central black hole mass of these nine blazars using intra-day variability timescales are found to be in the range of 1.22–25.30 × 107 M⊙ and corresponding Eddington luminosity in the range of 1.58–32.88 × 1045 erg s−1. The black hole mass and Eddington luminosity are in the range of 0.32–31.23 × 108 M⊙ and 1.23–31.20 × 1046 erg s−1, respectively when optical Doppler factor is taken into account. The comparison show, our estimated values of black hole mass are consistent with earlier reported values. Periodicity were present in two blazars OJ 287 and 1216−010 which give the central black hole mass of these blazars in the range of 1.32–14.6 × 107 M⊙ and corresponding Eddington luminosity in the range of 1.60–19.0 × 1045 erg s−1, respectively.

We have statistically investigated the infrared luminosity of clusters of galaxies in comparison with the known tracers of the cluster mass like the X-ray luminosity and the cluster richness (e.g. the number of member galaxies). Our results show that there is a clear positive correlation of the infrared luminosity with the cluster mass. Quantitatively speaking, the infrared luminosity is on average 20 times higher than the X-ray luminosity. Moreover, the infrared luminosity increases with the redshift. This probably shows that a major part of this infrared luminosity is due to star formation in the member galaxies. Another possible contribution would be the thermal emission from dust particles in the diffuse intracluster medium. However our method does not allow us to infer conclusions about this second hypothesis. Depending on their size and abundance, such particles would contribute to the infrared luminosity of galaxy cluster and have an impact on the cooling function of the baryons and thus on the formation of the large scale structures. This is an important cosmological question which still remains open.

Stationary flows of gas accreting onto a compact center are analyzed in the framework of general-relativistic radiation hydrodynamics, under assumptions of spherical symmetry and thin gas approximation. Numerical investigation shows that gas must be abundant in sources with luminosities approaching the Eddington limit. The gas abundance decreases with the increase of compactness of the central core and it can vary from almost 0.03 to 1/3.

In the absence of direct kinematic measurements, the mass of an accreting black hole is sometimes inferred from the X-ray spectral parameters of its accretion disk; specifically, from the temperature and normalization of a disk-blackbody model fit. Suitable corrections have to be introduced when the accretion rate approaches or exceeds the Eddington limit. We summarize phenomenological models that can explain the very high state, with apparently higher disk temperatures and lower inner-disk radii. Conversely, ultraluminous X-ray sources often contain cooler disks with large characteristic radii. We introduce another phenomenological model for this accretion state. We argue that a standard disk dominates the radiative output for radii larger than a characteristic transition radius R_c ~ mdot x R_{ISCO}, where mdot is the accretion rate in Eddington units and R_{ISCO} is the innermost stable orbit. For R_{ISCO} < R < R_c, most of the accretion power is released via non-thermal processes. We predict the location of such sources in a luminosity-temperature plot. We conclude that black holes with masses ~ 50-100 Msun accreting at mdot ~ 10-20 may explain the X-ray properties of many ULXs., 14 pages, accepted for publication on Advances in Space Research. Based on work presented at the 2006 Cospar Scientific Assembly

The transient luminous soft X-ray source RX J0513.9-6951 in the large magellanic cloud is a key object within the class of accreting binary supersoft X-ray sources. In this system, mass-transfer is thought to occur close to the Eddington limit of a solar mass white dwarf. The source switches quasi-periodically between two physically distinct states with anti-correlated X-ray and optical luminosities. We have obtained the first high-resolution X-ray spectrum of RX J0513.9-6951 on December 24, 2003 during an X-ray bright state as a 48 ks target of opportunity observation with the low energy transmission grating spectrograph (LETGS) on board Chandra. The X-ray observations were triggered using optical monitoring data obtained with ANDICAM on the 1.3-m telescope at Cerro Tololo, Chile of the SMARTS consortium. The X-ray spectrum deviates strongly from a smooth continuum and reveals complex structures which are probably a mixture of absorption and emission line patterns. Such features can be understood as a superposition of X-ray emission from a hot high-gravity stellar atmosphere and from an optically thin corona-like plasma enshrouding the system. Here, we present first results of our spectral analysis of the LETGS data using white dwarf atmosphere codes.

We derive bias-corrected X-ray luminosity functions (XLFs) of LMXBs detected in 14 E and S0 galaxies observed with Chandra. After correcting for incompleteness, the individual XLFs are statistically consistent with a single power-law. A break at or near L X , Eddington , as previously reported, is not required in any individual case. The combined XLF with a reduced error, however, suggests a possible break at L X = 5 × 10 38 erg s −1 , which may be consistent with the Eddington luminosity of neutron stars with the largest possible mass (3 M ⊙ ), or of He-enriched neutron star binaries. We confirm that the total X-ray luminosity of LMXBs is correlated with the the near-IR luminosities, but the scatter exceeds that expected from measurement errors. The scatter in L X (LMXB)/ L K appears to be correlated with the specific frequency of globular clusters, as reported earlier. We cross-correlate X-ray binaries with globular clusters determined by ground-based optical and HST observations in 6 giant elliptical galaxies. With the largest sample reported so far (∼300 GC LMXBs with a 5:2 ratio between red and blue GCs), we compare their X-ray properties, such as X-ray hardness, XLF and L X / L B and find no statistically significance difference between different groups of LMXBs. Regardless of their association with GCs, both GC and field LMXBs appear to follow the radial profile of the optical halo light, rather than that of more extended GCs. This suggests that while metallicity is a primary factor in the formation of LMXBs in GCs, there may be a secondary factor (e.g., encounter rate) playing a non-negligible role.

Accepted: 2006-06-26, 資料番号: SA1000580000

We present results from Rossi-XTE and BeppoSAX on X-ray flaring in three sources: Sco X-1, GX 349+2 and X 1624-490 which demonstrate major changes in the neutron star blackbody emission during flaring. In X 1624-490 and GX 349+2, there are dramatic decreases in the neutron star emitting area while the blackbody kT rises during flaring. In Sco X-1, with much higher luminosity, it appears that a similar decrease in emitting area had taken place before the source arrived at the Flaring Branch. We suggest that these changes in all 3 sources are due to a previously unrecognized Eddington limit effect in disk accretion due to the radiation pressure of the neutron star as flaring progresses, leading to major changes at the inner disk.

Changes in Eddington accretion ratios are thought to result in X-ray spectral index changes in Galactic binary black hole systems. Objects with higher Eddington ratios have softer X-ray spectra. Can we apply this result to much more massive black hole systems such as QSOs? If so, X-ray observations will give us valuable insight into the physics of QSOs. Among QSOs, X-ray spectral index is part of a large set of correlated optical and UV observational properties, especially optical Fe II and [O III] strengths in the Hβ region. To investigate whether this set of correlations is related to Eddington ratio, we use as probes, BALQSOs that have been suggested to be youthful super-accretors. We conducted infrared spectroscopy of the Hβ rest wavelength region for a sample of BALQSOs and compared line measurements with those for high and low redshift non-BAL QSOs. Hβ line widths and bolometric luminosity are used to calculate QSO black hole masses and Eddington ratios. Our results support the hypothesis that optical Fe II and [O III] line strengths are Eddington ratio indicators in QSO central engines. A possible explanation is that strong Fe II and weak [O III] indicate abundant cold gas that could fuel near Eddington accretion.

The binary X-ray pulsars which are away from the galactic plane and therefore experience less interstellar absorption, show the presence of a soft component in the spectrum which is often described as a black-body and/or thermal bremsstrahlung emission. A thermal component for the soft excess provides a satisfactory model in the Galactic sources like Her X-1 and 4U 1626-67. But for the pulsars in the Magellanic Clouds for which the distance is of the order of 60 kpc and the luminosity is close to the Eddington limit, a soft component dominating in the lower energy part of the spectrum requires emission region which is a few orders of magnitude larger than the size of a neutron star. Using ASCA observations, we show that a pulsating nature of the soft component in several bright pulsars is difficult to explain if a thermal origin is assumed for the low energy part of the spectrum. We investigate whether a two component power-law with different absorptions or an inversely broken power-law can instead explain the pulsations at low energy. A soft power-law component may also be a common feature of the binary X-ray pulsars, which is difficult to observe because most of the sources are in the galactic plane and experience large interstellar absorption.

The concept of an `effective' Eddington limit as a lower bound on the system luminosity required for mass loss to be radiation pressure driven is discussed and shown to fall in the interesting regime for high-state non-magnetic CV (nMCV). The results of recent hydrodynamical models of radiation-driven disk winds (Proga et al. 1998, Proga 1999) are summarised. Mass loss rates predicted by these models are then compared with observational constraints. It is shown that either mass accretion rates in high-state nMCV are a factor of 2–3 larger than presently supposed or that radiation pressure alone is not quite sufficient to drive the observed hypersonic flows.

We show that hydrodynamic instabilities arise when a radiative flux is present. These instabilities can be extremely important in various astrophysical settings that at first glance appear to be completely unrelated. Radiatively supported atmospheres as well as the early universe during the time of recombination can exhibit unstable acoustic modes that under certain conditions grow on a short enough time scale as to change the gross behavior of the systems. Atmospheric properties such as the effective opacity as well as the Eddington luminosity limit can change, and phenomena such as the formation of small-scale structure can take place in the early universe.

Beginning from a relatively simple set of dynamical equations for a fluid permeated by a radiative field strong enough to produce significant forces, we find the structure of plane-parallel equilibria and study their stability to small acoustic disturbances. In doing this, we neglect viscous effects and complications of nongreyness. We find that acoutic instabilities occur over a wide range of conditions below the Eddington limit. This result is in line with findings reported twenty years ago but it contradicts some more recent reports of the absence of instabilities. We briefly attempt to identify the causes of the discrepancies and then close with a discussion of the possible astrophysical interest of such instabilities., 10 pages, LaTeX, 5 postscript figures, to be published in Physics Reports

Eddington’s Internal Constitution of the Stars remains both a classic and in parts a tour de force . As a paradigm for a homogeneous star in thermal equilibrium, Eddington’s ‘standard model’ is better replaced by Cowling’s point-convective model. Jeans ultimately accepted the essence of Eddington’s approach, unlike Milne, whose lasting contributions were to the theory of stellar atmospheres. Some of Milne’s arguments turn out be relevant not to main sequence stars, but to pre-main sequence or to evolved, post-main sequence stars.

Two key problems on the ‘hidden’ nucleus of NGC 1068 are discussed, based on the archival Hubble Space Telescope images. First, we discuss the accurate location of the nucleus. We have found that the most probable location is only ∼ 0.″1 (∼ 7 pc) south of the UV brightest cloud. Second, we consider the intrinsic luminosity of the hidden nucleus. We show that its lower limit is as large as ∼ 2 × 10 45 erg/sec, suggesting that the luminosity is almost at the Eddington limit.

We explore the hydrodynamical evolution of dusty gas around active galactic nuclei (AGN) driven by the radiation from circumnuclear starbursts. For this purpose, we calculate the temporal equilibrium states between the radiation force by starburst regions and the gravity in galactic nuclei. As a result, we find that the equilibrium patterns between the radiation force and the gravity are roughly characterized by three types. The first is the situation where the starburst luminosity is larger than the Eddington luminosity. In this case, the dusty gas is blown out like a wind. We may detect intense infrared (IR) radiation from the starburst regions screened by blown-out dusty gas. The second is the situation when the radiation force is comparable to the gravity. In this case, the equilibrium surface surrounds the nuclear regions as well as starburst regions. Since the dusty gas absorbs UV or soft X-rays from the center and re-emits IR radiation, we may recognize it as a Seyfert 2 galaxy. The last is the situation where the starburst luminosity is small. In this case, the dusty wall of equilibrium would be built up only in the vicinity of starburst regions. The radiation from central regions is rarely obscured, because the dusty regions have only small angular extension. So, it would look like a Seyfert 1 galaxy which is characterized by intense soft X-rays. When we consider the stellar evolution in starburst regions, the starburst luminosity decreases with time. Therefore, we can recognize the above three types as time evolution; a starburst galaxy (first stage), a Seyfert 2 galaxy (second stage), and a Seyfert 1 galaxy (third stage). Note that we present here an alternative scenario for explaining the relation between Sy 1's and Sy 2's to the standard “Unified Scheme”.

For a neutron star in a dense environment, the gravitational energy of accreting matter can be lost to neutrinos. One such environment surrounds a newly formed neutron star in a supernova; for the conditions in SN 1987A, ≲ 0.1 M ⊙ may have fallen back onto the central neutron star on a timescale of hours after the explosion. The mass accretion rate subsequently drops more rapidly than t −1 , but steady accretion solutions with an extended shocked envelope around the neutron star and neutrino emission close to the surface are possible. Radiation is trapped in the flow until the mass accretion rate drops to 2 × 10 −4 M ⊙ yr −1 at which point radiation can begin to escape from the shocked envelope at an Eddington limit luminosity. Between this neutrino limit and the Eddington limit, 3 × 10 −8 M ⊙ yr −1 , there are no steady, spherical solutions for neutron star accretion. SN 1987A should have reached the neutrino limit within a year of the explosion; the current lack of an Eddington luminosity can be attributed to black hole formation or to a clearing of the neutron star envelope. There should be some conditions under which an explosion plus black hole formation occur, because of either accretion of matter brought back to the center by a reverse shock front or accretion of central matter that a low energy explosion is unable to unbind. Accretion above the neutrino limit also occurs for neutron stars in stellar envelopes. In massive stars, the neutron star may be converted to a black hole if the spiral-in is by gas drag.

We studied HST images of a complete sample of 33 FR I radio galaxies. Emission from an unresolved Central Compact Core (CCC) is detected in the great majority of the objects. CCC optical emission shows a striking correlation with the radio core fluxes, which extends over four decades with a slope of ∼1. This argues strongly for a non-thermal synchrotron origin of the CCCs, which would then dominate the nuclear emission both in the radio and in the optical bands. The high detection rate of CCCs sets strong constraints on the existence/geometry of any obscuring, optically thick structure (torus) in FR I. We also find evidence for a different behavior of low and high power objects belonging to our sample. CCC fluxes also represent upper limits to any unobscured thermal/disc emission, which translate into a fraction as small as ≲10 −7 −10 −5 of the Eddington luminosity (for a 10 9 M ⊙ black hole).

The X-ray spectra of broad line active galactic nuclei (AGN) of all types (Seyfert I's, NELG's, broadline radio galaxies) are well fit by a power law in the .5 to 100 keV band of man energy slope alpha = .68 + or - .15. There is, as yet, no strong evidence for time variability of this slope in a given object. The constraints that this places on simple models of the central energy source are discussed. BL Lac objects have quite different X-ray spectral properties and show pronounced X-ray spectral variability. On time scales longer than 12 hours most radio quiet AGN do not show strong, delta I/I .5, variability. The probability of variability of these AGN seems to be inversely related to their luminosity. However characteristics timescales for variability have not been measured for many objects. This general lack of variability may imply that most AGN are well below the Eddington limit. Radio bright AGN tend to be more variable than radio quiet AGN on long, tau approx 6 month, timescales.

An analysis of the variability timescale against bolometric luminosity for Active Galactic Nuclei shows that a number of sources violate the Eddington limit. The average ratio (L/LE) is found to change according to group classification. Whilst Seyfert Galaxies have luminosities well within the Eddington limit, Quasars and BL Lac object tend to approach and exceed this limit. Furthermore, BL Lac objects may be further subdivided on the basis of their (L/LE) ratio. The data on luminosity and variability timescale indicate the existence of two types of active galaxies, one having highly anisotropic emission, probably collimated into jets with pointing angles within few degrees to the line of sight, and the other relating to isotropic emission of photons from the nuclear region. The results are discussed in the light of the high gamma-ray luminosity suggested by recent observations of active galaxies. 9 references.

In this paper we review the discoveries made with EXOSAT during observations of Cir X-1. Type 1 X-ray bursts were seen in two observations. During the brightest burst, the energy flux was observed to saturate. If we assume this saturation is due to the Eddington limit then it is possible to estimate a distance to the source from the X-ray data alone. In another two observations Cir X-1 was in its high state. The peak energy flux during the high state exceeds the peak energy flux from the bursts by more than a factor of three. In one high-state observation 1.4 Hz quasi-periodic oscillations (QPO) were detected, and in the second high-state observation, QPO were seen to decline from 17 to 5 Hz as the X-ray flux slowly declined. Very high time resolution data taken during this period show the existence of a second, broad peak in the power spectrum near a frequency of 200 Hz.

A statistical analysis is made of the X-ray time variability Δtx and luminosity Lx of 28 quasars and Seyfert galaxies. Under the assumption of thick accretion disk, the range of variation of the ratio between the total luminosity Lt and Eddington luminosity LEdd was found, hence the mass of the central body M(Δtx) and the size of the emission region Rx. For comparison, dynamical masses based on the Hβ and [OIII] lines, M(Hβ) and M([OIII]) were also calculated and a good agreement was found between the masses derived by these two independent means. Also, Rx was found to increase with increasing Lx (or central mass M) ; for low and medium luminosities, Rx = 5 ∼ 10 Rg; for high luminosities, ∼ 100 Rg (Rg being the gravitational radius).

Spectral evolution is investigated and interpretation of the spectra are considered for a burst from the X-ray burster MXB 1728-34 detected by ASTRON. Interpretation of the spectra around the burst maximum in terms of radiation from an isothermal neutron star (NS) photosphere with dominating role of the Thomson scattering allows one to obtain reasonable constraints on NS mass M, radius R and distance D to the burster. In particular, M=(1.4−2)M ⊗ , R=(6.5−12) km for D=6 kpc and helium photosphere. This interpretation leads to a conclusion that the photosphere expands up to several tens of kilometers in the burst maximum. The luminosity remains close to the Eddington limit during expansion and contraction, maxima of the observed flux corresponding to minima of the luminosity due to general relativity effects.

The nuclear mass M , bolometric luminosity L bol , and the Eddington luminosity L Edd are determined for fifty Type-I Seyfert galaxies from data on the luminosity and line-width of nuclear Balmer line H β , assuming a mass accretion flow model. It is emphasized that the full width at zero intensity (FWZI), rather than the full width at half maximum (FWHM) should be used to give the velocity in the central broad line region. The histograms of M and of L bol / L Edd are shown in Figs. 1 and 2, for ready comparison with Type-II Seyferts and QSOs. Adding the data on the X-ray luminosities L X for 38 Seyferts on our list, we have obtained the following correlations: L x(2–10KcV) α (FWZI) 2 , with γ = 0.50, and L x(2–10KcV) α ( M ), with γ = 0.70 See Figs. 3 and 4. The implications of our statistical results are briefly discussed in terms of the spherically symmetric flow model of mass accretion.

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 precursor associated with a long X-ray burst is interpreted in terms of the stellar envelope expansion. The mass flow driven by the radiation pressure in excess of the local Eddington limit and the grey atmosphere model correctly describe the burst profiles in different energy ranges.

Thick accretion disks with narrow funnels around massive black holes are considered promising models for active galactic nuclei. These models assume a supercritical accretion rate and emit collimated beams with super-Eddington luminosities. We have made approximate calculations of the interaction between the emerging radiation and the walls for an optically thin funnel. The results are sensitive to the sound velocity and to the viscosity parameter α. They suggest that a significant particle luminosity can accompany the radiation in the super-Eddington case. By applying an Eddington type limit based on mechanical equilibrium to a suitably chosen interior surface in the disk, we find that energy transport, if radiative, can strongly limit the efficiency of these models.