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Papers by E. Szuszkiewicz

Monthly Notices of the Royal Astronomical Society

We consider the current flow in an accreting rotating neutron star (X-ray pulsator) and propose t... more We consider the current flow in an accreting rotating neutron star (X-ray pulsator) and propose that the active magnetosphere is limited by the Alfv\`en surface. Formulae for the luminosity and torque due to currents circulating in the neutron star are given, and astrophysical consequences for systems like Her X-1 and LMXRB are shortly discussed.

Galactic Bulges, 1993

We present evolutionary calculations which show the tumbling instability found in spherical stell... more We present evolutionary calculations which show the tumbling instability found in spherical stellar systems by Allen et al.(1992) also occurs in some initially oblate rotating systems.

Recent Developments in General Relativity, 2000

ABSTRACT An update will be given on the ongoing programme of work to investigate non-stationary a... more ABSTRACT An update will be given on the ongoing programme of work to investigate non-stationary accretion onto black holes.

Random errors of individual estimates of parameters of galaxies by visual inspection of plates ar... more Random errors of individual estimates of parameters of galaxies by visual inspection of plates are discussed.

Physics of Active Galactic Nuclei, 1992

EAS Publications Series, 2010

We have investigated the evolution of a pair of interacting planets embedded in a gaseous disc co... more We have investigated the evolution of a pair of interacting planets embedded in a gaseous disc considering a possibility of the resonant capture of a Super-Earth by an inward-migrating Jupiter mass gas giant. It has been found that the terrestrial planet is scattered from the disc or the gas giant captures the Super-Earth into an interior 3:2 or 4:3 mean motion resonance and the stability of such configuration depends on the initial planet positions and eccentricity evolution. The behaviour of the resulting resonant system has been studied numerically by means of the full 2D hydrodynamical simulations. The results are particularly interesting in light of the recent exoplanet discoveries and provide predictions of what will become observationally testable in the near future.

The dynamical interactions that occur in newly formed planetary systems may reflect the condition... more The dynamical interactions that occur in newly formed planetary systems may reflect the conditions occurring in the protoplanetary disk out of which they formed. With this in mind, we explore the attainment and maintenance of orbital resonances by migrating planets in the terrestrial mass range. Migration time scales varying between ∼ 10 6 yr and ∼ 10 3 yr are considered. In the former case, for which the migration time is comparable to the lifetime of the protoplanetary gas disk, a 2:1 resonance may be formed. In the latter, relatively rapid migration regime commensurabilities of high degree such as 8:7 or 11:10 may be formed. However, in any one large-scale migration several different commensurabilities may be formed sequentially, each being associated with significant orbital evolution. We also use a simple analytic theory to develop conditions for first order commensurabilities to be formed. These depend on the degree of the commensurability, the imposed migration and circularization rates, and the planet mass ratios. These conditions are found to be consistent with the results of our simulations.

In our recent paper we have investigated the mass distribution function of massive dark objects i... more In our recent paper we have investigated the mass distribution function of massive dark objects in galaxies, exploiting the available optical and radio observations. Under the assumption that massive black holes power active galactic nuclei, we have compared the mass functions of massive dark objects and black holes responsible for the observed activity. We have found that a scenario with a single short burst per active galactic nucleus is in a good agreement with the available data. Here we summarize and discuss the main points of our study.

We construct models of the inner part of a transonic adiabatic accretion disc assuming constant s... more We construct models of the inner part of a transonic adiabatic accretion disc assuming constant specific angular momentum taking the vertical structure fully into account.

EAS Publications Series, 2010

The first study of migration-induced resonances in a pair of Earth-like planets has been performe... more The first study of migration-induced resonances in a pair of Earth-like planets has been performed by . They concluded that in the case of disparate masses embedded in a disc with the surface density expected for a minimum mass solar nebula at 5.2 au, the most likely resonances are ratios of large integers, such as 8:7. For equal masses, planets tend to enter into the 2:1 or 3:2 resonance. In Papaloizou and Szuszkiewicz the two low-mass planets have masses equal to 4 Earth masses, chosen to mimic the very well known example of two pulsar planets which are close to the 3:2 resonance. That study has stimulated quite a few interesting questions. One of them is considered here, namely how the behaviour of the planets close to the mean-motion resonance depends on the actual values of the masses of the planets. We have chosen a 3:2 commensurability and investigated the outcome of an orbital migration in the vicinity of this resonance in the case of a pair of equal mass super-Earths, whose mass is either 5 or 8 Earth masses.

Theory of Accretion Disks, 1989

The Astrophysical Journal, 1996

We reexamine the hypothesis that the optical/UV/soft X-ray continuum of Active Galactic Nuclei is... more We reexamine the hypothesis that the optical/UV/soft X-ray continuum of Active Galactic Nuclei is thermal emission from an accretion disk. Previous studies have shown that fitting the spectra with the standard, optically thick and geometrically thin accretion disk models often led to luminosities which contradict the basic assumptions adopted in the standard model. There is no known reason why the accretion rates in AGN should not be larger than the thin disk limit. In fact, more general, slim accretion disk models are self-consistent even for moderately super-Eddington luminosities. We calculate here spectra from a set of thin and slim, optically thick accretion disks, assuming for simplicity a modified black body local emission with no relativistic corrections. We discuss the differences between the thin and slim disk models, stressing the implications of these differences for the interpretation of the observed properties of AGN. We found that the spectra can be fitted not only by models with a high mass and a low accretion rate (as in the case of thin disk fitting) but also by models with a low mass and a high accretion rate. In the first case fitting the observed spectra in various redshift categories gives black hole masses around 10 9 M ⊙ for a wide range of redshifts, and for accretion rates ranging from 0.4 (low redshift) to 8 M ⊙ /year (high redshift). In the second case the accretion rate is around 10 2 M ⊙ /year for all AGN and the mass ranges from 3·10 6 (low redshift) to 10 8 M ⊙ (high redshift). Unlike the disks with a low accretion rate, the spectra of the high-accretion-rate disks extend into the soft X-rays. A comparison with observations shows that such disks could produce the soft X-ray excesses claimed in some AGNs. We show also that the sequence of our models with fixed mass and different accretion rates can explain the time evolution of the observed spectra in Fairall 9.

Proceedings of the International Astronomical Union, 2005

ABSTRACT We review processes leading to the orbital migration of bodies ranging from dust particl... more ABSTRACT We review processes leading to the orbital migration of bodies ranging from dust particles up to protoplanets in the earth mass range in protoplanetary disks. The objects most at risk of being lost from the disk have dimensions of the order of metres. To retain these it may be necessary to invoke either strong turbulence or trapping due to special flow features such as vortices. Migration also becomes important for protoplanets with mass exceeding 0.1Moplus0.1M_{\oplus}0.1Moplus. In this case it can also lead to the attainment of commensurabilities for pairs of protoplanets. Such pairs could be left behind after disk dispersal. We review some recent work on the attainment of commensurabilities for protoplanets in the earth mass range.

EAS Publications Series, 2010

The aim of this talk is to present the most recent advances in establishing plausible planetary s... more The aim of this talk is to present the most recent advances in establishing plausible planetary system architectures determined by the gravitational tidal interactions between the planets and the disc in which they are embedded during the early epoch of planetary system formation. We concentrate on a very well defined and intensively studied process of the disc-planet interaction leading to the planet migration. We focus on the dynamics of the systems in which low-mass planets are present. Particular attention is devoted to investigation of the role of resonant configurations. Our studies, apart from being complementary to the fast progress occurring just now in observing the whole variety of planetary systems and uncovering their structure and origin, can also constitute a valuable contribution in support of the missions planned to enhance the number of detected multiple systems.

The subject of our research is to model the low mass planet migration in a gaseous disk. We are r... more The subject of our research is to model the low mass planet migration in a gaseous disk. We are running four numerical experiments, in each run we have two equal mass planets. They have 3, 5, 8 and 15 Earth masses, respectively. The surface disc density corresponds to Minimum Mass Solar Nebula value. We expect 3:2 resonances to occur for those configurations, so each experiment is set in such a way, that planets could reach the 3:2 commensurability after a relatively short period of a computational time. The planets with masses above 5 Earth masses seemed to approach the resonance initially, but after a few thousand of orbital periods their ratio of semi major axes started to grow and now it is still unclear if they will end up in this resonance. On the other hand systems of planets with 5 or 3 Earth masses, seem to approach slowly 3:2 commensurabilities.

The Astrophysical Journal, 1998

We examine all possible stationary, optically thick, geometrically thin accretion disc models rel... more We examine all possible stationary, optically thick, geometrically thin accretion disc models relevant for active galactic nuclei (AGN) and identify the physical regimes in which they are stable against the thermal-viscous hydrogen ionization instability. Self-gravity and irradiation effects are included. We find that most if not all AGN discs are unstable. Observed AGN therefore represent the outburst state, although some or all quasars could constitute a steady population having markedly higher fuelling rates than other AGN. It has important implications for the AGN mass supply and for the presence of supermassive black holes in nearby spirals.

Monthly Notices of the Royal Astronomical Society

We consider the current flow in an accreting rotating neutron star (X-ray pulsator) and propose t... more We consider the current flow in an accreting rotating neutron star (X-ray pulsator) and propose that the active magnetosphere is limited by the Alfv\`en surface. Formulae for the luminosity and torque due to currents circulating in the neutron star are given, and astrophysical consequences for systems like Her X-1 and LMXRB are shortly discussed.

Galactic Bulges, 1993

We present evolutionary calculations which show the tumbling instability found in spherical stell... more We present evolutionary calculations which show the tumbling instability found in spherical stellar systems by Allen et al.(1992) also occurs in some initially oblate rotating systems.

Recent Developments in General Relativity, 2000

ABSTRACT An update will be given on the ongoing programme of work to investigate non-stationary a... more ABSTRACT An update will be given on the ongoing programme of work to investigate non-stationary accretion onto black holes.

Random errors of individual estimates of parameters of galaxies by visual inspection of plates ar... more Random errors of individual estimates of parameters of galaxies by visual inspection of plates are discussed.

Physics of Active Galactic Nuclei, 1992

EAS Publications Series, 2010

We have investigated the evolution of a pair of interacting planets embedded in a gaseous disc co... more We have investigated the evolution of a pair of interacting planets embedded in a gaseous disc considering a possibility of the resonant capture of a Super-Earth by an inward-migrating Jupiter mass gas giant. It has been found that the terrestrial planet is scattered from the disc or the gas giant captures the Super-Earth into an interior 3:2 or 4:3 mean motion resonance and the stability of such configuration depends on the initial planet positions and eccentricity evolution. The behaviour of the resulting resonant system has been studied numerically by means of the full 2D hydrodynamical simulations. The results are particularly interesting in light of the recent exoplanet discoveries and provide predictions of what will become observationally testable in the near future.

The dynamical interactions that occur in newly formed planetary systems may reflect the condition... more The dynamical interactions that occur in newly formed planetary systems may reflect the conditions occurring in the protoplanetary disk out of which they formed. With this in mind, we explore the attainment and maintenance of orbital resonances by migrating planets in the terrestrial mass range. Migration time scales varying between ∼ 10 6 yr and ∼ 10 3 yr are considered. In the former case, for which the migration time is comparable to the lifetime of the protoplanetary gas disk, a 2:1 resonance may be formed. In the latter, relatively rapid migration regime commensurabilities of high degree such as 8:7 or 11:10 may be formed. However, in any one large-scale migration several different commensurabilities may be formed sequentially, each being associated with significant orbital evolution. We also use a simple analytic theory to develop conditions for first order commensurabilities to be formed. These depend on the degree of the commensurability, the imposed migration and circularization rates, and the planet mass ratios. These conditions are found to be consistent with the results of our simulations.

In our recent paper we have investigated the mass distribution function of massive dark objects i... more In our recent paper we have investigated the mass distribution function of massive dark objects in galaxies, exploiting the available optical and radio observations. Under the assumption that massive black holes power active galactic nuclei, we have compared the mass functions of massive dark objects and black holes responsible for the observed activity. We have found that a scenario with a single short burst per active galactic nucleus is in a good agreement with the available data. Here we summarize and discuss the main points of our study.

We construct models of the inner part of a transonic adiabatic accretion disc assuming constant s... more We construct models of the inner part of a transonic adiabatic accretion disc assuming constant specific angular momentum taking the vertical structure fully into account.

EAS Publications Series, 2010

The first study of migration-induced resonances in a pair of Earth-like planets has been performe... more The first study of migration-induced resonances in a pair of Earth-like planets has been performed by . They concluded that in the case of disparate masses embedded in a disc with the surface density expected for a minimum mass solar nebula at 5.2 au, the most likely resonances are ratios of large integers, such as 8:7. For equal masses, planets tend to enter into the 2:1 or 3:2 resonance. In Papaloizou and Szuszkiewicz the two low-mass planets have masses equal to 4 Earth masses, chosen to mimic the very well known example of two pulsar planets which are close to the 3:2 resonance. That study has stimulated quite a few interesting questions. One of them is considered here, namely how the behaviour of the planets close to the mean-motion resonance depends on the actual values of the masses of the planets. We have chosen a 3:2 commensurability and investigated the outcome of an orbital migration in the vicinity of this resonance in the case of a pair of equal mass super-Earths, whose mass is either 5 or 8 Earth masses.

Theory of Accretion Disks, 1989

The Astrophysical Journal, 1996

We reexamine the hypothesis that the optical/UV/soft X-ray continuum of Active Galactic Nuclei is... more We reexamine the hypothesis that the optical/UV/soft X-ray continuum of Active Galactic Nuclei is thermal emission from an accretion disk. Previous studies have shown that fitting the spectra with the standard, optically thick and geometrically thin accretion disk models often led to luminosities which contradict the basic assumptions adopted in the standard model. There is no known reason why the accretion rates in AGN should not be larger than the thin disk limit. In fact, more general, slim accretion disk models are self-consistent even for moderately super-Eddington luminosities. We calculate here spectra from a set of thin and slim, optically thick accretion disks, assuming for simplicity a modified black body local emission with no relativistic corrections. We discuss the differences between the thin and slim disk models, stressing the implications of these differences for the interpretation of the observed properties of AGN. We found that the spectra can be fitted not only by models with a high mass and a low accretion rate (as in the case of thin disk fitting) but also by models with a low mass and a high accretion rate. In the first case fitting the observed spectra in various redshift categories gives black hole masses around 10 9 M ⊙ for a wide range of redshifts, and for accretion rates ranging from 0.4 (low redshift) to 8 M ⊙ /year (high redshift). In the second case the accretion rate is around 10 2 M ⊙ /year for all AGN and the mass ranges from 3·10 6 (low redshift) to 10 8 M ⊙ (high redshift). Unlike the disks with a low accretion rate, the spectra of the high-accretion-rate disks extend into the soft X-rays. A comparison with observations shows that such disks could produce the soft X-ray excesses claimed in some AGNs. We show also that the sequence of our models with fixed mass and different accretion rates can explain the time evolution of the observed spectra in Fairall 9.

Proceedings of the International Astronomical Union, 2005

ABSTRACT We review processes leading to the orbital migration of bodies ranging from dust particl... more ABSTRACT We review processes leading to the orbital migration of bodies ranging from dust particles up to protoplanets in the earth mass range in protoplanetary disks. The objects most at risk of being lost from the disk have dimensions of the order of metres. To retain these it may be necessary to invoke either strong turbulence or trapping due to special flow features such as vortices. Migration also becomes important for protoplanets with mass exceeding 0.1Moplus0.1M_{\oplus}0.1Moplus. In this case it can also lead to the attainment of commensurabilities for pairs of protoplanets. Such pairs could be left behind after disk dispersal. We review some recent work on the attainment of commensurabilities for protoplanets in the earth mass range.

EAS Publications Series, 2010

The aim of this talk is to present the most recent advances in establishing plausible planetary s... more The aim of this talk is to present the most recent advances in establishing plausible planetary system architectures determined by the gravitational tidal interactions between the planets and the disc in which they are embedded during the early epoch of planetary system formation. We concentrate on a very well defined and intensively studied process of the disc-planet interaction leading to the planet migration. We focus on the dynamics of the systems in which low-mass planets are present. Particular attention is devoted to investigation of the role of resonant configurations. Our studies, apart from being complementary to the fast progress occurring just now in observing the whole variety of planetary systems and uncovering their structure and origin, can also constitute a valuable contribution in support of the missions planned to enhance the number of detected multiple systems.

The subject of our research is to model the low mass planet migration in a gaseous disk. We are r... more The subject of our research is to model the low mass planet migration in a gaseous disk. We are running four numerical experiments, in each run we have two equal mass planets. They have 3, 5, 8 and 15 Earth masses, respectively. The surface disc density corresponds to Minimum Mass Solar Nebula value. We expect 3:2 resonances to occur for those configurations, so each experiment is set in such a way, that planets could reach the 3:2 commensurability after a relatively short period of a computational time. The planets with masses above 5 Earth masses seemed to approach the resonance initially, but after a few thousand of orbital periods their ratio of semi major axes started to grow and now it is still unclear if they will end up in this resonance. On the other hand systems of planets with 5 or 3 Earth masses, seem to approach slowly 3:2 commensurabilities.

The Astrophysical Journal, 1998

We examine all possible stationary, optically thick, geometrically thin accretion disc models rel... more We examine all possible stationary, optically thick, geometrically thin accretion disc models relevant for active galactic nuclei (AGN) and identify the physical regimes in which they are stable against the thermal-viscous hydrogen ionization instability. Self-gravity and irradiation effects are included. We find that most if not all AGN discs are unstable. Observed AGN therefore represent the outburst state, although some or all quasars could constitute a steady population having markedly higher fuelling rates than other AGN. It has important implications for the AGN mass supply and for the presence of supermassive black holes in nearby spirals.