The influence of general-relativity effects, dynamical tides and collisions on planet-planet scattering close to the star

Planet--Planet scattering is an efficient and robust dynamical mechanism for producing eccentric exoplanets. Coupled to tidal interactions with the central star, it can also explain close--in giant planets on circularized and potentially misaligned orbits. We explore scattering events occurring close to the star and test if they can reproduce the main features of the observed orbital distribution of giant exoplanets on tight orbits.In our modeling we exploit a numerical integration code based on the Hermite algorithm and including the effects of general relativity, dynamical tides and two--body collisions.We find that P--P scattering events occurring in systems with three giant planets initially moving on circular orbits close to their star produce a population of planets similar to the presently observed one, including eccentric and misaligned close--in planets. The contribution of tides and general relativity is relevant in determining the final outcome of the chaotic phase. Even if two--body collisions dominate the chaotic evolution of three planets in crossing orbits close to their star, the final distribution shows a significant number of planets on eccentric orbits. The highly misaligned close--in giant planets are instead produced by systems where the initial semi--major axis of the inner planet was around 0.2 au or beyond.Comment: Accepted for publication on A&

Toward a Deterministic Model of Planetary Formation VII: Eccentricity Distribution of Gas Giants

The ubiquity of planets and diversity of planetary systems reveal planet formation encompass many complex and competing processes. In this series of papers, we develop and upgrade a population synthesis model as a tool to identify the dominant physical effects and to calibrate the range of physical conditions. Recent planet searches leads to the discovery of many multiple-planet systems. Any theoretical models of their origins must take into account dynamical interaction between emerging protoplanets. Here, we introduce a prescription to approximate the close encounters between multiple planets. We apply this method to simulate the growth, migration, and dynamical interaction of planetary systems. Our models show that in relatively massive disks, several gas giants and rocky/icy planets emerge, migrate, and undergo dynamical instability. Secular perturbation between planets leads to orbital crossings, eccentricity excitation, and planetary ejection. In disks with modest masses, two or less gas giants form with multiple super-Earths. Orbital stability in these systems is generally maintained and they retain the kinematic structure after gas in their natal disks is depleted. These results reproduce the observed planetary mass-eccentricity and semimajor axis-eccentricity correlations. They also suggest that emerging gas giants can scatter residual cores to the outer disk regions. Subsequent in situ gas accretion onto these cores can lead to the formation of distant (> 30AU) gas giants with nearly circular orbits.Comment: 54 pages, 14 Figures; accepted for publication in Astrophysical Journa

Development of human plasmacytoid dendritic cells and innate lymphoid cells

Innate immune cells play crucial role in the front line of defense against pathogens and harmful substances to protect the human body. One particular subtype are the innate lymphocytes which are characterized by an absence of rearranged antigen specific receptors. Innate lymphocytes have the ability to directly eliminate infected cells and to efficiently coordinate the advanced immune response during infections. In steady state innate lymphocytes are important for the immune tolerance, immune surveillance, maintenance and repair of damaged tissues. Dysregulation of their functions leads to chronic inflammation, autoimmune disease as well as cancer. It is therefore important to understand the essential factors involved in innate lymphocyte development and functionality. Ultimately this will provide clues on how to treat or prevent the aforementioned diseases. In this thesis we described the transcription factors involved in the development of human innate lymphocytes, namely natural killer (NK) cells, innate lymphoid cells (ILCs) and, plasmacytoid dendritic cells (pDCs). Furthermore, the cytokines that control ILCs plasticity are investigated

Formation of Hot Planets by a combination of planet scattering, tidal circularization, and Kozai mechanism

We have investigated the formation of close-in extrasolar giant planets through a coupling effect of mutual scattering, Kozai mechanism, and tidal circularization, by orbital integrations. We have carried out orbital integrations of three planets with Jupiter-mass, directly including the effect of tidal circularization. We have found that in about 30% runs close-in planets are formed, which is much higher than suggested by previous studies. We have found that Kozai mechanism by outer planets is responsible for the formation of close-in planets. During the three-planet orbital crossing, the Kozai excitation is repeated and the eccentricity is often increased secularly to values close enough to unity for tidal circularization to transform the inner planet to a close-in planet. Since a moderate eccentricity can remain for the close-in planet, this mechanism may account for the observed close-in planets with moderate eccentricities and without nearby secondary planets. Since these planets also remain a broad range of orbital inclinations (even retrograde ones), the contribution of this process would be clarified by more observations of Rossiter-McLaughlin effects for transiting planets.Comment: 15 pages, 16 figures, Accepted for publication in Ap

Extended supersymmetry and its reduction on a circle with point singularities

We investigate $N$-extended supersymmetry in one-dimensional quantum mechanics on a circle with point singularities. For any integer $n$, $N=2n+1$ supercharges are explicitly constructed in terms of discrete transformations, and a class of singularities compatible with supersymmetry is clarified. In our formulation, the supersymmetry can be reduced to $M$-extended supersymmetry for any integer $M<N$. The degeneracy of the spectrum and spontaneous supersymmetry breaking are also studied.Comment: 36 pages, 5 figures, 2 table