Simulation of the Scattering of Continuously Injected Pickup Ions outside the Heliopause

Hybrid simulations in 2D space and 3D velocity dimensions with continuous injection of pickup ions (PUIs) provide insight into the plasma processes that are responsible for the pitch angle scattering of PUIs outside the heliopause. The present investigation includes for the first time continuous injection of PUIs and shows how the scattering depends on the energy of the PUIs and the strength of the background magnetic field as well as the dependence on the injection rate of the time for the isotropization of the pitch angle distribution. The results demonstrate that, with the gradual injection of PUIs of a narrow ring velocity distribution perpendicular to the background magnetic field, oblique mirror mode waves develop first, followed by the growth of quasiparallel propagating ion cyclotron waves. Subsequently, the PUIs are scattered by the excited waves and gradually approach an isotropic distribution. A time for isotropization is defined to be the time at which T ∣∣/T ⊥, i.e., the ratio of the parallel to perpendicular PUI thermal energy changes from ≈0 to ≈0.15. By varying the PUI injection rate, estimates of the time for the PUI distribution to be isotropized are presented. The isotropization time obtained is shorter, ≈ months, than the time, ≈ years, required by the conventional secondary ENA mechanism to explain the IBEX ENA ribbon.

Population Properties of Neutron Stars in the Coalescing Compact Binaries

We perform a hierarchical Bayesian inference to investigate the population properties of the coalescing compact binaries involving at least one neutron star (NS). With the current gravitational-wave (GW) observation data, we can rule out none of the double Gaussian, single Gaussian, and uniform NS mass distribution models, though a specific double Gaussian model inferred from the Galactic NSs is found to be slightly more preferred. The mass distribution of black holes (BHs) in the neutron star–black hole (NSBH) population is found to be similar to that in the Galactic X-ray binaries. Additionally, the ratio of the merger rate densities between NSBHs and BNSs is estimated to be ∼3:7. The spin properties of the binaries, though constrained relatively poorly, play a nontrivial role in reconstructing the mass distribution of NSs and BHs. We find that a perfectly aligned spin distribution can be ruled out, while a purely isotropic distribution of spin orientation is still allowed. To evaluate the feasibility of reliably determining the population properties of NSs in the coalescing compact binaries with upcoming GW observations, we perform simulations with a mock population. We find that with 100 detections (including BNSs and NSBHs) the mass distribution of NSs can be well determined, and the fraction of BNSs can also be accurately estimated.

Gravity wave instability structures and turbulence from more than 1.5 years of OH* airglow imager observations in Slovenia

We analysed 286 nights of data from the OH* airglow imager FAIM 3 (Fast Airglow IMager) acquired at Otlica Observatory (45.93∘ N, 13.91∘ E), Slovenia, between 26 October 2017 and 6 June 2019. Measurements have been performed with a spatial resolution of 24 m per pixel and a temporal resolution of 2.8 s. A two-dimensional fast Fourier transform is applied to the image data to derive horizontal wavelengths between 48 m and 4.5 km in the upper mesosphere/lower thermosphere (UMLT) region. In contrast to the statistics of larger-scale gravity waves (horizontal wavelength up to ca. 50 km; Hannawald et al., 2019), we find a more isotropic distribution of directions of propagation, pointing to the presence of wave structures created above the stratospheric wind fields. A weak seasonal tendency of a majority of waves propagating eastward during winter may be due to instability features from breaking secondary gravity waves that were created in the stratosphere. We also observe an increased southward propagation during summer, which we interpret as an enhanced contribution of secondary gravity waves created as a consequence of primary wave filtering by the meridional mesospheric circulation. We present multiple observations of turbulence episodes captured by our high-resolution airglow imager and estimated the energy dissipation rate in the UMLT from image sequences in 25 cases. Values range around 0.08 and 9.03 W kg−1 and are on average higher than those in recent literature. The values found here would lead to an approximated localized maximum heating of 0.03–3.02 K per turbulence event. These are in the same range as the daily chemical heating rates for the entire atmosphere reported by Marsh (2011), which apparently stresses the importance of dynamical energy conversion in the UMLT.

Autophagy Is Polarized toward Cell Front during Migration and Spatially Perturbed by Oncogenic Ras

Autophagy is a physiological degradation process that removes unnecessary or dysfunctional components of cells. It is important for normal cellular homeostasis and as a response to a variety of stresses, such as nutrient deprivation. Defects in autophagy have been linked to numerous human diseases, including cancers. Cancer cells require autophagy to migrate and to invade. Here, we study the intracellular topology of this interplay between autophagy and cell migration by an interdisciplinary live imaging approach which combines micro-patterning techniques and an autophagy reporter (RFP-GFP-LC3) to monitor over time, during directed migration, the back–front spatial distribution of LC3-positive compartments (autophagosomes and autolysosomes). Moreover, by exploiting a genetically controlled cell model, we assessed the impact of transformation by the Ras oncogene, one of the most frequently mutated genes in human cancers, which is known to increase both cell motility and basal autophagy. Static cells displayed an isotropic distribution of autophagy LC3-positive compartments. Directed migration globally increased autophagy and polarized both autophagosomes and autolysosomes at the front of the nucleus of migrating cells. In Ras-transformed cells, the front polarization of LC3 compartments was much less organized, spatially and temporally, as compared to normal cells. This might be a consequence of altered lysosome positioning. In conclusion, this work reveals that autophagy organelles are polarized toward the cell front during migration and that their spatial-temporal dynamics are altered in motile cancer cells that express an oncogenic Ras protein.

Time-dependent lepto-hadronic modeling of the emission from blazar jets with SOPRANO: the case of TXS 0506+056, 3HSP J095507.9+355101 and 3C 279

The observation of a very-high-energy neutrino by IceCube (IceCube-170922A) and its association with the flaring blazar TXS 0506+056 provided the first multimessenger observations of blazar jets, demonstrating the important role of protons in their dynamics and emission. In this paper, we present SOPRANO, a new conservative implicit kinetic code which follows the time evolution of the isotropic distribution functions of protons, neutrons and the secondaries produced in photo-pion and photo-pair interactions, alongside with the evolution of photon and electron/positron distribution functions. SOPRANO is designed to study leptonic and hadronic processes in relativistic sources such as blazars and gamma-ray bursts. Here, we use SOPRANO to model the broadband spectrum of TXS 0506+056 and 3HSP J095507.9+355101, which are associated with neutrino events, and of the extreme flaring blazar 3C 279. The SEDs are interpreted within the guise of both a hadronic and a hybrid model. We discuss the implications of our assumptions in terms of jet power and neutrino flux.

Spatial Orientations of Angular Momentum Vectors of Galaxies in Supercluster S [247+040+0029] and Substructures

We present an analysis of spatial orientations of 1331 galaxies in the supercluster S [247+040+0029]. The main goal of this work is to search for a new substructure candidate and examine the orientation of angular momentum in the framework of three different scenarios (hierarchy, pancake, and primordial vorticity models) using “position angle-inclination method”, and to test the dependence on magnitude with the angular momentum orientations and their projections. We identified five substructures studying number density contour map with considerably high concentration of galaxies. Using random simulation method to remove the selection effect on database, we carried out expected isotropic distribution using cosmological principle. We then used three statistical tests: Chi-square, Auto-correlation, and Fourier to identify isotropy between observed and expected isotropic distributions. We varied radius in the range 0.3° to 1.0° to find substructures in supercluster. From this we found five sub-structures when taking radius 0.3° and two substructures for 1.0° radius in the number density counter maps of galaxies. By analyzing the result obtained through statistical tests, we are able to conform that evolution of galaxy in the supercluster and substructures supports “Hierarchy model" giving the angular momentum of galaxies in the large scale structure tends to be oriented random with respect to the reference coordinate system.

Spatial orientations of angular momentum vectors of galaxies in Supercluster S [173+014+0082]

The spin vector orientation of 1302 SDSS (Sloan Digital Sky Survey) galaxies in Supercluster S[173+014+0082] having redshift 0.076 to 0.091 has been analysed. The positions, position angles and inclination angles of galaxies are used to convert two-dimensional observed parameters into three-dimensional angular momentum vectors of the galaxy using the `position angle-inclination' method. The expected isotropic distribution curves are determined performing numerical simulation by generating 107 virtual galaxies. The observed distribution is compared with the expected isotropic distribution curves using three statistical tools namely Chi-square test, auto-correlation test and Fourier test. Redshift map is studied and found that the distributions fit with the Gaussian. No preferred alignment of angular momentum vectors is noticed, supporting Hierarchy model of galaxy formation. BIBECHANA 18 (2021) 26-32

High-resolution simulations of dark matter subhalo disruption in a Milky-Way-like tidal field

ABSTRACT We compare the results of high-resolution simulations of individual dark matter subhaloes evolving in external tidal fields with and without baryonic bulge and disc components, where the average dark matter particle mass is three orders of magnitude smaller than cosmological zoom-in simulations of galaxy formation. The Via Lactea II simulation is used to setup our initial conditions and provides a basis for our simulations of subhaloes in a dark-matter-only tidal field, while an observationally motivated model for the Milky-Way is used for the tidal field that is comprised of a dark matter halo, a stellar disc, and a stellar bulge. Our simulations indicate that including stellar components in the tidal field results in the number of subhaloes in Milky-Way-like galaxies being only $65{{\ \rm per\ cent}}$ of what is predicted by Λ cold dark matter (ΛCDM). For subhaloes with small pericentres (rp ≲ 25 kpc), the subhalo abundance is reduced further to $40{{\ \rm per\ cent}}$, with the surviving subhaloes being less dense and having a tangentially anisotropic orbital distribution. Conversely, subhaloes with larger pericentres are minimally affected by the inclusion of a stellar component in the tidal field, with the total number of outer subhaloes $\approx 75{{\ \rm per\ cent}}$ of the ΛCDM prediction. The densities of outer subhaloes are comparable to predictions from ΛCDM, with the subhaloes having an isotropic distribution of orbits. These ratios are higher than those found in previous studies that include the effects baryonic matter, which are affected by spurious disruption caused by low resolution.

Are inner disc misalignments common? ALMA reveals an isotropic outer disc inclination distribution for young dipper stars

ABSTRACT Dippers are a common class of young variable star exhibiting day-long dimmings with depths of up to several tens of per cent. A standard explanation is that dippers host nearly edge-on (id ≈ 70°) protoplanetary discs that allow close-in (<1 au) dust lifted slightly out of the mid-plane to partially occult the star. The identification of a face-on dipper disc and growing evidence of inner disc misalignments brings this scenario into question. Thus, we uniformly (re)derive the inclinations of 24 dipper discs resolved with (sub-)mm interferometry from ALMA. We find that dipper disc inclinations are consistent with an isotropic distribution over id ≈ 0−75°, above which the occurrence rate declines (likely an observational selection effect due to optically thick disc mid-planes blocking their host stars). These findings indicate that the dipper phenomenon is unrelated to the outer (>10 au) disc resolved by ALMA and that inner disc misalignments may be common during the protoplanetary phase. More than one mechanism may contribute to the dipper phenomenon, including accretion-driven warps and ‘broken’ discs caused by inclined (sub-)stellar or planetary companions.