Kinematic Signatures Research Articles

Are the Double-mode Bulge RR Lyrae Stars with Identical Period Ratios the Relic of a Disrupted Stellar System?

Abstract Radial velocities of 15 double-mode bulge RR Lyrae (RR01) stars are presented, 6 of which belong to a compact group of RR01 stars in pulsation space, with the ratio of first-overtone period to fundamental mode period, P fo /P f ∼ 0.74, and P f ∼ 0.44. It has been suggested that these pulsationally clumped RR01 stars are a relic of a disrupted dwarf galaxy or stellar cluster, as they also appear to be spatially coherent in a vertical strip across the bulge. However, the radial velocities of the stars presented here, along with proper motions from Gaia DR2, show a large range of radial velocities, proper motions, and distances for the bulge RR01 stars in the pulsation clump, much larger than the RR01 stars in the Sagittarius dwarf galaxy (Sgr). Therefore, in contrast to the kinematics of the RRL stars belonging to Sgr, and those in and surrounding the bulge globular cluster NGC 6441, there is no obvious kinematic signature within the pulsationally clumped RR01 stars. If the pulsationally clumped RR01 stars belonged to the same system in the past and were accreted, their accretion in the inner Galaxy was not recent, as the kinematic signature of this group has been lost (i.e., these stars are now well-mixed within the inner Galaxy). We show that the apparent spatial coherence reported for these stars could have been caused by small number statistics. The orbits of the RR01 stars in the inner Galaxy suggest that they are confined to the innermost ∼4 kpc of the Milky Way.

3D Radiation Hydrodynamics of a Dynamical Torus

Abstract We have developed a new dynamical model of the torus region in active galactic nuclei (AGNs), using a three-dimensional radiation hydrodynamics algorithm. These new simulations have the specific aim to explore the role of radiatively driven outflows, which is hotly debated in current literature as a possible explanation for the observed IR emission from the polar regions of AGNs. In this first paper, we only consider radiative effects induced by the primary radiation from the AGN. The simulations generate a disk and outflow structure that qualitatively agrees with observations, although the outflow is radial rather than polar, likely due to the lack of radiation pressure from hot dust. We find cutoffs between the wind and disk at gas temperatures of 1000 K and dust temperatures of 100 K, producing kinematic signatures that can be used for interpretation of high-resolution IR observations. We also produce line emission maps to aid in the interpretation of recent ALMA observations and future James Webb Space Telescope observations. We investigate a number of simulation parameters and find that the anisotropy of the radiation field is equally important to the Eddington factor, despite the anisotropy often being assumed to have a single, sometimes arbitrary form in many previous works. We also find that supernovae can have a small but significant impact, but only at extremely high star formation rates.

Somatosensory-guided tool use modifies arm representation for action

Tool-use changes both peripersonal space and body representations, with several effects being nowadays termed tool embodiment. Since somatosensation was typically accompanied by vision in most previous tool use studies, whether somatosensation alone is sufficient for tool embodiment remains unknown. Here we address this question via a task assessing arm length representation at an implicit level. Namely, we compared movement’s kinematics in blindfolded healthy participants when grasping an object before and after tool-use. Results showed longer latencies and smaller peaks in the arm transport component after tool-use, consistent with an increased length of arm representation. No changes were found in the hand grip component and correlations revealed similar kinematic signatures in naturally long-armed participants. Kinematics changes did not interact with target object position, further corroborating the finding that somatosensory-guided tool use may increase the represented size of the participants’ arm. Control experiments ruled out alternative interpretations based upon altered hand position sense. In addition, our findings indicate that tool-use effects are specific for the implicit level of arm representation, as no effect was observed on the explicit estimate of the forearm length. These findings demonstrate for the first time that somatosensation is sufficient for incorporating a tool that has never been seen, nor used before.

Buckling instability in tidally induced galactic bars

Strong galactic bars produced in simulations tend to undergo a period of buckling instability that weakens and thickens them and forms a boxy/peanut structure in their central parts. This theoretical prediction has been confirmed by identifying such morphologies in real galaxies. The nature and origin of this instability, however, remain poorly understood with some studies claiming that it is due to fire-hose instability while others relating it to vertical instability of stellar orbits supporting the bar. One of the channels for the formation of galactic bars is via the interaction of disky galaxies with perturbers of significant mass. Tidally induced bars offer a unique possibility of studying buckling instability because their formation can be controlled by changing the strength of the interaction while keeping the initial structure of the galaxy the same. We used a set of four simulations of flyby interactions where a galaxy on a prograde orbit forms a bar, which is stronger for stronger tidal forces. We studied their buckling by calculating different kinematic signatures, including profiles of the mean velocity in the vertical direction, as well as distortions of the bars out of the disk plane. Although our two strongest bars buckle most strongly, there is no direct relation between the ratio of vertical to horizontal velocity dispersion and the bar’s susceptibility to buckling, as required by the fire-hose instability interpretation. While our weakest bar buckles, a stronger one does not, its dispersion ratio remains low, and it grows to become the strongest of all at the end of evolution. Instead, we find that during buckling the resonance between the vertical and radial orbital frequencies becomes wide and therefore able to modify stellar orbits over a significant range of radii. We conclude that vertical orbital instability is the more plausible explanation for the origin of buckling.

Observing the gas component of circumplanetary disks around wide-orbit planet-mass companions in the (sub)mm regime

Context. Several detections of wide-orbit planet-mass/substellar companions around young solar-like stars were reported in the last decade. The origin of those possible planets is still unclear, but accretion tracers and VLT/SPHERE observations indicate that they are surrounded by circumplanetary material or even a circumplanetary disk (CPD). Aims. We want to investigate if the gas component of disks around wide-orbit companions is detectable with current (ALMA) and future (ngVLA; sub)mm telescopes and what constraints such gas observations can provide on the nature of the circumplanetary material and the mass of the companion. Methods. We applied the radiation thermochemical disk code PRODIMO to model the dust and gas component of passive CPDs and produced realistic synthetic observables. We considered different companion properties (mass, luminosity), disk parameters (mass, size, and dust properties) and radiative environments (background fields) and compared the resulting synthetic observables to telescope sensitivities and existing dust observations. Results. The main criterion for a successful detection is the size of the CPD. At a distance of about 150 pc, a CPD with an outer radius of about 10 au is detectable with ALMA in about six hours in optically thick CO lines. Other aspects, such as the luminosity, disk inclination, and background radiation fields of the companion, are also relevant and should be considered to optimize the observing strategy for detection experiments. Conclusions. For most of the known wide-orbit planet-mass companions, their maximum theoretical disk size of one-third of the Hill radius would be sufficient to allow detection of CO lines. It is therefore feasible to detect their gas disks and constrain the mass of the companion through the kinematic signature. Even in the case of non-detections such observations provide stringent constraints on disk size and gas mass, and this information is crucial for formation theories.

Dust traps in the protoplanetary disc MWC 758: two vortices produced by two giant planets?

Resolved ALMA and VLA observations indicate the existence of two dust traps in the protoplanetary disc MWC 758. By means of 2D gas+dust hydrodynamical simulations post-processed with 3D dust radiative transfer calculations, we show that the spirals in scattered light, the eccentric, asymmetric ring and the crescent-shaped structure in the (sub)millimetre can all be caused by two giant planets: a 1.5-Jupiter mass planet at 35 au (inside the spirals) and a 5-Jupiter mass planet at 140 au (outside the spirals). The outer planet forms a dust-trapping vortex at the inner edge of its gap (at ~85 au), and the continuum emission of this dust trap reproduces the ALMA and VLA observations well. The outer planet triggers several spiral arms which are similar to those observed in polarised scattered light. The inner planet also forms a vortex at the outer edge of its gap (at ~50 au), but it decays faster than the vortex induced by the outer planet, as a result of the disc's turbulent viscosity. The vortex decay can explain the eccentric inner ring seen with ALMA as well as the low signal and larger azimuthal spread of this dust trap in VLA observations. Finding the thermal and kinematic signatures of both giant planets could verify the proposed scenario.

The future of sensorimotor communication research: Reply to comments on “The body talks: Sensorimotor communication and its brain and kinematic signatures”

The future of sensorimotor communication research: Reply to comments on “The body talks: Sensorimotor communication and its brain and kinematic signatures”

Structure in mind, structure in vocal tract

We update our understanding of the view that grammar regulates inter-segmental temporal coordination and present an extension of that view to a new domain: we argue that inter-segmental coordination is basic to prosody. It is the glue joining segments together differently in different languages (here, illustrated with examples from Arabic and Spanish) and orchestrates their unfolding in ways corresponding to constructs posited in theoretical analysis. The correspondence is one between organization in mind-brain and organization in vocal tract. Moreover, for both mind-brain and vocal tract, the organization is phonological and abstract. It is so because it holds over segments of various identities: in Arabic, the first segment in // is not prosodified as part of the same unit as // and this holds true also for //, // and so on, regardless of sonority. In contrast, in English or Spanish, a different organization holds. Crucially, uniformity in organization (same organization presiding over sequences with varying segmental makeup) does not imply uniqueness of phonetic exponents: prosodic organization is pleiotropic, simultaneously expressed by more than one phonetic exponent. Finally, two properties of coordination relations are underscored: lawful flexibility and abstractness. The first is revealed in the degrees of freedom with which movements corresponding to any given effector begin; the second in invariances of task-relevant kinematic signatures regardless of the effectors implicated in any given segmental sequence. Once again, abstract phonological structure is mirrored in vocal tracts via coordination relations holding across physiology and the particular modes of its operation.

Kinematic signatures of prey capture from archival tags reveal sex differences in killer whale foraging activity.

Studies of odontocete foraging ecology have been limited by the challenges of observing prey capture events and outcomes underwater. We sought to determine whether subsurface movement behavior recorded from archival tags could accurately identify foraging events by fish-eating killer whales. We used multisensor bio-logging tags attached by suction cups to Southern Resident killer whales (Orcinus orca) to: (1) identify a stereotyped movement signature that co-occurred with visually confirmed prey capture dives; (2) construct a prey capture dive detector and validate it against acoustically confirmed prey capture dives; and (3) demonstrate the utility of the detector by testing hypotheses about foraging ecology. Predation events were significantly predicted by peaks in the rate of change of acceleration ('jerk peak'), roll angle and heading variance. Detection of prey capture dives by movement signatures enabled substantially more dives to be included in subsequent analyses compared with previous surface or acoustic detection methods. Males made significantly more prey capture dives than females and more dives to the depth of their preferred prey, Chinook salmon. Additionally, only half of the tag deployments on females (5 out of 10) included a prey capture dive, whereas all tag deployments on males exhibited at least one prey capture dive (12 out of 12). This dual approach of kinematic detection of prey capture coupled with hypothesis testing can be applied across odontocetes and other marine predators to investigate the impacts of social, environmental and anthropogenic factors on foraging ecology.

Sensorimotor communication at the intersection between kinematic coding and readout: Comment on “The body talks: Sensorimotor communication and its brain and kinematic signatures” by Giovanni Pezzulo, Francesco Donnarumma, Haris Dindo, Alessandro D'Ausilio, Ivana Konvalinka, Cristiano Castelfranchi

Sensorimotor communication at the intersection between kinematic coding and readout: Comment on “The body talks: Sensorimotor communication and its brain and kinematic signatures” by Giovanni Pezzulo, Francesco Donnarumma, Haris Dindo, Alessandro D'Ausilio, Ivana Konvalinka, Cristiano Castelfranchi

Neural correlates of action monitoring and mutual adaptation during interpersonal motor coordination: Comment on “The body talks: Sensorimotor communication and its brain and kinematic signatures” by G. Pezzulo et al.

Neural correlates of action monitoring and mutual adaptation during interpersonal motor coordination: Comment on “The body talks: Sensorimotor communication and its brain and kinematic signatures” by G. Pezzulo et al.

The role of social learning and socio-cognitive skills in sensorimotor communication: Comment on “The body talks: Sensorimotor communication and its brain and kinematic signatures” by Pezzulo et al.

The role of social learning and socio-cognitive skills in sensorimotor communication: Comment on “The body talks: Sensorimotor communication and its brain and kinematic signatures” by Pezzulo et al.

Implicit perception simplicity and explicit perception complexity in sensorimotor communication: Comment on “The body talks: Sensorimotor communication and its brain and kinematic signatures” by G. Pezzulo et al.

Implicit perception simplicity and explicit perception complexity in sensorimotor communication: Comment on “The body talks: Sensorimotor communication and its brain and kinematic signatures” by G. Pezzulo et al.

Sensorimotor communication beyond the body: The case of driving. Comment on “The body talks: sensorimotor communication and its brain and kinematic signatures” by G. Pezzulo et al.

Sensorimotor communication beyond the body: The case of driving. Comment on “The body talks: sensorimotor communication and its brain and kinematic signatures” by G. Pezzulo et al.

Sensorimotor communication and language: Comment on “The body talks: Sensorimotor communication and its brain and kinematic signatures” by G. Pezzulo et al.

Sensorimotor communication and language: Comment on “The body talks: Sensorimotor communication and its brain and kinematic signatures” by G. Pezzulo et al.

Deviations from optimality should be an integral part of a working definition of SMC: Comment on “The body talks: Sensorimotor communication and its brain and kinematic signatures” by Pezzulo et al.

Deviations from optimality should be an integral part of a working definition of SMC: Comment on “The body talks: Sensorimotor communication and its brain and kinematic signatures” by Pezzulo et al.

Does sensorimotor communication stabilize commitment in joint action?: Comment on “The body talks: Sensorimotor communication and its brain and kinematic signatures” by G. Pezzulo et al.

Pezzulo and colleagues (2018) present a comprehensive overview of empirical research on sensorimotor communication (SMC), and develop a systematic theoretical framework to provide structure and direction to that research. At the core of this theoretical framework is a working definition of SMC as ‘a signal that has a dual nature, and which combines a pragmatic action (e.g., offering the glass) and a communicative action (e.g., express politeness).’ This is a broad definition; most research on SMC to date (e.g. Sacheli et al., 2013; Vesper & Richardson, 2014; Pezzulo & Dindo, 2011) has focused on a narrower range of cases than that picked out by this definition.

CH4 fragmentation from single and double ionization by proton and electron impact

The fragmentation of methane by impact of electrons and protons is studied experimentally to reveal the mechanisms behind fragmentation by projectiles with opposite charges. Coincidence measurements are used to separate the single from double ionization, in the case of protons, and the DETOF (delayed extraction time-of-flight) technique is used, in the case of electrons, to untangle kinematic signatures of the single vacancy from that of the one-electron--two-vacancy satellite states populated during the collision. The substantial differences in the fragmentation cross sections observed between the two projectiles, when several hydrogen bonds are broken, are here attributed essentially to single ionization and interpreted as due to the interference term between the mechanisms of shakeup and the excitation ionization by double impact that appears in the perturbative expansion of the ionization cross section.

The Relation between Galaxy ISM and Circumgalactic O vi Gas Kinematics Derived from Observations and ΛCDM Simulations

Abstract We present the first galaxy–O vi absorption kinematic study for 20 absorption systems (EW > 0.1 Å) associated with isolated galaxies (0.15 ≤ z ≤ 0.55) that have accurate redshifts and rotation curves obtained using Keck/ESI. Our sample is split into two azimuthal angle bins: major axis (Φ < 25°) and minor axis (Φ > 33°). O vi absorption along the galaxy major axis is not correlated with galaxy rotation kinematics, with only 1/10 of systems that could be explained with rotation/accretion models. This is in contrast to corotation commonly observed for Mg ii absorption. O vi along the minor axis could be modeled by accelerating outflows, but only for small opening angles, while the majority of the O vi is decelerating. Along both axes, stacked O vi profiles reside at the galaxy systemic velocity with the absorption kinematics spanning the entire dynamical range of their galaxies. The O vi found in AMR cosmological simulations exists within filaments and in halos of ∼50 kpc surrounding galaxies. Simulations show that major-axis O vi gas inflows along filaments and decelerates as it approaches the galaxy, while increasing in its level of corotation. Minor-axis outflows in the simulations are effective within 50–75 kpc; beyond that they decelerate and fall back onto the galaxy. Although the simulations show clear O vi kinematic signatures, they are not directly comparable to observations. When we compare kinematic signatures integrated through the entire simulated galaxy halo, we find that these signatures are washed out owing to full velocity distribution of O vi throughout the halo. We conclude that O vi alone does not serve as a useful kinematic indicator of gas accretion, outflows, or star formation and likely best probes the halo virial temperature.

Fast and energetic AGN-driven outflows in simulated dwarf galaxies

The systematic analysis of optical large-scale surveys has revealed a population of dwarf galaxies hosting AGN, which have been confirmed by X-ray follow-up observations. Recently, the MaNGA survey identified six dwarf galaxies that appear to have an AGN that is preventing on-going star formation. It is therefore timely to study the physical properties of dwarf galaxies, in particular whether the presence of an AGN can affect their evolution. Using the moving mesh code AREPO, we have investigated different models of AGN activity, ranging from simple energy-driven spherical winds to collimated, mass-loaded, bipolar outflows in high resolution simulations of isolated dwarf galaxies hosting an active black hole. Our simulations also include a novel implementation of star formation and mechanical supernova (SN) feedback. We find that AGN outflows have a small but systematic effect on the central star formation rates (SFRs) for all set-ups explored, while substantial effects on the global SFR are only obtained with strong SNe and a sustained high-luminosity AGN with an isotropic wind. This suggests that AGN feedback in dwarf galaxies is unlikely to directly regulate their global SFRs. There is, however, a significant effect on outflow properties, which are notably enhanced by the AGN to much higher outflow temperatures and velocities, in agreement with kinematic signatures from the MaNGA survey. This indicates that AGN may play an indirect role in regulating the baryon cycle in dwarf galaxies by hindering cosmic gas inflows.