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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

AN HST PROPER-MOTION STUDY OF THE LARGE-SCALE JET OF 3C273

The radio galaxy 3C 273 hosts one of the nearest and best-studied powerful quasar jets. Having been imaged repeatedly by the Hubble Space Telescope (HST) over the past twenty years, it was chosen for an HST program to measure proper motions in the kiloparsec-scale resolved jets of nearby radio-loud active galaxies. The jet in 3C 273 is highly relativistic on sub-parsec scales, with apparent proper motions up to 15c observed by very long baseline interferometry. In contrast, we find that the kiloparsec-scale knots are compatible with being stationary, with a mean speed of −0.2 ± 0.5c over the whole jet. Assuming the knots are packets of moving plasma, an upper limit of 1c implies a bulk Lorentz factor Γ < 2.9. This suggests that the jet has either decelerated significantly by the time it reaches the kiloparsec scale, or that the knots in the jet are standing shock features. The second scenario is incompatible with the inverse Compton off the Cosmic Microwave Background (IC/CMB) model for the X-ray emission of these knots, which requires the knots to be in motion, but IC/CMB is also disfavored in the first scenario due to energetic considerations, in agreement with the recent finding of Meyer and Georganopoulos which ruled out the IC/CMB model for the X-ray emission of 3C 273 via gamma-ray upper limits.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

Broad Balmer absorption line variability: Evidence of gas transverse motion in the QSO SDSS J125942.80+121312.6

We report on the discovery of broad Balmer absorption lines variability in the QSO SDSS J125942.80+121312.6, based on the optical and near-infrared spectra taken from the SDSS-I, SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), and TripleSpec observations over a timescale of 5.8 years in the QSO's rest-frame. The blueshifted absorption profile of Hβ shows a variation of more than 5σ at a high velocity portion (>3000 km s{sup −1}) of the trough. We perform a detailed analysis for the physical conditions of the absorber using Balmer lines as well as metastable He i and optical Fe ii absorptions (λ4233 from b{sup 4}P{sub 5/2} level and λ5169 from a{sup 6}S{sub 5/2}) at the same velocity. These Fe ii lines are identified in the QSO spectra for the first time. According to the photoionization simulations, we estimate a gas density of n(H)≈10{sup 9.1} cm{sup −3} and a column density of N{sub col}(H)≈10{sup 23} cm{sup −2} for the BOSS data, but the model fails to predict the variations of ionic column densities between the SDSS and BOSS observations if changes in ionizing flux are assumed. We thus propose transverse motion of the absorbing gas being the cause of the observed broad Balmer absorption line variability. In fact, we find that the changes in covering factors of the absorber can well-reproduce all of the observed variations. The absorber is estimated ∼0.94 pc away from the central engine, which is where the outflow likely experiences deceleration due to the collision with the surrounding medium. This scheme is consistent with the argument that LoBAL QSOs may represent the transition from obscured star-forming galaxies to classic QSOs.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

A comprehensive investigation on the slowing down of cosmic acceleration

Shafieloo et al. first proposed the possibility that the current cosmic acceleration (CA) is slowing down. However, this is rather counterintuitive because a slowing down CA cannot be accommodated in most mainstream cosmological models. In this work, by exploring the evolutionary trajectories of the dark energy equation of state w(z) and deceleration parameter q(z), we present a comprehensive investigation on the slowing down of CA from both the theoretical and the observational sides. For the theoretical side, we study the impact of different w(z) using six parametrization models, and then we discuss the effects of spatial curvature. For the observational side, we investigate the effects of different type Ia supernovae (SNe Ia), baryon acoustic oscillation (BAO), and cosmic microwave background (CMB) data. We find that (1) the evolution of CA is insensitive to the specific form of w(z); in contrast, a non-flat universe favors a slowing down CA more than a flat universe. (2) SNLS3 SNe Ia data sets favor a slowing down CA at a 1σ confidence level, while JLA SNe Ia samples prefer an eternal CA; in contrast, the effects of different BAO data are negligible. (3) Compared with CMB distance prior data, full CMB data favor a slowing down CA more. (4) Due to the low significance, the slowing down of CA is still a theoretical possibility that cannot be confirmed by the current observations.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

THE ROLE OF SiO AS A TRACER OF PAST STAR FORMATION EVENTS: THE CASE OF THE HIGH-MASS PROTOCLUSTER NGC 2264-C

NGC 2264-C is a high-mass protocluster where several star formation events are known to have occurred. To investigate whether past protostellar activity has left a chemical imprint in this region, we mapped it in SiO(J=2−1), which is a shock tracer, and several other molecular lines with the Nobeyama 45 m telescope. Our observations show the presence of a complex network of protostellar outflows. The strongest SiO emission lies beyond a radius of ∼0.1 pc with respect to the center of the clump and is characterized by broad (>10 km s{sup −1}) lines and abundances of ∼1.4×10{sup −8} with respect to H{sub 2}. Interestingly, SiO appears to be relatively depleted (χ{sub SiO}∼4×10{sup −9}) within this radius, despite it being affected by molecular outflow activity. We attribute this to the fast condensation of SiO back onto dust grains and/or rapid gas-phase destruction of SiO, which is favored by the high density present in this area (>10{sup 6} cm{sup −3}). Finally, we identify a peripheral, narrow-line (∼2 km s{sup −1}) component where SiO has an abundance of a few times 10{sup −11}. After considering different options, we conclude that this weak emission may be tracing protostellar shocks from the star formation episode that preceded the current one, which have decelerated over time and eventually resulted in SiO being largely depleted/destroyed. Alternatively, a population of unresolved, low-mass protostars may be responsible for the narrow SiO emission. High-angular resolution observations are necessary to distinguish between these two possibilities, and thus to understand the role of SiO as a chemical tracer of past star formation episodes in massive protoclusters.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

Elevohi: a novel CME prediction tool for heliospheric imaging combining an elliptical front with drag-based model fitting

In this study, we present a new method for forecasting arrival times and speeds of coronal mass ejections (CMEs) at any location in the inner heliosphere. This new approach enables the adoption of a highly flexible geometrical shape for the CME front with an adjustable CME angular width and an adjustable radius of curvature of its leading edge, i.e., the assumed geometry is elliptical. Using, as input, Solar TErrestrial RElations Observatory (STEREO) heliospheric imager (HI) observations, a new elliptic conversion (ElCon) method is introduced and combined with the use of drag-based model (DBM) fitting to quantify the deceleration or acceleration experienced by CMEs during propagation. The result is then used as input for the Ellipse Evolution Model (ElEvo). Together, ElCon, DBM fitting, and ElEvo form the novel ElEvoHI forecasting utility. To demonstrate the applicability of ElEvoHI, we forecast the arrival times and speeds of 21 CMEs remotely observed from STEREO/HI and compare them to in situ arrival times and speeds at 1 AU. Compared to the commonly used STEREO/HI fitting techniques (Fixed-ϕ, Harmonic Mean, and Self-similar Expansion fitting), ElEvoHI improves the arrival time forecast by about 2 to ±6.5 hr and the arrival speed forecast by ≈250 to ±53 km s{sup −1}, depending on the ellipse aspect ratio assumed. In particular, the remarkable improvement of the arrival speed prediction is potentially beneficial for predicting geomagnetic storm strength at Earth.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

ON THE IMPORTANCE OF VERY LIGHT INTERNALLY SUBSONIC AGN JETS IN RADIO-MODE AGN FEEDBACK

Radio-mode active galactic nucleus (AGN) feedback plays a key role in the evolution of galaxy groups and clusters. Its physical origin lies in the kiloparsec-scale interaction of AGN jets with the intracluster medium. Large-scale jet simulations often initiate light internally supersonic jets with density contrast 0.01 < η < 1. Here we argue for the first time for the importance of very light ( η < 0.01) internally subsonic jets. We investigated the shapes of young X-ray cavities produced in a suite of hydrodynamic simulations, and found that bottom-wide cavities are always produced by internally subsonic jets, while internally supersonic jets inflate cylindrical, center-wide, or top-wide cavities. We found examples of real cavities with shapes analogous to those inflated in our simulations by internally subsonic and internally supersonic jets, suggesting a dichotomy of AGN jets according to their internal Mach numbers. We further studied the long-term cavity evolution, and found that old cavities resulted from light jets spread along the jet direction, while those produced by very light jets are significantly elongated along the perpendicular direction. The northwestern ghost cavity in Perseus is pancake shaped, providing tentative evidence for the existence of very light jets. Our simulations show that very light internally subsonic jets decelerate faster and rise much slower in the intracluster medium than light internally supersonic jets, possibly depositing a larger fraction of jet energy to cluster cores and alleviating the problem of low coupling efficiencies found previously. The internal Mach number points to the jet’s energy content, and internally subsonic jets are energetically dominated by non-kinetic energy, such as thermal energy, cosmic rays, or magnetic fields.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

THE DIMENSIONLESS AGE OF THE UNIVERSE: A RIDDLE FOR OUR TIME

We present the interesting coincidence of cosmology and astrophysics that points toward a dimensionless age of the Universe H {sub 0} t {sub 0} that is close to one. Despite cosmic deceleration for 9 Gyr and acceleration since then, we find H {sub 0} t {sub 0} = 0.96 ± 0.01 for the ΛCDM model that fits SN Ia data from Pan-STARRS, CMB power spectra, and baryon acoustic oscillations. Similarly, astrophysical measures of stellar ages and the Hubble constant derived from redshifts and distances point to H {sub 0} t ∼ 1.0 ± 0.1. The wide range of possible values for H {sub 0} t {sub 0} realized during cosmic evolution means that we live at what appears to be a special time. This “synchronicity problem” is not precisely the same as the usual coincidence problem , because there are combinations of Ω{sub M} and Ω{sub Λ} for which the usual coincidence problem holds but for which H {sub 0} t {sub 0} is not close to 1.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Two Strengths of Ordinary Chondritic Meteoroids as Derived from Their Atmospheric Fragmentation Modeling

The internal structure and strength of small asteroids and large meteoroids is poorly known. Observation of bright fireballs in the Earth’s atmosphere can explore meteoroid structure by studying meteoroid fragmentation during the flight. Earlier evaluations showed that the meteoroid’s strength is significantly lower than that of the recovered meteorites. We present a detailed study of atmospheric fragmentation of seven meteorite falls, all ordinary chondrites, and 14 other fireballs, where meteorite fall was predicted but the meteorites, probably also ordinary chondrites, were not recovered. All observations were made by the autonomous observatories of the European Fireball Network and include detailed radiometric light curves. A model, called the semiempirical fragmentation model, was developed to fit the light curves and decelerations. Videos showing individual fragments were available in some cases. The results demonstrated that meteoroids do not fragment randomly but in two distinct phases. The first phase typically corresponds to low strengths of 0.04–0.12 MPa. In two-thirds of cases, the first phase was catastrophic or nearly catastrophic with at least 40% of mass lost. The second phase corresponds to 0.9–5 MPa for confirmed meteorite falls and somewhat lower strengths, from about 0.5 MPa, for smaller meteoroids. All of these strengths are lower than the tensile strengths of ordinary chondritic meteorites cited in the literature, 20–40 MPa. We interpret the second phase as being due to cracks in meteoroids and the first phase as a separation of weakly cemented fragments, which reaccumulated at the surfaces of asteroids after asteroid collisions.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

A reverse shock in GRB L60509A

We present the second multi-frequency radio detection of a reverse shock in a γ-ray burst. By combining our extensive radio observations of the Fermi-Large Area Telescope γ-ray burst 160509A at z = 1.17 up to 20 days after the burst with Swift X-ray observations and ground-based optical and near-infrared data, we show that the afterglow emission comprises distinct reverse shock and forward shock contributions: the reverse shock emission dominates in the radio band at ≲10 days, while the forward shock emission dominates in the X-ray, optical, and near-infrared bands. Through multi-wavelength modeling, we determine a circumburst density of n{sub 0}≈10{sup −3} cm{sup −3}, supporting our previous suggestion that a low-density circumburst environment is conducive to the production of long-lasting reverse shock radiation in the radio band. We infer the presence of a large excess X-ray absorption column, N {sub H} ≈ 1.5 × 10{sup 22} cm{sup −2}, and a high rest-frame optical extinction, A {sub V} ≈ 3.4 mag. We identify a jet break in the X-ray light curve at t{sub jet}≈6 days, and thus derive a jet opening angle of θ{sub jet}≈4{sup ∘}, yielding a beaming-corrected kinetic energy and radiated γ-ray energy of E{sub K}≈4×10{sup 50} erg and E{sub γ}≈1.3×10{sup 51} erg (1–10{sup 4} keV, rest frame), respectively. Consistency arguments connecting the forward shocks and reverse shocks suggest a deceleration time of t{sub dec} ≈460 s ≈ T {sub 90}, a Lorentz factor of Γ(t{sub dec})≈330, and a reverse-shock-to-forward-shock fractional magnetic energy density ratio of R{sub B}≡ϵ{sub B,RS}/ϵ{sub B,FS}≈8. Our study highlights the power of rapid-response radio observations in the study of the properties and dynamics of γ-ray burst ejecta.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Exploding satellites—the tidal debris of the ultra-faint dwarf galaxy hercules

The ultra-faint satellite galaxy Hercules has a strongly elongated and irregular morphology with detections of tidal features up to 1.3 deg (3 kpc) from its center. This suggests that Hercules may be dissolving under the Milky Way’s gravitational influence, and hence could be a tidal stream in formation rather than a bound, dark-matter-dominated satellite. Using Bayesian inference in combination with N-body simulations, we show that Hercules has to be on a very eccentric orbit (ϵ≈0.95) within the Milky Way in this scenario. On such an orbit, Hercules “explodes” as a consequence of the last tidal shock at pericenter 0.5 Gyr ago. It is currently decelerating toward the apocenter of its orbit with a velocity of V = 157 km s{sup −1}—of which 99% is directed radially outwards. Due to differential orbital plane precession caused by the non-spherical nature of the Galactic potential, its debris fans out nearly perpendicular to its orbit. This explains why Hercules has an elongated shape without showing a distance gradient along its main body: it is in fact a stream that is significantly broader than it is long. In other words, it is moving perpendicular to its apparent major axis. In this scenario, there is a spike in the radial velocity profile created by the dominant debris component that formed through the last pericenter passage. This is similar to kinematic substructure that is observed in the real Hercules. Modeling a satellite on such a highly eccentric orbit is strongly dependent on the form of the Galactic potential. We therefore propose that detailed kinematic investigation of Hercules and other exploding satellite candidates can yield strong constraints on the potential of the Milky Way.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Geminga's puzzling pulsar wind nebula

We report on six new Chandra observations of the Geminga pulsar wind nebula (PWN). The PWN consists of three distinct elongated structures—two ≈0.2d{sub 250} pc long lateral tails and a segmented axial tail of ≈0.05d{sub 250} pc length, where d{sub 250}=d/(250 pc). The photon indices of the power-law spectra of the lateral tails, Γ≈1, are significantly harder than those of the pulsar (Γ≈1.5) and the axial tail (Γ≈1.6). There is no significant diffuse X-ray emission between the lateral tails—the ratio of the X-ray surface brightness between the south tail and this sky area is at least 12. The lateral tails apparently connect directly to the pulsar and show indications of moving footpoints. The axial tail comprises time-variable emission blobs. However, there is no evidence for constant or decelerated outward motion of these blobs. Different physical models are consistent with the observed morphology and spectra of the Geminga PWN. In one scenario, the lateral tails could represent an azimuthally asymmetric shell whose hard emission is caused by the Fermi acceleration mechanism of colliding winds. In another scenario, the lateral tails could be luminous, bent polar outflows, while the blobs in the axial tail could represent a crushed torus. In a resemblance to planetary magnetotails, the blobs of the axial tail might also represent short-lived plasmoids, which are formed by magnetic field reconnection in the relativistic plasma of the pulsar wind tail.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

The interpretation of the multi-wavelength afterglow emission of short GRB 140903A

GRB 140903A, a short duration γ-ray burst (SGRB) detected by Swift, is characterized by its long-lasting radio emission among SGRBs. In addition to the ∼10{sup 6} s radio afterglow emission, the afterglow of GRB 140903A displays a plateau from 10{sup 3} s to 7×10{sup 3} s in the X-rays. In this work, we attribute the X-ray plateau to the energy injection into the decelerating blast wave and then model the later radio/optical/X-ray afterglow emission within the standard fireball afterglow model. The afterglow emission has been well reproduced with reasonable physical parameters, including a jet half-opening angle of ∼0.05.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

A New Two-fluid Radiation-hydrodynamical Model for X-Ray Pulsar Accretion Columns

Previous research centered on the hydrodynamics in X-ray pulsar accretion columns has largely focused on the single-fluid model, in which the super-Eddington luminosity inside the column decelerates the flow to rest at the stellar surface. This type of model has been relatively successful in describing the overall properties of the accretion flows, but it does not account for the possible dynamical effect of the gas pressure. On the other hand, the most successful radiative transport models for pulsars generally do not include a rigorous treatment of the dynamical structure of the column, instead assuming an ad hoc velocity profile. In this paper, we explore the structure of X-ray pulsar accretion columns using a new, self-consistent, “two-fluid” model, which incorporates the dynamical effect of the gas and radiation pressures, the dipole variation of the magnetic field, the thermodynamic effect of all of the relevant coupling and cooling processes, and a rigorous set of physical boundary conditions. The model has six free parameters, which we vary in order to approximately fit the phase-averaged spectra in Her X-1, Cen X-3, and LMC X-4. In this paper, we focus on the dynamical results, which shed new light on the surface magnetic field strength, the inclination of the magnetic field axis relative to the rotation axis, the relative importance of gas and radiation pressures, and the radial variation of the ion, electron, and inverse-Compton temperatures. The results obtained for the X-ray spectra are presented in a separate paper.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Dynamical and Radiative Properties of X-Ray Pulsar Accretion Columns: Phase-averaged Spectra

The availability of the unprecedented spectral resolution provided by modern X-ray observatories is opening up new areas for study involving the coupled formation of the continuum emission and the cyclotron absorption features in accretion-powered X-ray pulsar spectra. Previous research focusing on the dynamics and the associated formation of the observed spectra has largely been confined to the single-fluid model, in which the super-Eddington luminosity inside the column decelerates the flow to rest at the stellar surface, while the dynamical effect of gas pressure is ignored. In a companion paper, we have presented a detailed analysis of the hydrodynamic and thermodynamic structure of the accretion column obtained using a new self-consistent model that includes the effects of both gas and radiation pressures. In this paper, we explore the formation of the associated X-ray spectra using a rigorous photon transport equation that is consistent with the hydrodynamic and thermodynamic structure of the column. We use the new model to obtain phase-averaged spectra and partially occulted spectra for Her X-1, Cen X-3, and LMC X-4. We also use the new model to constrain the emission geometry, and compare the resulting parameters with those obtained using previously published models. Our model sheds new light on the structure of the column, the relationship between the ionized gas and the photons, the competition between diffusive and advective transport, and the magnitude of the energy-averaged cyclotron scattering cross-section.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Solar Energetic Particle Transport Near a Heliospheric Current Sheet

Solar energetic particles (SEPs), a major component of space weather, propagate through the interplanetary medium strongly guided by the interplanetary magnetic field (IMF). In this work, we analyze the implications that a flat Heliospheric Current Sheet (HCS) has on proton propagation from SEP release sites to the Earth. We simulate proton propagation by integrating fully 3D trajectories near an analytically defined flat current sheet, collecting comprehensive statistics into histograms, fluence maps, and virtual observer time profiles within an energy range of 1–800 MeV. We show that protons experience significant current sheet drift to distant longitudes, causing time profiles to exhibit multiple components, which are a potential source of confusing interpretations of observations. We find that variation of the current sheet thickness within a realistic parameter range has little effect on particle propagation. We show that the IMF configuration strongly affects the deceleration of protons. We show that in our model, the presence of a flat equatorial HCS in the inner heliosphere limits the crossing of protons into the opposite hemisphere.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Shock–Cloud Interaction in the Solar Corona

Flare-associated coronal shock waves sometimes interact with solar prominences, leading to large-amplitude prominence oscillations (LAPOs). Such prominence activation gives us a unique opportunity to track the time evolution of shock–cloud interaction in cosmic plasmas. Although the dynamics of interstellar shock–cloud interaction has been extensively studied, coronal shock–solar prominence interaction is rarely studied in the context of shock–cloud interaction. Associated with the X5.4 class solar flare that occurred on 2012 March 7, a globally propagated coronal shock wave interacted with a polar prominence, leading to LAPO. In this paper, we studied bulk acceleration and excitation of the internal flow of the shocked prominence using three-dimensional magnetohydrodynamic (MHD) simulations. We studied eight MHD simulation runs, each with different mass density structure of the prominence, and one hydrodynamic simulation run, and we compared the result. In order to compare the observed motion of activated prominence with the corresponding simulation, we also studied prominence activation by injection of a triangular-shaped coronal shock. We found that the prominence is first accelerated mainly by magnetic tension force as well as direct transmission of the shock, and later decelerated mainly by magnetic tension force. The internal flow, on the other hand, is excited during the shock front sweeps through the prominence and damps almost exponentially. We construct a phenomenological model of bulk momentum transfer from the shock to the prominence, which agreed quantitatively with all the simulation results. Based on the phenomenological prominence activation model, we diagnosed physical parameters of the coronal shock wave. The estimated energy of the coronal shock is several percent of the total energy released during the X5.4 flare.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Anomalous Galactic Dynamics by Collusion of Rindler and Cosmological Horizons

In holography, the dimensional reduction of phase space to two dimensions defines a dynamical dark energy of Λ=(1−q)H{sup 2}, associated with the cosmological horizon at a Hubble radius of R{sub H}=c/H, and inertia m of baryonic matter at acceleration α in terms of a thermodynamic potential U=mc{sup 2} of Rindler horizons at ξ=c{sup 2}/α. Here, H is the Hubble parameter with deceleration q and c is the velocity of light. In weak gravity, m drops below Newton’s value m {sub 0} as α 2.5) versus ΛCDM (Q{sub 0}<1) and establish a bound of 10{sup −30} eV on the mass of the putative dark matter particle with clustering limited to galaxy clusters.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Radio Observations of the Tidal Disruption Event XMMSL1 J0740–85

We present radio observations of the tidal disruption event candidate (TDE) XMMSL1 J0740−85 spanning 592 to 875 days post X-ray discovery. We detect radio emission that fades from an initial peak flux density at 1.6 GHz of 1.19 ± 0.06 mJy to 0.65 ± 0.06 mJy, suggesting an association with the TDE. This makes XMMSL1 J0740−85 at d = 75 Mpc the nearest TDE with detected radio emission to date and only the fifth TDE with radio emission overall. The observed radio luminosity rules out a powerful relativistic jet like that seen in the relativistic TDE Swift J1644+57. Instead, we infer from an equipartition analysis that the radio emission most likely arises from a non-relativistic outflow similar to that seen in the nearby TDE ASASSN-14li, with a velocity of about 10{sup 4} km s{sup −1} and a kinetic energy of about 10{sup 48} erg, expanding into a medium with a density of about 10{sup 2} cm{sup −3}. Alternatively, the radio emission could arise from a weak initially relativistic but decelerated jet with an energy of ∼2×10{sup 50} erg, or (for an extreme disruption geometry) from the unbound debris. The radio data for XMMSL1 J0740−85 continues to support the previous suggestion of a bimodal distribution of common non-relativistic isotropic outflows and rare relativistic jets in TDEs (in analogy with the relation between Type Ib/c supernovae and long-duration gamma-ray bursts). The radio data also provide a new measurement of the circumnuclear density on a sub-parsec scale around an extragalactic supermassive black hole.

79 ASTRONOMY AND ASTROPHYSICS↗