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11.
Rubin Observatory's survey strategy performance for tidal disruption events
Katja Bricman, S. Van Velzen, M. Nicholl, Andreja Gomboc, 2023, izvirni znanstveni članek

Ključne besede: Rubin Observatory, legacy survey time, tidal disruption event, legacy survey of space
Objavljeno v RUNG: 29.08.2023; Ogledov: 707; Prenosov: 8
.pdf Celotno besedilo (1,18 MB)
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12.
RELATIVISTIC TIDAL DISRUPTIONS OF REALISTIC STARS BY SUPERMASSIVE BLACK HOLES
Taj Jankovič, 2023, doktorska disertacija

Opis: Stellar tidal disruption events (TDEs), where a star gets disrupted by strong tidal forces of a supermassive black hole (SMBH), offer a unique opportunity for studies of SMBHs and stellar dynamics in galactic nuclei and provide insights into accretion physics. Currently, there are ≈ 100 observed TDEs, however, this number is expected to increase significantly with the start of new wide-field optical surveys, e.g. with the Vera Rubin Observatory. We focus on hydrodynamic simulations of TDEs with the smoothed particle hydrodynamics code Phantom. To begin with, we simulate TDEs in a general relativistic and Newtonian description of an SMBH’s gravity. Stars, which are placed on parabolic orbits with different parameters β (to be defined here), are constructed with the stellar evolution code MESA and therefore have realistic stellar density profiles. We study the mass fallback rate of the debris Ṁ, a quantity often assumed to determine the TDE light curves, and its dependence on the β, stellar mass and age as well as the black hole’s spin and the choice of the gravity’s description. We find that relativistic disruptions at the same pericenter distance are stronger than disruptions in a Newtonian description of the SMBH’s gravity. We also determine the differences between Ṁ of realistic stars with various ages and masses. In addition, we characterize the effect of SMBH’s rotation on the Ṁ and find that it depends on the orientation of SMBH’s spin vector relative to the stellar orbital angular momentum. Encounters on prograde orbits result in narrower Ṁ curves with higher peak values, while the opposite occurs for retrograde orbits. Stellar disruption results in an elongated stream of gas that partly falls back to the pericenter. Due to apsidal precession, the returning stream may collide with itself, leading to a self-crossing shock that launches an outflow. If the black hole spins, this collision may additionally be affected by Lense-Thirring precession which can cause an offset between the two stream components. We study the impact of this effect on the outflow properties by carrying out local simulations of collisions between offset streams. As the offset increases, we find that the geometry of the outflow becomes less spherical and more collimated along the directions of the incoming streams, with less gas getting unbound by the interaction. However, even the most grazing collisions we consider significantly affect the trajectories of the colliding gas, likely promoting subsequent strong interactions near the black hole and rapid disc formation. We analytically compute the offset to stream width ratio, finding that even slowly spinning black holes can cause both strong and grazing collisions. We propose that the deviation from outflow sphericity may enhance the self-crossing shock luminosity due to a reduction of adiabatic losses, and cause significant variations of the efficiency at which X-ray radiation from the disc is reprocessed to the optical band depending on the viewing angle. These potentially observable features hold the promise of constraining the black hole spin from tidal disruption events.
Ključne besede: Computer modelling and simulation, hydrodynamics, black holes, infall
Objavljeno v RUNG: 29.08.2023; Ogledov: 613; Prenosov: 7
.pdf Celotno besedilo (16,29 MB)

13.
Gremo v Čile
Andreja Gomboc, 2023, poljudni članek

Ključne besede: poletna šola, GoChile
Objavljeno v RUNG: 18.08.2023; Ogledov: 614; Prenosov: 2
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14.
Astronomi in astronomke v Krakovu
Andreja Gomboc, 2023, poljudni članek

Ključne besede: astronomija, Evrospko astronomsko društvo
Objavljeno v RUNG: 31.07.2023; Ogledov: 669; Prenosov: 3
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15.
Tidal Disruption Events
Andreja Gomboc, objavljeni povzetek strokovnega prispevka na konferenci (vabljeno predavanje)

Ključne besede: black holes, tidal disruptions, Rubin observatory
Objavljeno v RUNG: 05.07.2023; Ogledov: 725; Prenosov: 2
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Dekolonizacija astronomije
Andreja Gomboc, 2023, polemika, diskusijski prispevek, komentar

Ključne besede: astronomija, kolonializem, observatoriji
Objavljeno v RUNG: 22.06.2023; Ogledov: 773; Prenosov: 6
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18.
Zemlja - vesoljska tarča
Andreja Gomboc, 2023, poljudni članek

Ključne besede: Zemlja, asteroidi, kometi
Objavljeno v RUNG: 22.06.2023; Ogledov: 740; Prenosov: 6
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Vtisi iz tujine
Andreja Gomboc, 2023, polemika, diskusijski prispevek, komentar

Ključne besede: raziskovalci, tujina, univerze
Objavljeno v RUNG: 26.04.2023; Ogledov: 785; Prenosov: 2
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