TY - JOUR

T1 - Modeling continuum polarization levels of tidal disruption events based on the collision-induced outflow model

AU - Charalampopoulos, P.

AU - Bulla, M.

AU - Bonnerot, C.

AU - Leloudas, G.

PY - 2023/2/17

Y1 - 2023/2/17

N2 - Tidal disruption events (TDEs) have been observed in the optical and ultraviolet (UV) for more than a decade, but the underlying emission mechanism still remains a puzzle. It has been suggested that viewing angle effects could potentially explain their large photometric and spectroscopic diversity. Polarization is indeed sensitive to the viewing angle and the first polarimetry studies of TDEs are now available, calling for a theoretical interpretation. In this study, we model the continuum polarization levels of TDEs using the three-dimensional (3D) Monte Carlo radiative transfer code POSSIS and the collision-induced outflow (CIO) TDE emission scenario, where unbound shocked gas originating from a debris stream intersection point offset from the black hole (BH), reprocesses the hard emission from the accretion flow into UV and optical bands. We explore two different cases of peak mass fallback rates (M) over dot(p) (similar to 3 M-circle dot yr(-1) and similar to 0.3 M-circle dot yr(-1)) while varying the following geometrical parameters: the distance R-int from the BH to the intersection point where the stellar debris stream self intersects; the radius of the photosphere around the BH R-ph, on the surface of which the optical and UV photons are generated; and the opening angle Delta theta that defines the fraction of the surface of the photosphere on which the photons are generated (anisotropic emission). For the high mass fallback rate case, we find for every viewing angle polarization levels below one (P

AB - Tidal disruption events (TDEs) have been observed in the optical and ultraviolet (UV) for more than a decade, but the underlying emission mechanism still remains a puzzle. It has been suggested that viewing angle effects could potentially explain their large photometric and spectroscopic diversity. Polarization is indeed sensitive to the viewing angle and the first polarimetry studies of TDEs are now available, calling for a theoretical interpretation. In this study, we model the continuum polarization levels of TDEs using the three-dimensional (3D) Monte Carlo radiative transfer code POSSIS and the collision-induced outflow (CIO) TDE emission scenario, where unbound shocked gas originating from a debris stream intersection point offset from the black hole (BH), reprocesses the hard emission from the accretion flow into UV and optical bands. We explore two different cases of peak mass fallback rates (M) over dot(p) (similar to 3 M-circle dot yr(-1) and similar to 0.3 M-circle dot yr(-1)) while varying the following geometrical parameters: the distance R-int from the BH to the intersection point where the stellar debris stream self intersects; the radius of the photosphere around the BH R-ph, on the surface of which the optical and UV photons are generated; and the opening angle Delta theta that defines the fraction of the surface of the photosphere on which the photons are generated (anisotropic emission). For the high mass fallback rate case, we find for every viewing angle polarization levels below one (P

KW - black hole physics

KW - polarization

KW - radiative transfer

KW - methods: numerical

KW - Galaxy: nucleus

KW - X-RAY

KW - LIGHT CURVES

KW - BLACK-HOLES

KW - POLARIMETRY

KW - STAR

KW - SPECTROPOLARIMETRY

KW - SUPERNOVAE

KW - SPECTRA

KW - POWERS

KW - ECHOES

U2 - 10.1051/0004-6361/202245014

DO - 10.1051/0004-6361/202245014

M3 - Journal article

VL - 670

JO - Astronomy & Astrophysics

JF - Astronomy & Astrophysics

SN - 0004-6361

M1 - A150

ER -