Jets from SANE Super-Eddington Accretion Disks: Morphology, Spectra, and Their Potential as Targets for ngEHT

Abstract

We present general relativistic radiation magnetohydrodynamics (GRRMHD) simulations of super-Eddington accretion flows around supermassive black holes (SMBHs) which may apply to tidal disruption events (TDEs). We perform long duration (t ≥ 81, 200 GM/c 3 ) simulations which achieve mass accretion rates 11 times the Eddington rate and produce thermal synchrotron spectra and images of their jets. The jet reaches a maximum velocity of v/c ≈ 0.5 − 0.9, but the density weighted outflow velocity is ∼ 0.2 − 0.35c. Gas flowing beyond the funnel wall expands conically and drives a strong shock at the jet head while variable mass ejection along the jet axis results in internal shocks and dissipation. For a T i /T e = 1 model, the radio/submillimeter spectra peak at > 100 GHz and the luminosity increases with BH spin, exceeding ∼ 10 41 erg s −1 in the brightest models. The emission is extremely sensitive to T i /T e as some models show an order of magnitude decrease in the peak frequency and up to four orders of magnitude decline in their radio/submillimeter luminosity as T i /T e approaches 20. Assuming a maximum VLBI baseline distance of 10 Gλ, 230 GHz images of T i /T e = 1 models shows that the jet head may be bright enough for its motion to be captured with the EHT (ngEHT) at D 110 (180) Mpc at the 5σ significance level. Resolving emission from internal shocks requires D 45 Mpc for both the EHT or ngEHT. The 5 GHz emission in each model is dimmer ( 10 36 erg s −1 ) than upper limits placed on TDEs with no radio emission which suggests jets similar to our models may have gone undetected in previous observations. Our models suggest that the ngEHT may be utilized for > 230 GHz radio/submillimeter followup of future TDEs.

Modeling Reconstructed Images of Jets Launched by SANE Super-Eddington Accretion Flows around SMBHs with the ngEHT

“…In the most common case in which no relativistic jet is launched (commonly referred to as "non-jetted" TDEs), the X-ray and optical/UV luminosity follows a roughly t −5/3 decline, similar to the fallback rate. If the TDE leads to prompt disk formation, the X-rays are thought to arise from an accretion disk, and the optical/UV emission arises from a large scale reprocessing layer [13,14]. TDEs have also been observed to launch relativistic X-ray jets in a few cases.…”

“…The first direct demonstration of circularization near the peak fallback rate was recently demonstrated in a numerical simulation by Steinberg and Stone [5]. Multiple authors have argued in favor of a picture in which an inner accretion flow is surrounded by a quasi-spherical reprocessing layer, since this naturally explains the sometimes delayed appearance of X-ray emission in optical/UV-discovered TDEs [13,14,24]. This picture naturally arises if the accretion flow is actually super-Eddington [13], which has motivated multiple studies of GRRMHD simulations magnetized of super-Eddington disks.…”

“…This picture naturally arises if the accretion flow is actually super-Eddington [13], which has motivated multiple studies of GRRMHD simulations magnetized of super-Eddington disks. Motivated by this fact and the demonstration that a "standard and normal evolution" (SANE) [15] super-Eddington accretion disk also leads to viewing angle effects which may explain the behavior in non-jetted TDEs [17], we conducted a study of the outflows launched by SANE models in Curd et al [14] and studied their radio-submm emission. We focus on these SANE models in this work as well.…”

“…We focus on these SANE models in this work as well. The BZ mechanism also acts in the SANE model [14,25]; however, the disk and BH have a much lower magnetic flux and thus a substantially lower jet power. Although BZ driven outflows in SANE disks can be relativistic, they are weakly comptonized and do not appear as powerful, beamed X-ray sources like the presently known jetted TDEs [14].…”

“…This could allow for interesting sources, such as jets from nearby tidal disruption events, to be imaged directly. In our previous work [14], we provided the first demonstration that SANE super-Eddington accretion flows can produce radio emission which is bright enough at 230 GHz to be detected and resolved. Here we take things a step further and produce reconstructed images assuming such jets happen in the nearby universe.…”