Literature Reviews

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AGN

  • Su, K.-Y+16
    • we focus primarily on non-cosmological simulations of isolated galaxies, because this allows us to achieve higher spatial and mass resolution, and to have well-controlled experiments with identical galaxy initial conditions. In cosmological runs, on the other hand, the inherently chaotic nature of the problem makes detailed one-to-one comparison of simulations with varied physics more complicated;
    • at the resolutions currently achievable in isolated galaxy and cosmological simulations, MHD, anisotropic conduction and viscosity, and sub-grid turbulent metal diffusion play a relatively minor role in the regulation of star formation and of the phases and energetics of the ISM when the dominant effects of stellar feedback are simultaneously modeled.
    • With stellar feedback, a multi-phase, turbulent medium with galactic fountains and winds is established.
  • Drouart+16
    • The transition regime between dust heated by the AGN and dust heated by star formation is at 40-60 µm and is therefore important to observe because it affects the total infrared emission and characterisation of each component.
  • Lobban, Porquet, Reeves+17
    • While the UV emission does not vary as rapidly as it does in the X-ray band (Mushotzky et al. 1993), one might expect to observe a correlation between the variability if the local accretion rate is responsible for modulating the X-ray and UV emission regions. In this scenario, there are two favoured mechanisms to couple the variability - (i) UV photons being Compton up-scattered to X-rays by a corona of hot electrons (e.g.Haardt &Maraschi 1991), and (ii) thermal reprocessing of X-rays in the disc (Guilbert & Rees 1988; Collier et al. 1998; Cackett et al. 2007). In either case, it is the time taken for the light to cross between the two emission sites that governs the observed time delays.

AGN - XRB similarity

  • Padovani, Alexander, Assef+17
    • the striking similarities of the X-ray timing properties of AGN and BH-XRBs suggest the existence of a common physical process driving the observed variability

TDE

  • Kara+16
    • reverberation arising from gravitationally redshifted iron Kα photons reflected off the inner accretion flow in the tidal disruption event Swift J1644+57.
    • Tidal disruption events , where a star orbiting an otherwise dormant black hole gets tidally shredded and accreted onto the black hole3, can provide a short, unbiased glimpse at the space-time around the other ninety per cent of black holes. Observations of tidal disruptions have hitherto revealed the formation of an accretion disk and the onset of an accretion-powered jet
  • Seifina,Titarchuk, Virgill 17
    • Rees (1988), hereafter R88, suggested that among bright X-ray flares that continue for a few years, some can be caused by tidal gravitational disruption of a star which passed too close to a super massive black hole (SMBH). If a star passes within the tidal radius of a black hole then the gravity rips the star apart (R88). As the stellar remnant approaches a black hole (BH), its gravitational potential energy is converted into heat through viscous effects. Some of the debris can be ejected, while the remaining part can be ingested by a central SMBH. In this case the accretion flow reaches a temperature of about 105 K and emits brightly at optical, ultraviolet, and X-ray wavelengths during the period from about 100 days to a few years.

Stellar Feedback

  • Forbes+16
    • a star formation law that depends on galaxy metallicity—as is expected with photoelectric heating, but not with supernovae—reproduces the present-day galaxy population better than does a metallicity-independent one.
    • supernovae are unable to account for the observed large gas depletion times in dwarf galaxies.
    • photoelectric heating is the dominant means by which dwarf galaxies regulate their star formation rate at any given time, suppressing the rate by more than an order of magnitude relative to simulations with only supernovae.