Testing the standard model for accretion


   Department of Physics and Astronomy

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  Dr M Goad  No more applications being accepted  Competition Funded PhD Project (Students Worldwide)

About the Project

Correlated continuum and broad emission line variability studies have proven a powerful probe of the central regions of Active Galactic Nuclei (AGN). Traditionally RM has focused on probing the spatial distribution and kinematics of the broad emission line region (BLR), and determining the mass of the central supermassive black hole. More recently, correlated continuum variations have been used to : (i) measure the distance to the hot dust (dust RM) which bounds the BLR, and (ii) map the disc radial temperature profile, T(r). Dust delays provide an upper limit to the BLR outer boundary necessary for constraining photoionization models of the BLR, while the disc inter-band continuum delays can be used to determine the nature of the accretion flow, and for AGN with known black hole mass, the mass accretion rate through the disc.

We have extensive ground-based data with Liverpool Telescope in support of a large HST program (AGNSTORM, 200 orbits with HST/COS) and Swift/XRT/UVOT monitoring programs, providing ground-based spectrophotometry, for disc, dust and broad emission-line variability studies, as well as related Intensive Disc Reverberation Mapping (IDRM) programs aimed at measuring the disc sizes in ~dozen nearby AGN.

This program will focus on constructing photoionization models of the broad emission line region (BLR) in low and high accretion rate sources in the context of self-consistent energy conserving models of the ionizing SED, necessary for quantifying the BLR diffuse continuum (DC) contribution to the total light (e.g., Fig 1), and inter-band continuum delays (the major contaminant to the disc delay signature). By quantifying and then removing the DC contribution to the delay signature we can use the residual delays to directly test the standard model for accretion. The work will involve a substantial computer modelling component and may also include some data reduction and analysis.

Enquiries to project supervisor [Email Address Removed] or [Email Address Removed]

TO APPLY

Refer to our website https://le.ac.uk/study/research-degrees/funded-opportunities/stfc


Physics (29)

Funding Notes

The projects listed are in competition for STFC funding. Usually the project which receives the best applicant will be awarded the funding.
The STFC studentship provides:
A full UK fee waiver for 3.5 years*
An annual tax free stipend (currently £18,622 for 2023/4) for 3.5 years
Research Training Support Grant (RTSG)
Conference Fees and UK Fieldwork fund
*Up to 2 international studentships are available and include a 3.5 year full overseas fee waiver and stipend as above.

References

• Cackett, E. et al. 2022, ApJ 925, 29.
• Vincentelli, F.M. et al. 2021, MNRAS 504, 4337.
• Korista, K.T. and Goad, M.R. 2019 MNRAS, 489, 5284. ·
• Lawther, D., Goad, M.R. et al. 2018 MNRAS 481, 533.
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