Modelling the energy dependent X-ray spectral variability from accreting black holes
Lead Research Organisation:
Durham University
Department Name: Physics
Abstract
The fastest x-ray variability arises from close to the event horizon of the black hole, and is known to be strongly energy dependent. Recent progress in understanding this focuses on density fluctuations propagating down through a radially stratified accretion flow. The project will build the first physically based numerical models of this, and fit them to real data, to derive constraints on the accretion flow close to the black hole.
Organisations
People |
ORCID iD |
| Chris Done (Primary Supervisor) | |
| Ra'ad Mahmoud (Student) |
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| ST/N50404X/1 | 01/10/2015 | 31/03/2021 | |||
| 1750780 | Studentship | ST/N50404X/1 | 01/10/2016 | 31/03/2020 | Ra'ad Mahmoud |
| Description | I have established a new model which ties together information from both the photon energy and the variation in photons from accreting black holes, which gives better constrains than ever before on the shape of the accretion structure. My second project has also revealed that the established picture of accretion in supermassive black holes at the centres of galaxies is wrong in at least one case, and the new paradigm requires a major re-assessment of established techniques in the field whose key assumptions I have shown to be false. |
| Exploitation Route | My studies have established new techniques which others can utilise and emphasised the importance of tying together information in different dimensions (energy, time), to build fully self-consistent models of black hole accretion. |
| Sectors | Other |
| Title | Propagating Fluctuations Spectral Timing Model |
| Description | In my papers, my supervisor and I have developed a spectral-timing for the accretion flows of astrophysical objects which incorporates - for the first time - data in the energy and the time domain in a self consistent way in order to model a wide range of observed statistics from accreting black holes in our galaxy. As spectral and timing data has improved in resolution over time, the need for self-consistent models which can simultaneously explain a range of higher order statistics has become more pressing, and or modelling framework represents the first of these models. In my papers I outline a `recipe' for these techniques. By the end of my PhD I also hope to make public some user-friendly code examples which people can use to test on their own data. |
| Type Of Material | Computer model/algorithm |
| Year Produced | 2018 |
| Provided To Others? | No |
| Impact | We have successfully reproduced both the spectrum and the timing behaviour in the accreting Galactic black holes Cygnus X-1 and GX 339-4, showing in the latter case that observations by De Marco (2017) are tracking the reflection of high energy X-rays from the thin accretion disc, as well as the underlying propagation of mass accretion rate fluctuations in these X-rays. This has allowed us to map the accretion geometry around GX 339-4 in a fully self-consistent way, combining spectral and timing data to reveal new insights previously unattainable by spectral-only studies. |
| Description | Celebrate Science Durham |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | Regional |
| Primary Audience | Public/other audiences |
| Results and Impact | Manned a number of stalls at the Celebrate Science event at Durham Castle, demonstrating to the public some interesting results coming from the department including galaxy formation, cosmic structure formation and virtual reality cosmology tours. This event, consisting of stalls from across scientific areas across the northeast, draws in approximately 3000 people each year - often families interested in science. Great interest was expressed by most of those who attended our stalls, with repeat visits common. |
| Year(s) Of Engagement Activity | 2016,2017 |
| URL | https://www.dur.ac.uk/celebrate.science/ |
| Description | Conference Talk in Guilin, China |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Professional Practitioners |
| Results and Impact | Gave a talk on my research at an international conference in Guilin, China, presenting new innovations at Durham in modeling black holes. Received very positive feedback and helped to foster contacts with other international institutes. |
| Year(s) Of Engagement Activity | 2019 |
| URL | https://indico.ihep.ac.cn/event/9238/ |
| Description | Invited Talk at the Nicolaus Copernicus Astronomical Center, Warsaw, Poland |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Professional Practitioners |
| Results and Impact | Gave an invited 30 minute talk to the astronomy department and physics undergraduates at CAMK in Poland, on my research. This provided the opportunity to spread my research to an international institution, and set up potential sources of future collaboration. |
| Year(s) Of Engagement Activity | 2019 |
| Description | KITP Conference: Disks, Dynamos, and Data: Confronting MHD Accretion Theory with Observations |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Professional Practitioners |
| Results and Impact | Contributed a poster to the Kavli Institute for Theoretical Physics conference, "Disks, Dynamos, and Data: Confronting MHD Accretion Theory with Observations" at the University of Santa Barbara, USA. This allowed my first-year work to be seen by an audience of around 75 conference attendees, all of whom had an interest in my field of research, from which I had a number of useful interactions which informed me of useful techniques in signal analysis and parameter estimation. These interactions also helped my new colleagues to augment their mental picture of the accretion disc structure based on my results. |
| Year(s) Of Engagement Activity | 2017 |
| URL | http://online.kitp.ucsb.edu/online/disks-c17/ |
| Description | TIME-DOMAIN ASTRONOMY: A HIGH ENERGY VIEW ESAC, MADRID, SPAIN, 13 - 15 JUNE 2018 |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Professional Practitioners |
| Results and Impact | Contributed a 15-minute talk at the XMM-Newton science workshop "TIME-DOMAIN ASTRONOMY: A HIGH ENERGY VIEW" at the European Space Astronomy Centre, Madrid, Spain. This allowed me to present the results of my first and second publications to the wider field, stimulating many interesting questions from related areas of research, and allowing me to improve techniques I used in the following studies performed in my third paper. This also gave me the chance to speak with other young academics and post-doctoral researchers, to give me an insight into life as a researcher in the earlier, professional years. |
| Year(s) Of Engagement Activity | 2018 |
| URL | https://www.cosmos.esa.int/web/xmm-newton/2018-workshop#3 |
| Description | Time for Accretion - Sigtuna, Sweden, August 2018 |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Professional Practitioners |
| Results and Impact | Contributed a 15-minute talk at the conference "Time for Accretion" in Sigtuna, Sweden. This conference allowed me to expose my work to experts in my field who have a deep understanding of my research topic, and for me to gather feedback and ideas from these people. This resulted in improvements to my modelling procedure, and has given me the confidence to continue to pursue the line of reasoning I have been on when modelling accretion physics. As my most recent paper referee put it, the techniques [I have] developed here, [and informed by this conference],] will be useful in the emerging field of spectral-timing modelling of accretion discs. |
| Year(s) Of Engagement Activity | 2018 |
| URL | https://ttt.astro.su.se/groups/head/accretion18/program.html |