Black Hole Journal Club

We meet every Tuesday at:

12:00 until 13:00 (UTC + 0)

The Zoom link has been emailed to the group.

NOTE: we will have a review of arxiv on the 10th december and there is no journal club on the 17th December. We will be restarting on 7th January.

Agenda

Presentation of chosen paper (~30 mins)
Discussion
Other papers from the week

Rota

To generate additional entries for the rota, use scripts/rota.py.

Date	Presenter
2024-11-19	Andy
2024-11-26	Fergus
2024-12-03	Gloria
2024-12-10	Arxiv
2024-01-07	Jiachen
2025-01-14	Darius
2025-01-21	Rhys
2025-01-28	Tom
2025-02-04	Belinda
2025-02-11	Teresa

Minutes

2024-12-10: Arxiv

Discussed papers: We very briefly mentioned some of the papers that were lightly discussed last week although not in great detail:

X-ray polarization from accretion disk winds (Nitindala et al., 11-2024)
Polarization of synchrotron radiation from blazar jets (Boris et al., 11-2024)
New Insights with XRISM & Cloudy: A novel Column Density Diagnostic (Gunasekera et al., 11-2024)

We discussed a few other papers in a little more detail.

Feedback from Intermediate Mass Black Holes on Dwarf Galaxy Morphology at z = 2 (Bi et al., 12-2024)
- Looking at IMBHs with AGN feedback influencing gas fraction, SF and galaxy structrue.
- Potential need for low-z diagnostics for high-z.
- Also looked at JWST pixelation effects.
Physical Pathways for JWST-Observed Supermassive Black Holes in the Early Universe (Jeon et al., 02-2024)
- Looking at masses of AGN compared to the stellar mass and different ratios.
- Investigates direct collapse black holes.
Lack of Rest-frame UV Variability in Little Red Dots Based on HST and JWST Observations (Tee et al., 12-2024)
- V-shaped SEDs appear less variable
- Possible heavy AGN obsuration
- No variability suggests stellar contributions
Probing orbits of stellar mass objects deep in galactic nuclei with quasi-periodic eruptions (Zhou et al., 05-2024)
- useful figures
- QPEs from TDE & stellar mass object collisions
- Looks at example GSN 069
A Comprehensive Hadronic Code Comparison for Active Galactic Nuclei (Cerruti et al,. 11-2024)
- SED comparisons with blazars
- comparing different models

2024-12-03: Gloria

Presented paper:

The Study of Jet Formation Mechanism in Fermi Blazars (Xie et al., 2024)
- Presentation slides are available here
- A study of 937 Blazars studied for jet formation mechanisms
- Jet power could come from the rotational energy of BH (BZ mdoel) or AD (BP model)
- Study finds no significant relationship between jet power and accretion rate. Possible week relationship for FSQR
- Adding BH mass gets stronger relationship (using F-test)
- BH more important in fueling jets than AD
- Neitehr BZ or BP fully explain jet-powering of blazars but $P_{jet}$ observations are difficult.
- FSRQ from BP (not BZ sufficient), BL Lacs could be BZ model
- BL Lacs ADAF dominated, for FSRQs standard disk dominates.
- BZ MAD disk model in BL Lacs

Other papers:

X-ray polarization from accretion disk winds (Nitindala et al., 2024)
- Scattering in winds reproduces polarization results
- Casts doubts on accretion disk geometries
A Short-lived Rejuvenation during the Decades-long Changing-look Transition in the Nucleus of Mrk 1018 (et al., 2024)
- Full cycle of transitions observed

2024-11-26: Fergus

Presented paper:

On the Morphology of Relativistically Broadened Line Emission from Axisymmetric Equatorial Accretion Disks (Gates et al., 2024)
- Uses geometrically thin, equatorial disk models & describes how to determine emission line morphologies from redshift and accretion disk patterns.
- Very interesting figures, Fig 1 maps different redshifted emission within in the disk to structure of emission line.
- Looks at an infinitely far outer disk radius (removing outer-outer and outer-inner paths) then at finite outer disk radius.
- Critical points dictating central regions
- Also compared different disk models: "Cunningham" model (with inter-ISCO contributions), and non-Keplerian (towards slim-disc) models, but keeping the same geometry. Overall effect of Cunningham model can be large depending on inclination, but for non-Keplerian is a stretching of the location of the critical values.
- Red-tail could overestimate very high BH spin if material is not inside the ISCO
- Changing keplarian factor by $5%$ can change line profile features, but more pronounced at blueshifted side.

Other papers:

Precession and Split of Tilted, Geometrically Thin Accretion Disk: an Analytical Study (Shen et al., 2024)
- This paper looks at cork-screw jet precessions in relation to the accretion disk.
Outgoing electromagnetic flux from rotating wormholes (Urtubey et al., 2024)
- On the predictions from Einstein's field equation
Changing Look AGN: An X-ray Look (Titarchuk et al., 2024)
- Looking at comptonization evolution of NGC 1566 X-ray sepctra

2024-11-19: Andy

Presented paper:

X-ray reverberation modelling of the continuum, optical/UV time-lags in quasars (Langis et al., 2024)
- Investigating variation that is wavelength dependent. UV/optical variations are well correlated
- Initial 191 AGN sample and using a G-band reference.
- Spread in time delay from BH mass.
- Model assumes thin disk & lamppost model with either spin 1 or spin 0.
- Skin of hot electrons compton scatter a blackbody.
- High source height for disk illumination (observation consistent?)
- Different BLR x-rays & Balmer jump at 4000 $\mathring{A}$
- Interesting $\chi^2$ values

Discussed papers:

Three similar papers on applying ray-tracing to image different types of black holes.
- Observational features of the rotating Bardeen black hole surrounded by perfect fluid dark matter (He et al., 2024)
- Shadow Images of Ghosh-Kumar Rotating Black Hole Illuminated By Spherical Light Sources and Thin Accretion Disks (Yang et al., 2024)
- Image of the Kerr–Newman Black Hole Surrounded by a Thin Accretion Disk (Guo et al., 2024)
Comparing indirect methods for black hole masses in AGN: the good, the bad, and the ugly (Gliozzi et al., 2023)
- Comparing different methods, such as the $M-\sigma_*$ relation with dynamical methods and have generated a correcting factor.
- Conducted on an 'unbiased', volume-limited and hard X-ray selected sample.

2024-11-12: No Presentation

Discussed Papers:

Effects of ultra-fast outflows on X-ray time lags in AGN (Xu et al., 2024)
- They observe 3 AGN with UFOs between $0.03-0.3$ c
- Disk fluctuations in cold (soft) and hot (hard) X-rays
- Low frequency hard-lags suppression in UFO states
- Magnetically Driven Accretion Disk Winds and Ultra-fast Outflows in PG 1211+143 (Keigo et al., 2015)
The XRISM/Resolve view of the Fe K region of Cyg X-3 (XRISM Collaboration, 2024)
- Wind-focused BH
- Orbital period ~5hrs
X-Ray View of Little Red Dots: Do They Host Supermassive Black Holes? (Ananna et al., 2024)
- Large uncertanties
- Compton thick
  - X-ray column density $n_H\gtrsim10^{25}$ $\text{cm}^{-2}$
  - JWST inconsistent with $n_H\sim10^{21}$ $\text{cm}^{-2}$
- AGN interpretation prefered in UNCOVER Spectroscopy Confirms the Surprising Ubiquity of Active Galactic Nuclei in Red Sources at z > 5 (Greene et al., 2024) but SF could fit.
- A small and vigorous black hole in the early Universe (Maiolino et al., 2024)
  - SMBH faster growth than stellar mass

Keeping up to date with papers:

Benty-fields: Uses ML to give papers heirachy
ADS emails: Sorts by key words - regular email updates

2024-11-05: Belinda

Discussed Papers:

The XRISM/Resolve view of the Fe K region of Cyg X-3 (XRISM Collaboration, 2024).
- Really nice detailed spectrum with a lot of Fe absorption and emission lines observed.
Little Red Dots: an abundant population of faint AGN at z∼5 revealed by the EIGER and FRESCO JWST surveys (Matthee, et al., 2024)
- A paper hinting towards the seeing early AGN feedback and early SMBH growth being highlt obscured.
Deep Chandra Observations of NGC 5728. III: Probing the High-Resolution X-ray Morphology and Multiphase ISM Interactions in the Circumnuclear Region (Falcao, et al., 2024)
- A paper looking at ISM interactions within a Seyfert 2 galaxy likely from X-ray binaries
Structural Decomposition of Merger-Free Galaxies Hosting Luminous AGNs (Fahey, et al., 2024)
- Investigates AGN evolution in merger-free galaxies. A weak correlations between bulge & SMBH masses, and for stellar & SMBH masses observed for disk-dominated galaxies.

Presented paper:

X-Ray View of Little Red Dots: Do They Host Supermassive Black Holes? (Ananna, et al., 2024)
- Unknown reason for JWST-observed 'little red dots', with flux either AGN dominated, young star formation dominated or both.
- Over 100 Chandra observations of lensing cluster Abell 2744 equating up to $\approx 2$ Ms or $\approx90$ Ms stacked.
- No significant detection until broad-line $H\alpha$ galaxies are stacked.
- Possibly Compton thick AGN to explain non-detections.
- Results from X-ray and NIR suggest scaling relations from virial relations may not be applicable at high redshift.
- LRDs likely either do not contain overmassive SMBHs or accrete at a low eddington rate.
Also discussed was UNCOVER Spectroscopy Confirms the Surprising Ubiquity of Active Galactic Nuclei in Red Sources at z > 5 (Greene, et al., 2024)
- Shows a absorbed component and either AGN scattering or star formation to contribute to the UV.