Kinsale, Ireland -- 29 April - 3 May 2024
Note: I was partially distracted by admin duties on Monday.
- Übler+ (2023b): BH pairs in JWST with emission lines. OIII 4363 is stronger than present-day AGN.
- Mazzolari+ (2024) Ways to identify moderate-luminosity AGN without broad lines
- Übler+ (2024b): AGN feeding / feedback at z~4 in GN20, obscured
- (in prep) Measuring proximity zone sizes at z>6.5 in 27 QSOs
- They vary from 0.23 to 6.19 Mpc. There is a large scatter wrt UV magnitude, which is probably related to QSO lifetime / duty cycle.
- Does the 0.23 Mpc case represent a young QSO?
- Matthee+ (2023): Are the little red dots (LRDs) massive galaxies or obscured QSOs? The obscured QSOs could have their blue light scattered to the red, skewing the bolometric luminosity estimates.
- Kocevski+ (2024): Studied 341 faint red AGN at z>2, most common at z>4. They select them through slopes blueward and redward of the Balmer break.
- Number density x10 above extrapolations of bright QSOs at z~5.
- Two X-ray detected LRDs that are moderately obscured.
- From RUBIES, 70-80% of their sample have broad lines (1400-4200 km/s). 25% of LRDs have narrow, blue-shifted HeI or H-alpha absorption. Indicates dense, low-ionization gas present within the dust sublimation radius.
- If LRDs are obscured AGN, where is the dust? Lack of MIRI detection is inconsistent with the presence of a host dust torus (Williams+ 2023). Are the LRD host obscured too?
- The broad lines could be caused by SNRs.
- Seuss+ (2024) UNCOVER 2.0 survey released. Using medium band NIRCam filters down to ~28.5 apparent magnitude.
- Williams+ (2023) MIRI observations showed that f_nu is flat, which isn't indicative of a dusty torus.
- Yue+ (2024) No X-ray detection even after 24 Ms of stacked Chandra data
- (Goudling+ 2023; Bogdan+ 2023; Atek+ 2024) UHZ1. 5-sigma X-ray detection at z~10. Heavily Compton thick.
- Kokorev+ (2023) UHZ1 favors heavy seeding or sustained hyper-Eddington accretion. Suggests that BHs grow first then the stellar component?
- Castellano+ (2024) UHZ2. New AGN candidate at z~12
- MIRI data will hold the key to unlock the uncertainties in the AGN properties
- Durodola+ (in prep) Determining where the high-z AGN candidates (Barro+ 2024) lie in the MBH-Mstar plane.
- Using CIGALE to estimate L_AGN and Mstar. Assume an Eddington limit and fix the rest-frame optical AGN fraction.
- As the AGN contribution increases in the model, Mstar decreases and the object becomes bluer while MBH slightly increases (~50%).
- For all of the fits, their work suggests that the MBHs are overmassive.
- Questions: Obscured stellar population? Dust-poor? MIRI results?
- Q&A session: Reines says that MBH-Mstar relation from early types (with dynamical masses) should be used, not the total one.
- (Ni+ 2020; Gilli+ 2022) Over 80% of z>=7 AGN are expected to be obscured.
- (Lambrides+ 2023) Radio detections of z~7 AGN within COSMOS
- (Kar Chowdary+ 2024) Pop III TDEs could be detected by RST.
- (Walker+ 2023) Overmassive BHs at low-z isn't related to seeding, but dynamical processing in dense environments and mergers. However high-z sources will probe the seeding.
- (Chon+ 2023) when the metallicity is over 1e-3 Zsun, the mass accretion rate drops by a factor of ~100 because of cooling and fragmentation. Above this metallicity, dust cooling promotes fragmentation but doesn't prevent rapid accretion.
- (in prep) now including radiation feedback. The stellar mass growth is most rapid in low metallicities at early times, but the higher metallicity (1e-3 and 1e-2 Zsun) eventually catch up at 2+ Myr.
- (Chiaki, Chon+ 2023) Used galaxy SAM and DCBH seeding model to make SMBH number density predictions.
- (Bhomick+ 2024) BRAHMA simulations: exploring different BH seeding models.
- Varying the formation criteria: amount of dense metal-poor/free gas; halo mass; BH seed mass
- Diaz+ (2024) B-field amplification in varying LW values, Jeans resolution, and initial B-field.
- Amplification factor varies by a few orders of a magnetic from halo to halo
- Askar+ (2021) Direct N-body simulations of NSC mergers, including IMBHs
- Also includes recoil kicks for the models with multiple IMBHs. To retain the resultant IMBH, the mass ratios need to be small (<~0.2).
- (Trinca+ in prep) Whether BHs grow through Eddington or super-Eddington will leave an imprint on the merger rates detected by LISA.
- ASTRID simulations: uses dynamical friction model for mergers in a MassiveBlack-II like (updated) simulation.
- Super interesting work with a set of embedded simulations (direct N-body, FMM) to follow SMBH mergers within a cosmological context. Work led by students.
- (Koudmani+ 2023) Accretion disk particle model. Tracks both the mass and AM of the BH and disk.
- Inspecting IllustrisTNG simulations to survey the accretion states of the SMBHs, especially with merger models without an instantaneous event.
- In particular, they inspect the distribution of Eddington ratio versus sSFR. They evolve from high fEdd and sSFR -> lower in both quantities -> lower in sSFR only -> significant drop in fEdd.
- Scoggins & Haiman (2024): Merger tree extension of Scoggins+ (2023) paper on the lifetime of outliers in the MBH/Mstar relation. Some are outliers for several million Myr.
- Hu, Inayoshi+ (2022a): 2D RHD simulations, showing a steady-state between inflow/outflow with super-Eddington accretion. Mass inflow rate
$\propto \sqrt{r}$ . Super-Eddington growth if inflow is$>10^2 - 10^3$ of Eddington at the Bondi radius. Above Eddington inflow rates, the BH growth rate increases as the square-root of the inflow rate. - Su, Bryan+ (2023) Bondi accretion with jet feedback simulation. Analytic prescription result for subgrid models. Depending on the parameters, the outflows are spherical or jetted once it reaches the Bondi radius.
- Subsequent growth explored in Su+ (2024). If the jet velocity is too high (~10^4 km/s), the dense inner gas is destroyed and further growth.
- (Tang+ 2017, Duffell+ 2020, Tiede+ 2021, Zrake+ 2021) Dense gaseous environments can solve the final-pc problem in galaxies without dense nuclear star clusters.
- Direct N-body simulations (BIFROST) of runaway collapse within a dense stellar cluster.
- (Adamo+ 2024) JWST observations of five close pc-size YSCs at z=10.2 with masses ~10^6 Msun.
- Takes one state of the GRIFFIN simulation within a 50 pc radius as the ICs.
- Very rich merger history and beautiful plots. In hierarchy assembly, IMBHs are resilient against GW kicks. Stellar collisions result in a lower growth rates.
- Using a sample of MBH mergers and their host galaxies from the Romulus25 simulation.
- Identified galaxy morphology and/or kinematics to select host MBH binaries and mergers.
- (Vaccaro+ 2023) Using SEVN stellar evolution code (Iorio+ 2023) to explore nuclear star cluster evolution and stellar binaries within an AGN disk.
- Also considering 3-body encounters -> Changes orbital AM direction, results in exchanges, and resets semi-major axis and eccentricity
- GW190521 might have an EM counterpart that's associated with an AGN flare
- (Reines+ 2013) BPT diagrams can identify AGN in dwarf galaxies but can have issues at low-metallicity that will decrease the strengths of the metal lines.
- (Baldassare+ 2020) Constructed 35k light curves for low-mass galaxies and found 237 variable AGN with masses
$10^7 - 10^{10} M_\odot$ . Most variable AGN aren't classified as AGN in BPT diagrams. Variability can constrain the MBH masses. - (Messick+ 2023) X-ray follow-ups of the 14 candidates. Found 4 with X-ray sources.
- (Birchall+ 2020) Found 50 X-Ray confirmed AGN in dwarf galaxies and also aren't selected as AGN in BPT diagram
- (Angus+ 2022) TDEs are a complementary BH mass estimate technique
- (Baldassare+ 2016) Broad lines in dwarf galaxies can also come from SNe. SF-dominated narrow lines remain, but the broad lines can fade -> consistent with SNe. There is a minority of objects whose broad lines are caused by AGN.
- (Mezcua+ 2020, 2024) Using MaNGA IFU survey to find 3.4k dwarf galaxies and identified AGN through BPT diagrams spaxel-by-spaxel. Galaxies have multiple classifications that are spatially connected (see below).
- (Mezcua+ 2023) Using VIPERS to study 7 dwarf galaxies between z=0.3-1 with MBH > 10^7 Msun. Overmassive BHs in dwarf galaxies. They also found 12 low-mass galaxies with overmassive SMBHs at z=1-3. DCBH seeds?
- (Pucha+ in prep) Using DESI, analyzed 40M galaxy spectra! Doing similar searches but in a much larger dataset.
- (Jones+ 2021) Using PanSTAARS they target 60k sources to search for young SNe. Found 3k QSOs, 758 with spectra, and about 30 with broad H-alpha lines.
- Uses Reines+ (2013) relation to estimate the MBH masses from the H-alpha FWHM and luminosity
- Also calculated the dampening timescale in the variability fitting.
- Reines+ (2022) Review
- BH occupation fractions may differ between early- and late-type dwarfs.
- Late types dominate at high masses and mostly have central BHs
- Schutte & Reines+ (2022) Could a young SNR or MBH cause these central sources? They went through many observational tests to determine. Confirmed MBH presence. Also found that the MBH outflows are triggering SF.
- (Gim+ 2024) Outflow-driven water maser for Henize 2-10. One side is spatially coincident with the triggered SF region.
- Uniform AGN selection through several surveys: SDSS, GAMA, WISE, Chandra, XMM, and PTF.
- [HeII] identifies half of the population. More sensitive to hardness than [OIII]/H-beta.
- Demonstrates the need for multi-wavelength studies to identify the full sample of AGN hosts.
- Dwarf morphology studies of variable AGN with HST. All are classified as SF in BPT diagrams.
- AGN selected through their variability are generally dimmer than BPT-selected ones, but they're brighter than dwarfs without AGN.
- Using the (Schutte+ 2019) MBH-Mbulge relation, they found central MBHs in the range
$3 \times 10^{3-5} M_\odot$ . The lower bound is very intriguing!
- Using COCO (N-body sim) and COLOR (zoom-in), along with LSS objects (voids, walls, filaments, halos) with GALFORM to inspect MBH growth.
- Dense environments produce early infall times, i.e. satellites falling into halos arrive earlier than ones falling into walls.
- Predicts >20% of galaxies with a stellar mass
$10^9 - 10^{10} M_\odot$ have central BHs. Depends on whether the halo is a central or satellite.
No notes for my own talk!
- Pacucci & Loeb (2024) model for overmassive BH galaxies.
- Assumption: BH feedback has a big impact on the compact system and prevents and quenches the galaxy.
- They have a MBH/Mstar criteria to determine when SF is quenched.
- All of the overmassive systems are above this criteria while the typical galaxies are below.
- Using the SAM called CAT (Trinca+ 2022) to follow BH growth in high-z galaxies, exploring different seeding models and accretion models
- Trinca+ (2023): Predicted number of AGN as a function of magnitude in each NIRCam FoV
- Schneider+ (2023): Synthetic AGN observations. Accretion model has a major impact on the MBH-Mstar scaling relations at high-z. Super-Eddington model fits the best.
- Juodzbalis+ (2024): CAT can predict the overmassive BH systems, and afterwards, the galaxy can grow further and approach the MBH-Mstar relation.
- Sassano+ (2023): Combining CAT and rad-hydro simulations of BH seeding, growth, and feedback.
- Testing CAT evolutionary paths with simulations
- Informing the SAM with simulation results
- Developing an open-source SAM called L-GalaxiesBH
- Using "grafting" between merger trees to combine multiple branches and trees from higher resolution simulations. They're using a suite of Millenium (DM) simulations, from 30 Mpc to ~1 Gpc.
- Spinoso+ (2023): Exploring multiple seeding scenarios. Uses spatial information, like LW radiation intensity and metallicity.
- Izqueirdo-Villalba+ (2024, in prep) To reconcile with PTA GWB with high-z JWST SMBHs, need super-Eddington.
- Polkas+ (2024) Using a Fokker-Planck solver in dense stellar clusters to predict TDEs
- All SMBHs will track through the LISA band sometime during their growth history
- LISA could determine the abundance of the BH seeds
- Crucial question: Given a set of LISA observations, what astrophysical info about the underlying population can we recover? (Plowman+ 2011)
- Constraints on dynamics (eccentricity) and spin. Most are expected to be highly spinning and circularized.
- Sky localization becomes better with "exposure" time. Below 1 deg around a day for MBH = 3e5 Msun.
- (Chen+ 2019) Constraints from PTA observations. The BBHs merge relatively quickly (300 Myr) and are supermassive (~10^8 Msun).
- Triple BH systems: Possible if BBH merger timescales are long and galaxy merger timescales are short.
- (Sayeb+ 2021, 2024) Identified triple candidates in IllustrisTNG. 30-35% of binaries overlap in time within a galaxy
- Bimodal distribution of the binary separation within the triples -- "strong" and "weak" triples.
- Satheesh+ (2024): Slingshot recoils dominate at high kick velocities
- Sivasankaran+ (2023): SMBH fueling, feedback, and dynamics in ISM. Central MBH wanders within a turbulent ISM and accretion and feedback are highly episodic
- Using KETJU that has direct N-body at small scales (determined by chaining particles together) and approximate (GADGET) methods are large scales. Includes 3.5PN corrections.
- (Rantala+ 2020) Updated gravity solver to use a MSTAR integrator that allows for many more particles because it's more efficient.
- In mid-2023, KETJU-GADGET4 released
- (Mannerkoski+ 2021, 2022) Cosmological KETJU simulations. Sees many triple systems and exchanges.
- Most binaries have high eccentricies (e > 0.65) and even one is kicked out of a galaxy
- Using DELPHI SAM (Dayal+ 2014...2024). Dayal+ (2022) found that early galaxies have a high dust content, matching the REBELS data in galaxies with Mstar = 1e8.7 - 1e10 Msun. 40-90% UV light is obscured. Suggests ~1 Msun of dust produced per SN.
- Dust production models with grain growth in dense clumpy environments reproduce the observations the best.
- Finding an overabundance of bright galaxies at z>=12, e.g. Mauerhofer & Dayal (2023), Ferrara+ (2023), Mason+ (2023)
- Predicted LISA event rates: 1-100 per year, depending on the model. "Astrophysics with LISA" white paper (2023)
- Galaxies with Mstar < 1e9 Msun contribute the most to reionization but then decrease after reionization and SMBHs overtake it afterwards.
- (Berger+ 2024) Synthetic observations of BlueTides galaxies to understand how to disentangle the QSO and galaxy contributions in JWST observations.
- Select analogs in BlueTides with L_QSO ~ 1e12 Lsun, M_BH ~ 1e8 Msun, Mstar ~ 1e10 Msun, r_1/2 ~ 1 kpc.
- These galaxies have SFRs between 1e2 - 1e3 Msun/yr
- (Jeon+ 2024) Cosomological simulation with GIZMO with Pop III star formation and feedback, along with BH seeding models
- DCBH seeding model: High density, metal-free/poor, warm, H2-poor
- DCBH growth model: Accretes nearby gas particles within some radius(?) instead of Bondi-Hoyle accretion.
- Can reproduce the JWST z~10 AGN observations in biased regions.
- (Lupi+ 2024) Zoom-in simulation of a z=6 QSO host (Mvir = 3e12 Msun) with super-Eddington accretion with a three-phase feedback model
- ADAF regime (f_edd < 0.003), Jet + radiation
- SS disk (f_edd = 0.003-1), Radiation-driven wind + radiation
- Super-Eddington regime (f_edd > 1), Jet + radiation
- (in prep) Modeling IMBHs in dwarf galaxies. Simulation has 100 Msun DM resolution and modeling star formation on a star-by-star basis! Many BHs but few stars within the central 300 pc. There are an abundance of BHs of stellar mass (10-30 Msun) and IMBHs (1000-3000 Msun) with few between.
- Shearing box MHD simulations with Athena++ of a strongly magnetized disk (
$\beta = 300$ ) - How do radiative outflows impact the mid and outer regions of the disk and beyond?
- In a separate project, they use radiation transport (Jiang+ 2021) in Athena++ to inspect its impact on DCBH growth
- Future work: longer duration, IMF for star formation embdedded in the disk, radiative outflows and impact on SMBH growth
- BH growth severely depends on its location and timing of overlap with dense gas.
- SMBHs typically sink to the galaxy center through dynamical friction from gas/DM, e.g. Tremmel+ (2015), Pfister+ (2019), Chen+ (2021).
- (Ma+ 2021) However low-mass BHs fail to sink and IMBHs get displaced easily by galaxy mergers (Bellovary+ 2021). Also clumpy galaxies lead to random orbits from perturbations. Should we give up on low-mass BH seeds, or are the simulations' accretion models inaccurate?
- (in prep) Even small offsets can kill BH growth, even on the pc-scale. Depends on the BH mass.
- Focusing on EMRIs, i.e. q = 1/150 - 1/30, within the Justice League simulations of LG dwarf galaxies.
- Initial inclination and galaxy compactness affects EMRI inspiral times
- Comparable BH pair orbits can circularize over can time, but a fraction actually have their eccentricities' increase. The distribution of
$\Delta e$ is flat.
- Combining Tremmel+ (2015) dynamical friction subgrid model with direct N-body KETJU integrator. Compared with analytical solution, and they are consistent with each other.
- However, the BHs have trouble staying at the galaxy center and depends on the BH/star particle mass.
- Use subgrid model only if BH/star particle mass is low and switch to KETJU afterwards.
- GRIFFIN model for ISM and SF. Following systems star-by-star with gas particles
$\le 4 M_\odot$ and sub-pc resolution. Chemical network with metal species. Using KETJU and BH dynamical friction. - (in prep) Test: isolated dwarf galaxy without AGN feedback. The IMBH (1e4 and 1e5 Msun) doesn't grow appreciably over a Gyr. The e-folding timescale is >2 Gyr. BH growth is suppressed as any inflowing gas cools and forms stars and then feedback disrupts any potential fuel. AGN feedback makes things worse (
$\sim 10^{-3}$ fractional growth over a Gyr). - A nuclear star cluster may boost BH accretion. They emulate one with a massive particle with a 5 pc smoothing length.
- (Partmann+ 2023) Cold dense inflows may also help BH growth in high-z galaxies. However they can be ejected and/or wander.
- Studying and searching for AGN within several surveys. Type-2 AGN are not identified from BPT diagrams because of low metallicities. Could HeII help? It is very faint but insensitive to metallicity. HeII 1640 is 7-10x brighter than 4686 but is blended with another line.
- (in prep) Looking at [CIII]1907,09/HeII1640 vs. [OIII]1666/HeII1640. Still messy.
- If an object is caused by an extreme IMF, then the emission lines should have the same morphology as the nebular continuum. Could be a discriminator between AGN and SF.
- (Scholtz+ 2023c) AGN fraction is flat at 15-30%
- The detection of these new AGN and assuming a standard AGN spectrum, the XRB is overestimated by 10x.
- Juodzbalis+ (in prep): There's a peculiar outlier that is X-ray bright. It has a very strong absorption feature in Balmer and Paschen series.
- Maiolino+ (2024): Where are the X-rays?
- Maiolino+ (2023): GN-z11. NIV] and NIII] quintuplet is very sensitive to gas density, constraining the density to 1e10 /cm3. Many other properties point toward it being a Type-1 AGN.
- In GN-z11, there's an iron bump between 3000-3550A coming from a complex of Fe lines.
- QSOs don't evolve with redshift at the same accretion and mass -- metallicity, lines, kinematics, radio, etc. But there are faster ionized outflows and more frequent broad lines (Biscetti+ 2022, 2023).
- (in press) First mid-IR spectrum of a z>7 QSO. H-alpha and Paschen lines and BB/PL accretion disk continuum + hot torus :: T_dust = 1400 K -> no silicates. Estimate BH mass through several methods. Mostly consistent between
$1-2 \times 10^9 M_\odot$ . No signs of obscuration. - (in prep) Three more z>7 QSOs, finding hot dusty torii again. No obscuration. Potentially hotter than low-z QSOs or has a "hottest dust" component has been present all along?
- (Pizzati+ 2024b) Joint inference of QSO+galaxies, using FLAMINGOS. Conditional LF -> QSO and galaxy properties.
- Large scatter in host halo mass while still compatible with observations. QSO duty cycle is <1%. OIII-emitter galaxies are in much smaller halos
$M_{\rm halo} < 10^{11} M_\odot$ with duty cycles ~20%.
- (Saio & Nandal 2024) Focusing on GR instability (GRI) in this talk. Any SMS with
$\dot{M} \ge 0.05 M_\odot/yr$ or if it reaches 80,000 Msun will experience GRI and collapse. About the PISN range, there's still a SN, unlike what previous models have predicted. - (Nandal+ 2024a) Dark collapses of SMSs -- followed several stellar masses to their endpoints, e.g. Mdot = 1e-2 Msun/yr reaches 28,000 Msun before collapsing. At the highest end, collapse may occur before hydrogen burning starts.
- (Nandal+ 2024b) Using SMS to match abundance ratios of high-z galaxy observations, e.g. GN-z11 with high N/O fractions.
- (Escala 2021) Central massive object formation based on three timescales: collsional, Hubble, and relaxation. Their equalities result in linear relations in mass-radius space.
- (Vergara, Escala+ 2023) Simulated several nuclear star clusters with direct N-body in this M-R space to test Escala (2021) predictions. Showed that the BH growth(?) efficiency increases only after their critical mass.
- (Prole+ 2022, 2023) Sub-AU resolution simulations of Pop III star formation, showing an IMF that peaks around 0.5 Msun and cuts off at 10 Msun in this halo, plus a single 30 Msun star.
- (Prole+ 2024) Including atomic cooling halos, find a power-law IMF at high mass (>3 Msun).
- (in prep) Dynamically heated halo. Atomic and warm envelope with a molecular and cool core within ~10 pc. Simulations still running with stars forming.
- (Gordon+ 2024) Characterizing accretion onto stellar-mass BHs. Increasing resolution from Smith+ (2018). 1.2 Msun DM resolution. BH particle with an initial mass of 270 Msun. Comparing Bondi-Hoyle-Lyttleton (BHL) accretion model and a sink particle model, using the mass flux (MF) through a sphere with a set radius.
- BHL and MF accretion models produce similar results at high resolution, however the MF over-accretes leaving a low density sphere around it because it consumes all gas within the accretion radius (~8 dx).
- As the resolution increases, more disk structure (smooth 1R_HL -> spiral arms 4R_HL -> fragmentation 16R_HL)
- They also simulated a 10 Msun BH but is ejected from the self-gravitating disk. Grows moderately (up to 29 Msun)
