Research
How close can gas get to a supermassive black hole?
A tidal disruption event is a flare created by a star's unraveling as it falls too close to a supermassive black hole. That flare is very energetic, outdoing most supernovae in brightness and even outshining the galaxy hosting the black hole itself! When that very bright flare full of visible, ultraviolet, and even X-ray light shines on intervening gas, that gas can become ionized, releasing its own light that we can detect millions of lightyears away. But astronomical "gas" (mostly Hydrogen and Helium but also including anything else that could come from a star like Iron and Oxygen) makes up ~99% of the visible matter floating around space, so why do we only see its interaction with TDE flares sometimes? Why don't all TDE flares end up hitting gas and ionizing it; is it because the black holes we are looking at happen to have bare environments surrounding them, which is what makes us able to find the TDE in the first place? Or are we discounting other events that could be TDEs after all? The quest continues!
A map of the gas uncovered from a TDE whose flare intersected the gas, making it glow from ionization! This gas is closer to the SMBH than previously expected, highlighting that SMBH environments can still reflect wider regions of potential star formation, and stands to show how TDE energetics can impact galaxies long-term.
We compared our near-infrared data of an otherwise-normal TDE (the red points) to what we would have expected at this wavelength (the red dashed line) - we can see immediately it is MUCH brighter than expected! We modeled what kind of dust would have to be near the black hole to intercept the tidal disruption event's flare and reproduce our observations (turquoise dosh-dat and dotted lines). Our data is best explained by two rings of graphite dust sitting around a supermassive black hole at the tiniest scales yet uncovered.
What about dust?
We found a tidal disruption event that looked totally normal (as "normal" as a TDE can be when we've only discovered ~100 of them so far, and there are plenty of weird ones) but completely stumped us in one small component. When tracking the event in near-infrared wavelengths, it was simply brighter than we knew to expect based on every other TDE studied so far, and it showed a sudden increase in brightness at a point with the flare was otherwise getting dimmer in every other wavelength! We know that dust (the 1% left of visible matter that's not gas, AKA larger structures of more than ~10 atoms in a molecule at a time, mostly carbon and silicate grains) has the distinct property of absorbing light but re-emitting only the reddest part of that light. So, we suspected that the unique redness of this event, and the extra flare when it was expected to keep fading, were the result of dust nearby the supermassive black hole where the flare originated. By modeling how dust would interact with TDE light, we found that the dust would have to exist in concentric rings at very, very small scales near the SMBH - the first discovery of its kind!
Publications
Lead author works:
Mapping the Inner 0.1 pc of a Supermassive Black Hole Environment with the Tidal Disruption Event and Extreme Coronal Line Emitter AT 2022upj. Newsome, M., Arcavi, I., Howell, D. A., McCully, C., Terreran, G., Hosseinzadeh, G., Bostroem, K. A., Dgany, Y., Farah, J., Faris, S., Padilla-Gonzalez, E., Pellegrino, C., Andrews, M. 12/2024. ApJ, 977, 258. DOI: 10.3847/1538-4357/ad8a69
Probing the Subparsec Dust of a Supermassive Black Hole with the Tidal Disruption Event AT 2020mot. Newsome, M., Arcavi, I., Howell, D. A., Burke, J., De, K., Dgany, Y., Faris, S., Farah, J., Hiramatsu, D., McCully, C., Padilla-Gonzalez, E., Pellegrino, C., Terreran, G. 02/2024. ApJ, 961, 239. DOI: 10.3847/1538-4357/ad036e
Selected co-author works:
A systematically-selected sample of luminous, long-duration, ambiguous nuclear transients. Wiseman, P., Williams, R. D., Arcavi, I., Galbany, L., Graham, M. J., Honig, S., Newsome, M., Subrayan, B., Sullivan, M., Wang, Y., Ilic, D., Nicholl, M., Oates, S., Petrushevska, T., Smith, K. W. 01/2025, MNRAS, staf116. DOI: 10.1093/mnras/staf116
AT2023vto: An Exceptionally Luminous Helium Tidal Disruption Event from a Massive Star. Kumar, H., Berger, E., Hiramatsu, D., Gomez, S., Blanchard, P. K., Cendes, Y., Bostroem, K. A., Farah, J., Padilla Gonzalez, E., Howell, A., McCully, C., Newsome, M., Terreran, G. 10/2024, ApJ, 974, 316. DOI: 10.3847/2041-8213/ad7eb8
Light-curve Structure and Hα Line Formation in the Tidal Disruption Event AT 2019azh. Faris, S., Arcavi, I., Makrygianni, L., Hiramatsu, D., Terreran, G., Farah, J., Howell, D. A., McCully, C., Newsome, M., Padilla Gonzalez, E., Pellegrino, C., Bostroem, K. A., Abojanb, W., Lam, M. C., Tomasella, L., Brink, T. G., Filippenko, A. V., French, K. D., Clark, P., Graur, O., Leloudas, G., Gromadzki, M., Anderson, J. P., Nicholl, M., Gutierrez, C. P., Kankare, E., Inserra, C., Galbany, L., Reynolds, T., Mattila, S., Heikkila, T., Wang, Y., Onori, F., Wevers, T., Coughlin, E. R., Charalampopoulos, P., Johansson, J. 07/2024, ApJ, 969, 104. DOI: 10.3847/1538-4357/ad4a72
A New Population of Mid-infrared-selected Tidal Disruption Events: Implications for Tidal Disruption Event Rates and Host Galaxy Properties. Masterson, M., De, K., Panagiotou, C., Kara, E., Arcavi, I., Eilers, A.-C., Frostig, D., Gezari, S., Grotova, I., Liu, Z., Malyali, A., Meisner, A. M., Merloni, A., Newsome, M., Rau, A., Simcoe, R. A., van Velzen, S. 02/2024, ApJ, 961, 211. DOI: 10.3847/1538-4357/ad18bb
AT 2020wey and the class of faint and fast tidal disruption events. Charalampopoulos, P., Pursiainen, M., Leloudas, G., Arcavi, I., Newsome, M., Schulze, S., Burke, J., Nicholl, M. 05/2023, A&A, 673, A95. DOI: 10.1051/0004-6361/202245065
An elliptical accretion disk following the tidal disruption event AT 2020zso. Wevers, T., Nicholl, M., Guolo, M., Charalampopoulos, P., Gromadzki, M., Reynolds, T. M., Kankare, E., Leloudas, G., Anderson, J. P., Arcavi, I., Cannizzaro, G., Chen, T.-W., Ihanec, N., Inserra, C., Guti´errez, C. P., Jonker, P. G., Lawrence, A., Magee, M. R., M¨uller-Bravo, T. E., Onori, F., Ridley, E., Schulze, S., Short, P., Hiramatsu, D., Newsome, M., Terwel, J. H., Yang, S., Young, D. 10/2022, A&A, 666, A6. DOI: 10.1051/0004-6361/202142616
Selected TDEs classified by the Nuclear Transients program at LCO
Name RA DEC Redshift
TDE 2024yqo 08:11:12.484 +20:22:49.44 0.06168
TDE 2024tvd 17:10:42.585 +28:50:15.11 0.044938
TDE 2023mhs 13:43:15.681 +19:15:00.90 0.0482
TDE 2022upj 00:23:56.846 -14:25:23.22 0.054
TDE 2022dbl 12:20:45.010 +49:33:04.68 0.0284
TDE 2022bdw 08:25:10.360 +18:34:57.50 0.03782
TDE 2021utq 15:18:29.080 +73:21:31.43 0.127
TDE 2020afhd 03:13:35.700 -02:09:06.37 0.027
TDE 2020vdq 10:08:53.440 +42:43:00.23 0.044
TDE 2018mli 11:07:52.832 +44:21:44.99 0.076