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Main Authors: McDonald, Michael, Khullar, Gourav, Lagattuta, David, Mahler, Guillaume, Dattathri, Shashank, Diego, Jose M., Edge, Alastair C., Floyd, Benjamin, Gladders, Michael D., Hughes, Scott A., Jauzac, Mathilde, Khonji, Nader, Leroy, Gavin, Massey, Richard, Montes, Mireia, Natarajan, Priyamvada, Reefe, Michael, Sharon, Keren, Bosch, Frank van den, Werner, Stepane, Zitrin, Adi
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2603.10104
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author McDonald, Michael
Khullar, Gourav
Lagattuta, David
Mahler, Guillaume
Dattathri, Shashank
Diego, Jose M.
Edge, Alastair C.
Floyd, Benjamin
Gladders, Michael D.
Hughes, Scott A.
Jauzac, Mathilde
Khonji, Nader
Leroy, Gavin
Massey, Richard
Montes, Mireia
Natarajan, Priyamvada
Reefe, Michael
Sharon, Keren
Bosch, Frank van den
Werner, Stepane
Zitrin, Adi
author_facet McDonald, Michael
Khullar, Gourav
Lagattuta, David
Mahler, Guillaume
Dattathri, Shashank
Diego, Jose M.
Edge, Alastair C.
Floyd, Benjamin
Gladders, Michael D.
Hughes, Scott A.
Jauzac, Mathilde
Khonji, Nader
Leroy, Gavin
Massey, Richard
Montes, Mireia
Natarajan, Priyamvada
Reefe, Michael
Sharon, Keren
Bosch, Frank van den
Werner, Stepane
Zitrin, Adi
contents We present new observations from JWST NIRCam that reveal a striking kpc-wide cavity in the stellar distribution of the central galaxy in the cluster Abell402. Supporting data from HST allow us to rule out extinction due to dust as an explanation and, instead, suggest that this is a localized depression in the stellar density field corresponding to ~2x10^9 Msun in missing stars within a volume of 0.5kpc^3. On larger scales, both the JWST and HST data show evidence for a 2.2kpc flattened core in the stellar distribution (on which the smaller-scale cavity is superimposed), which implies the presence of a central ultra-massive black hole with M_BH = 6 +/- 4 x10^10 Msun. We report evidence for a mid-IR-bright point source at one edge of the cavity, suggesting that this black hole is actively accreting. MUSE spectroscopy reveal that this source is a LINER AGN and that there is a second candidate AGN on the opposite side of the cavity with a relative velocity of 370km/s -- if real, this implies the presence of a kpc-separation dual AGN with a total binary mass of 6 +/- 2 x10^10 Msun, which would make this the most massive binary black hole system discovered to date. We propose that this unique stellar cavity is the result of a short-lived dynamical interaction between at least one supermassive black hole and the background stellar density field, caused either by three-body scattering during binary hardening or the induction of a dipole instability in the stellar density field.
format Preprint
id arxiv_https___arxiv_org_abs_2603_10104
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A Kiloparsec-Scale Stellar Cavity in the Center of Abell402-BCG May be Caused by Dynamic Interactions with an Ultramassive Black Hole
McDonald, Michael
Khullar, Gourav
Lagattuta, David
Mahler, Guillaume
Dattathri, Shashank
Diego, Jose M.
Edge, Alastair C.
Floyd, Benjamin
Gladders, Michael D.
Hughes, Scott A.
Jauzac, Mathilde
Khonji, Nader
Leroy, Gavin
Massey, Richard
Montes, Mireia
Natarajan, Priyamvada
Reefe, Michael
Sharon, Keren
Bosch, Frank van den
Werner, Stepane
Zitrin, Adi
Astrophysics of Galaxies
We present new observations from JWST NIRCam that reveal a striking kpc-wide cavity in the stellar distribution of the central galaxy in the cluster Abell402. Supporting data from HST allow us to rule out extinction due to dust as an explanation and, instead, suggest that this is a localized depression in the stellar density field corresponding to ~2x10^9 Msun in missing stars within a volume of 0.5kpc^3. On larger scales, both the JWST and HST data show evidence for a 2.2kpc flattened core in the stellar distribution (on which the smaller-scale cavity is superimposed), which implies the presence of a central ultra-massive black hole with M_BH = 6 +/- 4 x10^10 Msun. We report evidence for a mid-IR-bright point source at one edge of the cavity, suggesting that this black hole is actively accreting. MUSE spectroscopy reveal that this source is a LINER AGN and that there is a second candidate AGN on the opposite side of the cavity with a relative velocity of 370km/s -- if real, this implies the presence of a kpc-separation dual AGN with a total binary mass of 6 +/- 2 x10^10 Msun, which would make this the most massive binary black hole system discovered to date. We propose that this unique stellar cavity is the result of a short-lived dynamical interaction between at least one supermassive black hole and the background stellar density field, caused either by three-body scattering during binary hardening or the induction of a dipole instability in the stellar density field.
title A Kiloparsec-Scale Stellar Cavity in the Center of Abell402-BCG May be Caused by Dynamic Interactions with an Ultramassive Black Hole
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2603.10104