Extremely Large Telescope

Abstract:

<jats:p>We present accurate mass measurements of the central supermassive black hole (SMBH) in NGC 4736 (M 94). We used the “gold-standard” stellar absorption features (CO band heads) at ∼2.3 μm, as opposed to gas emission lines, to trace the dynamics in the nuclear region, easily resolving the SMBH’s sphere of influence. The analysis uses observations made with the integral field unit of the Near-Infrared Spectrograph (NIRSpec) on the <jats:italic>James Webb</jats:italic> Space Telescope and a surface brightness profile derived from <jats:italic>Hubble</jats:italic> Space Telescope archival images. We used Jeans anisotropic models within a Bayesian framework, and comprehensive Markov chain Monte Carlo optimization, to determine the best-fit black hole mass, orbital anisotropy, mass-to-light ratio, and nucleus kinematical inclination. We obtained a SMBH mass <jats:italic>M</jats:italic><jats:sub>BH</jats:sub> = (1.60 ± 0.16)×10<jats:sup>7</jats:sup> M<jats:sub>⊙</jats:sub> (1<jats:italic>σ</jats:italic> random error), which is consistent with the <jats:italic>M</jats:italic><jats:sub>BH</jats:sub>–<jats:italic>σ</jats:italic> and <jats:italic>M</jats:italic><jats:sub>BH</jats:sub>–<jats:italic>M</jats:italic><jats:sub>⋆</jats:sub> relations. This is the first dynamical measurement of a <jats:italic>M</jats:italic><jats:sub>BH</jats:sub> in NGC 4736 based on the stellar kinematics observed with NIRSpec. We thus settle a longstanding inconsistency between estimates based on nuclear emission-line tracers and the <jats:italic>M</jats:italic><jats:sub>BH</jats:sub>–<jats:italic>σ</jats:italic> relation. Our analysis shows that NIRSpec can detect SMBHs with <jats:italic>M</jats:italic><jats:sub>BH, min</jats:sub> ≈ 5 × 10<jats:sup>6</jats:sup> M<jats:sub>⊙</jats:sub> in galaxies within 5 Mpc and <jats:italic>σ</jats:italic> ≈ 100 km s<jats:sup>−1</jats:sup>.</jats:p>

Abstract:

Like many areas of astrophysics and cosmology, the Vera C. Rubin Observatory will be transformational for almost all the applications of strong lensing, thanks to the dramatic increase in the number of known strong lenses by two orders of magnitude or more and the readily available time-domain data for the lenses with transient sources. In this article, we provide an overview of the forecasted number of discovered lenses of different types and describe the primary science cases these large lens samples will enable. We provide an updated forecast on the joint constraint for the dark energy equation-of-state parameters, w0 and wa, from combining all strong-lensing probes of dark energy. We update the previous forecast from the Rubin Observatory Dark Energy Science Collaboration’s Science Review Document by adding two new crucial strong-lensing samples: lensed type Ia supernovae and single-deflector lenses with measured stellar kinematics. Finally, we describe the current and near-future activities and collaborative efforts within the strong-lensing community in preparation for the arrival of the first real dataset from Rubin in 2026. This article is part of the Theo Murphy meeting issue ‘Multi-messenger gravitational lensing (Part 2)’.