Velocity Structure and Variability of [O Iii] Emission in Black Hole Host Globular Cluster Rz2109

Abstract

We present a multi-facility study of the optical spectrum of the extragalactic globular cluster RZ2109, which hosts a bright black hole X-ray source. The optical spectrum of RZ2109 shows strong and very broad [O III]λλ4959,5007 emission in addition to the stellar absorption lines typical of a globular cluster. We use observations over an extended period of time to constrain the variability of these [O III] emission lines. We find that the equivalent width of the lines is similar in all of the datasets; the change in L[O III]λ5007 is < ∼ 10% between the first and last observations, which were separated by 467 days. The velocity profile of the line also shows no significant variability over this interval. Using a simple geometric model we demonstrate that the observed [O III]λ5007 line velocity structure can be described by a two component model with most of the flux contributed by a bipolar conical outflow of about 1,600 km s −1 , and the remainder from a Gaussian component with a FWHM of several hundred km s −1 .

Discovery of a long-lived, high-amplitude dusty infrared transient

“…As discussed in Section 3.4, the nebular emission lines are broad in each observation, while the allowed hydrogen lines transition from being narrow and single peaked with a broad base to broad and double peaked, with the blue peak suppressed relative to the red. This is a profile commonly seen in bipolar outflows (Steele et al 2011). The separation between peaks observed in the H α profile in 2015 is an order of magnitude higher than one would expect from a Keplerian disc at au scales.…”

Deep spectroscopy of the MV ∼ −14.8 host galaxy of a tidal disruption flare in A1795★

“…For example, a radiatively-driven wind could occur at large (< ∼ 4.6 pc) radii given an initial impulse from the early > ∼ 10 43 erg s −1 flare. Such winds have been attributed to [O III] emission from the Virgo elliptical galaxy NGC4472 globular cluster RZ 2109, possibly in conjunction with a stellar-mass black hole, and require relatively little gas mass (< ∼ 10 −3 M⊙ for L λ5007 ∼ 10 37 erg s −1 Steele et al 2011). Such gas likely exceeds the escape velocity of the galaxy.…”

Slow decline and rise of the broad [O iii] emission line in globular cluster black hole candidate RZ2109

“…We have been monitoring the [OIII]λλ4959,5007 emission of RZ2109 since 2007 to examine how the emission has changed over time, and how changes in the optical emission compare to any changes in the X-ray luminosity. Figure 3 plots the full [OIII]λ5007 equivalent widths from Steele et al (2011) and Table 1 to the X-ray luminosities of RZ2109 taken from Maccarone et al (2010), Dage et al (2018), and Table 2.…”

“…Optical spectroscopy obtained by Zepf et al (2007) revealed a very broad and luminous [OIII]λλ4959,5007 emission lines, with a velocity width of around 2000 km s −1 . The oxygen emission is also variable (Steele et al 2011). RZ2109 is the only globular cluster associated with NGC 4472 to show [OIII]5007 emission, which places constraints on geometric beaming of the system.…”