Unravelling the origin of the counter-rotating core in IC 1459 with KMOS and MUSE

Prichard, Laura; Vaughan, Sam P.; Davies, Roger L.

doi:10.1093/mnras/stz1191

Cited by 12 publications

(20 citation statements)

References 142 publications

(210 reference statements)

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“…B3, we see a clear counter-rotating core at the centre of IC 1459. This is well known and well studied (Franx & Illingworth 1988;Cappellari et al 2002;Prichard, Vaughan & Davies 2019). Counter-rotation has long been associated with galaxy mergers (see e.g.…”

Section: B1 Ic1459mentioning

confidence: 92%

Mapping accreted stars in early-type galaxies across the mass–size plane

Davison

Norris

Leaman

et al. 2021

Monthly Notices of the Royal Astronomical Society

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Galaxy mergers are instrumental in dictating the final mass, structure, stellar populations, and kinematics of galaxies. Cosmological galaxy simulations indicate that the most massive galaxies at z = 0 are dominated by high fractions of ‘ex-situ’ stars, which formed first in distinct independent galaxies, and then subsequently merged into the host galaxy. Using spatially resolved MUSE spectroscopy we quantify and map the ex-situ stars in thirteen massive early-type galaxies. We use full spectral fitting together with semi-analytic galaxy evolution models to isolate the signatures in the galaxies’ light which are indicative of ex-situ populations. Using the large MUSE field of view we find that all galaxies display an increase in ex-situ fraction with radius, with massive and more extended galaxies showing a more rapid increase in radial ex-situ fraction (reaching values between ∼30 per cent and 100 per cent at 2 effective radii) compared to less massive and more compact sources (reaching between ∼5 per cent and 40 per cent ex-situ fraction within the same radius). These results are in line with predictions from theory and simulations which suggest ex-situ fractions should increase significantly with radius at fixed mass for the most massive galaxies.

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Section: B1 Ic1459mentioning

confidence: 92%

Mapping accreted stars in early-type galaxies across the mass–size plane

Davison

Norris

Leaman

et al. 2021

Monthly Notices of the Royal Astronomical Society

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“…The galaxy hosts an active galactic nucleus with two symmetric radio jets (Tingay & Edwards 2015). Stellar kinematics revealed the existence of a fast counter-rotating stellar core that might result from the accretion of counter-rotating cold gas streams in early times (Franx & Illingworth 1988;Prichard et al 2019).…”

Section: The Ic 1459 Groupmentioning

confidence: 99%

VEGAS: a VST Early-type GAlaxy Survey

Iodice

Spavone

Cattapan

et al. 2020

A&A

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Context. This paper is based on the multi-band VST Early-type GAlaxy Survey (VEGAS) with the VLT Survey Telescope (VST). We present new deep photometry of the IC 1459 group in g and r band. Aims. The main goal of this work is to investigate the photometric properties of the IC 1459 group, and to compare our results with those obtained for other galaxy groups studied in VEGAS, in order to provide an initial view of the variation of their properties as a function of the evolution of the system. Methods. For all galaxies in the IC 1459 group, we fit isophotes and extract the azimuthally averaged surface-brightness profiles, the position angle, and ellipticity profiles as a function of the semi-major axis. We also extract the average colour profile. In each band, we estimate the total magnitude, effective radius, mean colour, and total stellar mass for each galaxy in the group. We then look at the structure of the brightest galaxies and the faint features in their outskirts, considering also the intragroup component. Results. The wide field of view, long integration time, high angular resolution, and arcsec-level seeing of OmegaCAM at VST allow us to map the light distribution of IC 1459 down to a surface brightness level of 29.26 mag arcsec−2 in g band and 28.85 mag arcsec−2 in r band, and out to 7−10Re, and to detect the optical counterpart of HI gas around IC 1459. We also carry out an in-depth exploration of three low-density environments and provide information to understand how galaxy and group properties change with the group evolution stage. Conclusions. Good agreement is found between our results and predictions of numerical simulations regarding the structural properties of the brightest galaxies of the groups. We suggest that the structure of the outer envelope of he brightest cluster galaxies (i.e. the signatures of past mergers and tidal interactions), the intra-group light, and the HI amount and distribution may be used as indicators of the evolutionary stage and mass assembly of galaxy groups.

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“…The MUSE data used in this work is the same cube presented and prepared as described in Prichard et al (2019). We briefly summarise the observations and reduction of the MUSE cube here.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

“…A recent optical (MUSE: Multi-Unit Spectroscopic Explorer, Bacon et al 2010) and infrared (KMOS: K-band Multi-Object Spectrograph, Sharples et al 2013) IFU study of IC 1459 investigated the evolution of the galaxy focusing on the stellar populations, initial mass function (IMF), and stellar kinematics (Prichard et al 2019). The stellar velocity dispersion revealed that IC 1459 is dynamically hot along the major axis, which is indicative of counter-rotating stel-lar components extending throughout the galaxy beyond the core.…”

Section: Introductionmentioning

confidence: 99%

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Deciphering the Origin of Ionized Gas in IC 1459 with VLT/MUSE

Mulcahey,

Prichard,

Krajnovic

et al. 2021

Preprint

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IC 1459 is an early-type galaxy (ETG) with a rapidly counter-rotating stellar core, and is the central galaxy in a gas-rich group of spirals. In this work, we investigate the abundant ionized gas in IC 1459 and present new stellar orbital models to connect its complex array of observed properties and build a more complete picture of its evolution. Using the Multi-Unit Spectroscopic Explorer (MUSE), the optical integral field unit (IFU) on the Very Large Telescope (VLT), we examine the gas and stellar properties of IC 1459 to decipher the origin and powering mechanism of the galaxy's ionized gas. We detect ionized gas in a non-disk-like structure rotating in the opposite sense to the central stars. Using emission-line flux ratios and velocity dispersion from full-spectral fitting, we find two kinematically distinct regions of shocked emission-line gas in IC 1459, which we distinguished using narrow (𝜎 ≤ 155 km s −1 ) and broad (𝜎 > 155 km s −1 ) profiles. Our results imply that the emission-line gas in IC 1459 has a different origin than that of its counter-rotating stellar component. We propose that the ionized gas is from late-stage accretion of gas from the group environment, which occurred long after the formation of the central stellar component. We find that shock heating and AGN activity are both ionizing mechanisms in IC 1459 but that the dominant excitation mechanism is by post-asymptotic giant branch stars from its old stellar population.

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Unravelling the origin of the counter-rotating core in IC 1459 with KMOS and MUSE

Cited by 12 publications

References 142 publications

Mapping accreted stars in early-type galaxies across the mass–size plane

Mapping accreted stars in early-type galaxies across the mass–size plane

VEGAS: a VST Early-type GAlaxy Survey

Deciphering the Origin of Ionized Gas in IC 1459 with VLT/MUSE

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