OASIS high‐resolution integral field spectroscopy of the SAURON ellipticals and lenticulars

McDermid, Richard M.; Emsellem, Éric; Cappellari, Michele; Küntschner, H.; Bacon, Roland; Bureau, Martin; Copin, Y.; Davies, R. L.; Falcón-Barroso, J.; Ferruit, Pierre; Krajnović, Davor; Peletier, Reynier F.; Shapiro, Kristen L.; Wernli, F.; Zeeuw, PT de

doi:10.1002/asna.200310184

Cited by 16 publications

(15 citation statements)

References 8 publications

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“…We measured an exceptionally enhanced [Na/H] = 0.67 +0.13 −0.13 dex in M85, which is typical of the cores of old, massive ETGs (Spiniello et al 2012). M85, however, is known to have a young, counter-rotating, kinematically decoupled core within the central 1 that may have formed from a recent, wet galaxy merger (McDermid et al 2004;Terlevich, & Forbes 2002). This burst of star formation in the core of M85 may be the cause of the enhanced Na abundance.…”

Section: Comparison To Previous Imf Resultsmentioning

confidence: 83%

Initial Mass Function Variation in Two Elliptical Galaxies Using Near-infrared Tracers

Meyer

Sivanandam

Moon

2019

ApJ

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Using integral field spectroscopy, we demonstrate that gravity-sensitive absorption features in the zJ-band (0.9-1.35 µm) can constrain the low-mass stellar initial mass function (IMF) in the cores of two elliptical galaxies, M85 and M87. Compared to the visible bands, the near-infrared (NIR) is more sensitive to light from low-mass dwarf stars, whose relative importance is the primary subject of the debate over IMF variations in nearby galaxies. Our analysis compares the observed spectra to the latest stellar population synthesis models by employing two different methods: equivalent widths and spectral fitting. We find that the IMF slopes in M85 are similar to the canonical Milky Way IMF with a median IMF-mismatch parameter α K = 1.26. In contrast, we find that the IMF in M87 is steeper than a Salpeter IMF with α K = 2.77. The derived stellar population parameters, including the IMF slopes, are consistent with those from recent results in the visible bands based on spectroscopic and kinematic techniques. Certain elemental abundances, e.g. Na and Fe, have dramatic effects on the IMF-sensitive features and therefore the derived IMF slopes. We show evidence for a high [Na/H] ∼ 0.65 dex in the core of M85 from two independent Na I absorption features. The high Na abundance may be the result of a recent galactic merger involving M85. This suggests that including [Na/H] in the stellar population model parameters is critical for constraining the IMF slopes in M85. These results confirm the viability of using NIR absorption features to investigate IMF variation in nearby galaxies.

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Section: Comparison To Previous Imf Resultsmentioning

confidence: 83%

Initial Mass Function Variation in Two Elliptical Galaxies Using Near-infrared Tracers

Meyer

Sivanandam

Moon

2019

ApJ

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“…Note that the counter-rotating "kinematically decoupled core" (KDC) found in the OASIS data does not necessarily imply deviations from axisymmetry (McDermid et al 2004). As can be seen from the images of the galaxy (Figures 6 and 7), the change in ellipticity near the center ( = 0.6 at r ≈ 0.…”

Section: Axisymmetric or Eccentric Disk?mentioning

confidence: 86%

Is There a Black Hole in NGC 4382?

Gültekin

Richstone

Gebhardt

et al. 2011

ApJ

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We present Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph observations of the galaxy NGC 4382 (M85) and axisymmetric models of the galaxy to determine mass-to-light ratio (ϒ V ) and central black hole mass (M BH ). We find7 M at an assumed distance of 17.9 Mpc, consistent with no black hole. The upper limit, M BH < 9.6 × 10 7 M (2σ ) or M BH < 1.4 × 10 8 (3σ ), is consistent with the current M-σ relation, which predicts M BH = 8.8 × 10 7 M at σ e = 182 km s −1 , but low for the current M -L relation, which predicts M BH = 7.8 × 10 8 M at L V = 8.9 × 10 10 L ,V . HST images show the nucleus to be double, suggesting the presence of a nuclear eccentric stellar disk, analogous to the Tremaine disk in M31. This conclusion is supported by the HST velocity dispersion profile. Despite the presence of this non-axisymmetric feature and evidence of a recent merger, we conclude that the reliability of our black hole mass determination is not hindered. The inferred low black hole mass may explain the lack of nuclear activity.

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“…The inner parts of elliptical or dwarf elliptical galaxies have shown via adaptive optics new kinematically decoupled structures (cores or central discs), which were previously unresolved (McDermid et al 2004b; Bacon et al 2001). Similarly, if decoupled structures are unresolved and remain so, even with adaptive optics, it may still be possible to separate components in age–velocity space.…”

Section: Discussionmentioning

confidence: 99%

STECKMAP: STEllar Content and Kinematics from high resolution galactic spectra via Maximum A Posteriori

Ocvirk

Lançon

Thiébaut

2006

Monthly Notices of the Royal Astronomical Society

175

140

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We introduce STECKMAP (STEllar Content and Kinematics via Maximum A Posteriori likelihood), a method for recovering the kinematic properties of a galaxy simultaneously with its stellar content from integrated light spectra. It is an extension of STECMAP (presented recently by Ocvirk et al.) to the general case where the velocity distribution of the underlying stars is also unknown. The reconstructions of the stellar age distribution, the age–metallicity relation and the line‐of‐sight velocity distribution (LOSVD) are all non‐parametric, i.e. no specific shape is assumed. The only a priori conditions that we use are positivity and the requirement that the solution is smooth enough. The smoothness parameter can be set by generalized cross‐validation according to the level of noise in the data in order to avoid overinterpretation. We use single stellar populations (SSPs) from Pégase‐HR (R= 10 000, λ= 4 000–6 800 Å, from Le Borgne et al.) to test the method through realistic simulations. Non‐Gaussianities in LOSVDs are reliably recovered with signal‐to‐noise ratio (SNR) as low as 20 per 0.2 Å pixel. It turns out that the recovery of the stellar content is not degraded by the simultaneous recovery of the kinematic distribution, so that the resolution in age and error estimates given in Ocvirk et al. remain appropriate when used with STECKMAP. We also explore the case of age‐dependent kinematics (i.e. when each stellar component has its own LOSVD). We separate the bulge and disc components of an idealized simplified spiral galaxy in integrated light from high‐quality pseudo‐data (SNR = 100 per pixel, R= 10 000), and constrain the kinematics (mean projected velocity, projected velocity dispersion) and age of both components.

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OASIS high‐resolution integral field spectroscopy of the SAURON ellipticals and lenticulars

Cited by 16 publications

References 8 publications

Initial Mass Function Variation in Two Elliptical Galaxies Using Near-infrared Tracers

Initial Mass Function Variation in Two Elliptical Galaxies Using Near-infrared Tracers

Is There a Black Hole in NGC 4382?

STECKMAP: STEllar Content and Kinematics from high resolution galactic spectra via Maximum A Posteriori

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