Stellar populations in NGC 5128 with the VLT: Evidence for recent star formation

Rejkuba, M.; Minniti, D.; Silva, David R.; Bedding, Timothy R.

doi:10.1051/0004-6361:20011315

Cited by 53 publications

(113 citation statements)

References 78 publications

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“…The AGB-tip in the Maffei 1 deep field occurs near M K ∼ −8.7, and thus is comparable to the peak brightnesses in M32 (Davidge 2000a;Davidge et al 2000), and the bulges of the Milky-Way and M31 (Davidge 2001a). Rejkuba et al (2001) find that the peak M K in the outer regions of NGC 5128 is ∼ −8.8, which is also in remarkable agreement with the peak brightness in Maffei 1.…”

Section: The Stellar Content Of Maffei 1 and Other Spheroidssupporting

confidence: 76%

The Upper Asymptotic Giant Branch of the Elliptical Galaxy Maffei 1 and Comparisons with M32 and NGC 5128

Davidge

2002

The Astronomical Journal

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Deep near-infrared images obtained with adaptive optics (AO) systems on the Gemini North and Canada-France-Hawaii telescopes are used to investigate the bright stellar content and central regions of the nearby elliptical galaxy Maffei 1. Stars evolving on the upper asymptotic giant branch (AGB) are resolved in a field 3 arcmin from the center of the galaxy. The locus of bright giants on the (K, H − K) color-magnitude diagram is consistent with a population of stars like those in Baade's Window reddened by E(H − K) = 0.28 ± 0.05 mag. This corresponds to A V = 4.5 ± 0.8 mag, and is consistent with previous estimates of the line of sight extinction computed from the integrated properties of Maffei 1. The AGB-tip occurs at K = 20.0, which correponds to M K = −8.7; hence, the AGB-tip brightness in Maffei 1 is comparable to that in M32, NGC 5128, and the bulges of M31 and the Milky-Way. The near-infrared luminosity functions (LFs) of bright AGB stars in Maffei 1, M32, and NGC 5128 are also in excellent agreement, both in terms of overall shape and the relative density of infrared-bright stars with respect to the fainter stars that dominate the light at visible and red wavelengths. It is concluded that the brightest AGB stars in Maffei 1, NGC 5128, M32, and the bulge of M31 trace an old, 1 Visiting Astronomer, Canada-France-Hawaii Telescope, which is operated by the National Research Council of Canada, the Centre National de le Recherche Scientifique, and the University of Hawaii.2 Visiting Astronomer, Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Research Council (Canada), the National Science Foundation (United States), the Particle Physics and Astronomy Research Council (United Kingdom), the Australian Reasearch Council (Australia), CNPq (Brazil), and CONICET (Argentina).-2 -metal-rich population, rather than an intermediate age population. It is also demonstrated that Maffei 1 contains a distinct red nucleus, and this is likely the optical signature of low-level nuclear activity and/or a distinct central stellar population. Finally, there is an absence of globular clusters brighter than the peak of the globular cluster LF in the central 700 × 700 parsecs of Maffei 1.

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Section: The Stellar Content Of Maffei 1 and Other Spheroidssupporting

confidence: 76%

The Upper Asymptotic Giant Branch of the Elliptical Galaxy Maffei 1 and Comparisons with M32 and NGC 5128

Davidge

2002

The Astronomical Journal

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“…Other mechanisms, such as dissipationless mergers of bulge-dominated galaxies ) may be able to better reproduce the elliptical galaxies with the smallest (V/ ) Ã and most negativeā 4 /a parameters. However, this does raise a host of other problems, including reproducing the fundamental plane and M BH -0 relations (e.g., Nipoti et al 2003;Kazantzidis et al 2005), as well as the presence of intermediate-age stellar populations and globular clusters in elliptical galaxies (e.g., Schweizer et al 1990;Whitmore et al 1997Whitmore et al , 2002Rejkuba et al 2001;Thomas et al 2004;Goudfrooij et al 2004;Trager et al 2005). Moreover, with recent deep surveys indicating the presence of a red sequence in color-magnitude diagrams of galaxies as far back as z $ 1 (Hogg et al 2004;Bell et al 2004;McIntosh et al 2005), new questions have been raised concerning the limitations of disk-disk mergers versus other mechanisms, including dissipationless mergers between bulge-dominated galaxies.…”

Section: Summary and Discussionmentioning

confidence: 99%

A Survey of Merger Remnants. III. Are Merger Remnants Supported by Rotation or Anisotropy?

Rothberg¹,

Joseph²

2006

Astron J

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A growing body of observational evidence suggests that the luminosity, photometric shape, and amount of rotational or anisotropic support in elliptical galaxies may provide vital clues to how they formed. Elliptical galaxies appear to fall into two distinct categories based on these parameters: bright, boxy-shaped, and having little or no rotation, and less luminous, disky-shaped, and having significant rotation. One viable formation scenario is the ''merger hypothesis,'' in which two disk galaxies merge to form a new elliptical galaxy. A comparison of the luminosity, photometric shape, and amount of rotation in advanced merger remnants may shed more light on the possible formation scenarios of elliptical galaxies. Yet little observational data exist for such merger remnants. This paper is the third in a series investigating the photometric and kinematic properties of a sample of 51 optically selected advanced merger remnants. Presented here are K-band isophotal shapes and spatially resolved kinematics for a subsample of 37 merger remnants. The results show that $11% of the sample is boxy and anisotropically supported, while $47% is disky and rotationally supported. The remainder of the sample shows variations among expected correlations between shape and rotation. This may suggest that the isophotal shapes are still ''in flux.'' There does appear to be a lower limit to the amount of anisotropy observed in the merger remnants. This may provide an observational diagnostic for discriminating among formation scenarios in elliptical galaxies.

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“…Later work identified regions of ongoing star formation in the filament (Mould et al 2000;Rejkuba et al 2001), while bright UV emission was detected with GALEX (Neff et al 2015).…”

Section: Special Region: the Outer Filamentmentioning

confidence: 99%

The missing link: Tracing molecular gas in the outer filament of Centaurus A

Morganti

Oosterloo

Oonk

et al. 2016

A&A

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We report the detection, using observations of the CO(2−1) line performed with the Atacama Pathfinder EXperiment (APEX), of molecular gas in the region of the outer filament of Centaurus A, a complex region known to show various signatures of an interaction between the radio jet, an H i cloud, and ionised gas filaments. We detect CO(2−1) at all observed locations, which were selected to represent regions with very different physical conditions. The H 2 masses of the detections range between 0.2 × 10 6 and 1.1 × 10 6 M , for conservative choices of the CO to H 2 conversion factor. Surprisingly, the stronger detections are not coincident with the H i cloud, but instead are in the region of the ionised filaments. We also find variations in the widths of the CO(2−1) lines throughout the region, with broader lines in the region of the ionised gas, i.e. where the jet-cloud interaction is strongest, and with narrow profiles in the H i cloud. This may indicate that the molecular gas in the region of the ionised gas has the momentum of the jet-cloud interaction encoded in it, in the same way as the ionised gas does. These molecular clouds may therefore be the result of very efficient cooling of the down-stream gas photo-or shock-ionised by the interaction. On the other hand, the molecular clouds with narrower profiles, which are closer to or inside the H i cloud, could be pre-existing cold H 2 cores which manage to survive the effects of the passing jet.

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Stellar populations in NGC 5128 with the VLT: Evidence for recent star formation

Cited by 53 publications

References 78 publications

The Upper Asymptotic Giant Branch of the Elliptical Galaxy Maffei 1 and Comparisons with M32 and NGC 5128

The Upper Asymptotic Giant Branch of the Elliptical Galaxy Maffei 1 and Comparisons with M32 and NGC 5128

A Survey of Merger Remnants. III. Are Merger Remnants Supported by Rotation or Anisotropy?

The missing link: Tracing molecular gas in the outer filament of Centaurus A

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