J/A+A/689/A342 Globular cluster candidates in NGC 4696 (Federle+, 2024)
The turbulent life of NGC 4696 as told by its globular cluster system.
Federle S., Gomez M., Mieske S., Harris W.E., Hilker M., Yegorova I.A.,
Harris G.L.H.
<Astron. Astrophys. 689, A342 (2024)>
=2024A&A...689A.342F 2024A&A...689A.342F (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Clusters, globular ; Galaxies, photometry ;
Photometry, SDSS
Keywords: galaxies: elliptical and lenticular, cD - galaxies: interactions -
galaxies: clusters: individual: NGC 4696 - galaxies: photometry
galaxies: star clusters: general
Abstract:
Globular clusters (GCs) are remarkable witnesses of their host
galaxy's interaction and merger history.
Our aim is to perform the photometric analysis of the globular cluster
system (GCS) of the giant elliptical NGC 4696, which is the brightest
member of Centaurus (d=38.36Mpc), a rich and dynamically young galaxy
cluster.
We obtained deep Magellan 6.5m/MegaCam (g', r', i') photometry, with
which we identified a sample of 3818 stellar clusters around NGC 4696
that were analyzed in the context of possible interactions and its
assembly history.
After carefully modeling and subtracting the galaxy light, we used
selection criteria based on the shape, colors, and magnitudes to
identify GC candidates. We find a number of features that indicate a
disturbed GCS that points toward a complex evolution with other
neighboring members of Centaurus. Formally, two subpopulations could
be found at (g'-i')0=0.763±0.004 and (g'-i')0=1.012±0.004.
Moreover, the color distribution does not show the presence of a
significant blue tilt, but it presents a trend with the radius, where
at small galactocentric distances a unimodal distribution is
preferable to a bimodal one, suggesting the presence of an
intermediate GC population. Besides the color distribution, the
metallicity distribution also shows a bimodal trend, with peaks at
[Fe/H]=-1.363±0.010 and [Fe/H]=-0.488±0.012. The radial density
profiles show different slopes for the blue and red populations and
the azimuthal distributions are well fitted by an asymmetrical
sinusoidal function, with peaks projecting toward two nearby galaxies,
NGC 4696B and NGC 4709, indicating past interactions among these three
galaxies. Finally, we derived a GC specific frequency of
SN=6.8±0.9, in good agreement with the values obtained for
other giant ellipticals and with previously estimated SN of
NGC 4696.
All these results point toward a complex GCS, strongly influenced by
the interaction history of NGC 4696 with the other galaxies of the
Centaurus cluster. In a future work, the spectroscopic follow-up of
the GC candidates analyzed in this study and broadening the
photometric baseline will allow us to highlight the formation and
evolution of the entire Centaurus cluster.
Description:
The photometric data were obtained with Magellan/MegaCam in the g',
r', and i' filters. We observed the central ∼8.795x11.494 arcmin2 of
the Centaurus cluster, covering the giant elliptical galaxy NGC 4696
with the aim to characterize its globular cluster system.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 81 3818 Properties of the globular cluster candidates
of the galaxy NGC 4696
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh Right ascension (J2000)
4- 5 I2 min RAm Right ascension (J2000)
7- 11 F5.2 s RAs Right ascension (J2000)
13 A1 --- DE- Declination (J2000)
14- 15 I2 deg DEd Declination (J2000)
17- 18 I2 arcmin DEm Declination (J2000)
20- 24 F5.2 arcsec DEs Declination (J2000)
26- 30 F5.3 --- Classgp Stellarity index in the g' band
32- 36 F5.3 --- Classrp Stellarity index in the r' band
38- 42 F5.3 --- Classip Stellarity index in the i' band
44- 49 F6.3 mag gp0mag Extinction corrected magnitude in the
g' band (AB) (1)
51- 55 F5.3 mag e_gp0mag Error on the g'0 magnitude
57- 62 F6.3 mag rp0mag Extinction corrected magnitude in the
r' band (AB) (1)
64- 68 F5.3 mag e_rp0mag Error on the r'0 magnitude
70- 75 F6.3 mag ip0mag Extinction corrected magnitude in the
i' band (AB) (1)
77- 81 F5.3 mag e_ip0mag Error on the i'0 magnitude
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Note (1): The adopted absorption corrections are taken from
Schlafly & Finkbeiner (2011ApJ...737..103S 2011ApJ...737..103S).
The magnitudes in our work are in the AB system.
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Acknowledgements:
Sara Federle, sara.federle89(at)gmail.com
(End) Patricia Vannier [CDS] 12-Jun-2024