A close look at the Centaurus A group of galaxies

Crnojević, Denija; Grebel, Eva K.; Cole, A. A.

doi:10.1051/0004-6361/201015474

Cited by 16 publications

(46 citation statements)

References 113 publications

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“…As already extensively discussed in Crnojević et al (2011a), at an average Galactic latitude of b ∼ 20 • the foreground stellar contamination from Milky Way stars is not negligible. This effect can be estimated by simulating the Galactic foreground stars with theoretical models as, for example, the TRILEGAL models (Girardi et al 2005), and then overplotting their expected distribution on to the CMDs of the target dwarf galaxies (see, e.g., Fig.…”

Section: Color-magnitude Diagramsmentioning

confidence: 65%

“…We afterwards apply stricter quality cuts (−0.2 ≤ sharpness ≤ 0.2) in order to separate bona fide stars from spurious objects. For more details about the quality parameters and cuts, we refer the reader to the explanation in Crnojević et al (2011a).…”

Section: Data and Photometrymentioning

confidence: 99%

“…We note that the models do not always perfectly represent the observed evolutionary sequences, which is particularly true for the RSG phase (e.g., McQuinn et al 2011, and references therein). As already mentioned in Crnojević et al (2011a), the observed RSG sequence is in fact redder than the models, and we thus draw the selection box accordingly to the observed sequence.…”

Section: Color-magnitude Diagramsmentioning

confidence: 99%

“…The first systematic HST study of the resolved stellar populations of its dwarf members was carried out by Karachentsev et al (2002b), followed by more recent, even deeper HST observations (Karachentsev et al 2007). In Crnojević et al (2011a) we derive recent ( < ∼ 1 Gyr) SFHs for five dIrr members of the M 83 subgroup with the synthetic CMD modeling technique (e.g., Dolphin 2002;Cole et al 2007;Cignoni & Tosi 2010).…”

Section: Introductionmentioning

confidence: 99%

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A close look at the Centaurus A group of galaxies

Crnojević

Grebel

Cole

2012

A&A

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Aims. We study a sample of five dwarf irregular galaxies in the CenA/M 83 group, which are companions to the giant elliptical CenA. We aim at deriving their physical properties over their lifetime and compare them to those of dwarfs located in different environments. Methods. We use archival HST/ACS data and apply synthetic color-magnitude diagram fitting in order to reconstruct the past star formation activity of the target galaxies. Results. The average star formation rate for the studied galaxies ranges from 10 −3 M yr −1 up to ∼7 × 10 −2 M yr −1 , and their mean metallicities correlate with their luminosities (from [Fe/H] ∼ −1.4 up to ∼−1.0). The form of the star formation histories varies across the sample, with quiescent periods alternating with intermittent enhancements in the star formation (from a few up to several times the average lifetime value). The dwarfs in this sample formed ∼35% to 60% of their stellar content prior to ∼5 Gyr ago. Conclusions. The resulting star formation histories for the CenA companions are similar to those found for comparable Local Group and M 81 group dwarfs. We consider this sample of dwarfs together with five previously studied M 83 dwarf irregular companions. We find no trend of the average star formation rate with tidal index or distance from the main galaxy of the group. However, dwarfs with higher baryonic masses do show higher average star formation rates, underlining the importance of intrinsic properties in governing the evolution of these galaxies. On the other hand, there is also a clear trend when looking at the recent (∼0.5−1 Gyr) level of activity. Namely, dwarfs within a denser region of the group appear to have had their star formation quenched while dwarfs located in the group outskirts show a wide range of possible star formation rates, thus indicating that external processes play a fundamental role, complementary to mass, in shaping the star formation histories of dwarf galaxies.

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Section: Color-magnitude Diagramsmentioning

confidence: 65%

Section: Data and Photometrymentioning

confidence: 99%

Section: Color-magnitude Diagramsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A close look at the Centaurus A group of galaxies

Crnojević

Grebel

Cole

2012

A&A

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“…How do the stellar populations in the new Centaurus dwarfs compare to Local Group look-alikes? Crnojević et al (2010Crnojević et al ( , 2011aCrnojević et al ( ,b, 2012 conducted an extensive study of the resolved stellar content of dwarf galaxies in the Centaurus group. They investigated their star formation histories and metallicity content, and what effect the denser environment has on shaping these properties.…”

Section: Discussionmentioning

confidence: 99%

New low surface brightness dwarf galaxies in the Centaurus group

Müller

Jerjen

Binggeli

2016

A&A

101

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Context. The distribution of satellite galaxies around the Milky Way and Andromeda and their correlation in phase space pose a major challenge to the standard ΛCDM model of structure formation. Other nearby groups of galaxies are now being scrutinized to test for the ubiquity of the phenomenon. Aims. We conducted an extensive CCD imaging survey for faint, unresolved dwarf galaxies of very low surface brightness in the whole Centaurus group region, encompassing the Cen A and M 83 subgroups lying at a distance of roughly 4 and 5 Mpc, respectively. The aim is to significantly increase the sample of known Centaurus group members down to a fainter level of completeness, serving as a basis for future studies of the 3D structure of the group. Methods. Following our previous survey of 60 square degrees covering the M 83 subgroup, we extended and completed our survey of the Centaurus group region by imaging another 500 square degrees area in the g and r bands with the wide-field Dark Energy Survey camera at the 4 m Blanco telescope at CTIO. The surface brightness limit reached for unresolved dwarf galaxies is µ r ≈ 29 mag arcsec −2 . The faintest suspected Centaurus members found have m r ≈ 19.5 mag or M r ≈ −8.8 mag at the mean distance of the group. The images were enhanced using different filtering techniques. Results. We found 41 new dwarf galaxy candidates, which together with the previously discovered 16 dwarf candidates in the M 83 subgroup amounts to almost a doubling of the number of known galaxies in the Centaurus complex, if the candidates are confirmed. We carried out surface photometry in g and r, and report the photometric parameters derived therefrom, for all new candidates as well as previously known members in the surveyed area. The photometric properties of the candidates, when compared to those of Local Group dwarfs and previously known Centaurus dwarfs, suggest membership in the Centaurus group. The sky distribution of the new objects is generally following a common envelope around the Cen A and M 83 subgroups. How the new dwarfs are connected to the intriguing double-planar feature recently reported must await distance information for the candidates.

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Distances from the tip of the red giant branch to the dwarf galaxies dw1335-29 and dw1340-30 in the Centaurus group

Müller

Rejkuba

Jerjen

2018

A&A

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Context. The abundance and spatial distribution of dwarf galaxies are excellent empirical benchmarks to test models of structure formation on small scales. The nearby Centaurus group, with its two subgroups centered on Cen A and M 83, stands out as an important alternative to the Local Group for scrutinizing cosmological model predictions in a group of galaxies context. Aims. We have obtained deep optical images of three recently discovered M 83 satellite galaxy candidates with the FORS2 instrument mounted on the Very Large Telescope. We aim to confirm their group membership and study their stellar population. Methods. Deep V I-band photometry is used to resolve the brightest stars in our targets. Artificial star tests are performed to estimate the completeness and uncertainties of the photometry. The color-magnitude diagrams reveal the red giant branch (RGB) stars allowing to use the Sobel edge detection method to measure the magnitude of the RGB tip and thus derive distances and group membership for our targets. The mean metallicity of the dwarf galaxies are further determined by fitting BASTI model isochrones to the mean RGB locus. Results. We confirm the two candidates, dw1335-29 and dw1340-30, to be dwarf satellites of the M 83 subgroup, with estimated distances of 5.03 ± 0.24 Mpc and 5.06 ± 0.24 Mpc, respectively. Their respective mean metallicities of [Fe/H] = −1.79 ± 0.4 and [Fe/H] = −2.27 ± 0.4 are consistent with the metallicity-luminosity relation for dwarf galaxies. The third candidate, dw1325-33, could not be resolved into stars due to insufficiently deep images, implying its distance must be larger than 5.3 Mpc. Using the two newly derived distances we assess the spatial distribution of the galaxies in the M 83 subgroup and discuss a potential plane-ofsatellites around M 83.

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A close look at the Centaurus A group of galaxies

Cited by 16 publications

References 113 publications

A close look at the Centaurus A group of galaxies

A close look at the Centaurus A group of galaxies

New low surface brightness dwarf galaxies in the Centaurus group

Distances from the tip of the red giant branch to the dwarf galaxies dw1335-29 and dw1340-30 in the Centaurus group

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