Deep Surface Photometry of M87 with 13 Optical Bands

Liu, Ying; Xu, Zhiyong; Ma, Jun; Wu, Hong; Yang, Yanbin; Li, Jiuli; Chen, Jiansheng

doi:10.1086/430186

Cited by 39 publications

(62 citation statements)

References 41 publications

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“…The presence of an accreted component is usually identified as an excess of light over the extrapolation of the galaxy's inner profile (Zibetti et al 2005;Gonzalez et al 2007;D'Souza et al 2014), or by high Sersic indexes (n > 4; Kormendy et al 2009). Observations of blue colour gradients from the centres of early-type galaxies towards their outskirts (Peletier et al 1990;Liu et al 2005;Rudick et al 2010), mainly attributed to a gradient in metallicty (Tamura et al 2000;Loubser & Sánchez-Blázquez 2012;Montes et al 2014), are also in agreement with a change in stellar properties driven by the accretion of smaller systems. Records of accretion events are also Based on observations made with the VLT at Paranal Observatory under programme 088.B-0288(A) and 093.B-066(A), and with the Subaru Telescope under programme S10A-039.…”

Section: Introductionsupporting

confidence: 71%

The build-up of the cD halo of M 87: evidence for accretion in the last Gyr

Longobardi

Arnaboldi

Gerhard

et al. 2015

A&A

100

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Aims. We present kinematic and photometric evidence for an accretion event in the halo of the cD galaxy M 87 in the last Gyr. Methods. Using velocities for ∼300 planetary nebulas (PNs) in the M 87 halo, we identify a chevron-like substructure in the PN phasespace. We implement a probabilistic Gaussian mixture model to identify PNs that belong to the chevron. From analysis of deep V-band images of M 87, we find that the region with the highest density of chevron PNs is a crown-shaped substructure in the light. Results. We assign a total of N PN,sub = 54 to the substructure, which extends over ∼50 kpc along the major axis where we also observe radial variations of the ellipticity profile and a colour gradient. The substructure has highest surface brightness in a 20 kpc × 60 kpc region around 70 kpc in radius. In this region, the substructure causes an increase in surface brightness by 60%. The accretion event is consistent with a progenitor galaxy with a V-band luminosity of L = 2.8 ± 1.0 × 10 9 L ,V , a colour of (B − V) = 0.76 ± 0.05, and a stellar mass of M = 6.4 ± 2.3 × 10 9 M . Conclusions. The accretion of this progenitor galaxy has caused an important modification of the outer halo of M 87 in the last Gyr. This result provides strong evidence that the galaxy's cD halo is growing through the accretion of smaller galaxies as predicted by hierarchical galaxy evolution models.

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Section: Introductionsupporting

confidence: 71%

The build-up of the cD halo of M 87: evidence for accretion in the last Gyr

Longobardi

Arnaboldi

Gerhard

et al. 2015

A&A

100

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“…On the other hand, the metallicity and age distributions of ICL red giants in a field at R ∼ 190 kpc from HST ACS star photometry are dominated by metal-poor ([M/H] < ∼ −1), > ∼ 10 Gyr old stars (Williams et al 2007). Because of the large velocities and shallow surface density profile of the IC stars, these IC population parameters are likely to be similar in the radial range probed by our observations, R ∼ 50−140 kpc, whereas the M 87 halo stars might reach ∼0.5 solar in the outer regions if the outward gradient continues, as inferred by Liu et al (2005).…”

Section: Distinct Halo and Ic Populations Around M 87supporting

confidence: 59%

“…The giant elliptical galaxy M 87 has one of the oldest stellar populations in the local Universe (Liu et al 2005), and a stellar halo containing 70% of the galaxy light down to μ V = 27.0 mag arcsec −2 (Kormendy et al 2009). It is close to the centre of sub-cluster A in the Virgo cluster (Binggeli et al 1987), the nearest galaxy cluster, and it is expected to have transformed over larger timescales because of galaxy mergers (De Lucia & Blaizot 2007).…”

Section: Introductionmentioning

confidence: 99%

The outer regions of the giant Virgo galaxy M 87 Kinematic separation of stellar halo and intracluster light

Longobardi

Arnaboldi

Gerhard

et al. 2015

A&A

144

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Aims. We present a spectroscopic study of a sample of 287 planetary nebulas (PNs) around the brightest cluster galaxy (BCG) M 87 in Virgo A, of which 211 are located between 40 kpc and 150 kpc from the galaxy centre. With these data we can distinguish the stellar halo from the co-spatial intracluster light (ICL) and study both components separately. Methods. We obtained PN velocities with a high resolution FLAMES/VLT survey targeting eight fields in a total area of ∼0.4 deg 2 . We identified PNs from their narrow and symmetric redshifted λ5007 Å [OIII] emission line, the presence of the second λ4959 Å [OIII] emission line, and the absence of significant continuum. We implement a robust technique to measure the halo velocity dispersion from the projected phase-space to identify PNs associated with the M 87 halo and ICL. Using photometric magnitudes, we construct PN luminosity functions (PNLFs), which are complete down to m 5007 = 28.8. Results. The velocity distribution of the spectroscopically confirmed PNs is bimodal, containing a narrow component centred on the systemic velocity of the BCG and an off-centred broader component, which we identify as halo and ICL, respectively. We find that 243 PNs are part of the velocity distribution of the M 87 halo, while the remaining subsample of 44 PNs are intracluster PNs (ICPNs). Halo and ICPNs have different spatial distributions: the number density of halo PNs follow the galaxy's surface brightness profile, whereas the ICPNs are characterised by a shallower power-law profile, I ICL ∝ R γ with γ in the range [−0.34, −0.04]. No evidence is found for an asymmetry in the halo and ICPN density distributions when the NW and SE fields are studied separately. A study of the composite PN number density profile confirms the superposition of different PN populations associated with the M 87 halo and the ICL, characterised by different PN specific numbers α. We derive α halo = 1.06 × 10 −8 N PN L −1 ,bol and α ICL = 2.72 × 10 −8 N PN L −1 ,bol , respectively. The M 87 halo PNLF has fewer bright PNs and a steeper slope towards faint magnitudes than the ICPNLF, and both are steeper than the standard PNLF for the M 31 bulge. Moreover, the ICPNLF has a dip at ∼1−1.5 mag fainter than the bright cut-off, reminiscent of the PNLFs of systems with extended star formation history, such as M 33 or the Magellanic clouds. Conclusions. The BCG halo of M 87 and the Virgo ICL are dynamically distinct components with different density profiles and velocity distributions. Moreover, the different α-parameter values and PNLF shapes of the halo and ICL indicate distinct parent stellar populations, consistent with the existence of a gradient towards bluer colours at large radii. These results reflect the hierarchical build-up of the Virgo cluster.

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“…Comparing ellipticity and position angle of blue and red clusters with those of M87 isophotes (from Liu et al 2005) we find that the ellipticities of the GC distributions follow those of the isophotes in the outer regions of our survey ( 80 ∼ ″), but then the GC distributions become significantly flattened toward the center whereas the behavior of the isophotes is opposite, becoming even more circular within the central 20″. The orientation of flattening of red and blue GCs is broadly consistent with that of the outer isophotes of M87.…”

Section: F606w F814wmentioning

confidence: 99%

Uv Insights Into the Complex Populations of M87 Globular Clusters

Bellini

Renzini

Anderson

et al. 2015

ApJ

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We have imaged with Hubble Space Telescope WFC3/UVIS the central 2.7 2.7 ′ × ′ region of the giant elliptical galaxy M87, using the ultraviolet filter F275W. In combination with archival ACS/WFC data taken through the F606W and F814W filters, covering the same field, we have constructed integrated-light UV-optical colors and magnitudes for 1460 objects, most of which are believed to be globular clusters (GCs) belonging to M87. The purpose was to ascertain whether the multiple-populations syndrome, ubiquitous among Galactic GCs, also exists among the M87 family of clusters. To achieve this goal, we sought those GCs with exceptionally blue UV-tooptical colors because helium-enriched sub-populations produce a horizontal-branch morphology that is well populated at high effective temperature. For comparison, integrated, synthetic UV-optical and purely optical colors and magnitudes have been constructed for 45 Galactic GCs, starting from individual-star photometry obtained with the same instruments and the same filters. We identify a small group of M87 clusters exhibiting a radial UVoptical color gradient, representing our best candidate GCs hosting multiple populations with extreme helium content. We also find that the central spatial distribution of the bluer GCs is flattened in a direction parallel to the jet, while the distribution of redder GCs is more spherical. We release to the astronomical community our photometric catalog in F275W, F606W, and F814W bands and the high-quality image stacks in the same bands.

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Deep Surface Photometry of M87 with 13 Optical Bands

Cited by 39 publications

References 41 publications

The build-up of the cD halo of M 87: evidence for accretion in the last Gyr

The build-up of the cD halo of M 87: evidence for accretion in the last Gyr

The outer regions of the giant Virgo galaxy M 87 Kinematic separation of stellar halo and intracluster light

Uv Insights Into the Complex Populations of M87 Globular Clusters

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