Spectral Energy Distributions and Age Estimates of 39 Globular Clusters in M31

Ma, Jun; Zhang, Fan; Grijs, Richard de; Wu, Zhenyu; Zhou, Xu; Wu, Jianghua; Jiang, Zhongjing; Chen, Jiansheng

doi:10.1088/0004-6256/137/6/4884

Cited by 41 publications

(102 citation statements)

References 93 publications

(193 reference statements)

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“…A series of papers using the BATC photometric system combined with other photometry has produced several tables of ages for clusters, young and old (Fan et al 2006;Ma et al 2009;Wang et al 2010). The ages were derived using SPS models, based on Padova isochrones.…”

Section: Discussion Of Agesmentioning

confidence: 99%

Star Clusters in M31. Ii. Old Cluster Metallicities and Ages From Hectospec Data

Caldwell

Schiavon

Morrison

et al. 2011

The Astronomical Journal

166

400

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We present new high signal-to-noise spectroscopic data on the M31 globular cluster (GC) system, obtained with the Hectospec multifiber spectrograph on the 6.5 m MMT. More than 300 clusters have been observed at a resolution of 5 Å and with a median S/N of 75 per Å, providing velocities with a median uncertainty of 6 km s −1 . The primary focus of this paper is the determination of mean cluster metallicities, ages, and reddenings. Metallicities were estimated using a calibration of Lick indices with [Fe/H] provided by Galactic GCs. These match well the metallicities of 24 M31 clusters determined from Hubble Space Telescope color-magnitude diagrams, the differences having an rms of 0.2 dex. The metallicity distribution is not generally bimodal, in strong distinction with the bimodal Galactic globular distribution. Rather, the M31 distribution shows a broad peak, centered at [Fe/H] = −1, possibly with minor peaks at [Fe/H] = −1.4, −0.7, and −0.2, suggesting that the cluster systems of M31 and the Milky Way had different formation histories. Ages for clusters with [Fe/H] > −1 were determined using the automatic stellar population analysis program EZ_Ages. We find no evidence for massive clusters in M31 with intermediate ages, those between 2 and 6 Gyr. Moreover, we find that the mean ages of the old GCs are remarkably constant over about a decade in metallicity (−0.95 [Fe/H] 0.0).

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Section: Discussion Of Agesmentioning

confidence: 99%

Star Clusters in M31. Ii. Old Cluster Metallicities and Ages From Hectospec Data

Caldwell

Schiavon

Morrison

et al. 2011

The Astronomical Journal

166

400

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show abstract

“…2 The blue line shows the cosmic age in the R h = ct using the best-fit value from SNe Ia and the Hubble parameter, the red lines are for the 1σ deviation. The red circles are the nine extremely old GCs and this also gives the error of their age B050 measured by [24,25] are higher than those of [48]. The values are significantly different.…”

Section: Constraining the R H = Ct Universe With Sne Ia And H (Z) Datamentioning

confidence: 93%

“…In this paper, we will use the old quasar APM 08279+5255 at redshift z = 3.91 and the nine extremely old Global Clusters [24,25] to investigate the cosmic age problem in the R h = ct universe. The data of these nine extremely old GCs listed in Table 1 are acquired from the Beijing-ArizonaTaiwan-Connecticut system with up-to-date theoretical synthesis models.…”

Section: Introductionmentioning

confidence: 99%

“…In [24,25], they get the ages of those GCs by using multi-color photometric CCD data and comparing them with up-to-date theoretical synthesis models. But the ages of GCs derived by different authors based on different measurements using same method are not always consistent [24]. We find that the nine of those GCs can give stronger constraints on the age of universe than the old quasar APM 08279+5255.…”

Section: Introductionmentioning

confidence: 99%

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Reconciling the cosmic age problem in the $$R_\mathrm{h}=ct$$ R h = c t universe

Wang

2014

Eur. Phys. J. C

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Many dark energy models fail to pass the cosmic age test. In this paper, we investigate the cosmic age problem associated with nine extremely old Global Clusters (GCs) and the old quasar APM 08279+5255 in the R h = ct universe. The age data of these oldest GCs in M31 are acquired from the Beijing-Arizona-Taiwan-Connecticut system with up-to-date theoretical synthesis models. They have not been used to test the cosmic age problem in the R h = ct universe in previous literature. By evaluating the age of the R h = ct universe with the observational constraints from the type Ia supernovae and the Hubble parameter, we find that the R h = ct universe can accommodate five GCs and the quasar APM 08279+5255 at redshift z = 3.91. But for other models, such as CDM, the interacting dark energy model, the generalized Chaplygin gas model, and holographic dark energy model, cannot accommodate all GCs and the quasar APM 08279+5255. It is worthwhile to note that the age estimates of some GCs are controversial. So, unlike other cosmological models, the R h = ct universe can marginally solve the cosmic age problem, especially at high redshift.

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“…Another widely used method to age-date extragalactic star clusters relies on multi-band photometry: the age can be derived from the spectral energy distributions (SED) measured in broad-band photometric systems, by comparing them with simple stellar population (SSP 3 ) synthesis models (e.g. Jiang et al 2003;Fan et al 2006Fan et al , 2008Fan et al , 2010Ma et al 2007Ma et al , 2009. Clearly, photometrybased technique are prone to errors owing to the uncertainty in the interstellar extinction, while spectral indices are virtually free from this effect.…”

Section: Introductionmentioning

confidence: 99%

HST/ACS color-magnitude diagrams of candidate intermediate-age M 31 globular clusters

Perina¹,

Galleti²,

Pecci³

et al. 2011

A&A

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We present deep (V 28.0) BV photometry obtained with the wide field channel of the Advanced Camera for Surveys on board HST for four M 31 globular clusters that were identified as candidate intermediate-age (age ∼ 1−9 Gyr) by various authors, based on their integrated spectra and/or broad/intermediate-band colors. Two of them (B292 and B350) display an obvious blue horizontal branch, indicating that they are as old as the oldest Galactic globulars. On the other hand, for the other two (B058 and B337), which display red horizontal branches, it was not possible either to confirm or disconfirm the age estimate from integrated spectra. The analysis of the distribution in the spectral indices Mg2 and Hβ of the M 31 and Milky Way clusters whose horizontal branch can be classified as red or blue based on existing CMDs, strongly suggests that classical age diagnostics from integrated spectra may be significantly influenced by the HB morphology of the clusters and can lead to erroneous age-classifications. We also provide the CMD for another two clusters that fall into the field of the main targets, B336, an old and metal-poor globular with a significant population of RR Lyrae variables, and the newly discovered B531, a cluster with a very red red giant branch.

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Spectral Energy Distributions and Age Estimates of 39 Globular Clusters in M31

Cited by 41 publications

References 93 publications

Star Clusters in M31. Ii. Old Cluster Metallicities and Ages From Hectospec Data

Star Clusters in M31. Ii. Old Cluster Metallicities and Ages From Hectospec Data

Reconciling the cosmic age problem in the $$R_\mathrm{h}=ct$$ R h = c t universe

HST/ACS color-magnitude diagrams of candidate intermediate-age M 31 globular clusters

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