Evolutionary history of the elliptical galaxy NGC 1052

We have obtained Keck spectra for 16 globular clusters (GCs) associated with the merger remnant elliptical NGC 1052, as well as a long-slit spectrum of the galaxy. We derive ages, metallicities and abundance ratios from simple stellar population models using the recently published methods of Proctor & Sansom, applied to extragalactic GCs for the first time. A number of GCs indicate the presence of strong blue horizontal branches that are not fully accounted for in the current stellar population models. We find all of the GCs to be ∼13 Gyr old according to simple stellar populations, with a large range of metallicities. From the galaxy spectrum we find NGC 1052 to have a luminosity-weighted central age of ∼2 Gyr and metallicity of [Fe/H] ∼+ 0.6. No strong gradients in either age or metallicity were found to the maximum radius measured (0.3 r e � 1 kpc). However, we do find a strong radial gradient in α-element abundance, which reaches a very high central value. The young central starburst age is consistent with the age inferred from the H I tidal tails and infalling gas of ∼1 Gyr. Thus, although NGC 1052 shows substantial evidence for a recent merger and an associated starburst, it appears that the merger did not induce the formation of new GCs, perhaps suggesting that little recent star formation occurred. This interpretation is consistent with ‘frosting’ models for early-type galaxy formation. Ke yw ords: globular clusters: general ‐ galaxies: individual: NGC 1052 ‐ galaxies: star clusters.

[1]  R. Terlevich,et al.  Group, field and isolated early‐type galaxies – I. Observations and nuclear data , 2004, astro-ph/0411100.

[2]  R. Proctor,et al.  A robust method for the analysis of integrated spectra from globular clusters using Lick indices , 2004, astro-ph/0409526.

[3]  J. Strader,et al.  A Principal Components Analysis of the Lick Indices of Galactic Globular Clusters , 2004, astro-ph/0407001.

[4]  J. Strader,et al.  The Chemical Properties of Milky Way and M31 Globular Clusters. I. A Comparative Study , 2004, astro-ph/0405009.

[5]  R. Schiavon,et al.  The Identification of Blue Horizontal-Branch Stars in the Integrated Spectra of Globular Clusters , 2004, astro-ph/0404592.

[6]  C. Maraston,et al.  Higher‐order Balmer line indices in α/Fe‐enhanced stellar population models , 2004, astro-ph/0404511.

[7]  F. Schweizer,et al.  Keck Spectroscopy of Two Young Globular Clusters in the Merger Remnant NGC 3921 , 2004, astro-ph/0404424.

[8]  J. Strader,et al.  Revisiting the Globular Cluster System of the Merger Remnant Elliptical Galaxy NGC 3610 , 2003, astro-ph/0310611.

[9]  G. Bruzual,et al.  Stellar population synthesis at the resolution of 2003 , 2003, astro-ph/0309134.

[10]  R. Bender,et al.  Spatially resolved spectroscopy of Coma cluster early-type galaxies III. The stellar population gradients ? , 2003, astro-ph/0306219.

[11]  T. Puzia,et al.  Evidence for an Intermediate-Age, Metal-rich Population of Globular Clusters in NGC 4365 , 2002, astro-ph/0211434.

[12]  J. Strader,et al.  Keck Spectroscopy of Globular Clusters in the Elliptical Galaxy NGC 3610 , 2002, astro-ph/0211156.

[13]  N. Evans,et al.  New Mass Estimators For Tracer Populations , 2002, astro-ph/0210255.

[14]  Garching,et al.  Stellar population models of Lick indices with variable element abundance ratios , 2002, astro-ph/0209250.

[15]  H. Kuntschner,et al.  VLT spectroscopy of NGC 3115 globular clusters , 2002, astro-ph/0209129.

[16]  B. Whitmore,et al.  The Luminosity Functions of Old and Intermediate-Age Globular Clusters in NGC 3610 , 2002, astro-ph/0205001.

[17]  A. Sansom,et al.  A comparison of stellar populations in galaxy spheroids across a wide range of Hubble types , 2002, astro-ph/0202390.

[18]  C. Baugh,et al.  On the formation of globular cluster systems in a hierarchical Universe , 2002, astro-ph/0202191.

[19]  D. Forbes,et al.  Age Estimates for Globular Clusters in NGC 1399 , 2001, astro-ph/0111185.

[20]  D. Forbes,et al.  A catalogue and analysis of local galaxy ages and metallicities , 2001, astro-ph/0110413.

[21]  A. Georgakakis,et al.  Keck imaging of the globular cluster systems in the early-type galaxies NGC 1052 and 7332 , 2001, astro-ph/0103464.

[22]  C. Maraston,et al.  The AGB phase-transition outside the local group: K-band observations of young star clusters in NGC 7252 , 2001, astro-ph/0101556.

[23]  P. T. de Zeeuw,et al.  Galaxy Mapping with the SAURON Integral-Field Spectrograph: The Star Formation History of NGC 4365 , 2000, astro-ph/0011254.

[24]  G. Meylan,et al.  Kinematics, ages and metallicities of star clusters in NGC 1316: A 3-Gyr-old merger remnant , 2000, astro-ph/0010275.

[25]  Hyun-chul Lee,et al.  The Hβ Index as an Age Indicator of Old Stellar Systems: The Effects of Horizontal-Branch Stars , 2000, astro-ph/0004247.

[26]  UCOLick,et al.  The Stellar Population Histories of Early-Type Galaxies. II. Controlling Parameters of the Stellar Populations , 2000, astro-ph/0004095.

[27]  S. Faber,et al.  The Stellar Population Histories of Local Early-Type Galaxies. I. Population Parameters , 2000, astro-ph/0001072.

[28]  C. Maraston,et al.  The Uncertainties in the Synthetic Indices for Stellar Populations , 1999, astro-ph/9906088.

[29]  A. Vazdekis,et al.  Evolutionary Stellar Population Synthesis at 2 Å Spectral Resolution , 1999, astro-ph/9901181.

[30]  D. Forbes,et al.  Dependence of the Fundamental Plane Scatter on Galaxy Age , 1998, astro-ph/9809319.

[31]  F. Schweizer,et al.  Ages and Metallicities of Young Globular Clusters in the Merger Remnant NGC 7252 , 1998, astro-ph/9809026.

[32]  P. Côté,et al.  The Formation of Giant Elliptical Galaxies and Their Globular Cluster Systems , 1998, astro-ph/9804319.

[33]  S. Faber,et al.  Old Stellar Populations. VI. Absorption-Line Spectra of Galaxy Nuclei and Globular Clusters , 1997, astro-ph/9712258.

[34]  S. M. Fall,et al.  The Star Cluster System of the Merger Remnant NGC 7252 , 1997 .

[35]  D. Ottaviani,et al.  Hγ and Hδ Absorption Features in Stars and Stellar Populations , 1997 .

[36]  S. Djorgovski,et al.  Discovery of Extended Blue Horizontal Branches in Two Metal-rich Globular Clusters , 1997, astro-ph/9705039.

[37]  C. Grillmair,et al.  On the origin of globular clusters in elliptical and cD galaxies , 1997, astro-ph/9702146.

[38]  S. M. Fall,et al.  Hubble Space Telescope Observations of Candidate Young Globular Clusters and Stellar Associations in the Recent Merger Remnant NGC 3921 , 1996 .

[39]  Harland W. Epps,et al.  THE KECK LOW-RESOLUTION IMAGING SPECTROMETER , 1995 .

[40]  B. Whitmore,et al.  Hubble space telescope observations of young star clusters in NGC-4038/4039, 'the antennae' galaxies , 1995 .

[41]  G. Worthey.  Comprehensive stellar population models and the disentanglement of age and metallicity effects , 1994 .

[42]  Patrick Seitzer,et al.  Correlations between UBV colors and fine structure in E and S0 galaxies: A First attempt at dating ancient merger events , 1992 .

[43]  C. Norman.  Paired and Interacting Galaxies: Conference Summary , 1990 .

[44]  J. Huchra,et al.  Extragalactic globular clusters. I, The metallicity calibration , 1990 .

[45]  J. Binney,et al.  Velocity mapping and models of the elliptical galaxies NGC 720, NGC 1052, and NGC 4697 , 1990 .

[46]  G. Knapp,et al.  H I Absorption in Radio Elliptical Galaxies---Evidence for Infall , 1989 .

[47]  M. Tripicco.  Spectroscopy of metal-rich M31 globular clusters , 1986 .

[48]  S. Faber,et al.  Distribution and kinematics of H I in the active elliptical galaxy NGC 1052 , 1986 .

[49]  J. Rose.  Spectral anomalies in the Hyades and Pleiades and in field stars wih active chromospheres. , 1984 .

[50]  Stephen E. Zepf,et al.  The Formation of Globular Clusters in Merging and Interacting Galaxies , 1992 .