A Multiwavelength Study of the Young Star Clusters and Interstellar Medium in the Antennae Galaxies

By Qing Zhang, S. M. Fall, B. Whitmore. 2001

163 citations recorded by the source corpus.

We report on a multiwavelength study of the relationship between young star clusters in the Antennae galaxies (NGC 4038/9) and their interstellar environment, with the goal of understanding the formation and feedback effects of star clusters in merging galaxies. This is possible for the first time because various new observations (from X-rays to radio wavelengths) have become available in the past several years. Quantitative comparisons are made between the positions of the star clusters (broken into three age groups) and the properties of the interstellar medium by calculating the two-point correlation functions. We find that young star clusters are distributed in a clustered fashion, demonstrated by power-law angular autocorrelation functions with slopes in the range -0.8 to -1.0. The young embedded clusters (ages ~5 Myr) are found to be more associated with long-wavelength radiation (mid-infrared and longer), while clusters with ages ~10 Myr or older are more associated with short-wavelength radiation (e.g., far-UV and X-ray). The youngest star clusters are associated with molecular cloud complexes with characteristic radii of about 1 kpc. In addition, there is a weak tendency for them to be found in regions with higher H I velocity dispersions. There is some evidence that both cloud-cloud collisions and shocks from recent star formation can trigger star cluster formation, but no dominant triggering mechanism is identified for the majority of the clusters in the Antennae. Feedback from young bright cluster complexes reveals itself in the form of large Hα bubbles and Hα velocity gradients in shells around the complexes. We estimate the current star formation rate to be ≈20 M☉ yr-1 and the gas consumption timescale to be ~700 Myr. The latter is comparable to the merging timescale and indicates that star formation has been enhanced by the merger event. Finally, we find that the Schmidt law, with index N ≈ -1.4, is also a good description of the cluster formation triggered by merging in the Antennae. There is some evidence that feedback effects may modify the Schmidt law at scales below 1 kpc.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/56c32d80ef02e9f12893f1a40014144f5a0a91fb

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Citations in the corpus

The mass function of young star clusters in spiral galaxies (2008, background): “There is some evidence of shock-triggered cluster formation in the Antennae, but large-scale shocks are probably not directly responsible for most cluster formation there (Zhang et al. 2001).”
A Multi-Transition HCN and HCO+ Study of 12 Nearby Active Galaxies: Active Galactic Nucleus versus Starburst Environments (2007, background): “…gas densities may be that the molecular gas traced by the HCN and HCO+ emission does not split up into as many high density clumps/GMCs in our AGN sources as it seems to be the case in SB environments (compare Zhang et al. 2001; Alonso-Herrero et al. 2002; Wilson et al. 2003; Galliano et al. 2005).”
Globular Cluster Systems in Brightest Cluster Galaxies: Bimodal Metallicity Distributions and the Nature of the High-Luminosity Clusters (2005, background): “…of these major bursts could have assembled gas clouds (GMCs and GMC complexes) of a very wide range of sizes and masses, within which star clusters of a similarly broad range could form, such as we see happening in contemporary mergers (Whitmore et al. 1999; Zhang et al. 2001; Wilson et al. 2003).”
Star Cluster Demographics. I. A General Framework and Application to the Antennae Galaxies (2006, background): “We find that the Antennae, the Milky Way, and the SMC all follow the same dN /d / 1 relation over the first 108 yr.”
Star Formation in NGC 5194 (M51a). II. The Spatially Resolved Star Formation Law (2007, result): “Likewise Zhang et al. (2001) derive N = 1.20–1.38 from an analysis of star-forming regions in the Antennae (NGC 4038/9); their fits apply to the total gas surface density, but since most of the regions are dominated by molecular gas this is consistent with the other results cited here.”
The Survey for Ionization in Neutral Gas Galaxies. III. Diffuse, Warm Ionized Medium and Escape of Ionizing Radiation (2007, methodology): “This clustering law appears to be universal (e.g., Elmegreen & Efremov 1997) and is supported by observations of super star clusters (Meurer et al. 1995; Zhang et al. 2001) and ordinary H ii regions (Oey & Clarke 1998).”
THE DRIVING MECHANISM OF STARBURSTS IN GALAXY MERGERS (2010, result): “Our low-resolution models reaches SFRs around 10 M yr−1 just after the second pericenter passage and during only 50 Myr: these properties are in broad agreement with recent SPH simulations by Karl et al. (2010) and with the observed SFR (Zhang et al. 2001).”
Formation of Globular Clusters in Hierarchical Cosmology (2003, result): “The morphology of the distribution is very similar to that of young stellar clusters observed in starburst galaxies (e.g., Whitmore & Schweizer 1995; Zhang et al. 2001).”
THE ANTENNAE GALAXIES (NGC 4038/4039) REVISITED: ADVANCED CAMERA FOR SURVEYS AND NICMOS OBSERVATIONS OF A PROTOTYPICAL MERGER (2010, background): “Hence, high collision velocities are not required for making clusters, a result also found by Zhang et al. (2001) and Whitmore et al. (2005), and supported by theory – 26 – (Renaud et al. 2008).”
Star Formation from Galaxies to Globules (2001, background): “…crossing time (Feitzinger & Galinski 1987; Gomez et al. 1993; Efremov 1995; Elmegreen &Efremov 1996; Battinelli, Efremov, &Magnier 1996; Harris & Zaritsky 1999; Testi et al. 2000; Elmegreen 2000; Heydari-Malayeri et al. 2001; Pietrzynski et al. 2001; Elmegreen & Elmegreen 2001; Zhang et al. 2001).”
THE STAR FORMATION RATE AND GAS SURFACE DENSITY RELATION IN THE MILKY WAY: IMPLICATIONS FOR EXTRAGALACTIC STUDIES (2010, methodology): “…global scales (Kennicutt 1989, 1998b) or using either radial (Martin & Kennicutt 2001; Wong & Blitz 2002; Boissier et al. 2003; Heyer et al. 2004; Komugi et al. 2005; Schuster et al. 2007) or point–by– point measurements (Kuno et al. 1995; Zhang et al. 2001) that find values of N ranging from 1–2.”