Two Populations of Young Massive Star Clusters in Arp 220

Wilson, C. D.; Harris, William E.; Longden, Rebecca; Scoville, N. Z.

doi:10.1086/500577

Cited by 73 publications

(114 citation statements)

References 57 publications

(106 reference statements)

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“…Similar results are found in other evolved mergers, such as Arp 220 and NGC 7252 (Miller et al 1997;Wilson et al 2006), while in contrast, in early-stage mergers such as the Antennae, IC 1623 and NGC 6090, the young stellar populations are not so centrally concentrated, but widespread over several kpc scales (Zhang et al 2001;Cortijo-Ferrero et al 2017).…”

Section: Merger-induced Star Formation and Evolutionary Schemesupporting

confidence: 84%

“…We estimated the mass range of the star clusters, by comparing their 1.6 µm absolute magnitude with the absolute magnitude of SSP models of masses ranging from 10 8 M ⊙ . These impressively large masses are comparable to the most massive globular clusters seen in giant elliptical galaxies and the massive, intermediate-age clusters seen in NGC 7252 and NGC 1316 (Maraston et al 2004;Bastian et al 2006), and some YMC in Arp 220 (Wilson et al 2006). We think, however, that we are not measuring masses of individual clusters, but aggregates of them.…”

Section: A2 Clusters Massesmentioning

confidence: 82%

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The spatially resolved stellar population and ionized gas properties in the merger LIRG NGC 2623

Cortijo-Ferrero

Delgado

Pérez

et al. 2017

A&A

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We report on a detailed study of the stellar populations and ionized gas properties in the merger LIRG NGC 2623, analyzing optical integral field spectroscopy from the CALIFA survey and PMAS LArr, multiwavelength HST imaging, and OSIRIS narrow band Hα and [NII]λ6584 imaging. The spectra were processed with the starlight full spectral fitting code, and the results are compared with those for two early-stage merger LIRGs (IC 1623 W and NGC 6090), together with CALIFA Sbc/Sc galaxies. We find that NGC 2623 went through two periods of increased star formation (SF), a first and widespread episode, traced by intermediate-age stellar populations ISP (140 Myr-1.4 Gyr), and a second one, traced by young stellar populations YSP (<140 Myr), which is concentrated in the central regions (<1.4 kpc). Our results are in agreement with the epochs of the first peri-center passage (∼200 Myr ago) and coalescence (<100 Myr ago) predicted by dynamical models, and with high-resolution merger simulations in the literature, consistent with NGC 2623 representing an evolved version of the early-stage mergers. Most ionized gas is concentrated within <2.8 kpc, where LINER-like ionization and high-velocity dispersion (∼220 km s −1 ) are found, consistent with the previously reported outflow. As revealed by the highest-resolution OSIRIS and HST data, a collection of HII regions is also present in the plane of the galaxy, which explains the mixture of ionization mechanisms in this system. It is unlikely that the outflow in NGC 2623 will escape from the galaxy, given the low SFR intensity (∼0.5 M ⊙ yr −1 kpc −2 ), the fact that the outflow rate is three times lower than the current SFR, and the escape velocity in the central areas is higher than the outflow velocity.

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Section: Merger-induced Star Formation and Evolutionary Schemesupporting

confidence: 84%

Section: A2 Clusters Massesmentioning

confidence: 82%

The spatially resolved stellar population and ionized gas properties in the merger LIRG NGC 2623

Cortijo-Ferrero

Delgado

Pérez

et al. 2017

A&A

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“…These massive clumps can migrate inwards via dynamical friction and coalesce with the central galaxy within a Gyr time scale (Noguchi 1999;Hopkins et al 2012;Inoue & Saitoh 2012). We note that the sizes and ubiquity of the clumps are similar to the young super star clusters found in the central region of Arp 220 (Scoville et al 1998;Shioya et al 2001;Wilson et al 2006).…”

Section: Nature Of the Clumpy And Extended Emission In Aztec1supporting

confidence: 56%

Clumpy and Extended Starbursts in the Brightest Unlensed Submillimeter Galaxies

Iono

Yun

Aretxaga

et al. 2016

ApJL

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The central structure in three of the brightest unlensed z = 3 − 4 submillimeter galaxies are investigated through 0.′′ 015 -0. ′′ 05 (120 -360 pc) 860µm continuum images obtained using the Atacama Large Millimeter/submillimeter Array (ALMA). The distribution in the central kpc in AzTEC1 and AzTEC8 are extremely complex, and they are composed of multiple ∼ 200 pc clumps. AzTEC4 consists of two sources that are separated by ∼ 1.5 kpc, indicating a mid-stage merger. The peak star formation rate densities in the central clumps are ∼ 300 − 3000 M ⊙ yr −1 kpc −2 , suggesting regions with extreme star formation near the Eddington Limit. By comparing the flux obtained by ALMA and Submillimeter Array (SMA), we find that 68−90% of the emission is extended ( 1 kpc) in AzTEC 4 and 8. For AzTEC1, we identify at least 11 additional compact (∼ 200 pc) clumps in the extended 3 -4 kpc region. Overall, the data presented here suggest that the luminosity surface densities observed at 150 pc scales are roughly similar to that observed in local ULIRGs, as in the eastern nucleus of Arp 220. Between 10 to 30% of the 860µm continuum is concentrated in clumpy structures in the central kpc while the remaining flux is distributed over 1 kpc regions, some of which could also be clumpy. These sources can be explained by a rapid inflow of gas such as a merger of gas-rich galaxies, surrounded by extended and clumpy starbursts. However, the cold mode accretion model is not ruled out.

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“…The combined dataset of the three publications demonstrates that the median size of YMCs in the mass range between 10 5 M and 10 6 M is about 4 pc. YMCs with masses of a few times 10 7 M have only been observed in strong starburst environments like for example in the interacting galaxy NGC 6745 (de Grijs et al 2003) and the late-stage merger galaxies NGC 7252 (Maraston et al 2004) and Arp220 (Wilson et al 2006).…”

Section: An Eo Formation Scenariomentioning

confidence: 99%

“…It is expected that these super massive gas clouds will be the birth sites of very massive CCs. Some starburst galaxies like for example Arp 220 at a distance of 77 Mpc host YMCs/CCs as massive as 10 7 M with ages less than 10 Myr (Wilson et al 2006). Arp 220 also represents two colliding spiral galaxies, but already in the end phase of the merging process.…”

Section: An Eo Formation Scenariomentioning

confidence: 99%

A catalog of extended clusters and ultra-compact dwarf galaxies

Kroupa

2012

A&A

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Context. In the past decade, very extended old stellar clusters with masses in the range from a few 10 4 to 10 8 M and effective radii larger than 10 pc have been found in various types of galaxies in different environments. Objects with masses comparable to normal globular clusters (GCs) are called extended clusters (ECs), while objects with masses in the dwarf galaxy regime are called ultra-compact dwarf galaxies (UCDs). Aims. The paper analyses the observational parameters total luminosity, M V , effective radius, r eff , and projected distance to the host galaxy, R proj , of all known ECs and UCDs and the dependence of these parameters on the type and the total luminosity of their host galaxy. Methods. We searched the available literature to compile a catalog of star clusters with effective radii larger than 10 pc. As there is no clear distinction between ECs and UCDs, both types of objects will be called extended stellar objects -abbreviated "EOs" -in this paper.Results. In total, we found 813 EOs of which 171 are associated with late-type galaxies and 642 EOs associated with early-type galaxies. EOs cover a luminosity range from about M V = −4 to −14 mag. However, the vast majority of EOs brighter than M V = −10 mag are associated with giant elliptical galaxies. At each magnitude extended objects are found with effective radii between 10 pc and an upper size limit, which shows a clear trend: the more luminous the object the larger is the upper size limit. For EOs associated with early-and late-type galaxies, the EO luminosity functions peak at −6.40 mag and −6.47 mag, respectively, which is about one magnitude fainter than the peak of the GC luminosity function. EOs and GCs form a coherent structure in the r eff vs. M V parameter space, while there is a clear gap between EOs and early-type dwarf galaxies. However, there is a small potential overlap at the high-mass end, where the most extended EOs are close to the parameters of some compact elliptical galaxies. We compare the EO sample with the numerical models of a previous paper and conclude that the parameters of the EO sample as a whole can be very well explained by a star cluster origin, where EOs are the results of merged star clusters of cluster complexes.

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Two Populations of Young Massive Star Clusters in Arp 220

Cited by 73 publications

References 57 publications

The spatially resolved stellar population and ionized gas properties in the merger LIRG NGC 2623

The spatially resolved stellar population and ionized gas properties in the merger LIRG NGC 2623

Clumpy and Extended Starbursts in the Brightest Unlensed Submillimeter Galaxies

A catalog of extended clusters and ultra-compact dwarf galaxies

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