The Importance of Nebular Continuum and Line Emission in Observations of Young Massive Star Clusters

Reines, Amy E.; Nidever, David L.; Whelan, David G.; Johnson, K. E.

doi:10.1088/0004-637x/708/1/26

Cited by 88 publications

(142 citation statements)

References 32 publications

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“…The position of many of them below the theoretical line is consistent with internal reddening shifting their colors to redder values consistent with the dusty clouds in which they are born. Reines et al (2010) show that nebular emission can significantly affect magnitudes and colors of young massive star clusters (<5 Myr). Figure 6 shows the spatial distribution of these very young clusters on a Galex FUV image.…”

Section: Color-color Diagramsmentioning

confidence: 95%

Photometric Properties of the M33 Star Cluster System

Roman

Sarajedini

Aparicio

2010

ApJ

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We present a catalog of 2990 extended sources in a 1• × 1 • area centered on M33 using the MegaCam camera on the 3.6 m Canada-France-Hawaii Telescope. The catalog includes 599 new candidate stellar clusters, 204 previously confirmed clusters, 1969 likely background galaxies, and 218 unknown extended objects. We present ugriz integrated magnitudes of the candidates and confirmed star clusters (SCs) as well as the full width at half maximum, ellipticity, and stellarity. Based on the properties of the confirmed SCs, we select a sub-sample of highly probable clusters composed of 246 objects. The integrated photometry of the complete cluster catalog reveals a wide range of colors of −0.4 < (g − r) < 1.5 and −1.0 < (r − i) < 1.0 with no obvious cluster subpopulations. Comparisons with models of simple stellar populations suggest a large range of ages some as old as ∼10 Gyr. In addition, we find a sequence in the color-color diagrams that deviates from the expected direction of evolution. This feature could be associated with very young clusters (<10 7 yr) possessing significant nebular emission. Analysis of the radial density distribution suggests that the cluster system of M33 has suffered from significant depletion possibly due to interactions with M31. We also detect a gap in the cluster distribution in the color-color diagram at (g − r) 0.3 and (u − g) 0.8. This gap could be interpreted as an evolutionary effect. This complete catalog provides promising targets for deep photometry and high-resolution spectroscopy to study the structure and star formation history of M33.

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Section: Color-color Diagramsmentioning

confidence: 95%

Photometric Properties of the M33 Star Cluster System

Roman

Sarajedini

Aparicio

2010

ApJ

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“…We do not include attenuation for the AGN SED, although we include it statistically as an obscured fraction, an approach that Ricci et al (2017b) showed to produce a good match between UV and X-ray AGN LFs. We do not include emission lines either, which can boost both the AGN (Vanden Berk et al 2001;Hainline et al 2011) and the galaxy magnitude (Reines et al 2010;Atek et al 2011;Stark et al 2013;de Barros et al 2014). Nebular emission will be studied in a companion paper.…”

Section: Agn Spectramentioning

confidence: 99%

High-redshift Galaxies and Black Holes Detectable with the JWST: A Population Synthesis Model from Infrared to X-Rays

Volonteri

Reines

Atek

et al. 2017

ApJ

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The first billion years of the Universe has been a pivotal time: stars, black holes (BHs), and galaxies formed and assembled, sowing the seeds of galaxies as we know them today. Detecting, identifying, and understanding the first galaxies and BHs is one of the current observational and theoretical challenges in galaxy formation. In this paper we present a population synthesis model aimed at galaxies, BHs, and active galactic nuclei (AGNs) at high redshift. The model builds a population based on empirical relations. The spectral energy distribution of galaxies is determined by age and metallicity, and that of AGNs by BH mass and accretion rate. We validate the model against observations, and predict properties of galaxies and AGN in other wavelength and/or luminosity ranges, estimating the contamination of stellar populations (normal stars and high-mass X-ray binaries) for AGN searches from the infrared to X-rays, and vice versa for galaxy searches. For high-redshift galaxies with stellar ages 1 Gyr < , we find that disentangling stellar and AGN emission is challenging at restframe UV/optical wavelengths, while high-mass X-ray binaries become more important sources of confusion in X-rays. We propose a color-color selection in the James Webb Space Telescope bands to separate AGN versus star-dominated galaxies in photometric observations. We also estimate the AGN contribution, with respect to massive, hot, and metal-poor stars, at driving high-ionization lines, such as C IV and He II. Finally, we test the influence of the minimum BH mass and occupation fraction of BHs in low-mass galaxies on the restframe UV/near-IR and X-ray AGN luminosity function.

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“…This is caused by the contribution of neighbouring sources as well as the nebular emission from nearby (often related) ionised gas which is stronger at redder wavelengths (e.g., Reines et al 2010;Adamo et al 2010a). Models that include nebular emission can explain some of this excess near-IR emission, however, for some clusters the models cannot account for the additional flux.…”

Section: Discussionmentioning

confidence: 99%

“…Part of the excess comes from the nebular emission 2 from the ionised gas around the clusters (Reines et al 2010, Adamo et al 2010a, which begins to significantly contribute to the integrated flux of the cluster from the I-band red-ward. However, even when taking the nebular emission into account, a number of clusters show near-IR excess that increases with increasing wavelength (e..g, Adamo et al 2010a).…”

Section: Introductionmentioning

confidence: 99%

The effect of spatial resolution on optical and near-IR studies of stellar clusters: implications for the origin of the red excess

Bastian

Adamo

Schirmer

et al. 2014

Monthly Notices of the Royal Astronomical Society

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Recent ground based near-IR studies of stellar clusters in nearby galaxies have suggested that young clusters remain embedded for 7 − 10 Myr in their progenitor molecular cloud, in conflict with optical based studies which find that clusters are exposed after 1 − 3 Myr. Here, we investigate the role that spatial resolution plays in this apparent conflict. We use a recent catalogue of young (< 10 Myr) massive (> 5000 M ⊙ ) clusters in the nearby spiral galaxy, M83, along with Hubble Space Telescope (HST) imaging in the optical and near-IR, and ground based near-IR imaging, to see how the colours (and hence estimated properties such as age and extinction) are affected by the aperture size employed, in order to simulate studies of differing resolution. We find that the near-IR is heavily affected by the resolution, and when aperture sizes > 40 pc are used, all young/blue clusters move red-ward in colour space, which results in their appearance as heavily extincted clusters. However, this is due to contamination from nearby sources and nebular emission, and is not an extinction effect. Optical colours are much less affected by resolution. Due to the larger affect of contamination in the near-IR, we find that, in some cases, clusters will appear to show near-IR excess when large (> 20 pc) apertures are used. Our results explain why few young (< 6 Myr), low extinction (A V < 1 mag) clusters have been found in recent ground based near-IR studies of cluster populations, while many such clusters have been found in higher resolution HST based studies. Additionally, resolution effects appear to (at least partially) explain the origin of the near-IR excess that has been found in a number of extragalactic YMCs.

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The Importance of Nebular Continuum and Line Emission in Observations of Young Massive Star Clusters

Cited by 88 publications

References 32 publications

Photometric Properties of the M33 Star Cluster System

Photometric Properties of the M33 Star Cluster System

High-redshift Galaxies and Black Holes Detectable with the JWST: A Population Synthesis Model from Infrared to X-Rays

The effect of spatial resolution on optical and near-IR studies of stellar clusters: implications for the origin of the red excess

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