Little Blue Dots in the Hubble Space Telescope Frontier Fields: Precursors to Globular Clusters?

Elmegreen, D. M.; Elmegreen, Bruce G.

doi:10.3847/2041-8213/aaa0ce

Cited by 18 publications

(13 citation statements)

References 30 publications

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“…The mass and characteristic scale of the SIGOs seems to be consistent with Little Blue Dots (Elmegreen & Elmegreen 2017) and the star forming dwarf detected recently by Vanzella et al (2019). The aforementioned observed objects have been suggested to be GCs progenitors, their similarity to SIGOs is uncanny and may suggest a strong link between high redshift, star-forming SIGOs and GCs progenitors.…”

Section: Q(h) the Luminosity Is Given Bysupporting

confidence: 90%

The Supersonic Project: Shining Light on SIGOs—A New Formation Channel for Globular Clusters

Chiou

Naoz

Burkhart

et al. 2019

ApJL

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Supersonically induced gas objects (SIGOs) with little to no dark matter component are predicted to exist in patches of the Universe with non-negligible relative velocity between baryons and the dark matter at the time of recombination. Using arepo hydrodynamic simulations we find that the gas densities inside these objects are high enough to allow stars to form. An estimate of the luminosity of the first star clusters formed within these SIGOs suggests that they may be observed at high redshift using future HST and JWST observations. Furthermore, our simulations indicate that SIGOs lie in a distinct place in the luminosity-radius parameter space, which can be used observationally to distinguish SIGOs from dark-matter hosting gas systems. Finally, as a proof-of-concept, we model star formation before reionization and evolve these systems to current times. We find that SIGOs occupy a similar part of the magnitude-radius parameter space as globular clusters. These results suggest that SIGOs may be linked with present-day metal-poor local globular clusters. Since the relative velocity between the baryons and dark matter is coherent over a few Mpc scales, we predict that if this is the dominant mechanism for the formation of globular clusters, their abundance should vary significantly over these scales.

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Section: Q(h) the Luminosity Is Given Bysupporting

confidence: 90%

The Supersonic Project: Shining Light on SIGOs—A New Formation Channel for Globular Clusters

Chiou

Naoz

Burkhart

et al. 2019

ApJL

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“…Indeed, following Eq. 4 and discussion in Elmegreen & Elmegreen (2017) Howard et al 2018), the total expected mass of a star forming region hosting a single massive cluster with M = 10 6 M is Mstar 2 × 10 7 M , a mass that is fully consistent with what inferred for D1. This mass is also compatible for the values expected in some scenarios for GC formation, in which such systems host multiple stellar populations (D'Ercole et al 2008;Calura et al 2015;Vanzella et al 2017b and Calura et al, in preparation).…”

Section: A Possible Young Massive Star Cluster Hosted By D1supporting

confidence: 78%

Massive star cluster formation under the microscope atz = 6

Vanzella¹,

Calura²,

Meneghetti³

et al. 2018

Monthly Notices of the Royal Astronomical Society

123

138

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We report on a superdense star-forming region with an effective radius (R e ) smaller than 13 pc identified at z=6.143 and showing a star-formation rate density Σ SF R ∼ 1000 M yr −1 kpc −2 (or conservatively > 300 M yr −1 kpc −2 ). Such a dense region is detected with S/N 40 hosted by a dwarf extending over 440 pc, dubbed D1. D1 is magnified by a factor 17.4(±5.0) behind the Hubble Frontier Field galaxy cluster MACS J0416 and elongated tangentially by a factor 13.2±4.0 (including the systematic errors). The lens model accurately reproduces the positions of the confirmed multiple images with a r.m.s. of 0.35 . D1 is part of an interacting star-forming complex extending over 800 pc. The SED−fitting, the very blue ultraviolet slope (β −2.5, F λ ∼ λ β ) and the prominent Lyα emission of the stellar complex imply that very young (< 10 − 100Myr), moderately dust-attenuated (E(B-V)<0.15) stellar populations are present and organised in dense subcomponents. We argue that D1 (with a stellar mass of 2 × 10 7 M ) might contain a young massive star cluster of M 10 6 M and M U V −15.6 (or m U V = 31.1), confined within a region of 13 pc, and not dissimilar from some local super star clusters (SSCs). The ultraviolet appearance of D1 is also consistent with a simulated local dwarf hosting a SSC placed at z=6 and lensed back to the observer. This compact system fits into some popular globular cluster formation scenarios. We show that future high spatial resolution imaging (e.g., E−ELT/MAORY-MICADO and VLT/MAVIS) will allow us to spatially resolve light profiles of 2-8 pc.

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“…The large spin parameter, if inferred from observational data, might serve as an indication for a high stream velocity patch. Recently, HST has observed a potentially promising candidate, the so-called "Little Blue Dots" (Elmegreen & Elmegreen 2017). These objects are thought to be gas-dominated systems in the early Universe, with high specific star formation rates.…”

Section: Discussionmentioning

confidence: 99%

The Supersonic Project: rotational effects of supersonic motions on the first structures in the Universe

Chiou¹,

Naoz²,

Marinacci

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We introduce the "Supersonic Project," aimed at investigating the effects of the supersonic relative velocity between dark matter (DM) and baryons at high redshift using a combination of analytical calculations and cosmological simulations. In this paper, we study the effect of this stream velocity on the angular momentum of the first structures in the early Universe using simulations. We focus on DM haloes and their gas component as well as the recently predicted supersonically-induced gas objects (SIGOs) that arise as a result of the stream velocity phase shift. We find that the spin parameter of the gas component in these first haloes is increased with the stream velocity. Moreover, we find that when the stream velocity is taken into account, the angular momentum vectors of the DM component and the gas component are typically misaligned and this misalignment angle has a nearly isotropic distribution. The spin parameter value of the gas component is higher than in the no stream velocity case, which even in the absence of cooling, may result in more prolate objects. We also generalize the spin parameter to the SIGOs and find that they typically have a larger spin parameter with respect to their dark matter counterparts and that there is no correlation of the spin parameter and the prolateness of such structures. We speculate that SIGOs may be observed as very low luminosity objects in the early Universe and may serve as potential progenitors of Little Blue Dot-like systems.

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Little Blue Dots in the Hubble Space Telescope Frontier Fields: Precursors to Globular Clusters?

Cited by 18 publications

References 30 publications

The Supersonic Project: Shining Light on SIGOs—A New Formation Channel for Globular Clusters

The Supersonic Project: Shining Light on SIGOs—A New Formation Channel for Globular Clusters

Massive star cluster formation under the microscope atz = 6

The Supersonic Project: rotational effects of supersonic motions on the first structures in the Universe

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