The Impossibly Early Galaxy Problem

Steinhardt, Charles L.; Capak, P.; Masters, Dan; Speagle, Joshua S.

doi:10.3847/0004-637x/824/1/21

Cited by 185 publications

(227 citation statements)

References 71 publications

(134 reference statements)

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“…At the highest redshifts of our sample z > 4.5, we find that the SFR follows a linear SFR ∝ M α , without an apparent turnoff at high mass. Although our sample may not be large enough to identify a turn-off, this result is comparable to Steinhardt et al (2014). Assuming that the fraction of high-mass, high SFR, dustobscured galaxies is not higher at these redshifts than for z < 4.5, a possible interpretation is that at these high redshifts the SFR quenching mechanisms are not yet fully in place.…”

Section: A Turn-off In the Sfr-m Relation: Evolution With Redshiftmentioning

confidence: 68%

The evolving star formation rate:M_⋆relation and sSFR sincez≃ 5 from the VUDS spectroscopic survey

Tasca

Fèvre

Hathi

et al. 2015

A&A

180

203

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We study the evolution of the star formation rate (SFR) -stellar mass (M ) relation and specific star formation rate (sSFR) of star-forming galaxies (SFGs) since a redshift z 5.5 using 2435 (4531) galaxies with highly reliable spectroscopic redshifts in the VIMOS Ultra-Deep Survey (VUDS). It is the first time that these relations can be followed over such a large redshift range from a single homogeneously selected sample of galaxies with spectroscopic redshifts. The log(SFR) − log(M ) relation for SFGs remains roughly linear all the way up to z = 5, but the SFR steadily increases at fixed mass with increasing redshift. We find that for stellar masses M ≥ 3.2 × 10 9 M the SFR increases by a factor of ∼13 between z = 0.4 and z = 2.3. We extend this relation up to z = 5, finding an additional increase in SFR by a factor of 1.7 from z = 2.3 to z = 4.8 for masses M ≥ 10 10 M . We observe a turn-off in the SFR-M relation at the highest mass end up to a redshift z ∼ 3.5. We interpret this turn-off as the signature of a strong on-going quenching mechanism and rapid mass growth. The sSFR increases strongly up to z ∼ 2, but it grows much less rapidly in 2 < z < 5. We find that the shape of the sSFR evolution is not well reproduced by cold gas accretion-driven models or the latest hydrodynamical models. Below z ∼ 2 these models have a flatter evolution (1 + z) Φ with Φ = 2−2.25 compared to the data which evolves more rapidly with Φ = 2.8 ± 0.2. Above z ∼ 2, the reverse is happening with the data evolving more slowly with Φ = 1.2 ± 0.1. The observed sSFR evolution over a large redshift range 0 < z < 5 and our finding of a non-linear main sequence at high mass both indicate that the evolution of SFR and M is not solely driven by gas accretion. The results presented in this paper emphasize the need to invoke a more complex mix of physical processes including major and minor merging to further understand the co-evolution of the SFR and stellar mass growth.

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Section: A Turn-off In the Sfr-m Relation: Evolution With Redshiftmentioning

confidence: 68%

The evolving star formation rate:M_⋆relation and sSFR sincez≃ 5 from the VUDS spectroscopic survey

Tasca

Fèvre

Hathi

et al. 2015

A&A

180

203

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“…In this context, recent studies have found that high-z galaxies may have had to form surprisingly early to account for the weakening of the exponential decline at the bright end of the LF with increasing redshift Finkelstein et al (2015). This could be achieved by an unusually early collapse with respect to standard clustering theory, or an increased star formation efficiency making the stellar-to-halo mass ratio appear to rise with increasing redshift (Steinhardt et al 2015). In order to have a significant impact on the CIB however, these effect must also be present in lower mass systems which contribute the bulk of the CIB.…”

Section: Summary and Discussionmentioning

confidence: 99%

On the physical requirements for a pre-reionization origin of the unresolved near-infrared background

Helgason

Ricotti

Kashlinsky

2015

Monthly Notices of the Royal Astronomical Society

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The study of the Cosmic Near-Infrared Background (CIB) light after subtraction of resolved sources can push the limits of current observations and yield information on galaxies and quasars in the early universe. Spatial fluctuations of the CIB exhibit a clustering excess at angular scales ∼1• whose origin has not been conclusively identified, but disentangling the relative contribution from low-and high-redshift sources is not trivial. We explore the likelihood that this signal is dominated by emission from galaxies and accreting black holes in the early Universe. We find that, the measured fluctuation signal is too large to be produced by galaxies at redshifts z>8, which only contribute ∼0.01−0.05 nWm −2 sr −1 to the CIB. Additionally, if the first small mass galaxies have a normal IMF, the light of their ageing stars (fossils) integrated over cosmic time contributes a comparable amount to the CIB as their pre-reionization progenitors. In order to produce the observed level of CIB fluctuation without violating constraints from galaxy counts and the electron optical depth of the IGM, minihalos at z>12 must form preferably top-heavy stars with efficiency f ⋆ 0.1 and at the same time maintain a very low escape fraction of ionizing radiation, f esc <0.1%. If instead the CIB fluctuations are produced by high-z black holes, one requires vigorous accretion in the early universe reaching ρ acc 10 5 M ⊙ Mpc −3 by z≃10. This growth must stop by z∼6 and be significantly obscured not to overproduce the soft cosmic X-ray background (CXB) and its observed coherence with the CIB. We therefore find the range of suitable high-z explanations to be narrow, but could possibly be widened by including additional physics and evolution at those epochs.

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“…A correlation between the SFR and the stellar mass, known as the star formation main sequence (SFMS), has been found to exist for star-forming galaxies in the full range from low (z < 1; Brinchmann et al 2004) to high (z ∼ 6; Steinhardt et al 2014) redshifts. Both the slope and normalisation of the correlation are observed to change over cosmic time (e.g.…”

Section: Sfr Vs Stellar Mass Relationmentioning

confidence: 99%

Are long gamma-ray bursts biased tracers of star formation? Clues from the host galaxies of theSwift/BAT6 complete sample of bright LGRBs

Japelj

Vergani

Salvaterra

et al. 2016

A&A

100

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Aims. Long gamma-ray bursts (LGRBs) are associated with the deaths of massive stars and might therefore be a potentially powerful tool for tracing cosmic star formation. However, especially at low redshifts (z < 1.5) LGRBs seem to prefer particular types of environment. Our aim is to study the host galaxies of a complete sample of bright LGRBs to investigate the effect of the environment on GRB formation. Methods. We studied host galaxy spectra of the Swift/BAT6 complete sample of 14 z < 1 bright LGRBs. We used the detected nebular emission lines to measure the dust extinction, star formation rate (SFR), and nebular metallicity (Z) of the hosts and supplemented the data set with previously measured stellar masses M . The distributions of the obtained properties and their interrelations (e.g. mass-metallicity and SFR-M relations) are compared to samples of field star-forming galaxies. Results. We find that LGRB hosts at z < 1 have on average lower SFRs than if they were direct star formation tracers. By directly comparing metallicity distributions of LGRB hosts and star-forming galaxies, we find a good match between the two populations up to 12 + log O H ∼ 8.4−8.5, after which the paucity of metal-rich LGRB hosts becomes apparent. The LGRB host galaxies of our complete sample are consistent with the mass-metallicity relation at similar mean redshift and stellar masses. The cutoff against high metallicities (and high masses) can explain the low SFR values of LGRB hosts. We find a hint of an increased incidence of starburst galaxies in the Swift/BAT6 z < 1 sample with respect to that of a field star-forming population. Given that the SFRs are low on average, the latter is ascribed to low stellar masses. Nevertheless, the limits on the completeness and metallicity availability of current surveys, coupled with the limited number of LGRB host galaxies, prevents us from investigating more quantitatively whether the starburst incidence is such as expected after taking into account the high-metallicity aversion of LGRB host galaxies.

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The Impossibly Early Galaxy Problem

Cited by 185 publications

References 71 publications

The evolving star formation rate:M_⋆relation and sSFR sincez≃ 5 from the VUDS spectroscopic survey

The evolving star formation rate:M_⋆relation and sSFR sincez≃ 5 from the VUDS spectroscopic survey

On the physical requirements for a pre-reionization origin of the unresolved near-infrared background

Are long gamma-ray bursts biased tracers of star formation? Clues from the host galaxies of theSwift/BAT6 complete sample of bright LGRBs

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The Impossibly Early Galaxy Problem

Cited by 185 publications

References 71 publications

The evolving star formation rate:M⋆relation and sSFR sincez≃ 5 from the VUDS spectroscopic survey

The evolving star formation rate:M⋆relation and sSFR sincez≃ 5 from the VUDS spectroscopic survey

On the physical requirements for a pre-reionization origin of the unresolved near-infrared background

Are long gamma-ray bursts biased tracers of star formation? Clues from the host galaxies of theSwift/BAT6 complete sample of bright LGRBs

Contact Info

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The evolving star formation rate:M_⋆relation and sSFR sincez≃ 5 from the VUDS spectroscopic survey

The evolving star formation rate:M_⋆relation and sSFR sincez≃ 5 from the VUDS spectroscopic survey