The Star Formation History of the Universe as Revealed by Deep Radio Observations

By N. Seymour, T. Dwelly, D. Moss, I. McHardy, A. Zoghbi, G. Rieke, M. Page, Andrew M. Hopkins, N. A. A. S. Center, U. Southampton and 6 more. 2008

166 citations recorded by the source corpus.

Discerning the exact nature of the sub-mJy radio population has been historically difficult due to the low luminosity of these sources at most wavelengths. Using deep ground based optical follow-up and observations from the Spitzer Space Telescope we are able to disentangle the radio-selected active galactic nuclei (AGN) and star-forming galaxy (SFG) populations for the first time in a deep multifrequency VLA/MERLIN Survey of the 13^H XMM Newton/Chandra Deep Field. The discrimination diagnostics include radio morphology, radio spectral index, radio/near-infrared (near-IR) and mid-IR/radio flux density ratios. We are nowable to calculate the extragalactic Euclidean normalized source counts separately for AGN and SFGs. We find that while SFGs dominate at the faintest flux densities and account for the majority of the upturn in the counts, AGN still make up around one quarter of the counts at ∼50 μJy (1.4 GHz). Using radio luminosity as an unobscured star formation rate (SFR) measure we are then able to examine the comoving SFR density of the Universe up to z = 3 which agrees well with measures at other wavelengths. We find a rough correlation of SFR with stellar mass for both the sample presented here and a sample of local radio-selected SFGs from the 6df-NVSS survey. This work also confirms the existence of, and provides alternative evidence for, the evolution of distribution of star formation by galaxy mass: ‘downsizing’. As both these samples are SFR-selected, this result suggests that there is a maximum SFR for a given galaxy that depends linearly on its stellar mass. The low ‘characteristic times’ (inverse specific SFR) of the SFGs in our sample are similar to those of the 6dF-NVSS sample, implying that most of these sources are in a current phase of enhanced star formation.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/2026669310db2de3322f9c9356c337d0f59ee1f7

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. D. M. Alexander
2. L. Hernquist
3. P. Hopkins
4. E. Daddi
5. D. Elbaz
6. D. Narayanan
7. Mark Dickinson
8. R. Dav'e

In Instrumentation

1. D. M. Alexander
2. E. Daddi
3. Mark Dickinson
4. D. Elbaz
5. P. V. van Dokkum
6. A. Koekemoer
7. R. Dav'e
8. C. Conroy

Citations in the corpus

• A UNIFIED EMPIRICAL MODEL FOR INFRARED GALAXY COUNTS BASED ON THE OBSERVED PHYSICAL EVOLUTION OF DISTANT GALAXIES (2012, result): “According to our model, the 1.4 GHz counts are dominated by SF objects below 200µJy, in agreement with the observations of e.g. Seymour et al. (2008).”
• The star formation history of K-selected galaxies (2008, background): “In contrast, a recent study by Seymour et al. (2008), using VLA and MERLIN images, has been able to separate radio sources into AGN and SFGs on the basis of radio morphology, spectral index and radio/near-IR and mid-IR/radio flux density ratios.”
• The VLA-COSMOS 3 GHz Large Project: Continuum data and source catalog release (2017, background): “These past surveys have shown that deep observations at high angular resolution (.1′′) with exquisite panchromatic coverage are critical to comprehensively study the radio properties of the main galaxy populations, avoiding cosmic variance with large area coverage (e.g., Padovani et al. 2009; Padova”
• THE SPITZER DEEP, WIDE-FIELD SURVEY (2009, background): “As expected (e.g., Seymour et al. 2008) at these fainter radio fluxes, we see a large population of star-forming galaxies as shown by their red [5.8] − [8.0] colors due to PAH emission in the reddest IRAC bandpass.”
• Evolution of magnetic fields in galaxies and future observational tests with the Square Kilometre Array (2008, background): “Another indication of strong magnetic fields in young galaxies is the tight radio – far-infrared correlation, which is valid in galaxies at least to distances of z 3 (Seymour et al. 2008).”
• DETERMINING STAR FORMATION RATES FOR INFRARED GALAXIES (2008, background): “Figure 12 (reproduced from Seymour et al. 2008) explores the relation at z ∼ 2.”
• The faint radio sky: radio astronomy becomes mainstream (2016, background): “Traditionally, however, their role has been somewhat limited (but see, e.g., Haarsma et al., 2000; Seymour et al., 2008; Karim et al., 2011) although other, more “standard” methods all have their own limitations.”
• Radio and millimeter continuum surveys and their astrophysical implications (2009, methodology): “Seymour et al. (2008) used four diagnostics (radio morphology, radio spectral index, radio/near-IR and mid-IR/radio flux-density ratios) to single out, in a statistical sense, radio emission powered by AGN activity.”
• A semi-empirical simulation of the extragalactic radio continuum sky for next generation radio telescopes (2008, background): “Recent multi-wavelength identification work on several deep fields appears to substantiate this claim (e.g. Simpson et al. 2006; Seymour et al. 2008; Smolcic et al. 2008), suggesting that possibly as many as half the sources at the level of a few tens ofµJy may be radio-quiet AGN.”
• EMU: Evolutionary Map of the Universe (2011, background): “…et al. 2008; Ibar et al. 2009), but, even at these levels, there is still a significant proportion of low-luminosity AGNs (Jarvis et al. 2004; Afonso et al. 2005, 2006; Norris et al. 2006; Simpson et al. 2006; Smolcic et al. 2008; Seymour et al. 2008; Mignano et al. 2008; Padovani et al. 2009).”
• Cosmic evolution of submillimeter galaxies and their contribution to stellar mass assembly (2009, unknown): “…0.1479 0.0666 0.0812 radio Seymour et al. (2008) Micha lowski et al.: Evolution of submillimeter galaxies 33 Table A.4. continued. z ∆z ρSFR −∆ρSFR +∆ρSFR Estimator Reference 2.450 0.550 0.1202 0.0756 0.1036 radio Seymour et al. (2008) 0.100 0.100 0.0087 0.0063 0.0062 radio Dunne et al. (2009)…”
• The Very Large Array Low-frequency Sky Survey Redux (VLSSr) (2014, background): “Archibald et al. 2001; Seymour et al. 2008).”
• The deepest Herschel-PACS far-infrared survey: number counts and infrared luminosity functions from combined PEP/GOODS-H observations (2013, result): “Finally, we note that the cosmic star-formation history derived here is fully consistent with the combination of indicators, either obscured or corrected for dust extinction, as compiled by Hopkins & Beacom (2006), Seymour et al. (2008) and Karim et al. (2011, not shown in Fig.”
• Evolution of the dusty infrared luminosity function from z = 0 to z = 2.3 using observations from Spitzer (2011, result): “We also notice a very good agreement between the cosmic star-formation history derived in our work and the ones derived by Seymour et al. (2008) using deep radio observations.”
• LOFAR 150-MHz observations of the Boötes field: catalogue and source counts (2016, background): “…from the compilation of de Zotti et al. (2010) (including counts from Bridle et al. 1972; White et al. 1997; Ciliegi et al. 1999; Gruppioni et al. 1999; Richards 2000; Hopkins et al. 2003; Fomalont et al. 2006; Bondi et al. 2008; Kellermann et al. 2008; Owen & Morrison 2008; Seymour et al. 2008).”