scholarly journals AGN and star formation across cosmic time

2021 ◽  
Vol 503 (3) ◽  
pp. 3992-4007
Author(s):  
M Symeonidis ◽  
M J Page
Keyword(s):  
Star Formation ◽  
High Redshift ◽  
Cosmic Time ◽  
Balance Of Power ◽  
High Luminosity ◽  
Observable Universe ◽  
Luminous Galaxies ◽  
Galaxy Luminosity Function ◽  
Cosmic History ◽  
Shed Light

ABSTRACT We investigate the balance of power between stars and AGN across cosmic history, based on the comparison between the infrared (IR) galaxy luminosity function (LF) and the IR AGN LF. The former corresponds to emission from dust heated by stars and AGN, whereas the latter includes emission from AGN-heated dust only. We find that at all redshifts (at least up to z ∼ 2.5), the high-luminosity tails of the two LFs converge, indicating that the most IR-luminous galaxies are AGN-powered. Our results shed light to the decades-old conundrum regarding the flatter high-luminosity slope seen in the IR galaxy LF compared to that in the UV and optical. We attribute this difference to the increasing fraction of AGN-dominated galaxies with increasing total IR luminosity (LIR). We partition the LIR−z parameter space into a star formation-dominated and an AGN-dominated region, finding that the most luminous galaxies at all epochs lie in the AGN-dominated region. This sets a potential ‘limit’ to attainable star formation rates, casting doubt on the abundance of ‘extreme starbursts’: if AGN did not exist, LIR > 1013 L⊙ galaxies would be significantly rarer than they currently are in our observable Universe. We also find that AGN affect the average dust temperatures (Tdust) of galaxies and hence the shape of the well-known LIR−Tdust relation. We propose that the reason why local ULIRGs are hotter than their high-redshift counterparts is because of a higher fraction of AGN-dominated galaxies amongst the former group.

scholarly journals Properties of the ISM in UV-luminous galaxies: clues from the low-redshift universe

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
Thiago S. Gonçalves
Keyword(s):  
Star Formation ◽  
Conversion Factor ◽  
High Redshift ◽  
Cosmic Time ◽  
Molecular Gas ◽  
Gas Reservoir ◽  
Local Universe ◽  
Star Forming ◽  
Luminous Galaxies ◽  
Co Observations

AbstractHow is gas converted into stars across cosmic time? Observations of star-forming galaxies at high redshift indicate that the conditions of the interstellar medium (ISM) were remarkably distinct from typical spirals in the local universe. Nevertheless, these observations are biased towards objects brighter than L*, due to the large luminosity distances involved. Here I present a survey targeting the molecular gas in galaxies at low redshift (z ~ 0.2) with ISM conditions remarkably similar to those observed at earlier epochs, including high star formation rates and lower metallicities. CO observations performed with CARMA indicate that these galaxies follow the same star-formation law as local spirals and other galaxies at the same redshift, albeit at much higher densities. We also present recent results from our ALMA program studying galaxies down to 12 + log(O/H) ~ 8, and discuss the implications of these data to our understanding of the molecular gas reservoir and the conversion factor between CO luminosity and gas mass in environments that are simultaneously low in metal content and extremely dense.

scholarly journals Galaxy and mass assembly (GAMA): the inferred mass–metallicity relation from z = 0 to 3.5 via forensic SED fitting

2021 ◽  
Vol 503 (3) ◽  
pp. 3309-3325
Author(s):  
Sabine Bellstedt ◽  
Aaron S G Robotham ◽  
Simon P Driver ◽  
Jessica E Thorne ◽  
Luke J M Davies ◽  
...  
Keyword(s):  
Star Formation ◽  
Gas Phase ◽  
Large Range ◽  
Three Dimensional ◽  
Cosmic Time ◽  
Slowing Down ◽  
History Of ◽  
Mass Assembly ◽  
Star Formation Histories ◽  
Cosmic History

ABSTRACT We analyse the metallicity histories of ∼4500 galaxies from the GAMA survey at z < 0.06 modelled by the SED-fitting code ProSpect using an evolving metallicity implementation. These metallicity histories, in combination with the associated star formation histories, allow us to analyse the inferred gas-phase mass–metallicity relation. Furthermore, we extract the mass–metallicity relation at a sequence of epochs in cosmic history, to track the evolving mass–metallicity relation with time. Through comparison with observations of gas-phase metallicity over a large range of redshifts, we show that, remarkably, our forensic SED analysis has produced an evolving mass–metallicity relationship that is consistent with observations at all epochs. We additionally analyse the three-dimensional mass–metallicity–SFR space, showing that galaxies occupy a clearly defined plane. This plane is shown to be subtly evolving, displaying an increased tilt with time caused by general enrichment, and also the slowing down of star formation with cosmic time. This evolution is most apparent at lookback times greater than 7 Gyr. The trends in metallicity recovered in this work highlight that the evolving metallicity implementation used within the SED-fitting code ProSpect produces reasonable metallicity results over the history of a galaxy. This is expected to provide a significant improvement to the accuracy of the SED-fitting outputs.

scholarly journals Galaxy Metabolism

2010 ◽  
Vol 27 (3) ◽  
pp. 233-233
Author(s):  
Andrew Hopkins
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Mass Density ◽  
High Redshift ◽  
Large Population ◽  
Star Formation History ◽  
Global Constraints ◽  
Great Success ◽  
Mass Dependent ◽  
Cosmic History

‘Galaxy Metabolism' was the second in the annual ‘Southern Cross Astrophysics Conference Series’ (http://www.aao.gov.au/AAO/southerncross/), supported by the Anglo-Australian Observatory and the Australia Telescope National Facility. It was held at the Australian National Maritime Museum in Darling Harbour, Sydney, from 22 to 26 June 2009, and was attended by 91 delegates from around the world.Over the past decade, both the star formation history and stellar mass density in galaxies spanning most of cosmic history have been well constrained. This provides the backdrop and framework within which many detailed investigations of galaxy growth are now placed. The mass-dependent and environment-dependent evolution of galaxies over cosmic history is now the focus of several surveys. Many studies are also exploring the role of gas infall and outflow in driving galaxy evolution, and the connection of these processes to massive star formation within galaxies.The aims of ‘Galaxy Metabolism’ were to bring together the global constraints on galaxy evolution, at both low and high redshift, with detailed studies of well-resolved systems, to define a clear picture of our understanding of galaxy metabolism: How do the processes of ingestion (infall), digestion (ISM physics, star formation) and excretion (outflow) govern the global properties of galaxies; how do these change over a galaxy's lifetime; and are the constraints from nearby well resolved studies consistent with those from large population surveys at low and high redshift?The conference was a great success, with an extensive variety of topics covered spanning many aspects of galaxy evolution, and brought together eloquently in a comprehensive conference summary by Warrick Couch. The four papers by De Lucia (2010), Cole (2010), Vlajić (2010) and Stocke et al. (2010) presented in this special collection of PASA are just a sampling of the depth and variety of the resentations given during the conference.

scholarly journals Star Formation Through Cosmic Time

2006 ◽  
Vol 2 (S235) ◽  
pp. 261-267
Author(s):  
Michael A. Dopita
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Globular Clusters ◽  
High Redshift ◽  
Cosmic Time ◽  
Star Formation History ◽  
Massive Black Holes ◽  
Massive Galaxies ◽  
History Of ◽  
Population Iii Stars

AbstractThis paper reviews the star formation history of the Universe, from the first stars to the current day, with emphasis on the critical analysis of the techniques that have been used to determine it, especially considering the role of dust. We consider the first population of stars, the Population III stars, were formed at redshifts ranging as high as z ~ 60, the formation of the Globular Clusters, the main epoch of galaxy formation. In the sub-mm galaxies and high-redshift radio galaxies the collapse of massive galaxies was surprisingly rapid, and that the growth of super-massive black holes at their centers provides the energy input to eject the galactic interstellar medium while at the same time precipitating a final burst of star formation and the ejection of their ISM so that the subsequent evolution of these galaxies is passive.

scholarly journals BALANCING THE ENERGY BUDGET BETWEEN STAR FORMATION AND ACTIVE GALACTIC NUCLEI IN HIGH-REDSHIFT INFRARED LUMINOUS GALAXIES

2009 ◽  
Vol 698 (2) ◽  
pp. 1380-1397 ◽  
Author(s):  
E. J. Murphy ◽  
R.-R. Chary ◽  
D. M. Alexander ◽  
M. Dickinson ◽  
B. Magnelli ◽  
...  
Keyword(s):  
Star Formation ◽  
Active Galactic Nuclei ◽  
Energy Budget ◽  
High Redshift ◽  
Galactic Nuclei ◽  
Luminous Galaxies

scholarly journals The elephant in the bathtub: when the physics of star formation regulate the baryon cycle of galaxies

2020 ◽  
Vol 500 (2) ◽  
pp. 2000-2011
Author(s):  
Jindra Gensior ◽  
J M Diederik Kruijssen
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Galaxy Formation ◽  
High Redshift ◽  
Formation Rate ◽  
Cosmic Time ◽  
Free Fall ◽  
Isolated Galaxies ◽  
The Galaxy ◽  
Galaxy Masses

ABSTRACT In simple models of galaxy formation and evolution, star formation is solely regulated by the amount of gas present in the galaxy. However, it has recently been shown that star formation can be suppressed by galactic dynamics in galaxies that contain a dominant spheroidal component and a low gas fraction. This ‘dynamical suppression’ is hypothesized to also contribute to quenching gas-rich galaxies at high redshift, but its impact on the galaxy population at large remains unclear. In this paper, we assess the importance of dynamical suppression in the context of gas regulator models of galaxy evolution through hydrodynamic simulations of isolated galaxies, with gas-to-stellar mass ratios of 0.01–0.20 and a range of galactic gravitational potentials from disc-dominated to spheroidal. Star formation is modelled using a dynamics-dependent efficiency per free-fall time, which depends on the virial parameter of the gas. We find that dynamical suppression becomes more effective at lower gas fractions and quantify its impact on the star formation rate as a function of gas fraction and stellar spheroid mass surface density. We combine the results of our simulations with observed scaling relations that describe the change of galaxy properties across cosmic time, and determine the galaxy mass and redshift range where dynamical suppression may affect the baryon cycle. We predict that the physics of star formation can limit and regulate the baryon cycle at low redshifts (z ≲ 1.4) and high galaxy masses (M* ≳ 3 × 1010 M⊙), where dynamical suppression can drive galaxies off the star formation main sequence.

scholarly journals Tracing the Evolution of Dust Obscured Star Formation and Accretion Back to the Reionisation Epoch withSPICA

2017 ◽  
Vol 34 ◽  
Author(s):  
C. Gruppioni ◽  
L. Ciesla ◽  
E. Hatziminaoglou ◽  
F. Pozzi ◽  
G. Rodighiero ◽  
...  
Keyword(s):  
Star Formation ◽  
Current Knowledge ◽  
High Redshift ◽  
Formation Rate ◽  
Cosmic Time ◽  
Star Forming ◽  
Infrared Instrumentation ◽  
Black Hole Accretion ◽  
Hole Accretion ◽  
Early Phases

AbstractOur current knowledge of star formation and accretion luminosity at high redshift (z> 3–4), as well as the possible connections between them, relies mostly on observations in the rest-frame ultraviolet, which are strongly affected by dust obscuration. Due to the lack of sensitivity of past and current infrared instrumentation, so far it has not been possible to get a glimpse into the early phases of the dust-obscured Universe. Among the next generation of infrared observatories,SPICA, observing in the 12–350 µm range, will be the only facility that can enable us to trace the evolution of the obscured star-formation rate and black-hole accretion rate densities over cosmic time, from the peak of their activity back to the reionisation epoch (i.e., 3 <z≲ 6–7), where its predecessors had severe limitations. Here, we discuss the potential of photometric surveys performed with theSPICAmid-infrared instrument, enabled by the very low level of impact of dust obscuration in a band centred at 34 µm. These unique unbiased photometric surveys thatSPICAwill perform will fully characterise the evolution of AGNs and star-forming galaxies after reionisation.

scholarly journals The evolution of rest-frame UV properties, Ly α EWs, and the SFR–stellar mass relation at z ∼ 2–6 for SC4K LAEs

2020 ◽  
Vol 493 (1) ◽  
pp. 141-160 ◽  
Author(s):  
S Santos ◽  
D Sobral ◽  
J Matthee ◽  
J Calhau ◽  
E da Cunha ◽  
...  
Keyword(s):  
Star Formation ◽  
Rest Frame ◽  
High Redshift ◽  
Cosmic Time ◽  
Stellar Mass ◽  
Spectral Energy ◽  
Mass Relation ◽  
Star Forming ◽  
The Individual ◽  
Stellar Masses

ABSTRACT We explore deep rest-frame UV to FIR data in the COSMOS field to measure the individual spectral energy distributions (SED) of the ∼4000 SC4K (Sobral et al.) Lyman α (Ly α) emitters (LAEs) at z ∼ 2–6. We find typical stellar masses of 109.3 ± 0.6 M⊙ and star formation rates (SFR) of SFR$_{\rm SED}=4.4^{+10.5}_{-2.4}$ M⊙ yr−1 and SFR$_{\rm Ly\,\alpha }=5.9^{+6.3}_{-2.6}$ M⊙ yr−1, combined with very blue UV slopes of $\beta =-2.1^{+0.5}_{-0.4}$, but with significant variations within the population. MUV and β are correlated in a similar way to UV-selected sources, but LAEs are consistently bluer. This suggests that LAEs are the youngest and/or most dust-poor subset of the UV-selected population. We also study the Ly α rest-frame equivalent width (EW0) and find 45 ‘extreme’ LAEs with EW0 &gt; 240 Å (3σ), implying a low number density of (7 ± 1) × 10−7 Mpc−3. Overall, we measure little to no evolution of the Ly α EW0 and scale length parameter (w0), which are consistently high (EW$_0=140^{+280}_{-70}$ Å, $w_0=129^{+11}_{-11}$ Å) from z ∼ 6 to z ∼ 2 and below. However, w0 is anticorrelated with MUV and stellar mass. Our results imply that sources selected as LAEs have a high Ly α escape fraction (fesc,Ly α) irrespective of cosmic time, but fesc,Ly α is still higher for UV-fainter and lower mass LAEs. The least massive LAEs (&lt;109.5 M⊙) are typically located above the star formation ‘main sequence’ (MS), but the offset from the MS decreases towards z ∼ 6 and towards 1010 M⊙. Our results imply a lack of evolution in the properties of LAEs across time and reveals the increasing overlap in properties of LAEs and UV-continuum selected galaxies as typical star-forming galaxies at high redshift effectively become LAEs.

scholarly journals Star Formation Efficiency at Intermediate Redshift

2012 ◽  
Vol 8 (S292) ◽  
pp. 303-306
Author(s):  
F. Combes ◽  
S. García-Burillo ◽  
J. Braine ◽  
E. Schinnerer ◽  
F. Walter ◽  
...  
Keyword(s):  
Star Formation ◽  
Conversion Factor ◽  
High Redshift ◽  
Star Formation History ◽  
Gas Content ◽  
Formation History ◽  
Luminous Galaxies ◽  
Formation Efficiency ◽  
Intermediate Redshift

AbstractStar formation is evolving very fast in the second half of the Universe, and it is as yet unclear whether this is due to evolving gas content, or evolving star formation efficiency (SFE). We have carried out a survey of ultra-luminous galaxies (ULIRG) between z = 0.2 and 1, to check the gas fraction in this domain of redshift which is still poorly known. Our survey with the IRAM-30m detected 33 galaxies out of 69, and we derive a significant evolution of both the gas fraction and SFE of ULIRGs over the whole period, and in particular a turning point around z = 0.35. The result is sensitive to the CO-to-H2 conversion factor adopted, and both gas fraction and SFE have comparable evolution, when we adopt the low starburst conversion factor of α = 0.8 M⊙ (K km s−1 pc2)−1. Adopting a higher α will increase the role of the gas fraction. Using α = 0.8, the SFE and the gas fraction for z∼0.2-1.0 ULIRGs are found to be significantly higher, by a factor 3, than for local ULIRGs, and are comparable to high redshift ones. We compare this evolution to the expected cosmic H2 abundance and the cosmic star formation history.

scholarly journals Simulating star clusters across cosmic time – I. Initial mass function, star formation rates, and efficiencies

2019 ◽  
Vol 489 (2) ◽  
pp. 1880-1898 ◽  
Author(s):  
Chong-Chong He ◽  
Massimo Ricotti ◽  
Sam Geen
Keyword(s):  
Star Formation ◽  
Power Law ◽  
High Redshift ◽  
Star Clusters ◽  
Cosmic Time ◽  
Mass Function ◽  
Initial Mass Function ◽  
High Mass ◽  
Initial Mass ◽  
Solar Metallicity

ABSTRACT We present radiation-magneto-hydrodynamic simulations of star formation in self-gravitating, turbulent molecular clouds, modelling the formation of individual massive stars, including their UV radiation feedback. The set of simulations have cloud masses between mgas = 103 M⊙ and 3 × 105 M⊙ and gas densities typical of clouds in the local Universe ($\overline{n}_{\rm gas} \sim 1.8\times 10^2$ cm−3) and 10× and 100× denser, expected to exist in high-redshift galaxies. The main results are as follows. (i) The observed Salpeter power-law slope and normalization of the stellar initial mass function at the high-mass end can be reproduced if we assume that each star-forming gas clump (sink particle) fragments into stars producing on average a maximum stellar mass about $40{{\ \rm per\ cent}}$ of the mass of the sink particle, while the remaining $60{{\ \rm per\ cent}}$ is distributed into smaller mass stars. Assuming that the sinks fragment according to a power-law mass function flatter than Salpeter, with log-slope 0.8, satisfy this empirical prescription. (ii) The star formation law that best describes our set of simulation is ${\rm d}\rho _*/{\rm d}t \propto \rho _{\rm gas}^{1.5}$ if $\overline{n}_{\rm gas}\lt n_{\rm cri}\approx 10^3$ cm−3, and ${\rm d}\rho _*/{\rm d}t \propto \rho _{\rm gas}^{2.5}$ otherwise. The duration of the star formation episode is roughly six cloud’s sound crossing times (with cs = 10 km s−1). (iii) The total star formation efficiency in the cloud is $f_*=2{{\ \rm per\ cent}} (m_{\rm gas}/10^4~\mathrm{M}_\odot)^{0.4}(1+\overline{n}_{\rm gas}/n_{\rm cri})^{0.91}$, for gas at solar metallicity, while for metallicity Z &lt; 0.1 Z⊙, based on our limited sample, f* is reduced by a factor of ∼5. (iv) The most compact and massive clouds appear to form globular cluster progenitors, in the sense that star clusters remain gravitationally bound after the gas has been expelled.

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