scholarly journals COLDz: Probing Cosmic Star Formation With Radio Free–Free Emission

2022 ◽  
Vol 924 (2) ◽  
pp. 76
Author(s):  
Hiddo S. B. Algera ◽  
Jacqueline A. Hodge ◽  
Dominik A. Riechers ◽  
Sarah K. Leslie ◽  
Ian Smail ◽  
...  
Keyword(s):  
Star Formation ◽  
High Redshift ◽  
Formation Rate ◽  
Radio Spectrum ◽  
Star Formation History ◽  
Starburst Galaxy ◽  
Synchrotron Emission ◽  
Very Large Array ◽  
Star Forming ◽  
Order Of Magnitude

Abstract Radio free–free emission is considered to be one of the most reliable tracers of star formation in galaxies. However, as it constitutes the faintest part of the radio spectrum—being roughly an order of magnitude less luminous than radio synchrotron emission at the GHz frequencies typically targeted in radio surveys—the usage of free–free emission as a star formation rate tracer has mostly remained limited to the local universe. Here, we perform a multifrequency radio stacking analysis using deep Karl G. Jansky Very Large Array observations at 1.4, 3, 5, 10, and 34 GHz in the COSMOS and GOODS-North fields to probe free–free emission in typical galaxies at the peak of cosmic star formation. We find that z ∼ 0.5–3 star-forming galaxies exhibit radio emission at rest-frame frequencies of ∼65–90 GHz that is ∼1.5–2 times fainter than would be expected from a simple combination of free–free and synchrotron emission, as in the prototypical starburst galaxy M82. We interpret this as a deficit in high-frequency synchrotron emission, while the level of free–free emission is as expected from M82. We additionally provide the first constraints on the cosmic star formation history using free–free emission at 0.5 ≲ z ≲ 3, which are in good agreement with more established tracers at high redshift. In the future, deep multifrequency radio surveys will be crucial in order to accurately determine the shape of the radio spectrum of faint star-forming galaxies, and to further establish radio free–free emission as a tracer of high-redshift star formation.

scholarly journals New submillimeter diagnostics of physical properties of ISM in high redshift galaxies

2006 ◽  
Vol 2 (S235) ◽  
pp. 430-430
Author(s):  
Yoichi Tamura ◽  
Kouichiro Nakanishi ◽  
Kotaro Kohno ◽  
Ryohei Kawabe
Keyword(s):  
Star Formation ◽  
Physical Properties ◽  
High Redshift ◽  
Formation Rate ◽  
Host Galaxies ◽  
Power Sources ◽  
High Redshift Galaxies ◽  
Star Forming ◽  
Order Of Magnitude ◽  
New Diagnosis

AbstractWe present a new diagnosis method for determining physical properties of star-forming gas in high-z galaxies. In this method, we employed three key observational quantities, [CI], CO, and FIR luminosities, including our new detections of CO J = 4–3 emission from the pure-starburst (non-AGN) submm galaxy SMM J14011+0252 (z = 2.6) and the type-2 AGN IRAS FSC 10214+4724 (z = 2.3) obtained with the Nobeyama Millimeter Array (NMA) at the Nobeyama Radio Observatory. These two sources have extremely high star formation rate, and exhibit strong emission of CO and [CI] 609 μm lines. We determined ISM physical conditions for the two objects and another three high-z quasars in order to investigate the relationship between their ISM and power sources (i.e., massive star formation or AGN). A new PDR analysis (Wolfire et al. 2005, private communication) using CO, [CI], and FIR on five high-z sources provides new evidence that AGN host galaxies harbor denser (log nH ~ 5–6) ISM exposed to stronger far-UV fluxes of log G0 ~ 3.5–4 than the non-AGN submm galaxy. Volume filling factors of the star-forming dense gas in the AGN hosts are an order of magnitude smaller than that of the pure-starburst submm galaxy. This suggests that, in these AGN hosts, dense molecular clouds are dominating the central kpc around AGN, triggering extensive circumnuclear starbursts, and possibly feeding their central supermassive black hole simultaneously.

scholarly journals The life cycle of the Central Molecular Zone – I. Inflow, star formation, and winds

2019 ◽  
Vol 490 (3) ◽  
pp. 4401-4418 ◽  
Author(s):  
Lucia Armillotta ◽  
Mark R Krumholz ◽  
Enrico M Di Teodoro ◽  
N M McClure-Griffiths
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Star Formation History ◽  
Galactic Centre ◽  
Two Phase ◽  
Star Forming ◽  
Stellar Feedback ◽  
Order Of Magnitude ◽  
Hydrodynamical Simulations

ABSTRACT We present a study of the gas cycle and star formation history in the central 500 pc of the Milky Way, known as Central Molecular Zone (CMZ). Through hydrodynamical simulations of the inner 4.5 kpc of our Galaxy, we follow the gas cycle in a completely self-consistent way, starting from gas radial inflow due to the Galactic bar, the channelling of this gas into a dense, star-forming ring/stream at ≈200–300 pc from the Galactic centre, and the launching of galactic outflows powered by stellar feedback. We find that star formation activity in the CMZ goes through oscillatory burst/quench cycles, with a period of tens to hundreds of Myr, characterized by roughly constant gas mass but order-of-magnitude level variations in the star formation rate. Comparison with the observed present-day star formation rate of the CMZ suggests that we are currently near a minimum of this cycle. Stellar feedback drives a mainly two-phase wind off the Galactic disc. The warm phase dominates the mass flux, and carries $100\!-\!200{{\ \rm per\ cent}}$ of the gas mass converted into stars. However, most of this gas goes into a fountain and falls back on to the disc rather than escaping the Galaxy. The hot phase carries most of the energy, with a time-averaged energy outflow rate of $10\!-\!20{{\ \rm per\ cent}}$ of the supernova energy budget.

scholarly journals Resolved star formation relations at high redshift from the IRAM PHIBSS program

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
Jonathan Freundlich ◽  
Françoise Combes ◽  
Linda Tacconi ◽  
Michael Cooper ◽  
Reinhard Genzel ◽  
...  
Keyword(s):  
Star Formation ◽  
High Redshift ◽  
Formation Rate ◽  
Molecular Gas ◽  
Formation Processes ◽  
Massive Galaxies ◽  
Star Forming ◽  
Star Forming Regions ◽  
Order Of Magnitude ◽  
Formation Efficiency

AbstractObserved massive galaxies in the distant Universe form stars at much higher rates than today. High levels of star formation are sustained by a continuous supply of fresh gas and high molecular gas fractions. But after a peak around redshift z=2-3, the star formation rate decreases by an order of magnitude. Is this evolution mostly driven by the available cold gas reservoir, or are the star formation processes qualitatively different near the star formation peak? The Kennicutt-Schmidt relation enables to characterize the star formation efficiency at low and high redshift, but resolved measurements at the scale of the star-forming regions themselves are still challenging at high redshift. Molecular gas observations carried out at the IRAM Plateau de Bure interferometer within the PHIBSS program (Tacconi, Combes et al.) permit us to study the star formation efficiency at sub-galactic scales around z=1.2 and 1.5 for a limited sample of galaxies, and thus help characterize the star formation processes at this epoch. Our results lay in the continuation of the resolved low-redshift measurements, but further studies would be necessary to complement our sample and validate our conclusions.

scholarly journals The DIANOGA simulations of galaxy clusters: characterising star formation in protoclusters

2020 ◽  
Vol 642 ◽  
pp. A37 ◽  
Author(s):  
L. Bassini ◽  
E. Rasia ◽  
S. Borgani ◽  
G. L. Granato ◽  
C. Ragone-Figueroa ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Clusters ◽  
High Redshift ◽  
Formation Rate ◽  
Star Formation History ◽  
Formation Model ◽  
Star Forming ◽  
Subgrid Model ◽  
The Difference ◽  
Hydrodynamical Simulations

Aims. We studied the star formation rate (SFR) in cosmological hydrodynamical simulations of galaxy (proto-)clusters in the redshift range 0 <  z <  4, comparing them to recent observational studies; we also investigated the effect of varying the parameters of the star formation model on galaxy properties such as SFR, star-formation efficiency, and gas fraction. Methods. We analyse a set of zoom-in cosmological hydrodynamical simulations centred on 12 clusters. The simulations are carried out with the GADGET-3 Tree-PM smoothed-particle hydro-dynamics code which includes various subgrid models to treat unresolved baryonic physics, including AGN feedback. Results. Simulations do not reproduce the high values of SFR observed within protocluster cores, where the values of SFR are underpredicted by a factor ≳4 both at z ∼ 2 and z ∼ 4. The difference arises as simulations are unable to reproduce the observed starburst population and is greater at z ∼ 2 because simulations underpredict the normalisation of the main sequence (MS) of star forming galaxies (i.e. the correlation between stellar mass and SFR) by a factor of ∼3. As the low normalisation of the MS seems to be driven by an underestimated gas fraction, it remains unclear whether numerical simulations miss starburst galaxies due to overly underpredicted gas fractions or overly low star formation efficiencies. Our results are stable against varying several parameters of the star formation subgrid model and do not depend on the details of AGN feedback. Conclusions. The subgrid model for star formation, introduced to reproduce the self-regulated evolution of quiescent galaxies, is not suitable to describe violent events like high-redshift starbursts. We find that this conclusion holds, independently of the parameter choice for the star formation and AGN models. The increasing number of multi-wavelength high-redshift observations will help to improve the current star formation model, which is needed to fully recover the observed star formation history of galaxy clusters.

scholarly journals The effects of star formation history in the SFR–M* relation of H ii galaxies

2020 ◽  
Vol 500 (3) ◽  
pp. 3240-3253
Author(s):  
Amanda R Lopes ◽  
Eduardo Telles ◽  
Jorge Melnick
Keyword(s):  
Star Formation ◽  
Spectral Energy Distribution ◽  
Formation Rate ◽  
Star Formation History ◽  
Spectral Energy ◽  
Distribution Fitting ◽  
Good Tool ◽  
Star Forming ◽  
Additional Information ◽  
Star Formation Histories

ABSTRACT We discuss the implications of assuming different star formation histories (SFH) in the relation between star formation rate (SFR) and mass derived by the spectral energy distribution fitting (SED). Our analysis focuses on a sample of H ii galaxies, dwarf starburst galaxies spectroscopically selected through their strong narrow emission lines in SDSS DR13 at z &lt; 0.4, cross-matched with photometric catalogues from GALEX, SDSS, UKIDSS, and WISE. We modelled and fitted the SEDs with the code CIGALE adopting different descriptions of SFH. By adding information from different independent studies, we find that H ii galaxies are best described by episodic SFHs including an old (10 Gyr), an intermediate age (100−1000 Myr) and a recent population with ages &lt; 10 Myr. H ii galaxies agree with the SFR−M* relation from local star-forming galaxies, and only lie above such relation when the current SFR is adopted as opposed to the average over the entire SFH. The SFR−M* demonstrated not to be a good tool to provide additional information about the SFH of H ii galaxies, as different SFH present a similar behaviour with a spread of &lt;0.1 dex.

scholarly journals Quenching by gas compression and consumption

2019 ◽  
Vol 624 ◽  
pp. A81 ◽  
Author(s):  
Allison W. S. Man ◽  
Matthew D. Lehnert ◽  
Joël D. R. Vernet ◽  
Carlos De Breuck ◽  
Theresa Falkendal
Keyword(s):  
Star Formation ◽  
Formation Rate ◽  
Relative Strength ◽  
Star Formation History ◽  
Molecular Gas ◽  
Host Galaxies ◽  
Massive Galaxies ◽  
Star Forming ◽  
Gas Compression ◽  
Formation History

The objective of this work is to study how active galactic nuclei (AGN) influence star formation in host galaxies. We present a detailed investigation of the star-formation history and conditions of a z = 2.57 massive radio galaxy based on VLT/X-shooter and ALMA observations. The deep rest-frame ultraviolet spectrum contains photospheric absorption lines and wind features indicating the presence of OB-type stars. The most significantly detected photospheric features are used to characterize the recent star formation: neither instantaneous nor continuous star-formation history is consistent with the relative strength of the Si IIλ1485 and S Vλ1502 absorption. Rather, at least two bursts of star formation took place in the recent past, at 6+1-2 Myr and ≳20 Myr ago, respectively. We deduce a molecular H2 gas mass of (3.9 ± 1.0) × 1010 M⊙ based on ALMA observations of the [C I] 3P2−3P1 emission. The molecular gas mass is only 13% of its stellar mass. Combined with its high star-formation rate of (1020-170+190 M⊙ yr-1, this implies a high star-formation efficiency of (26 ± 8) Gyr−1 and a short depletion time of (38 ± 12) Myr. We attribute the efficient star formation to compressive gas motions in order to explain the modest velocity dispersions (⩽55 km s−1) of the photospheric lines and of the star-forming gas traced by [C I]. Because of the likely very young age of the radio source, our findings suggest that vigorous star formation consumes much of the gas and works in concert with the AGN to remove any residual molecular gas, and eventually quenching star formation in massive galaxies.

scholarly journals Exploration of the high-redshift universe enabled by THESEUS

2021 ◽  
Author(s):  
N. R. Tanvir ◽  
E. Le Floc’h ◽  
L. Christensen ◽  
J. Caruana ◽  
R. Salvaterra ◽  
...  
Keyword(s):  
Star Formation ◽  
Gamma Ray ◽  
High Redshift ◽  
Formation Rate ◽  
Star Forming ◽  
Chemical Enrichment ◽  
Long Duration ◽  
Absorption Studies ◽  
Population Iii Stars ◽  
High Redshift Universe

AbstractAt peak, long-duration gamma-ray bursts are the most luminous sources of electromagnetic radiation known. Since their progenitors are massive stars, they provide a tracer of star formation and star-forming galaxies over the whole of cosmic history. Their bright power-law afterglows provide ideal backlights for absorption studies of the interstellar and intergalactic medium back to the reionization era. The proposed THESEUS mission is designed to detect large samples of GRBs at z > 6 in the 2030s, at a time when supporting observations with major next generation facilities will be possible, thus enabling a range of transformative science. THESEUS will allow us to explore the faint end of the luminosity function of galaxies and the star formation rate density to high redshifts; constrain the progress of re-ionisation beyond $z\gtrsim 6$ z ≳ 6 ; study in detail early chemical enrichment from stellar explosions, including signatures of Population III stars; and potentially characterize the dark energy equation of state at the highest redshifts.

scholarly journals Dependence of gravitational wave transient rates on cosmic star formation and metallicity evolution history

2020 ◽  
Vol 493 (1) ◽  
pp. L6-L10 ◽  
Author(s):  
Petra N Tang ◽  
J J Eldridge ◽  
Elizabeth R Stanway ◽  
J C Bray
Keyword(s):  
Star Formation ◽  
Neutron Star ◽  
Gravitational Wave ◽  
Formation Rate ◽  
Compact Objects ◽  
Star Formation History ◽  
Compact Binary ◽  
Formation History ◽  
Order Of Magnitude ◽  
History Of

ABSTRACT We compare the impacts of uncertainties in both binary population synthesis models and the cosmic star formation history on the predicted rates of gravitational wave (GW) compact binary merger events. These uncertainties cause the predicted rates of GW events to vary by up to an order of magnitude. Varying the volume-averaged star formation rate density history of the Universe causes the weakest change to our predictions, while varying the metallicity evolution has the strongest effect. Double neutron star merger rates are more sensitive to assumed neutron star kick velocity than the cosmic star formation history. Varying certain parameters affects merger rates in different ways depending on the mass of the merging compact objects; thus some of the degeneracy may be broken by looking at all the event rates rather than restricting ourselves to one class of mergers.

scholarly journals Observations of the Lyman-α Universe

2020 ◽  
Vol 58 (1) ◽  
pp. 617-659
Author(s):  
Masami Ouchi ◽  
Yoshiaki Ono ◽  
Takatoshi Shibuya
Keyword(s):  
Star Formation ◽  
Dwarf Galaxy ◽  
High Redshift ◽  
Formation Rate ◽  
Neutral Hydrogen ◽  
Resonant Scattering ◽  
Dark Matter Halo ◽  
Emission Data ◽  
Star Forming ◽  
High Redshift Universe

Hydrogen Lyman-α (Lyα) emission has been one of the major observational probes for the high-redshift Universe since the first discoveries of high- z Lyα-emitting galaxies in the late 1990s. Due to the strong Lyα emission originated by resonant scattering and recombination of the most abundant element, Lyα observations witness not only Hii regions of star formation and active galactic nuclei (AGNs) but also diffuse Hi gas in the circumgalactic medium (CGM) and the intergalactic medium (IGM). Here, we review Lyα sources and present theoretical interpretations reached to date. We conclude the following: ▪  A typical Lyα emitter (LAE) at z ≳ 2 with a L* Lyα luminosity is a high- z counterpart of a local dwarf galaxy, a compact metal-poor star-forming galaxy (SFG) with an approximate stellar (dark matter halo) mass and star-formation rate of 108−9M⊙ (1010−11M⊙) and 1–10 M⊙ year−1, respectively. ▪  High- z SFGs ubiquitously have a diffuse Lyα-emitting halo in the CGM extending to the halo virial radius and beyond. ▪  Remaining neutral hydrogen at the epoch of cosmic reionization makes a strong dimming of Lyα emission for galaxies at z > 6 that suggests the late reionization history. The next-generation large-telescope projects will combine Lyα emission data with Hi Lyα absorptions and 21-cm radio data that map out the majority of hydrogen (Hi+Hii) gas, uncovering the exchanges of ( a) matter by outflow and inflow and ( b) radiation, relevant to cosmic reionization, between galaxies and the CGM/IGM.

scholarly journals The 1.4-GHz cosmic star formation history at z < 1.3

2019 ◽  
Vol 36 ◽  
Author(s):  
James E. Upjohn ◽  
Michael J. I. Brown ◽  
Andrew M. Hopkins ◽  
Nicolas J. Bonne
Keyword(s):  
Star Formation ◽  
Luminosity Function ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Radio Continuum ◽  
Star Formation History ◽  
Star Forming ◽  
Formation History ◽  
Radio Measurements ◽  
Radio Luminosity Function

AbstractWe measure the cosmic star formation history out to z = 1.3 using a sample of 918 radio-selected star-forming galaxies within the 2-deg2 COSMOS field. To increase our sample size, we combine 1.4-GHz flux densities from the VLA-COSMOS catalogue with flux densities measured from the VLA-COSMOS radio continuum image at the positions of I &lt; 26.5 galaxies, enabling us to detect 1.4-GHz sources as faint as 40 μJy. We find that radio measurements of the cosmic star formation history are highly dependent on sample completeness and models used to extrapolate the faint end of the radio luminosity function. For our preferred model of the luminosity function, we find the star formation rate density increases from 0.017 M⊙ yr−1 Mpc−3 at z ∼ 0.225 to 0.092 M⊙ yr−1 Mpc−3 at z ∼ 1.1, which agrees to within 40% of recent UV, IR and 3-GHz measurements of the cosmic star formation history.

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