scholarly journals Rest-frame optical line emission from the high-redshift galaxy 1614 + 051A

1995 ◽  
Keyword(s):  
Rest Frame ◽  
High Redshift ◽  
Line Emission ◽  
Redshift Galaxy ◽  
Optical Line

scholarly journals High-Redshift Radio Galaxies

1995 ◽  
Vol 10 ◽  
pp. 543-546
Author(s):  
George Miley
Keyword(s):  
Galaxy Formation ◽  
High Redshift ◽  
Line Emission ◽  
Optical Emission ◽  
Delta Function ◽  
Radio Galaxies ◽  
Radio Continuum ◽  
Spatially Resolved ◽  
A Value ◽  
Optical Line

Radio galaxies are unique cosmological probes. As with radio-loud quasars, the presence of luminous radio continuum and optical line emission enable radio galaxies to be observed and recognized at large distances, up to z = 4.2. However, unlike the situation for most quasars, their optical emission can be spatially resolved from the ground and studied in detail.Progress in detecting distant radio galaxies has been rapid in recent years due to the use of CCDs and the exploitation of new selection criteria. Now, more than 60 radio galaxies are known with z > 2. More than half of these have been found by our group by concentrating on radio sources with the steepest spectra, most of these in a “Key Programme” of the European Southern Observatory. Although several people contributed to this Key Programme, most of the work was done by Huub Röttgering, who presented his Ph.D thesis in January and Rob van Ojik, who succeededhim. Redshifts of 1.5 to 4 correspond to a time when the Universe was 10% -20% of its present age. This was a crucial period in history when galaxy formation must have been rampant. It corresponds to the AGN era, a two-billion year “delta function” in the population evolution of luminous quasars and radio galaxies, when their space-density rose to a value several hundred times larger than the present density before the species mysteriously and suddenly became almost extinct.

scholarly journals Rest-frame UV spectroscopy of extreme [OIII] emitters at 1.3 < z < 3.7: Toward a high-redshift UV reference sample for JWST

2020 ◽  
Author(s):  
Mengtao Tang ◽  
Daniel P Stark ◽  
Jacopo Chevallard ◽  
Stéphane Charlot ◽  
Ryan Endsley ◽  
...  
Keyword(s):  
Rest Frame ◽  
Uv Spectroscopy ◽  
High Redshift ◽  
Reference Sample ◽  
Line Emission ◽  
Uv Emission ◽  
Consistent Picture ◽  
Low Metallicity ◽  
Extreme Sensitivity ◽  
Galaxy Population

Abstract Deep spectroscopy of galaxies in the reionization era has revealed intense C III] and C IV line emission (EW &gt;15 − 20 Å). In order to interpret the nebular emission emerging at z &gt; 6, we have begun targeting rest-frame UV emission lines in galaxies with large specific star formation rates (sSFRs) at 1.3 &lt; z &lt; 3.7. We find that C III] reaches the EWs seen at z &gt; 6 only in large sSFR galaxies with [O III]+Hβ EW &gt;1500 Å. In contrast to previous studies, we find that many galaxies with intense [O III] have weak C III] emission (EW =5 − 8 Å), suggesting that the radiation field associated with young stellar populations is not sufficient to power strong C III]. Photoionization models demonstrate that the spread in C III] among systems with large sSFRs ([O III]+Hβ EW &gt;1500 Å) is driven by variations in metallicity, a result of the extreme sensitivity of C III] to electron temperature. We find that the strong C III] emission seen at z &gt; 6 (EW &gt;15 Å) requires metal poor gas (≃ 0.1 Z⊙) whereas the weaker C III] emission in our sample tends to be found at moderate metallicities (≃ 0.3 Z⊙). The luminosity distribution of the C III] emitters in our z ≃ 1 − 3 sample presents a consistent picture, with stronger emission generally linked to low luminosity systems (MUV &gt; −19.5) where low metallicities are more likely. We quantify the fraction of strong C III] and C IV emitters at z ≃ 1 − 3, providing a baseline for comparison against z &gt; 6 samples. We suggest that the first UV line detections at z &gt; 6 can be explained if a significant fraction of the early galaxy population is found at large sSFR (&gt;200 Gyr−1) and low metallicity (&lt;0.1 Z⊙).

scholarly journals The MOSDEF-LRIS Survey: The connection between massive stars and ionized gas in individual galaxies at z ∼ 2

2020 ◽  
Vol 499 (2) ◽  
pp. 1652-1665
Author(s):  
Michael W Topping ◽  
Alice E Shapley ◽  
Naveen A Reddy ◽  
Ryan L Sanders ◽  
Alison L Coil ◽  
...  
Keyword(s):  
High Redshift ◽  
Uv Spectra ◽  
Ionized Gas ◽  
Oxygen Abundance ◽  
Star Forming ◽  
Redshift Galaxy ◽  
Show Evidence ◽  
Optical Line ◽  
Ionization Parameter ◽  
Individual Galaxies

ABSTRACT We present constraints on the massive star and ionized gas properties for a sample of 62 star-forming galaxies at z ∼ 2.3. Using BPASS stellar population models, we fit the rest-UV spectra of galaxies in our sample to estimate age and stellar metallicity which, in turn, determine the ionizing spectrum. In addition to the median properties of well-defined subsets of our sample, we derive the ages and stellar metallicities for 30 high-SNR individual galaxies – the largest sample of individual galaxies at high redshift with such measurements. Most galaxies in this high-SNR subsample have stellar metallicities of 0.001 &lt; Z* &lt; 0.004. We then use Cloudy + BPASS photoionization models to match observed rest-optical line ratios and infer nebular properties. Our high-SNR subsample is characterized by a median ionization parameter and oxygen abundance, respectively, of log (U)med = −2.98 ± 0.25 and 12 + log (O/H)med = 8.48 ± 0.11. Accordingly, we find that all galaxies in our sample show evidence for α-enhancement. In addition, based on inferred log (U) and 12 + log (O/H) values, we find that the local relationship between ionization parameter and metallicity applies at z ∼ 2. Finally, we find that the high-redshift galaxies most offset from the local excitation sequence in the BPT diagram are the most α-enhanced. This trend suggests that α-enhancement resulting in a harder ionizing spectrum at fixed oxygen abundance is a significant driver of the high-redshift galaxy offset on the BPT diagram relative to local systems. The ubiquity of α-enhancement among z ∼ 2.3 star-forming galaxies indicates important differences between high-redshift and local galaxies that must be accounted for in order to derive physical properties at high redshift.

scholarly journals A search for dust and molecular gas in enormous Lyα nebulae at z ≈ 2

2020 ◽  
Vol 645 ◽  
pp. L3
Author(s):  
Roberto Decarli ◽  
Fabrizio Arrigoni-Battaia ◽  
Joseph F. Hennawi ◽  
Fabian Walter ◽  
Jason X. Prochaska ◽  
...  
Keyword(s):  
Rest Frame ◽  
High Redshift ◽  
Cluster Formation ◽  
Line Emission ◽  
Galactic Nuclei ◽  
Molecular Gas ◽  
Gas Reservoirs ◽  
Time Investment ◽  
Significant Step ◽  
Radio Power

Enormous Lyα nebulae, extending over 300−500 kpc around quasars, represent the pinnacle of galaxy and cluster formation. Here we present IRAM Plateau de Bure Interferometer observations of the enormous Lyα nebulae “Slug” (z = 2.282) and “Jackpot” (z = 2.041). Our data reveal bright, synchrotron emission associated with the two radio-loud active galactic nuclei embedded in the targeted nebulae as well as molecular gas, as traced via the CO(3−2) line, in three galaxies (two sources in Slug, and one in Jackpot). All of the CO emission is associated with galaxies detected in their rest-frame UV stellar emission. The total mass in molecular gas of these three galaxies [∼(3 − 5) × 1010 M⊙] is comparable with the total ionized gas mass responsible for the diffuse nebular emission. Our observations place limits on the molecular gas emission in the nebulae: the molecular gas surface density is ΣH2 <  12 − 25 M⊙ pc−2 for the Slug nebula and ΣH2 <  34 − 68 M⊙ pc−2 for the Jackpot nebula. These are consistent with the expected molecular gas surface densities, as predicted via photoionization models of the rest-frame UV line emission in the nebulae, and via Lyα absorption in the Jackpot nebula. Compared to other radio-loud quasars at z >  1 and high-redshift radio-loud galaxies, we do not find any strong trends relating the molecular gas reservoirs, the radio power, and the Lyα luminosities of these systems. The significant step in sensitivity required to achieve a detection of the molecular gas from the nebulae, if present, will require a substantial time investment with JVLA, NOEMA, or ALMA.

scholarly journals Interpreting the Spitzer/IRAC colours of 7 ≤ z ≤ 9 galaxies: distinguishing between line emission and starlight using ALMA

2020 ◽  
Vol 497 (3) ◽  
pp. 3440-3450 ◽  
Author(s):  
G W Roberts-Borsani ◽  
R S Ellis ◽  
N Laporte
Keyword(s):  
Optical Properties ◽  
Rest Frame ◽  
High Redshift ◽  
Line Emission ◽  
Intense Line ◽  
High Redshift Galaxies ◽  
Star Forming ◽  
History Of ◽  
Dependent Behaviour ◽  
Lower Redshift

ABSTRACT Prior to the launch of JWST, Spitzer/IRAC photometry offers the only means of studying the rest-frame optical properties of z &gt;7 galaxies. Many such high-redshift galaxies display a red [3.6]−[4.5] micron colour, often referred to as the ‘IRAC excess’, which has conventionally been interpreted as arising from intense [O iii]+H β emission within the [4.5] micron bandpass. An appealing aspect of this interpretation is similarly intense line emission seen in star-forming galaxies at lower redshift as well as the redshift-dependent behaviour of the IRAC colours beyond z ∼ 7 modelled as the various nebular lines move through the two bandpasses. In this paper, we demonstrate that, given the photometric uncertainties, established stellar populations with Balmer (4000 Å rest frame) breaks, such as those inferred at z &gt; 9 where line emission does not contaminate the IRAC bands, can equally well explain the redshift-dependent behaviour of the IRAC colours in 7 ≲ z ≲ 9 galaxies. We discuss possible ways of distinguishing between the two hypotheses using ALMA measures of [O iii] λ88 micron and dust continuum fluxes. Prior to further studies with JWST, we show that the distinction is important in determining the assembly history of galaxies in the first 500 Myr.

scholarly journals A review of spectral energy distribution modeling at high-redshift

2019 ◽  
Vol 15 (S352) ◽  
pp. 77-77
Author(s):  
Stéphane Charlot
Keyword(s):  
Interstellar Medium ◽  
Energy Distribution ◽  
Rest Frame ◽  
High Redshift ◽  
Spectral Energy Distribution ◽  
Optical Emission ◽  
Spectral Energy ◽  
Distribution Modeling ◽  
Redshift Galaxy ◽  
Recent Developments

AbstractI will review recent developments in the modeling of high-redshift galaxy spectra, focusing in particular on the rest-frame ultraviolet and optical emission from young stellar populations and the interstellar medium.

scholarly journals Optical Line Emission fromz∼ 6.8 Sources with Deep Constraints on LyαVisibility

2017 ◽  
Vol 839 (2) ◽  
pp. 73 ◽  
Author(s):  
M. Castellano ◽  
L. Pentericci ◽  
A. Fontana ◽  
E. Vanzella ◽  
E. Merlin ◽  
...  
Keyword(s):  
Line Emission ◽  
Optical Line

scholarly journals Molecular gas in the Herschel-selected strongly lensed submillimeter galaxies at z ~ 2–4 as probed by multi-J CO lines

2017 ◽  
Vol 608 ◽  
pp. A144 ◽  
Author(s):  
C. Yang ◽  
A. Omont ◽  
A. Beelen ◽  
Y. Gao ◽  
P. van der Werf ◽  
...  
Keyword(s):  
Star Formation ◽  
High Redshift ◽  
Line Emission ◽  
Far Infrared ◽  
Molecular Gas ◽  
Kinetic Temperature ◽  
Large Area ◽  
Line Energy ◽  
Submillimeter Galaxies ◽  
Dust Mass

We present the IRAM-30 m observations of multiple-J CO (Jup mostly from 3 up to 8) and [C I](3P2 → 3P1) ([C I](2–1) hereafter) line emission in a sample of redshift ~2–4 submillimeter galaxies (SMGs). These SMGs are selected among the brightest-lensed galaxies discovered in the Herschel-Astrophysical Terahertz Large Area Survey (H-ATLAS). Forty-seven CO lines and 7 [C I](2–1) lines have been detected in 15 lensed SMGs. A non-negligible effect of differential lensing is found for the CO emission lines, which could have caused significant underestimations of the linewidths, and hence of the dynamical masses. The CO spectral line energy distributions (SLEDs), peaking around Jup ~ 5–7, are found to be similar to those of the local starburst-dominated ultra-luminous infrared galaxies and of the previously studied SMGs. After correcting for lensing amplification, we derived the global properties of the bulk of molecular gas in the SMGs using non-LTE radiative transfer modelling, such as the molecular gas density nH2 ~ 102.5–104.1 cm-3 and the kinetic temperature Tk  ~ 20–750 K. The gas thermal pressure Pth ranging from~105 K cm-3 to 106 K cm-3 is found to be correlated with star formation efficiency. Further decomposing the CO SLEDs into two excitation components, we find a low-excitation component with nH2 ~ 102.8–104.6 cm-3 and Tk  ~ 20–30 K, which is less correlated with star formation, and a high-excitation one (nH2 ~ 102.7–104.2 cm-3, Tk  ~ 60–400 K) which is tightly related to the on-going star-forming activity. Additionally, tight linear correlations between the far-infrared and CO line luminosities have been confirmed for the Jup ≥ 5 CO lines of these SMGs, implying that these CO lines are good tracers of star formation. The [C I](2–1) lines follow the tight linear correlation between the luminosities of the [C I](2–1) and the CO(1–0) line found in local starbursts, indicating that [C I] lines could serve as good total molecular gas mass tracers for high-redshift SMGs as well. The total mass of the molecular gas reservoir, (1–30) × 1010M⊙, derived based on the CO(3–2) fluxes and αCO(1–0) = 0.8 M⊙ ( K km s-1 pc2)-1, suggests a typical molecular gas depletion time tdep ~ 20–100 Myr and a gas to dust mass ratio δGDR ~ 30–100 with ~20%–60% uncertainty for the SMGs. The ratio between CO line luminosity and the dust mass L′CO/Mdust appears to be slowly increasing with redshift for high-redshift SMGs, which need to be further confirmed by a more complete SMG sample at various redshifts. Finally, through comparing the linewidth of CO and H2O lines, we find that they agree well in almost all our SMGs, confirming that the emitting regions of the CO and H2O lines are co-spatially located.

scholarly journals Accurately predicting the escape fraction of ionizing photons using rest-frame ultraviolet absorption lines

2018 ◽  
Vol 616 ◽  
pp. A30 ◽  
Author(s):  
J. Chisholm ◽  
S. Gazagnes ◽  
D. Schaerer ◽  
A. Verhamme ◽  
J. R. Rigby ◽  
...  
Keyword(s):  
Early Universe ◽  
Rest Frame ◽  
High Redshift ◽  
Flux Ratio ◽  
Companion Paper ◽  
Absorption Lines ◽  
Indirect Methods ◽  
High Redshift Galaxies ◽  
Lyman Continuum ◽  
Redshift Galaxies

The fraction of ionizing photons that escape high-redshift galaxies sensitively determines whether galaxies reionized the early Universe. However, this escape fraction cannot be measured from high-redshift galaxies because the opacity of the intergalactic medium is large at high redshifts. Without methods to measure the escape fraction of high-redshift galaxies indirectly, it is unlikely that we will know what reionized the Universe. Here, we analyze the far-ultraviolet (UV) H I (Lyman series) and low-ionization metal absorption lines of nine low-redshift, confirmed Lyman continuum emitting galaxies. We use the H I covering fractions, column densities, and dust attenuations measured in a companion paper to predict the escape fraction of ionizing photons. We find good agreement between the predicted and observed Lyman continuum escape fractions (within 1.4σ) using both the H I and ISM absorption lines. The ionizing photons escape through holes in the H I, but we show that dust attenuation reduces the fraction of photons that escape galaxies. This means that the average high-redshift galaxy likely emits more ionizing photons than low-redshift galaxies. Two other indirect methods accurately predict the escape fractions: the Lyα escape fraction and the optical [O III]/[O II] flux ratio. We use these indirect methods to predict the escape fraction of a sample of 21 galaxies with rest-frame UV spectra but without Lyman continuum observations. Many of these galaxies have low escape fractions (fesc ≤ 1%), but 11 have escape fractions >1%. Future studies will use these methods to measure the escape fractions of high-redshift galaxies, enabling upcoming telescopes to determine whether star-forming galaxies reionized the early Universe.

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