scholarly journals Discovery of a Protocluster Core Associated with an Enormous Lya Nebula at z = 2.3

2021 ◽  
Vol 922 (2) ◽  
pp. 236
Author(s):  
Qiong Li ◽  
Ran Wang ◽  
Helmut Dannerbauer ◽  
Zheng Cai ◽  
Bjorn Emonts ◽  
...  
Keyword(s):  
Star Formation ◽  
Rest Frame ◽  
Line Emission ◽  
Peak Position ◽  
The Other ◽  
Line Ratio ◽  
Continuum Emission ◽  
Mass Estimation ◽  
Massive Galaxies

Abstract The MAMMOTH-1 nebula at z = 2.317 is an enormous Lyα nebula (ELAN) extending to a ∼440 kpc scale at the center of the extreme galaxy overdensity BOSS 1441. In this paper, we present observations of the CO(3 − 2) and 250 GHz dust-continuum emission from MAMMOTH-1 using the IRAM NOrthern Extended Millimeter Array. Our observations show that CO(3 − 2) emission in this ELAN has not extended widespread emission into the circum- and inter-galactic media. We also find a remarkable concentration of six massive galaxies in CO(3 − 2) emission in the central ∼100 kpc region of the ELAN. Their velocity dispersions suggest a total halo mass of M 200c ∼ 1013.1 M ⊙, marking a possible protocluster core associated with the ELAN. The peak position of the CO(3 − 2) line emission from the obscured AGN is consistent with the location of the intensity peak of MAMMOTH-1 in the rest-frame UV band. Its luminosity line ratio between the CO(3 − 2) and CO(1 − 0)r 3,1 is 0.61 ± 0.17. The other five galaxies have CO(3 − 2) luminosities in the range of (2.1–7.1) × 109 K km s−1 pc2, with the star-formation rates derived from the 250 GHz continuum of (<36)–224 M ⊙ yr−1. Follow-up spectroscopic observations will further confirm more member galaxies and improve the accuracy of the halo mass estimation.

scholarly journals Water maser and radio continuum emission towards IRAS 23139+5939

2007 ◽  
Vol 3 (S242) ◽  
pp. 180-181
Author(s):  
M. A. Trinidad ◽  
S. Curiel ◽  
J. M. Torrelles ◽  
L. F. Rodríguez ◽  
V. Migenes ◽  
...  
Keyword(s):  
Flux Density ◽  
Line Emission ◽  
The Other ◽  
Radio Continuum ◽  
High Mass ◽  
Continuum Emission ◽  
Maser Line ◽  
Water Masers ◽  
Water Maser ◽  
The Continuum

AbstractWe present simultaneous observations of continuum (3.5 and 1.3cm) and water maser line emission (1.3cm) carried out with the VLA-A toward the high-mass object IRAS 23139+5939. We detected two radio continuum sources at 3.5cm separated by 0”5 (~2400 AU), I23139 and I23139S. Based on the observed continuum flux density and the spectral index, we suggest that I23139 is a thermal radio jet associated with a high-mass YSO. On the other hand, based on the spatio-kinematical distribution of the water masers, together with the continuum emission information, we speculate that I23139S is also a jet source powering some of the masers detected in the region.

scholarly journals Unveiling the nature of the brightest z > 6 galaxies with ALMA and JWST

2019 ◽  
Vol 15 (S352) ◽  
pp. 20-20
Author(s):  
Rebecca Bowler
Keyword(s):  
Star Formation ◽  
Rest Frame ◽  
Small Samples ◽  
Star Forming ◽  
Lyman Alpha ◽  
Alpha Emission ◽  
Formation Conditions ◽  
Formation And Evolution ◽  
Insight Into

AbstractThe very brightest z > 6 galaxies are ideal laboratories for studying the physical properties of star-forming objects into the epoch of reionization. Selected from degree-scale, ground-based fields, these rare objects provide a key insight into early dust production and may harbour faint AGN. Targeted follow-up of small samples have unexpectedly shown both Lyman-alpha emission and other rest-frame UV lines (e.g CIV and HeII), suggesting unique star-formation conditions (or AGN) at early times. Furthermore, ALMA observations have revealed that 75% of the star-formation in these galaxies may be obscured. I will talk about HST/ALMA follow-up of bright z ∼ 7 LBGs in COSMOS and present new results from even brighter samples from z = 6 – 9 selected over ∼ 5 deg2. The power of both ALMA and JWST, coupled with the intrinsic luminosity of these sources, will provide a unique insight into the formation and evolution of vigorously star-forming galaxies in the first billion years.

scholarly journals MMT/MMIRS spectroscopy of z = 1.3 - 2.4 extreme [O iii] emitters: implications for galaxies in the reionization era

2019 ◽  
Vol 489 (2) ◽  
pp. 2572-2594 ◽  
Author(s):  
Mengtao Tang ◽  
Daniel P Stark ◽  
Jacopo Chevallard ◽  
Stéphane Charlot
Keyword(s):  
Star Formation ◽  
Radiation Field ◽  
Production Efficiency ◽  
Rest Frame ◽  
Optical Emission ◽  
Intense Line ◽  
Massive Galaxies ◽  
Stellar Masses ◽  
The Impact ◽  
Intense Radiation

ABSTRACT Galaxies in the reionization era have been shown to have prominent [O iii] + H β emission. Little is known about the gas conditions and radiation field of this population, making it challenging to interpret the spectra emerging at z ≳ 6. Motivated by this shortcoming, we have initiated a large MMT spectroscopic survey identifying rest-frame optical emission lines in 227 intense [O iii] emitting galaxies at 1.3 &lt; z &lt; 2.4. This sample complements the MOSDEF and KBSS surveys, extending to much lower stellar masses ($10^7\!-\!10^8 \, \mathrm{M}_\odot$) and larger specific star formation rates (5–300 Gyr−1), providing a window on galaxies directly following a burst or recent upturn in star formation. The hydrogen ionizing production efficiency (ξion) is found to increase with the [O iii] equivalent width (EW), in a manner similar to that found in local galaxies. We describe how this relationship helps explain the anomalous success rate in identifying Ly α emission in z ≳ 7 galaxies with strong [O iii] + H β emission. We probe the impact of the intense radiation field on the ISM using O32 and Ne3O2, two ionization-sensitive indices. Both are found to scale with the [O iii] EW, revealing extreme ionization conditions not commonly seen in older and more massive galaxies. In the most intense line emitters, the indices have very large average values (O32 = 9.1, Ne3O2 = 0.5) that have been shown to be linked to ionizing photon escape. We discuss implications for the nature of galaxies most likely to have O32 values associated with significant LyC escape. Finally we consider the optimal strategy for JWST spectroscopic investigations of galaxies at z ≳ 10 where the strongest rest-frame optical lines are no longer visible with NIRSpec.

scholarly journals Evolution of Massive Galaxy Structural Properties and Sizes via Star Formation

2012 ◽  
Vol 10 (H16) ◽  
pp. 128-128
Author(s):  
Jamie R. Ownsworth ◽  
Christopher J. Conselice ◽  
Alice Mortlock ◽  
William G. Hartley ◽  
Fernando Buitrago
Keyword(s):  
Star Formation ◽  
Rest Frame ◽  
High Redshift ◽  
Formation Rate ◽  
Stellar Mass ◽  
Massive Galaxies ◽  
Mass Profile ◽  
Individual Galaxy ◽  
Mass Profiles

We investigate the resolved star formation properties of a sample of 45 massive galaxies (M* > 1011 M⊙) within a redshift range of 1.5 ⩽ z ⩽ 3 detected in the GOODS NICMOS Survey (Conselice et al. 2011), a HST H160-band imaging program. We derive the star formation rate as a function of radius using rest frame UV data from deep z850 ACS imaging. The star formation present at high redshift is then extrapolated to z = 0, and we examine the stellar mass produced in individual regions within each galaxy. We also construct new stellar mass profiles of the in situ stellar mass at high redshift from Sérsic fits to rest-frame optical, H160-band, data. We combine the two stellar mass profiles to produce an evolved stellar mass profile. We then fit a new Sérsic profile to the evolved profile, from which we examine what effect the resulting stellar mass distribution added via star formation has on the structure and size of each individual galaxy.

Reconstruction of Star Formation and AGNs Activities in Galaxies Classified with the Balmer Break, 1.6 μm Bump and PAH Features up to z ≃2

2010 ◽  
Vol 6 (S277) ◽  
pp. 182-185
Author(s):  
Hitoshi Hanami ◽  
Tsuyoshi Ishigaki ◽  
Keyword(s):  
Star Formation ◽  
Rest Frame ◽  
Formation Rate ◽  
Massive Galaxies ◽  
Star Forming ◽  
Luminous Infrared Galaxies ◽  
The North ◽  
Deep Survey ◽  
Multi Wavelength ◽  
Dusty Torus

AbstractWe have studied the star-forming and AGN activity of massive galaxies in the redshift range z = 0.4−2, which are detected in a deep survey field using the AKARI and Subaru telescopes toward the North Ecliptic Pole (NEP). The multi-wavelength survey allows us to select Mid-InfraRed (MIR) bright populations as Luminous InfraRed Galaxies (LIRGs) with L(IR) ≃ 1010–11 L⊙, which can be also sub-classified into Balmer Break Galaxies (BBGs) and Infra-Red (IR) Bump Galaxies (IRBGs). AKARI/IRC multiband photometry can distinguish their star-forming/AGN activity for LIRGs with/without the Polycyclic-Aromatic Hydrocarbon (PAH) emission bands at 6.2, 7.7 and 11.3 μm, and estimate the Star Formation Rate (SFR) from their total emitting InfraRed (IR) luminosities for star-formings and the emissions from dusty torus for AGNs. The results are summarised as below: 1) The rest-frame 7.7 μm luminosity is still a good tracer of the total IR (tIR) luminosity, as the PAH emission dominates for star-forming galaxies even up to z ≃ 2, 2) Rest-frame 5μm Luminosities may trace emissions from dusty torus of AGN in the LIRGs, 3) SFR of Starburst-AGN LIRGs (s/a-LIRGs) tends to quench at z < 0.8 more rapidly than that of Starburst dominated LIRGs (sb-LIRGs), 4) Intrinsic Stellar populations in the s/a-LIRGs show redder colours than those in the sb-LIRGs. These results suggest that Super Massive Black Holes (SMBH) could already have grown to ≃ 3 × 108M⊙ in the agn-LIRGs, with ≃ 1011L⊙ at z > 1.2, and the growth of SMBH tends to follow the star-forming activities around z = 1–2.

scholarly journals Molecular Gas in Galaxies at all Redshifts

2010 ◽  
Vol 6 (S277) ◽  
pp. 47-54
Author(s):  
Françoise Combes
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Star Formation History ◽  
Gas Content ◽  
Continuum Emission ◽  
Massive Galaxies ◽  
Normal Galaxies ◽  
Galaxy Type ◽  
Formation History ◽  
Formation Efficiency

AbstractI review some recent results about the molecular content of galaxies, obtained essentially from the CO lines, but also dense tracers, or the dust continuum emission. New results have been obtained on molecular cloud physics, and their efficiency to form stars, shedding light on the Kennicutt-Schmidt law as a function of surface density and galaxy type. Large progress has been made on galaxy at moderate and high redshifts, allowing to interprete the star formation history and star formation efficiency as a function of gas content, or galaxy evolution. In massive galaxies, the gas fraction was higher in the past, and galaxy disks were more unstable and more turbulent. ALMA observations will allow the study of more normal galaxies at high z with higher spatial resolution and sensitivity.

scholarly journals Resolving a dusty, star-forming SHiZELS galaxy at z = 2.2 with HST, ALMA and SINFONI on kiloparsec scales

2021 ◽  
Author(s):  
R K Cochrane ◽  
P N Best ◽  
I Smail ◽  
E Ibar ◽  
C Cheng ◽  
...  
Keyword(s):  
Star Formation ◽  
Emission Line ◽  
Rest Frame ◽  
Far Infrared ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Star Forming ◽  
Alpha Emission ◽  
The Galaxy ◽  
Dust Distribution

Abstract We present ∼0.15″ spatial resolution imaging of SHiZELS-14, a massive ($M_{*}\sim 10^{11}\, \rm {M_{\odot }}$), dusty, star-forming galaxy at z = 2.24. Our rest-frame $\sim 1\, \rm {kpc}$-scale, matched-resolution data comprise four different widely used tracers of star formation: the $\rm {H}\alpha$ emission line (from SINFONI/VLT), rest-frame UV continuum (from HST F606W imaging), the rest-frame far-infrared (from ALMA), and the radio continuum (from JVLA). Although originally identified by its modest $\rm {H}\alpha$ emission line flux, SHiZELS-14 appears to be a vigorously star-forming ($\rm {SFR}\sim 1000\, \rm {M_{\odot }\, yr^{-1}}$) example of a submillimeter galaxy, probably undergoing a merger. SHiZELS-14 displays a compact, dusty central starburst, as well as extended emission in $\rm {H}\alpha$ and the rest-frame optical and FIR. The UV emission is spatially offset from the peak of the dust continuum emission, and appears to trace holes in the dust distribution. We find that the dust attenuation varies across the spatial extent of the galaxy, reaching a peak of at least AHα ∼ 5 in the most dusty regions, although the extinction in the central starburst is likely to be much higher. Global star-formation rates inferred using standard calibrations for the different tracers vary from $\sim 10\!-\!1000\, \rm {M_{\odot }\, yr^{-1}}$, and are particularly discrepant in the galaxy’s dusty centre. This galaxy highlights the biased view of the evolution of star-forming galaxies provided by shorter wavelength data.

scholarly journals GOODS-Herschel: Dust attenuation up to z∼4

2012 ◽  
Vol 8 (S292) ◽  
pp. 289-289 ◽  
Author(s):  
M. Pannella ◽  
D. Elbaz ◽  
E. Daddi
Keyword(s):  
Star Formation ◽  
High Redshift ◽  
Line Emission ◽  
Stellar Mass ◽  
Massive Galaxies ◽  
Star Forming ◽  
Main Driver ◽  
Galaxy Sample ◽  
Stellar Masses ◽  
Dust Attenuation

AbstractWe quantitatively explore in a unbiased way the evolution of dust attenuation up to z ≈ 4 as a function of galaxy properties. We have used one of the deepest datasets available at present, in the GOODS-N field, to select a star forming galaxy sample and robustly measure galaxy redshifts, star formation rates, stellar masses and UV restframe properties. Our main results can be summarized as follows: i) we confirm that galaxy stellar mass is a main driver of UV dust attenuation in star forming galaxies: more massive galaxies are more dust attenuated than less massive ones; ii) strikingly, we find that the correlation does not evolve with redshift: the amount of dust attenuation is the same at all cosmic epochs for a fixed stellar mass; iii) this finding explains why and how the SFR–AUV relation evolves with redshift: the same amount of star formation is less attenuated at higher redshift because it is hosted in less massive galaxies; iv) combining our finding with results from line emission surveys, we confirm that line reddening is larger than continuum reddening, at least up to z ≈ 1.5; v) given the redshift evolution of the mass-metallicity relation, we predict that star forming galaxies at a fixed metal content are more attenuated at high redshift. Finally, we explored the correlation between UV dust attenuation and the spectral slope: vi) the correlation is evolving with redshift with star forming galaxies at lower redshift having redder spectra than higher redshift ones for the same amount of dust attenuation.

scholarly journals An ALMA survey of the SCUBA-2 cosmology legacy survey UKIDSS/UDS field: Dust attenuation in high-redshift Lyman-break galaxies

2020 ◽  
Vol 492 (4) ◽  
pp. 4927-4944 ◽  
Author(s):  
M P Koprowski ◽  
K E K Coppin ◽  
J E Geach ◽  
U Dudzevičiūtė ◽  
Ian Smail ◽  
...  
Keyword(s):  
Star Formation ◽  
High Redshift ◽  
Infrared Excess ◽  
Massive Galaxies ◽  
Lyman Break Galaxies ◽  
Deep Survey ◽  
Dust Component ◽  
Stellar Masses ◽  
Dust Attenuation

ABSTRACT We analyse 870 $\mu$m Atacama Large Millimetre Array (ALMA) dust continuum detections of 41 canonically selected $z$ ≃ 3 Lyman-break galaxies (LBGs), as well as 209 ALMA-undetected LBGs, in follow-up of SCUBA-2 mapping of the UKIDSS Ultra Deep Survey (UDS) field. We find that our ALMA-bright LBGs lie significantly off the local IRX-beta relation and have relatively bluer rest-frame UV slopes (as parametrized by β), given their high values of the ‘infrared excess’ (IRX ≡ LIR/LUV), relative to the average ‘local’ IRX-β relation. We attribute this finding in part to the young ages of the underlying stellar populations but we find that the main reason behind the unusually blue UV slopes are the relatively shallow slopes of the corresponding dust attenuation curves. We show that, when stellar masses, M*, are being established via SED fitting, it is absolutely crucial to allow the attenuation curves to vary (rather than fixing it on Calzetti-like law), where we find that the inappropriate curves may underestimate the resulting stellar masses by a factor of ≃2–3× on average. In addition, we find these LBGs to have relatively high specific star-formation rates (sSFRs), dominated by the dust component, as quantified via the fraction of obscured star formation $(f_{\rm obs}\equiv {\rm SFR_{\rm IR}/{\rm SFR}_{\rm UV+IR}})$. We conclude that the ALMA-bright LBGs are, by selection, massive galaxies undergoing a burst of a star formation (large sSFRs, driven, for example, by secular or merger processes), with a likely geometrical disconnection of the dust and stars, responsible for producing shallow dust attenuation curves.

High-redshift starbursts as progenitors of massive galaxies

2020 ◽  
Vol 15 (S359) ◽  
pp. 22-26
Author(s):  
Carlos Gómez-Guijarro
Keyword(s):  
Star Formation ◽  
Compact Star ◽  
High Redshift ◽  
Stellar Mass ◽  
Starburst Galaxies ◽  
The Other ◽  
Massive Galaxies ◽  
Star Forming ◽  
Spatially Resolved ◽  
Minor Mergers

AbstractStarbursting dust-rich galaxies are capable of assembling large amounts of stellar mass very quickly. They have been proposed as progenitors of the population of compact massive quiescent galaxies at z ˜ 2. To test this connection, we present a detailed spatially-resolved study of the stars, dust, and stellar mass in a sample of six submillimeter-bright starburst galaxies at z ˜ 4.5. We found that the systems are undergoing minor mergers and the bulk star formation is located in extremely compact regions. On the other hand, optically-compact star forming galaxies have also been proposed as immediate progenitors of compact massive quiescent galaxies. Were they formed in slow secular processes or in rapid merger-driven starbursts? We explored the location of galaxies with respect to star-forming and structural relations and study the burstiness of star formation. Our results suggest that compact star-forming galaxies could be starbursts winding down and eventually becoming quiescent.

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