We report the detection of a non-corotating gas component in a bright unlensed submillimeter galaxy at z=4.3, COSMOS-AzTEC-1, hosting a compact starburst. ALMA 0.17 and 0.09 arcsec resolution observations of [CII] emission clearly demonstrate that the gas kinematics is characterized by an ordered rotation. After subtracting the best-fit model of a rotating disk, we kinematically identify two residual components in the channel maps. Both observing simulations and analysis of dirty images confirm that these two subcomponents are not artificially created by noise fluctuations and beam deconvolution. One of the two has a velocity offset of 200 km/s and a physical separation of 2 kpc from the primary disk and is located along the kinematic minor axis of disk rotation. We conclude that this gas component is falling into the galaxy from a direction perpendicular to the disk rotation. The accretion of such small non-corotating gas components could stimulate violent disk instability, driving radial gas inflows into the center of galaxies and leading to formation of in-situ clumps such as identified in dust continuum and CO. We require more theoretical studies on high gas fraction mergers with mass ratio of 1:>10 to verify this process.
One of the most prominent features of galaxy clusters is the presence of a dominant population of massive ellipticals in their cores. Stellar archaeology suggests that these gigantic beasts assembled most of their stars in the early Universe via starbursts. However, the role of dense environments and their detailed physical mechanisms in triggering starburst activities remain unknown. Here we report spatially resolved Atacama Large Millimeter/submillimeter Array (ALMA) observations of the CO $J= 3-2$ emission line, with a resolution of about 2.5 kiloparsecs, toward a forming galaxy cluster cor…
Interstellar ultraviolet absorption-lines provide crucial information about the properties of galactic outflows. In this paper, we augment our previous analysis of the systematic properties of starburst-driven galactic outflows by expanding our sample to include a rare population of starbursts with exceptionally high outflow velocities. In principle, these could be a qualitatively different phenomenon from more typical outflows. However, we find that instead these starbursts lie on, or along the extrapolation of, the trends defined by the more typical systems studied previously by us. We explo…
We conduct for the first time a theoretical investigation of the mid-infrared spectral energy distribution (SED) produced by dust heated by an active galactic nucleus (AGN) and an extreme starburst. These models employ an integrated modeling approach using photoionization and stellar population synthesis models in which both the line and emergent continuum is predicted from gas exposed to the ionizing radiation from a young starburst and an AGN. In this work, we focus on the infrared colors from the {\it Wide-field Infrared Survey Explorer}, predicting the dependence of the colors on the input…
We present ALMA $^{12}$CO (J=1-0, 3-2 and 6-5), $^{13}$CO (J=1-0) and C$^{18}$O (J=1-0) observations of the local Ultra Luminous Infrared Galaxy, IRAS 13120-5453 (dubbed "The Yo-yo"). The morphologies of the three isotopic species differ, where $^{13}$CO shows a hole in emission towards the center. We measure integrated brightness temperature line ratios of $^{12}$CO/$^{13}$CO $\geq$ 60 (exceeding 200) and $^{13}$CO/C$^{18}$O $\leq$ 1 in the central region. Assuming optical thin emission, C$^{18}$O is more abundant than $^{13}$CO in several regions. The abundances within the central 500 pc are…
We use two catalogues, a Herschel catalogue selected at 500 mu (HerMES) and an IRAS catalogue selected at 60 mu (RIFSCz), to contrast the sky at these two wavelengths. Both surveys demonstrate the existence of extreme starbursts, with star-formation rates (SFRs) > 5000 Msun/yr. The maximum intrinsic star-formation rate appears to be ~30,000 Msun/yr. The sources with apparent SFR estimates higher than this are in all cases either lensed systems, blazars, or erroneous photometric redshifts. At redshifts of 3 to 5, the time-scale for the Herschel galaxies to make their current mass of stars at th…
Extreme MgII Emission in Recently-Quenched Galaxies: A New Sample of Intermediate-Redshift Post-Starburst Quasars from the DESI Early Data Release
University of Illinois Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校）；The Johns Hopkins University（约翰斯·霍普金斯大学）；Princeton University（普林斯顿大学）；University of Nottingham（诺丁汉大学）；Space Telescope Science Institute（太空望远镜科学研究所）
We examine variations of the stellar initial mass function (IMF) in extreme environments within the formalism derived by Hennebelle \& Chabrier. We focus on conditions encountered in progenitors of massive early type galaxies and starburst regions. We show that, when applying the concept of turbulent Jeans mass as the characteristic mass for fragmentation in a turbulent medium, instead of the standard thermal Jeans mass for purely gravitational fragmentation, the peak of the IMF in such environments is shifted towards smaller masses, leading to a bottom-heavy IMF, as suggested by various obser…
Submillimetre galaxies represent a rapid growth phase of both star formation and massive galaxies. Mapping SMGs in galaxy protoclusters provides key insights into where and how these extreme starbursts take place in connections with the assembly of the large-scale structure in the early Universe. We search for SMGs at 850$\,μm$ using JCMT/SCUBA-2 in two massive protoclusters at $z=2.24$, BOSS1244 and BOSS1542, and detect 43 and 54 sources with $S_{850}>4\,$mJy at the $4σ$ level within an effective area of 264$\,$arcmin$^2$, respectively. We construct the intrinsic number counts and find that t…
Galaxies which strongly deviate from the radio-far IR correlation are of great importance for studies of galaxy evolution as they may be tracing early, short-lived stages of starbursts and active galactic nuclei (AGNs). The most extreme FIR-excess galaxy NGC1377 has long been interpreted as a young dusty starburst, but millimeter observations of CO lines revealed a powerful collimated molecular outflow which cannot be explained by star formation alone. We present new radio observations at 1.5 and 10 GHz obtained with the Jansky Very Large Array (JVLA) and Chandra X-ray observations towards NGC…
Pox 186 is an exceptionally small dwarf starburst galaxy hosting a stellar mass of $\sim10^5$ M$_{\odot}$. Undetected in HI (M $ < 10^6$ M$_{\odot}$) from deep 21 cm observations and with an [OIII]/[OII]\ (5007/3727) ratio of 18.3 $\pm$ 0.11, Pox~186 is a promising candidate Lyman continuum emitter. It may be a possible analog of low-mass reionization-era galaxies. We present a spatially resolved kinematic study of Pox 186 and identify two distinct ionized gas components: a broad one with $σ> 400$ \kmps, and a narrow one with $σ< 30$ \kmps. We find strikingly different morphologies between the…
Searching for extreme emission line galaxies allows us to find low-mass metal-poor galaxies that are good analogs of high redshift Ly$α$ emitting galaxies. These low-mass extreme emission line galaxies are also potential Lyman-continuum leakers. Finding them at very low redshifts ($z\lesssim0.05$) allows us to be sensitive to even lower stellar masses and metallicities. We report on a sample of extreme emission line galaxies at $z\lesssim0.05$ (blueberry galaxies). We selected them from SDSS broadband images on the basis of their broad band colors, and studied their properties with MMT spectro…
Green pea galaxies are starbursting, low-mass galaxies that are good analogues to star-forming galaxies in the early universe. We perform a survey of 23 Green Peas using the MUSE Integral Field Unit spectrograph on the VLT to search for companion galaxies. The survey reaches an average point-source depth of $\sim 10^{-18}$ erg cm$^{-2}$ s$^{-1}$ for emission lines. The MUSE field of view allows us to probe a 1$\times$1 arcmin$^2$ field around these galaxies and to search their surroundings for faint companions that could have interacted with them and induced their starburst episodes. We search…
We report molecular gas observations of IRAS 20100-4156 and IRAS 03158+4227, two local ultraluminous infrared galaxies (ULIRGs) hosting some of the fastest and most massive molecular outflows known. Using ALMA and PdBI observations, we spatially resolve the CO(1-0) emission from the outflowing molecular gas in both and find maximum outflow velocities of $ v_{\rm max} \sim 1600$ and $\sim 1700$ km/s for IRAS 20100-4156 and IRAS 03158+4227, respectively. We find total gas mass outflow rates of $\dot M_{\rm OF} \sim 670$ and $\sim 350$ Msun/yr, respectively, corresponding to molecular gas depleti…
Extreme star formation includes star formation in starbursts and regions forming super star clusters. We survey the current problems in our understanding of the star formation process in starbursts and super star clusters - initial mass functions, cluster mass functions, star formation efficiencies, and radiative feedback into molecular clouds - that are critical to our understanding of the formation and survival of large star clusters, topics that will be the drivers of the observations of the next decade.
We present ALMA ultra-high-spatial resolution ($\sim 20 \, {\rm mas}$) observations of dust continuum at $920 \, {\rm μm}$ and $1.2 \, {\rm mm}$ in a pair of submm galaxies (SMGs) at $z = 3.442$, ALMACAL-1 (A-1: $S_{\rm 870 μm} = 6.5 \pm 0.2 \, {\rm mJy}$) and ALMACAL-2 (A-2: $S_{\rm 870 μm} = 4.4 \pm 0.2 \, {\rm mJy}$). The spectroscopic redshifts of A-1 and A-2 have been confirmed via serendipitous detection of up to nine emission lines. Our ultra-high-spatial resolution data reveal that about half of the star formation in each of these starbursts is dominated by a single compact clump (FWHM…
We use high quality VLT/MUSE data to study the kinematics and the ionized gas properties of Haro 11, a well known starburst merger system and the closest confirmed Lyman continuum leaking galaxy. We present results from integrated line maps, and from maps in three velocity bins comprising the blueshifted, systemic and redshifted emission. The kinematic analysis reveals complex velocities resulting from the interplay of virial motions and momentum feedback. Star formation happens intensively in three compact knots (knots A, B and C), but one, knot C, dominates the energy released in supernovae.…
This paper introduces the Multi-wavelength Extreme Starburst Sample (MESS), a new catalog of 138 star-forming galaxies (0.1 < z < 0.3) optically selected from the SDSS using emission line strength diagnostics to have high absolute SFR (minimum 11 solar masses per year, with median SFR approx 61 solar masses per year based on a Kroupa IMF). The MESS was designed to complement samples of nearby star-forming galaxies such as the luminous infrared galaxies (LIRGs), and ultraviolet luminous galaxies (UVLGs). Observations using the multiband imaging photometer (MIPS; 24, 70, and 160μm channels) on t…
We present results on the nature of extreme ejective feedback episodes and the physical conditions of a population of massive ($\rm M_* \sim 10^{11} M_{\odot}$), compact starburst galaxies at z = 0.4-0.7. We use data from Keck/NIRSPEC, SDSS, Gemini/GMOS, MMT, and Magellan/MagE to measure rest-frame optical and near-IR spectra of 14 starburst galaxies with extremely high star formation rate surface densities (mean $\rm Σ_{SFR} \sim 3000 \,M_{\odot} yr^{-1} kpc^{-2}$) and powerful galactic outflows (maximum speeds v$_{98} \sim$ 1000-3000 km s$^{-1}$). Our unique data set includes an ensemble of …
Context. The fraction of field binaries on retrograde orbits about the Milky Way is significantly lower compared to its prograde counterpart. Chemical and dynamical evidence suggests that the retrograde stellar population originates from $ω$ Centauri, which is either the most massive globular cluster (GC) of the Milky Way or the putative core of a former dwarf galaxy. Aims. Star formation conditions required to produce the retrograde binary population are constrained assuming that the retrograde stellar population originates from $ω$ Centauri's progenitor. Methods. We match the observed low bi…
We report on the internal distribution of star formation efficiency in IRAS 08339+6517 (hereafter IRAS08), using $\sim$200~pc resolution CO(2-1) observations from NOEMA. The molecular gas depletion time changes by 2 orders-of-magnitude from disk-like values in the outer parts to less than 10$^8$~yr inside the half-light radius. This translates to a star formation efficiency per free-fall time that also changes by 2 orders-of-magnitude, reaching 50-100\%, different than local spiral galaxies and typical assumption of constant, low star formation efficiencies. Our target is a compact, massive di…
We obtained optical/near-IR rest-frame Magellan FIRE spectra (including Pa$β$ and Pa$γ$) of 25 starburst galaxies at 0.5<z<0.9, with average star formation rates (SFR) x7 above the Main Sequence (MS). We find that Paschen-to-Balmer line ratios saturate around a constant value corresponding to $A_{\rm V}\sim$2-3 mag, while line to IR luminosity ratios suggest a large range of more extreme obscurations and appear to be uncorrelated to the former. This behavior is not consistent with standard attenuation laws derived for local and distant galaxies, while being remarkably consistent with observati…
Galaxies are believed to experience star formation and black hole driven nuclear activity symbiotically. The symbiosis may be more extreme in the distant universe, as far-infrared photometry with the Herschel Space Observatory has found many cases of ultra-luminous cool dust emission in z>1 radio galaxies and quasars, which could have its origin in the central black hole activity, or in extreme starbursts. We here present strong evidence for an extreme circumnuclear starburst in the z=1.439 quasar 3C298. Our unparalleled 0.18 arcsecond resolution ALMA image at rest-frame 410micrometer waveleng…
We report the discovery of a high-redshift, massive molecular outflow in the starburst galaxy SPT0346-52 ($z=5.656$) via the detected absorption of high-excitation water transitions (H$_2$O $4_{2,3}-4_{1,4}$ and H$_2$O $3_{3,0}-3_{2,1}$) with the Atacama Large Millimeter/submillimeter Array (ALMA). The host galaxy is one of the most powerful starburst galaxies at high redshift (star formation rate; SFR $\sim3,600$M$_\odot$year$^{-1}$), with an extremely compact ($\sim320$pc) star formation region and a star formation rate surface density ($Σ_{SFR}\sim5,500$M$_{\odot}~$year$^{-1}~$kpc$^{-2}$) f…
We have made the first detections of the 88 micron [OIII] line from galaxies in the early Universe, detecting the line from the lensed AGN/starburst composite systems APM 08279+5255 at z = 3.911 and SMM J02399-0136 at z = 2.8076. The line is exceptionally bright from both systems, with apparent (lensed) luminosities ~10^11 L_solar. For APM 08279, the [OIII] line flux can be modeled in a star formation paradigm, with the stellar radiation field dominated by stars with effective temperatures, Teff >36,000 K, similar to the starburst found in M82. The model implies ~35% of the total far-IR lumino…
A population of so-called "blueberry" starbursting dwarf galaxies with extremely blue colors, low-metallicities, and enormous ionization ratios, has recently been found by Yang et al. (2017). Yet we still do not know their detailed properties, such as morphologies, AGN occupations, massive star contents, infrared emission, dust properties, etc. As a pilot study of the blueberries, we investigate the spectroscopic and photometric properties of two blueberry candidates, RGG B and RGG 5, for which Hubble Space Telescope high-resolution images are available. We find that RGG B and RGG 5 perhaps ar…
We present a detailed study of a high-redshift iron low-ionization broad absorption line (FeLoBAL) quasar (SDSS1214 at $z = 1.046$), including new interferometric $^{12}$CO $J$=2-1 observations, optical through far-infrared photometry, and mid-infrared spectroscopy. The CO line is well-fit by a single Gaussian centered 40 kms$^{-1}$ away from the systemic velocity and implies a total molecular gas mass of $M_\textrm{gas} = 7.3 \times 10^{10} \textrm{M}_\odot$. The infrared SED requires three components: an active galactic nucleus (AGN) torus, an AGN polar dust component, and a starburst. The s…
Revealing the nature of the starburst galaxies in the $z=2.4$ overdensity HATLAS J0849
Research School of Astronomy and Astrophysics, Australian National University（澳大利亚国立大学天体物理与天文研究学院）；Kapteyn Astronomical Institute, University of Groningen（格罗宁根大学卡普坦天文研究所）；Cosmic Dawn Center (DAWN)（宇宙黎明中心）；DTU Space, Technical University of Denmark（丹麦技术大学空间研究中心）；DARK, Niels Bohr Institute, University of Copenhagen（哥本哈根大学尼尔斯·玻尔研究所DARK中心）；Max-Planck-Institut für Extraterrestrische Physik (MPE)（马克斯·普朗克地外物理学研究所）；Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study The University of Tokyo（东京大学宇宙起源研究科 Kavli 宇宙物质与物理全球卓越中心）；Sub-department of Astrophysics, Department of Physics, University of Oxford（牛津大学物理系天体物理小组）
We present the discovery and analysis of J1316+2614 at z=3.6130, a UV-bright star-forming galaxy ($M_{\rm UV} \simeq -24.7$) with large escape of Lyman continuum (LyC) radiation. J1316+2614 is a young ($\simeq 10$ Myr) star-forming galaxy with $SFR \simeq 500 M_{\odot}$ yr$^{-1}$ and a starburst mass of log($M_{\star}/M_{\odot}) \simeq 9.7$. It shows a very steep UV continuum, $β_{\rm UV} \simeq -2.59 \pm 0.05$, consistent with residual dust obscuration, $E(B-V)\simeq 0$. LyC emission is detected with high significance ($\simeq 17 σ$) down to $830$Å, for which a very high relative (absolute) L…
Radio Spectral Energy Distribution of Low-$z$ Metal Poor Extreme Starburst Galaxies: Novel insights on the escape of ionizing photons
National Radio Astronomy Observatory（国家射电天文台）；The NSF-Simons AI Institute for Cosmic Origins（NSF-西蒙斯宇宙起源人工智能研究所）；SKA Observatory, Jodrell Bank（平方公里阵列射电望远镜天文台，乔德尔银行）；Observatoire de Genève, Université de Genève（日内瓦天文台，日内瓦大学）；CNRS, IRAP（法国国家科学研究中心，天体物理研究研究所）；Bogolyubov Institute for Theoretical Physics（博戈留博夫理论物理研究所）；Space Telescope Science Institute（太空望远镜科学研究所）
We report the discovery of a low-mass $z=5.200\pm 0.002$ galaxy that is in the process of ceasing its star formation. The galaxy, MACS0417-z5PSB, is multiply imaged with magnification factors $\sim40$ by the galaxy cluster MACS J0417.5-1154, observed as part of the CAnadian NIRISS Unbiased Cluster Survey (CANUCS). Using observations of MACS0417-z5PSB with a JWST/NIRSpec Prism spectrum and NIRCam imaging, we investigate the mechanism responsible for the cessation of star formation of the galaxy, and speculate about possibilities for its future. Using spectrophotometric fitting, we find a remark…
Near infrared slitless spectroscopy with the Wide Field Camera 3, onboard the Hubble Space Telescope, offers a unique opportunity to study low-mass galaxy populations at high-redshift ($z\sim$1-2). While most high$-z$ surveys are biased towards massive galaxies, we are able to select sources via their emission lines that have very-faint continua. We investigate the star formation rate (SFR)-stellar mass ($M_{\star}$) relation for about 1000 emission-line galaxies identified over a wide redshift range of $0.3 \lesssim z \lesssim 2.3$. We use the H$_α$ emission as an accurate SFR indicator and c…
Galactic outflows can be powered either by nuclear starbursts (SB) or active galactic nuclei (AGN). It has been argued that extreme starbursts can power extreme outflows, without the need to invoke AGN feedback. However, contributions from past and/or hidden AGN activity cannot be ruled out. Here, we constrain the potential role of the central black hole in driving powerful outflows in starburst galaxies (with no sign of ongoing AGN activity). We examine whether the galactic outflows can be explained by AGN luminosity evolution in the framework of our AGN `radiative dusty feedback' scenario. W…
We report the identification of an extreme proto-cluster of galaxies in the early Universe whose core (nicknamed Distant Red Core, DRC) is formed by at least ten dusty star-forming galaxies (DSFGs), confirmed to lie at $z_{\rm spec} = 4.002$ via detection of [CI](1-0), $^{12}$CO(6-5), $^{12}$CO(4-3), $^{12}$CO(2-1) and ${\rm H_2O} (2_{11} - 2_{02})$ emission lines, detected using ALMA and ATCA. The spectroscopically-confirmed components of the proto-cluster are distributed over a ${\rm 260\, kpc \times 310\, kpc}$ region and have a collective obscured star-formation rate (SFR) of $\sim 6500 \,…
Extreme equivalent width-selected low-mass starbursts at $z=4-9$: insights into their role in cosmic reionization
INAF - Osservatorio Astronomico di Roma（意大利国家天体物理研究所罗马天文台）；Instituto de Astrofísica de Andalucía (CSIC)（安达卢西亚天体物理学研究所（西班牙高等科学研究委员会））；Scuola Normale Superiore（比萨高等师范学院）；NSF NOIRLab（美国国家科学基金会NOIR天文台实验室）；Dipartimento di Fisica, Università di Roma Sapienza（罗马大学物理系）；Institute of Science and Technology Austria (ISTA)（奥地利科学技术研究所）；Astrophysics Science Division, NASA Goddard Space Flight Center（NASA戈达德太空飞行中心天体物理学科学部）；Armagh Obs（阿马赫天文台）
CR7 is among the most luminous Lyman-$α$ emitters (LAEs) known at $z = 6.6$ and consists of at least three UV components that are surrounded by Lyman-$α$ (Ly$α$) emission. Previous studies have suggested that it may host an extreme ionising source. Here, we present deep integral field spectroscopy of CR7 with VLT/MUSE. We measure extended emission with a similar halo scale length as typical LAEs at $z\approx5$. CR7's Ly$α$ halo is clearly elongated along the direction connecting the multiple components, likely tracing the underlying gas distribution. The Ly$α$ emission originates almost exclus…
Recent literature suggests that there are two modes through which galaxies grow their stellar mass - a normal mode characterized by quasi-steady star formation, and a highly efficient starburst mode possibly triggered by stochastic events such as galaxy mergers. While these differences are established for extreme cases, the population of galaxies in-between these two regimes is poorly studied and it is not clear where the transition between these two modes of star formation occurs. We utilize ALMA observations of the CO J=3-2 line luminosity in a sample of 20 infrared luminous galaxies that li…
Sparks II: Panchromatic SED modeling and galaxy physical properties across the starburst to post-starburst sequence
Kavli Institute for Particle Astrophysics & Cosmology, Stanford University（斯坦福大学卡弗里粒子天体物理与宇宙学研究所）；Center for Decoding the Universe, Stanford University（斯坦福大学解码宇宙中心）；Department of Astrophysical Sciences, Princeton University（普林斯顿大学天体物理科学系）；Department of Astronomy and Astrophysics, University of California Santa Cruz（加州大学圣克鲁兹分校天文与天体物理系）；Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU)（宇宙物理与数学卡弗里研究所）；Division of Science, National Astronomical Observatory of Japan（日本国立天文台科学部）；Max-Planck-Institut für extraterrestrische Physik（马克斯·普朗克地外物理学研究所）
Submillimeter bright galaxies in the early Universe are vigorously forming stars at ~1000 times higher rate than the Milky Way. A large fraction of stars is formed in the central 1 kiloparsec region, that is comparable in size to massive, quiescent galaxies found at the peak of the cosmic star formation history, and eventually the core of giant elliptical galaxies in the present-day Universe. However, the physical and kinematic properties inside a compact starburst core are poorly understood because dissecting it requires angular resolution even higher than the Hubble Space Telescope can offer…
In this work, we test the validity of $T_e$ - $T_e$ relations in resolved (10-200~pc) measurements of four nearby, low-metallicity (7.25 $\leq$ 12+log(O/H) $\leq$ 8.33), low-mass (10$^{6.78}$ $\leq$ M$_*$/M$_\odot$ $\leq$ 10$^{8.7}$), starburst (10$^{-4.5}$ $\leq$ sSFR $\leq$ 10$^{-0.3}$) galaxies. We obtain VLT/X-Shooter spectra of NGC~5253, NGC~0625, SBS~0335-052E and IC~2828, targeting regions within these galaxies with bright point-like sources and diffuse gas. Our observations are designed to extend from the galaxy midplane into extraplanar gas likely belonging to galactic winds. We measu…
Models of galaxy formation predict that gas accretion from the cosmic web is a primary driver of star formation over cosmic history. Except in very dense environments where galaxy mergers are also important, model galaxies feed from cold streams of gas from the web that penetrate their dark matter haloes. Although these predictions are unambiguous, the observational support has been indirect so far. Here we report spectroscopic evidence for this process in extremely metal-poor galaxies (XMPs) of the local Universe, taking the form of localized starbursts associated with gas having low metallic…
Post-starburst (PSB), or 'E+A', galaxies represent a rapid transitional phase between major, gas-rich mergers and gas-poor, quiescent early-type galaxies. Surprisingly, many PSBs have been shown to host a significant interstellar medium (ISM), despite theoretical predictions that the majority of star-forming gas should be expelled in AGN- or starburst-driven outflows. To-date, the resolved properties of this surviving ISM have remained unknown. We present high resolution ALMA continuum and CO(2$-$1) observations in six gas- and dust-rich PSBs, revealing for the first time the spatial and kinem…
We report interferometric measurements of [NII] 205 um fine-structure line emission from a representative sample of three galaxies at z=5-6 using the Atacama Large (sub)Millimeter Array (ALMA). These galaxies were previously detected in [CII] and far-infrared continuum emission and span almost two orders of magnitude in star formation rate (SFR). Our results show at least two different regimes of ionized inter-stellar medium properties for galaxies in the first billion years of cosmic time, separated by their L_[CII]/L_[NII] ratio. We find extremely low [NII] emission compared to [CII] (L_ [CI…
We have discovered an optically rich galaxy cluster at z=1.7089 with star formation occurring in close proximity to the central galaxy. The system, SpARCS104922.6+564032.5, was detected within the Spitzer Adaptation of the red-sequence Cluster Survey, (SpARCS), and confirmed through Keck-MOSFIRE spectroscopy. The rest-frame optical richness of Ngal(500kpc) = 30+/-8 implies a total halo mass, within 500kpc, of ~3.8+/-1.2 x 10^14 Msun, comparable to other clusters at or above this redshift. There is a wealth of ancillary data available, including Canada-France-Hawaii Telescope optical, UKIRT-K, …
The detection of two $z\sim 13$ galaxy candidates has opened a new window on galaxy formation at an era only $330$ Myr after the Big Bang. Here, we investigate the physical nature of these sources: are we witnessing star forming galaxies or quasars at such early epochs? If powered by star formation, the observed ultraviolet (UV) luminosities and number densities can be jointly explained if: (i) these galaxies are extreme star-formers with star formation rates $5-24\times$ higher than those expected from extrapolations of average lower-redshift relations; (ii) the star formation efficiency incr…
Starburst galaxies at the peak of cosmic star formation are among the most extreme starforming engines in the universe, producing stars over ~100 Myr. The star formation rates of these galaxies, which exceed 100 $M_\odot$ per year, require large reservoirs of cold molecular gas to be delivered to their cores, despite strong feedback from stars or active galactic nuclei. Starburst galaxies are therefore ideal targets to unravel the critical interplay between this feedback and the growth of a galaxy. The methylidyne cation, CH$^+$, is a most useful molecule for such studies because it cannot for…
We present a new observational study of the CO(1-0) line emission as an H2 gas mass tracer under extreme conditions in extragalactic environments. Our approach is to study the full neutral interstellar medium (H2, HI and dust) of two galaxies whose bulk interstellar medium (ISM) resides in environments that mark (and bracket) the excitation extremes of the ISM conditions found in infrared luminous galaxies, the starburst NGC3310 and the quiescent spiral NGC157. Our study maintains a robust statistical notion of the so-called X factor (i.e. a large ensemble of clouds is involved) while explorin…
High redshift quasars emit copious X-ray photons which heat the intergalactic medium to temperatures up to $\sim$ 10$^6$ K. At such high temperatures the primordial gas will not form stars until it is assembled into dark matter haloes with masses of up to $\sim$ 10$^{11}$ M$_{\odot}$, at which point the hot gas collapses and cools under the influence of gravity. Once this occurs, there is a massive reservoir of primordial gas from which stars can form, potentially setting the stage for the brightest Population (Pop) III starbursts in the early Universe. Supporting this scenario, recent observa…
Star formation rates in the centers of disk galaxies often vastly exceed those at larger radii. We investigate the idea that these central starbursts are self-regulated, with the momentum flux injected to the ISM by star formation balancing the gravitational force confining the gas. For most starbursts, supernovae are the largest contributor to the momentum flux, and turbulence provides the main pressure support for the predominantly-molecular ISM. If the momentum feedback per stellar mass formed is p_*/m_* ~ 3000 km/s, the predicted star formation rate is Sigma_SFR=2 pi G Sigma^2 m_*/p_* ~0.1…
