scholarly journals Planck’s Dusty GEMS

2019 ◽  
Vol 624 ◽  
pp. A23 ◽  
Author(s):  
N. P. H. Nesvadba ◽  
R. Cañameras ◽  
R. Kneissl ◽  
S. Koenig ◽  
C. Yang ◽  
...  
Keyword(s):  
High Redshift ◽  
Starburst Galaxies ◽  
Molecular Gas ◽  
Atomic Carbon ◽  
High Redshift Galaxies ◽  
Neutral Gas ◽  
The Common ◽  
The Masses ◽  
Better Than ◽  
Good Agreement

The bright 3P1–3P0 ([CI] 1–0) and 3P2–3P1 ([CI] 2–1) lines of atomic carbon are becoming more and more widely employed as tracers of the cold neutral gas in high-redshift galaxies. Here we present observations of these lines in the 11 galaxies of the set of Planck’s Dusty GEMS, the brightest gravitationally lensed galaxies on the extragalactic submillimeter sky probed by the Planck satellite. We have [CI] 1–0 and [CI] 2–1 measurements for seven and eight of these galaxies, respectively, including four galaxies where both lines have been measured. We use our observations to constrain the gas excitation mechanism, excitation temperatures, optical depths, atomic carbon and molecular gas masses, and carbon abundances. Ratios of LCI/LFIR are similar to those found in the local universe, and suggest that the total cooling budget through atomic carbon has not significantly changed in the last 12 Gyr. Both lines are optically thin and trace 1 − 6 × 107 M⊙ of atomic carbon. Carbon abundances, XCI, are between 2.5 and 4 × 10−5, for an ultra-luminous infrared galaxy (ULIRG) CO-to-H2 conversion factor of αCO = 0.8 M⊙ / [K km s−1 pc2]. Ratios of molecular gas masses derived from [CI] 1–0 and CO agree within the measurement uncertainties for five galaxies, and agree to better than a factor of two for another two with [CI] 1–0 measurements, after carefully taking CO excitation into account. This does not support the idea that intense, high-redshift starburst galaxies host large quantities of “CO-dark” gas. These results support the common assumptions underlying most molecular gas mass estimates made for massive, dusty, high-redshift starburst galaxies, although the good agreement between the masses obtained with both tracers cannot be taken as independent confirmation of either αCO or XCI.

scholarly journals Extreme conditions in the molecular gas of lensed star-forming galaxies at z ~3

2018 ◽  
Vol 615 ◽  
pp. A142 ◽  
Author(s):  
Paola Andreani ◽  
Edwin Retana-Montenegro ◽  
Zhi-Yu Zhang ◽  
Padelis Papadopoulos ◽  
Chentao Yang ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Gas Phase ◽  
High Redshift ◽  
Molecular Gas ◽  
Extreme Conditions ◽  
Atomic Carbon ◽  
Power Sources ◽  
High Redshift Galaxies ◽  
Star Forming ◽  
Nearby Galaxies

Context. Atomic carbon can be an efficient tracer of the molecular gas mass, and when combined to the detection of high-J and low-J CO lines it yields also a sensitive probe of the power sources in the molecular gas of high-redshift galaxies. Aims. The recently installed SEPIA 5 receiver at the focus of the APEX telescope has opened up a new window at frequencies 159–211 GHz allowing the exploration of the atomic carbon in high-z galaxies, at previously inaccessible frequencies from the ground. We have targeted three gravitationally lensed galaxies at redshift of about 3 and conducted a comparative study of the observed high-J CO/CI ratios with well-studied nearby galaxies. Methods. Atomic carbon (CI(2–1)) was detected in one of the three targets and marginally in a second, while in all three targets the J = 7→6 CO line is detected. Results. The CO(7–6)/CI(2–1), CO(7–6)/CO(1–0) line ratios and the CO(7–6)/(far-IR continuum) luminosity ratio are compared to those of nearby objects. A large excitation status in the ISM of these high-z objects is seen, unless differential lensing unevenly boosts the CO line fluxes from the warm and dense gas more than the CO(1–0), CI(2–1), tracing a more widely distributed cold gas phase. We provide estimates of total molecular gas masses derived from the atomic carbon and the carbon monoxide CO(1–0), which within the uncertainties turn out to be equal.

scholarly journals Observations of Molecules in High Redshift Galaxies

2011 ◽  
Vol 7 (S280) ◽  
pp. 325-338
Author(s):  
Kirsten Kraiberg Knudsen
Keyword(s):  
Small Molecules ◽  
High Redshift ◽  
Molecular Gas ◽  
Molecular Line ◽  
High Redshift Galaxies ◽  
The Past ◽  
Tremendous Progress ◽  
Submillimeter Galaxies ◽  
Redshift Galaxies

AbstractI present an overview of the molecular gas observations in high redshift galaxies. This field has seen tremendous progress in the past few years, with an increased number of detections of other molecules than CO. The molecular line observations are done towards different classes of massive starbursts, including submillimeter galaxies, quasars, and massive gas-rich disks. I will highlight results of detections of HCN, HCO+, and other small molecules, as well as the Spitzer detections of PAHs. Additionally, I will discuss about the excitation of CO and other species in the high-z galaxies and put this in the context of new telescopes such as ALMA.

scholarly journals Gone with the heat: a fundamental constraint on the imaging of dust and molecular gas in the early Universe

2016 ◽  
Vol 3 (6) ◽  
pp. 160025 ◽  
Author(s):  
Zhi-Yu Zhang ◽  
Padelis P. Papadopoulos ◽  
R. J. Ivison ◽  
Maud Galametz ◽  
M. W. L. Smith ◽  
...  
Keyword(s):  
Structural Characteristics ◽  
High Redshift ◽  
Line Emission ◽  
Velocity Fields ◽  
Molecular Gas ◽  
Gas Velocity ◽  
High Redshift Galaxies ◽  
Mass Distributions ◽  
Line Imaging ◽  
Cold Dust

Images of dust continuum and carbon monoxide (CO) line emission are powerful tools for deducing structural characteristics of galaxies, such as disc sizes, H 2 gas velocity fields and enclosed H 2 and dynamical masses. We report on a fundamental constraint set by the cosmic microwave background (CMB) on the observed structural and dynamical characteristics of galaxies, as deduced from dust continuum and CO-line imaging at high redshifts. As the CMB temperature rises in the distant Universe, the ensuing thermal equilibrium between the CMB and the cold dust and H 2 gas progressively erases all spatial and spectral contrasts between their brightness distributions and the CMB. For high-redshift galaxies, this strongly biases the recoverable H 2 gas and dust mass distributions, scale lengths, gas velocity fields and dynamical mass estimates. This limitation is unique to millimetre/submillimetre wavelengths and unlike its known effect on the global dust continuum and molecular line emission of galaxies, it cannot be addressed simply. We nevertheless identify a unique signature of CMB-affected continuum brightness distributions, namely an increasing rather than diminishing contrast between such brightness distributions and the CMB when the cold dust in distant galaxies is imaged at frequencies beyond the Raleigh–Jeans limit. For the molecular gas tracers, the same effect makes the atomic carbon lines maintain a larger contrast than the CO lines against the CMB.

Constraining Galaxy Formation Epoch

2005 ◽  
Vol 201 ◽  
pp. 536-537
Author(s):  
Sukyoung. Yi ◽  
T. Brown ◽  
S. Heap ◽  
I. Hubeny ◽  
W. Landsman ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
High Redshift ◽  
Population Synthesis ◽  
High Redshift Galaxies ◽  
The Galaxy ◽  
The Difference ◽  
Age Estimates ◽  
Good Agreement ◽  
Redshift Galaxies

Pinning down the ages of high redshift galaxies is the most direct way of constraining the galaxy formation epoch. There has been a debate on the age of LBDS 53W091, a red galaxy at z=1.5. The discrepancy in the age estimates of various groups is due to the difference in the population synthesis model. However, there is generally a good agreement among popular models. Polishing the models and assessing their internal uncertainties are crucial in the analysis of high redshift galaxies.

scholarly journals The mass–metallicity and the fundamental metallicity relation revisited on a fully Te-based abundance scale for galaxies

2019 ◽  
Vol 491 (1) ◽  
pp. 944-964 ◽  
Author(s):  
Mirko Curti ◽  
Filippo Mannucci ◽  
Giovanni Cresci ◽  
Roberto Maiolino
Keyword(s):  
High Redshift ◽  
Formation Rate ◽  
Cosmic Time ◽  
Stellar Mass ◽  
Strong Line ◽  
High Redshift Galaxies ◽  
Star Forming ◽  
Theoretical Predictions ◽  
Galaxy Population ◽  
Good Agreement

ABSTRACT The relationships between stellar mass, gas-phase metallicity and star-formation rate (i.e. the mass–metallicity, MZR, and the fundamental metallicity relation, FMR) in the local Universe are revisited by fully anchoring the metallicity determination for SDSS galaxies on the Te abundance scale defined exploiting the strong-line metallicity calibrations presented by Curti et al. Self-consistent metallicity measurements allow a more unbiased assessment of the scaling relations involving M, Z and SFR, which provide powerful constraints for the chemical evolution models. We parametrize the MZR with a new functional form that allows us to better characterize the turnover mass. The slope and saturation metallicity are in good agreement with previous determinations of the MZR based on the Te method, while showing significantly lower normalization compared to those based on photoionization models. The Z–SFR dependence at fixed stellar mass is also investigated, being particularly evident for highly star-forming galaxies, where the scatter in metallicity is reduced up to a factor of ${\sim}30{{\ \rm per\ cent}}$. A new parametrization of the FMR is given by explicitly introducing the SFR dependence of the turnover mass into the MZR. The residual scatter in metallicity for the global galaxy population around the new FMR is 0.054 dex. The new FMR presented in this work represents a useful local benchmark to compare theoretical predictions and observational studies (of both local and high-redshift galaxies) whose metallicity measurements are tied to the abundance scale defined by the Te method, hence allowing proper assessment of its evolution with cosmic time.

scholarly journals Towards a multi-scale understanding of the gas-star formation cycle in the Central Molecular Zone

2016 ◽  
Vol 11 (S322) ◽  
pp. 64-74
Author(s):  
J. M. Diederik Kruijssen
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
High Redshift ◽  
Three Dimensional ◽  
Orbital Dynamics ◽  
Molecular Gas ◽  
Stellar Clusters ◽  
High Redshift Galaxies ◽  
Multi Scale ◽  
The Galaxy

AbstractThe Central Molecular Zone (CMZ, the central 500 pc of the Milky Way) contains the largest reservoir of high-density molecular gas in the Galaxy, but forms stars at a rate 10–100 times below commonly-used star formation relations. We discuss recent efforts in understanding how the nearest galactic nucleus forms its stars. The latest models of the gas inflow, star formation, and feedback duty cycle reproduce the main observable features of the CMZ, showing that star formation is episodic and that the CMZ currently resides at a star formation minimum. Using orbital modelling, we derive the three-dimensional geometry of the CMZ and show how the orbital dynamics and the star formation potential of the gas are closely coupled. We discuss how this coupling reveals the physics of star formation and feedback under the conditions seen in high-redshift galaxies, and promotes the formation of the densest stellar clusters in the Galaxy.

scholarly journals Atomic carbon as a powerful tracer of molecular gas in the high-redshift Universe: perspectives for ALMA

2014 ◽  
Vol 445 (1) ◽  
pp. L124-L128 ◽  
Author(s):  
M. Tomassetti ◽  
C. Porciani ◽  
E. Romano-Díaz ◽  
A. D. Ludlow ◽  
P. P. Papadopoulos
Keyword(s):  
High Redshift ◽  
Molecular Gas ◽  
Atomic Carbon ◽  
High Redshift Universe

scholarly journals Star Formation in Damped Lyman α Selected Galaxies

2007 ◽  
Vol 3 (S244) ◽  
pp. 284-288
Author(s):  
Lise Christensen
Keyword(s):  
Star Formation ◽  
Emission Line ◽  
High Redshift ◽  
Neutral Hydrogen ◽  
Disk Galaxies ◽  
Local Universe ◽  
High Redshift Galaxies ◽  
Neutral Gas ◽  
Integral Field Spectroscopy ◽  
Integral Field

AbstractI present results from an ongoing survey to study galaxies associated with damped Lyman-α (DLA) systems at redshifts z>2. Integral field spectroscopy is used to search for Lyα emission line objects at the wavelengths where the emission from the quasars have been absorbed by the DLAs. The DLA galaxy candidates detected in this survey are found at distances of 10–20 kpc from the quasar line of sight, implying that galaxies are surrounded by neutral hydrogen at large distances. If we assume that the distribution of neutral gas is exponential, the scale length of the neutral gas is ~6 kpc, similar to large disk galaxies in the local Universe. The emission line luminosities imply smaller star formation rates compared to other high redshift galaxies found in luminosity selected samples.

Experimental Measurements of Ingestion Through Turbine Rim Seals—Part II: Rotationally Induced Ingress

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
Carl M. Sangan ◽  
Oliver J. Pountney ◽  
Kunyuan Zhou ◽  
J. Michael Owen ◽  
Mike Wilson ◽  
...  
Keyword(s):  
Experimental Results ◽  
Radial Clearance ◽  
Rotating Fluid ◽  
Flow Rates ◽  
Hot Gas ◽  
Wide Range ◽  
The Common ◽  
Axial Clearance ◽  
Better Than ◽  
Good Agreement

Part I of this two-part paper presented experimental results for externally-induced (EI) ingress, where the ingestion of hot gas through the rim seal into the wheel-space of a gas turbine is controlled by the circumferential variation of pressure in the external annulus. In Part II, experimental results are presented for rotationally-induced (RI) ingress, where the ingestion is controlled by the pressure generated by the rotating fluid in the wheel-space. Although EI ingress is the common form of ingestion through turbine rim seals, RI ingress or combined ingress (where EI and RI ingress are both significant) is particularly important for double seals, where the pressure asymmetries are attenuated in the annular space between the inner and outer seals. In this paper, the sealing effectiveness was determined from concentration measurements, and the variation of effectiveness with sealing flow rate was compared with theoretical curves for RI ingress obtained from an orifice model. Using a nondimensional sealing parameter Φ0 the data could be collapsed onto a single curve, and the theoretical variation of effectiveness with Φ0 was in very good agreement with the data for a wide range of flow rates and rotational speeds. It was shown that the sealing flow required to prevent RI ingress was much less than that needed for EI ingress, and it was also shown that the effectiveness of a radial-clearance seal is significantly better than that for an axial-clearance seal for both EI and RI ingress.

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