scholarly journals Oxygen abundances of zCOSMOS galaxies at z ∼ 1.4 based on five lines and implications for the fundamental metallicity relation

2014 ◽  
Vol 10 (S309) ◽  
pp. 281-282 ◽  
Author(s):  
Christian Maier ◽  
Simon J. Lilly ◽  
Bodo L. Ziegler ◽  
Keyword(s):  
Gas Phase ◽  
Near Infrared ◽  
Nir Spectroscopy ◽  
Stellar Mass ◽  
Emission Lines ◽  
Star Forming

AbstractA relation between the stellar mass M and the gas-phase metallicity Z of galaxies, the MZR, is observed up to higher redshifts. It is a matter of debate, however, if the SFR is a second parameter in the MZR. To explore this issue at z > 1, we used VLT-SINFONI near-infrared (NIR) spectroscopy of eight zCOSMOS galaxies at 1.3 < z < 1.4 to measure the strengths of four emission lines: Hβ, [OIII]λ5007, Hα, and [NII]λ6584, additional to [OII]λ3727 measured from VIMOS. We derive reliable O/H metallicities based on five lines, and also SFRs from extinction corrected Hα measurements. We find that the MZR of these star-forming galaxies at z ≈ 1.4 is lower than the local SDSS MZR by a factor of three to five, a larger change than reported in the literature using [NII]/Hα-based metallicities from individual and stacked spectra. Correcting N2-based O/Hs using recent results by Newman et al. (2014), also the larger FMOS sample at z ∼ 1.4 of Zahid et al. (2014) shows a similar evolution of the MZR like the zCOSMOS objects. These observations seem also in agreement with a non-evolving FMR using the physically motivated formulation of the FMR from Lilly et al. (2013).

scholarly journals LSD and AMAZE: the mass-metallicity relation at z > 3

2008 ◽  
Vol 4 (S255) ◽  
pp. 106-110 ◽  
Author(s):  
F. Mannucci ◽  
R. Maiolino
Keyword(s):  
Gas Phase ◽  
Galaxy Evolution ◽  
Near Infrared ◽  
Stellar Populations ◽  
Stellar Mass ◽  
Emission Lines ◽  
Preliminary Results ◽  
Lyman Break Galaxies ◽  
First Results ◽  
Lower Redshift

AbstractWe present the first results on galaxy metallicity evolution at z > 3 from two projects, LSD (Lyman-break galaxies Stellar populations and Dynamics) and AMAZE (Assessing the Mass Abundance redshift Evolution). These projects use deep near-infrared spectroscopic observations of a sample of ~40 LBGs to estimate the gas-phase metallicity from the emission lines. We derive the mass-metallicity relation at z > 3 and compare it with the same relation at lower redshift. Strong evolution from z = 0 and z = 2 to z = 3 is observed, and this finding puts strong constraints on the models of galaxy evolution. These preliminary results show that the effective oxygen yields do not increase with stellar mass, implying that the simple outflow model does not apply at z > 3.

scholarly journals Shocked Molecular Hydrogen from Star Forming Regions

1987 ◽  
Vol 115 ◽  
pp. 181-181 ◽  
Author(s):  
Adair P. Lane ◽  
John Bally
Keyword(s):  
Shock Waves ◽  
High Velocity ◽  
Molecular Hydrogen ◽  
Near Infrared ◽  
Young Stars ◽  
Emission Lines ◽  
Molecular Gas ◽  
Star Forming ◽  
Star Forming Regions ◽  
Post Shock

Near infrared (2 micron) emission lines from molecular hydrogen provide a powerful probe of the morphology and energetics of outflows associated with stellar birth. The H2 emission regions trace the location of shock waves formed when the high velocity outflow from young stars encounters dense quiescent gas. Since H2 is the dominant coolant of the hot post-shock molecular gas, the H2 lines provide a measure of the fraction of the total mechanical luminosity radiated away from the cloud.

scholarly journals X-shooter and ALMA spectroscopy of GRB 161023A

2018 ◽  
Vol 620 ◽  
pp. A119 ◽  
Author(s):  
A. de Ugarte Postigo ◽  
C. C. Thöne ◽  
J. Bolmer ◽  
S. Schulze ◽  
S. Martín ◽  
...  
Keyword(s):  
Near Infrared ◽  
Gamma Ray ◽  
High Redshift ◽  
Nir Spectroscopy ◽  
Host Galaxy ◽  
Star Forming ◽  
Star Forming Regions ◽  
Molecular Features ◽  
Short Period ◽  
Luminous Objects

Context. Long gamma-ray bursts (GRBs) are produced during the dramatic deaths of massive stars with very short lifetimes, meaning that they explode close to the birth place of their progenitors. Over a short period they become the most luminous objects observable in the Universe, being perfect beacons to study high-redshift star-forming regions. Aims. We aim to use the afterglow of GRB 161023A at a redshift z = 2.710 as a background source to study the environment of the explosion and the intervening systems along its line of sight. Methods. For the first time, we complement ultraviolet (UV), optical and near-infrared (NIR) spectroscopy with millimetre spectroscopy using the Atacama Large Millimeter Array (ALMA), which allows us to probe the molecular content of the host galaxy. The X-shooter spectrum shows a plethora of absorption features including fine-structure and metastable transitions of Fe, Ni, Si, C, and O. We present photometry ranging from 43 s to over 500 days after the burst. Results. We infer a host-galaxy metallicity of [Zn/H] = −1.11 ± 0.07, which, corrected for dust depletion, results in [X/H] = −0.94 ± 0.08. We do not detect molecular features in the ALMA data, but we derive limits on the molecular content of log(NCO/cm−2) < 15.7 and log(NHCO+/cm−-12, which are consistent with those that we obtain from the optical spectra, log(NH2/cm−2)< 15.2 and log(NCO/cm−2) < 14.5. Within the host galaxy, we detect three velocity systems through UV, optical and NIR absorption spectroscopy, all with levels that were excited by the GRB afterglow. We determine the distance from these systems to the GRB to be in the range between 0.7 and 1.0 kpc. The sight line to GRB 161023A shows nine independent intervening systems, most of them with multiple components. Conclusions. Although no molecular absorption was detected for GRB 161023A, we show that GRB millimetre spectroscopy is now feasible and is opening a new window on the study of molecular gas within star-forming galaxies at all redshifts. The most favoured lines of sight for this purpose will be those with high metallicity and dust.

scholarly journals ALMA Deep Field in SSA22

2020 ◽  
Vol 640 ◽  
pp. L8 ◽  
Author(s):  
Hideki Umehata ◽  
Ian Smail ◽  
A. M. Swinbank ◽  
Kotaro Kohno ◽  
Yoichi Tamura ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Near Infrared ◽  
Formation Rate ◽  
Stellar Mass ◽  
Star Forming ◽  
Submillimeter Galaxies ◽  
The Galaxy ◽  
Deep Survey ◽  
Multi Wavelength

Deep surveys with the Atacama Large Millimeter Array (ALMA) have uncovered a population of dusty star-forming galaxies which are faint or even undetected at optical to near-infrared wavelengths. Their faintness at short wavelengths makes the detailed characterization of the population challenging. Here we present a spectroscopic redshift identification and a characterization of one of these near-infrared-dark galaxies discovered by an ALMA deep survey. The detection of [C I](1–0) and CO(4–3) emission lines determines the precise redshift of the galaxy, ADF22.A2, to be z = 3.9913 ± 0.0008. On the basis of a multi-wavelength analysis, ADF22.A2 is found to be a massive, star-forming galaxy with a stellar mass of M∗ = 1.1−0.6+1.3 × 1011 M⊙ and SFR = 430−150+230 M⊙ yr−1. The molecular gas mass was derived to be M(H2)[CI] = (5.9 ± 1.5)×1010 M⊙, indicating a gas fraction of ≈35%, and the ratios of L[CI](1−0)/LIR and L[CI](1−0)/LCO(4−3) suggest that the nature of the interstellar medium in ADF22.A2 is in accordance with those of other bright submillimeter galaxies. The properties of ADF22.A2, including the redshift, star-formation rate, stellar mass, and depletion time scale (τdep ≈ 0.1−0.2 Gyr), also suggest that ADF22.A2 has the characteristics expected for the progenitors of quiescent galaxies at z ≳ 3. Our results demonstrate the power of ALMA contiguous mapping and line scan, which help us to obtain an unbiased view of galaxy formation in the early Universe.

scholarly journals The origin of R CrA variability

2019 ◽  
Vol 630 ◽  
pp. A132 ◽  
Author(s):  
E. Sissa ◽  
R. Gratton ◽  
J. M. Alcalà ◽  
S. Desidera ◽  
S. Messina ◽  
...  
Keyword(s):  
Light Curve ◽  
Spectroscopic Data ◽  
Near Infrared ◽  
Progressive Increase ◽  
Emission Lines ◽  
Periodic Modulation ◽  
Star Forming ◽  
Stable Period ◽  
Total Luminosity ◽  
M Dwarf

Context. R CrA is the brightest member of the Coronet star-forming region and is the closest Herbig AeBe star with a spectrum dominated by emission lines. Its luminosity has been monitored since the end of the nineteenth century, but the origin of its variability, which shows a stable period of 65.767 ± 0.007 days, is still unknown. Aims. We studied photometric and spectroscopic data for this star to investigate the nature of the variability of R CrA. Methods. We exploited the fact that the near-infrared luminosity of the Herbig AeBe stars is roughly proportional to the total luminosity of the stars to derive the absorption, and then mass and age of R CrA. In addition, we modeled the periodic modulation of the light curve as due to partial attenuation of a central binary by a circumbinary disk. This model reproduces the observations very well. Results. We found that the central object in R CrA is a very young (1.5 ± 1.5 Myr) highly absorbed (AV = 5.47 ± 0.4 mag) binary; we obtain masses of MA = 3.02 ± 0.43 M⊙ and MB = 2.32 ± 0.35 M⊙ for the two components. We propose that the secular decrease of the apparent luminosity of R CrA is due to a progressive increase of the disk absorption. This might be related to precession of a slightly inclined disk caused by the recently discovered M-dwarf companion. This means that R CrA might be a triple system hosting a disk.

scholarly journals The Metal Abundances across Cosmic Time (MACT) Survey. III – The relationship between stellar mass and star formation rate in extremely low-mass galaxies

2020 ◽  
Vol 501 (2) ◽  
pp. 2231-2249 ◽  
Author(s):  
Kaitlyn Shin ◽  
Chun Ly ◽  
Matthew A Malkan ◽  
Sangeeta Malhotra ◽  
Mithi de los Reyes ◽  
...  
Keyword(s):  
Star Formation ◽  
Near Infrared ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Cosmic Time ◽  
Stellar Mass ◽  
Star Forming ◽  
Dependent Relation ◽  
Photometric Measurements ◽  
Stellar Masses

ABSTRACT Extragalactic studies have demonstrated that there is a moderately tight (≈0.3 dex) relationship between galaxy stellar mass (M⋆) and star formation rate (SFR) that holds for star-forming galaxies at M⋆ ∼ 3 × 108–1011 M⊙, i.e. the ‘star formation main sequence’. However, it has yet to be determined whether such a relationship extends to even lower mass galaxies, particularly at intermediate or higher redshifts. We present new results using observations for 714 narrow-band H α-selected galaxies with stellar masses between 106 and 1010 M⊙ (average of 108.2 M⊙) at z ≈ 0.07–0.5. These galaxies have sensitive ultraviolet (UV) to near-infrared photometric measurements and optical spectroscopy. The latter allows us to correct our H α SFRs for dust attenuation using Balmer decrements. Our study reveals that: (1) for low-SFR galaxies, our H α SFRs systematically underpredict compared to far-UV measurements, consistent with other studies; (2) at a given stellar mass (≈108 M⊙), log (specific SFR) evolves as A log (1 + z) with A = 5.26 ± 0.75, and on average, specific SFR increases with decreasing stellar mass; (3) the SFR–M⋆ relation holds for galaxies down to ∼106 M⊙ (∼1.5 dex below previous studies), and over lookback times of up to 5 Gyr, follows a redshift-dependent relation of log (SFR) ∝ α log (M⋆/M⊙) + β z with α = 0.60 ± 0.01 and β = 1.86 ± 0.07; and (4) the observed dispersion in the SFR–M⋆ relation at low stellar masses is ≈0.3 dex. Accounting for survey selection effects using simulated galaxies, we estimate that the true dispersion is ≈0.5 dex.

scholarly journals First demonstration of OH suppression in a high-efficiency near-infrared spectrograph

2020 ◽  
Vol 492 (2) ◽  
pp. 2796-2806 ◽  
Author(s):  
S C Ellis ◽  
J Bland-Hawthorn ◽  
J S Lawrence ◽  
A J Horton ◽  
R Content ◽  
...  
Keyword(s):  
Temporal Variability ◽  
Near Infrared ◽  
High Efficiency ◽  
Nir Spectroscopy ◽  
Upper Atmosphere ◽  
Emission Lines ◽  
Spatial And Temporal Variability ◽  
Atmospheric Emission ◽  
Fibre Bragg Gratings ◽  
First Time

ABSTRACT Ground-based near-infrared (NIR) astronomy is severely hampered by the forest of atmospheric emission lines resulting from the rovibrational decay of OH molecules in the upper atmosphere. The extreme brightness of these lines, as well as their spatial and temporal variability, makes accurate sky subtraction difficult. Selectively filtering these lines with OH suppression instruments has been a long standing goal for NIR spectroscopy. We have shown previously the efficacy of fibre Bragg gratings (FBGs) combined with photonic lanterns for achieving OH suppression. Here we report on PRAXIS, a unique NIR spectrograph that is optimized for OH suppression with FBGs. We show for the first time that OH suppression (of any kind) is possible with high overall throughput (18 per cent end-to-end), and provide examples of the relative benefits of OH suppression.

scholarly journals FIGS: spectral fitting constraints on the star formation history of massive galaxies since the cosmic noon

2019 ◽  
Vol 486 (1) ◽  
pp. 1358-1376 ◽  
Author(s):  
Ignacio Ferreras ◽  
Anna Pasquali ◽  
Nor Pirzkal ◽  
John Pharo ◽  
Sangeeta Malhotra ◽  
...  
Keyword(s):  
Star Formation ◽  
Near Infrared ◽  
Age Distribution ◽  
Principal Component ◽  
Stellar Mass ◽  
Star Formation History ◽  
Population Parameters ◽  
Massive Galaxies ◽  
Star Forming ◽  
Spectral Fitting

Abstract We constrain the stellar population properties of a sample of 52 massive galaxies – with stellar mass log (Ms/M⊙) ≳ 10.5 – over the redshift range 0.5 &lt; z &lt; 2 by use of observer-frame optical and near-infrared slitless spectra from Hubble Space Telescope’s ACS and WFC3 grisms. The deep exposures (∼100 ks) allow us to target individual spectra of massive galaxies to F160W = 22.5 AB. Our spectral fitting approach uses a set of six base models adapted to the redshift and spectral resolution of each observation, and fits the weights of the base models, including potential dust attenuation, via a Markov Chain Monte Carlo method. Our sample comprises a mixed distribution of quiescent (19) and star-forming galaxies (33). We quantify the width of the age distribution (Δt) that is found to dominate the variance of the retrieved parameters according to principal component analysis. The population parameters follow the expected trend towards older ages with increasing mass, and Δt appears to weakly anticorrelate with stellar mass, suggesting a more efficient star formation at the massive end. As expected, the redshift dependence of the relative stellar age (measured in units of the age of the Universe at the source) in the quiescent sample rejects the hypothesis of a single burst (aka monolithic collapse). Radial colour gradients within each galaxy are also explored, finding a wider scatter in the star-forming subsample, but no conclusive trend with respect to the population parameters.

scholarly journals Measuring the physical conditions of accreting gas in T Tauri systems

2007 ◽  
Vol 3 (S243) ◽  
pp. 95-102
Author(s):  
Jeffrey S. Bary ◽  
Sean P. Matt
Keyword(s):  
Near Infrared ◽  
Young Star ◽  
Emission Lines ◽  
Line Flux ◽  
Star Forming ◽  
Physical Conditions ◽  
T Tauri ◽  
Hydrogen Emission Lines ◽  
Line Theory ◽  
Magnetospheric Accretion

AbstractHydrogen emission lines observed from T Tauri stars (TTS) are associated with the accretion/outflow of gas in these young star forming systems. Magnetospheric accretion models have been moderately successful at reproducing the shapes of several Hi emission line profiles, suggesting that the emission arises in the accretion funnels. Despite considerable effort to model and observe these emission features, the physical conditions of the gas confined to the funnel flows remain poorly constrained by observation. We conducted a mutli-epoch near-infrared spectroscopic survey of 16 actively accreting classical TTS in the Taurus-Auriga star forming region. We present an analysis of these simultaneously acquired line flux ratios of many Paschen and Brackett series emission lines, in which we compare the observed ratios to those predicted by the Case B approximation of hydrogen recombination line theory. We find that the line flux ratios for the Paschen and Brackett decrements as well as a comparison between Brγ and Paschen transitions agree well with the Case B models with T < 5000 K and ne ≈ 1010 cm−3.

Star Formation Rates of a z~1 DEEP2 Galaxy Sample from LIRIS Multi-slit Hα Spectroscopy

2006 ◽  
Vol 2 (S235) ◽  
pp. 417-418
Author(s):  
Nayra Rodríguez-Eugenio ◽  
Kai G. Noeske ◽  
Jose Acosta-Pulido ◽  
Francisco Prada ◽  
Arturo Manchado ◽  
...  
Keyword(s):  
Star Formation ◽  
Rest Frame ◽  
Near Infrared ◽  
Nir Spectroscopy ◽  
Star Forming ◽  
Preliminary Results ◽  
Galaxy Sample ◽  
Redshift Survey ◽  
Galaxy Redshift ◽  
Stellar Masses

AbstractWe present preliminary results of Hα near-infrared (NIR) spectroscopy of 16 galaxies with redshifts in the range 0.8 ≤ z ≤ 1.0 drawn from the DEEP2 Galaxy Redshift Survey. The spectra were taken using the multi-slit mode of LIRIS (Long-slit Intermediate Resolution Infrared Spectrograph), installed at the 4.2-m WHT. Twelve out of 16 spectra yield robust (>5σ) Hα detections. We compare star formation rates (SFRs) from Hα luminosities to those derived from DEEP2 rest-frame UV measurements. This study is part of a larger program to obtain accurate Hα luminosities of about 50 star-forming galaxies at z ~ 1 in the Extended Groth Strip. Our scientific goals are the measurement of SFRs from Hα, and the comparison and calibration of Hα and other SFR tracers at z ~ 1. The study will be complemented with galaxy stellar masses, reddening estimates, galaxy morphologies and metallicities.

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