We present a study of six far-infrared fine structure lines in the z = 4.225 lensed dusty star-forming galaxy SPT 0418−47 to probe the physical conditions of its interstellar medium (ISM). In ...particular, we report Atacama Pathfinder EXperiment (APEX) detections of the OI 145 μm and OIII 88 μm lines and Atacama Compact Array (ACA) detections of the NII 122 and 205 μm lines. The OI 145 μm/CII 158 μm line ratio is ∼5× higher compared to the average of local galaxies. We interpret this as evidence that the ISM is dominated by photo-dissociation regions with high gas densities. The line ratios, and in particular those of OIII 88 μm and NII 122 μm imply that the ISM in SPT 0418−47 is already chemically enriched to nearly solar metallicity. While the strong gravitational amplification was required to detect these lines with APEX, larger samples can be observed with the Atacama Large Millimeter/submillimeter Array (ALMA), and should allow observers to determine if the dense, solar metallicity ISM is common among these highly star-forming galaxies.
Aims. We present and study spatially resolved imaging obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) of multiple 12CO(J = 6 − 5, 8−7, and 9−8) and two H2O(202−111 and 211−202) ...emission lines and cold dust continuum toward the gravitationally lensed dusty star-forming galaxy SPT 0346-52 at z = 5.656. Methods. Using a visibility-domain source-plane reconstruction we probe the structure and dynamics of the different components of the interstellar medium (ISM) in this galaxy down to scales of 1 kpc in the source plane. Results. Measurements of the intrinsic sizes of the different CO emission lines indicate that the higher J transitions trace more compact regions in the galaxy. Similarly, we find smaller dust continuum intrinsic sizes with decreasing wavelength, based on observations at rest frame 130, 300, and 450 μm. The source shows significant velocity structure, and clear asymmetry where an elongated structure is observed in the source plane with significant variations in their reconstructed sizes. This could be attributed to a compact merger or turbulent disk rotation. The differences in velocity structure through the different line tracers, however, hint at the former scenario in agreement with previous CII line imaging results. Measurements of the CO line ratios and magnifications yield significant variations as a function of velocity, suggesting that modeling of the ISM using integrated values could be misinterpreted. Modeling of the ISM in SPT 0346-52 based on delensed fluxes indicates a highly dense and warm medium, qualitatively similar to that observed in high-redshift quasar hosts.
Water (H2O), one of the most ubiquitous molecules in the universe, has bright millimeter-wave emission lines that are easily observed at high redshift with the current generation of instruments. The ...low-excitation transition of H2O, ( rest = 987.927 GHz), is known to trace the far-infrared (FIR) radiation field independent of the presence of active galactic nuclei (AGNs) over many orders of magnitude in FIR luminosity ( ). This indicates that this transition arises mainly due to star formation. In this paper, we present spatially (∼0 5 corresponding to ∼1 kiloparsec) and spectrally resolved (∼100 kms−1) observations of in a sample of four strong gravitationally lensed high-redshift galaxies with the Atacama Large Millimeter/submillimeter Array. In addition to increasing the sample of luminous (>1012 L ) galaxies observed with H2O, this paper examines the relation on resolved scales for the first time at high redshift. We find that is correlated with on both global and resolved kiloparsec scales within the galaxy in starbursts and AGN with average . We find that the scatter in the observed relation does not obviously correlate with the effective temperature of the dust spectral energy distribution or the molecular gas surface density. This is a first step in developing as a resolved star formation rate calibrator.
Abstract
SPT0311-58, a system of two interacting galaxies in the Epoch of Reionization, exists in one of the rarest, most massive dark matter halos theoretically possible in that era. Studying the ...interstellar medium (ISM) in these galaxies can illuminate the process of galaxy formation in the early Universe. In this work, we explore the multiphase ISM in this system, using ALMA observations of the C
ii
158, O
i
146, N
ii
122, and O
iii
88 fine-structure lines and dust continuum. We find wide variations in line ratios between the eastern and western galaxies, as well as across the western galaxy. Continuum colors indicate that SPT0311-58 E has a higher ionization parameter (
log
U
≈
−
2.8
) than SPT0311-58 W (
log
U
≈
−
3.1
). The ratio of O
iii
88–N
ii
122 and the ionization parameter constraints combine to demonstrate near-solar metallicity in these objects just 800 Myr after the Big Bang.
ABSTRACT
We present APEX-LABOCA 870-μm observations of the fields surrounding the nine brightest high-redshift unlensed objects discovered in the South Pole Telescope’s (SPT) 2500 deg2 survey. ...Initially seen as point sources by SPT’s 1-arcmin beam, the 19-arcsec resolution of our new data enables us to deblend these objects and search for submillimetre (submm) sources in the surrounding fields. We find a total of 98 sources above a threshold of 3.7σ in the observed area of 1300 arcmin2, where the bright central cores resolve into multiple components. After applying a radial cut to our LABOCA sources to achieve uniform sensitivity and angular size across each of the nine fields, we compute the cumulative and differential number counts and compare them to estimates of the background, finding a significant overdensity of $\delta \, {\approx }\,$10 at $S_{870}= 14$ mJy. The large overdensities of bright submm sources surrounding these fields suggest that they could be candidate protoclusters undergoing massive star formation events. Photometric and spectroscopic redshifts of the unlensed central objects range from $z= $3 to 7, implying a volume density of star-forming protoclusters of approximately 0.1 Gpc−3. If the surrounding submm sources in these fields are at the same redshifts as the central objects, then the total star formation rates of these candidate protoclusters reach 10 000 M⊙ yr−1, making them much more active at these redshifts than seen so far in either simulations or observations.
We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of high-J CO lines (Jup = 6, 7, 8) and associated dust continuum toward five strongly lensed, dusty, star-forming galaxies ...at redshift z = 2.7-5.7. These galaxies, discovered in the South Pole Telescope survey, are observed at 0 2-0 4 resolution with ALMA. Our high-resolution imaging coupled with the lensing magnification provides a measurement of the structure and kinematics of molecular gas in the background galaxies with spatial resolutions down to kiloparsec scales. We derive visibility-based lens models for each galaxy, accurately reproducing observations of four of the galaxies. Of these four targets, three show clear velocity gradients, of which two are likely rotating disks. We find that the reconstructed region of CO emission is less concentrated than the region emitting dust continuum even for the moderate-excitation CO lines, similar to what has been seen in the literature for lower-excitation transitions. We find that the lensing magnification of a given source can vary by 20%-50% across the line profile, between the continuum and line, and between different CO transitions. We apply Large Velocity Gradient modeling using apparent and intrinsic line ratios between lower-J and high-J CO lines. Ignoring these magnification variations can bias the estimate of physical properties of interstellar medium of the galaxies. The magnitude of the bias varies from galaxy to galaxy and is not necessarily predictable without high-resolution observations.
Abstract
In this first paper in a series, we present 1298 low-redshift (z ≲ 0.2) optical spectra of 582 Type Ia supernovae (SNe Ia) observed from 1989 to 2008 as part of the Berkeley Supernova Ia ...Program (BSNIP). 584 spectra of 199 SNe Ia have well-calibrated light curves with measured distance moduli, and many of the spectra have been corrected for host-galaxy contamination. Most of the data were obtained using the Kast double spectrograph mounted on the Shane 3 m telescope at Lick Observatory and have a typical wavelength range of 3300-10 400 Å, roughly twice as wide as spectra from most previously published data sets. We present our observing and reduction procedures, and we describe the resulting SN Database, which will be an online, public, searchable data base containing all of our fully reduced spectra and companion photometry. In addition, we discuss our spectral classification scheme (using the SuperNova IDentification code, snid; Blondin & Tonry), utilizing our newly constructed set of snid spectral templates. These templates allow us to accurately classify our entire data set, and by doing so we are able to reclassify a handful of objects as bona fide SNe Ia and a few other objects as members of some of the peculiar SN Ia subtypes. In fact, our data set includes spectra of nearly 90 spectroscopically peculiar SNe Ia. We also present spectroscopic host-galaxy redshifts of some SNe Ia where these values were previously unknown. The sheer size of the BSNIP data set and the consistency of our observation and reduction methods make this sample unique among all other published SN Ia data sets and complementary in many ways to the large, low-redshift SN Ia spectra presented by Matheson et al. and Blondin et al. In other BSNIP papers in this series, we use these data to examine the relationships between spectroscopic characteristics and various observables such as photometric and host-galaxy properties.
Abstract
With Σ
SFR
∼ 4200
M
⊙
yr
−1
kpc
−2
, SPT 0346–52 (
z
= 5.7) is the most intensely star-forming galaxy discovered by the South Pole Telescope. In this paper, we expand on previous spatially ...resolved studies, using ALMA observations of dust continuum, N
ii
205
μ
m, C
ii
158
μ
m, O
i
146
μ
m, and undetected N
ii
122
μ
m and O
i
63
μ
m emission to study the multiphase interstellar medium (ISM) in SPT 0346–52. We use pixelated, visibility-based lens modeling to reconstruct the source-plane emission. We also model the source-plane emission using the photoionization code
cloudy
and find a supersolar metallicity system. We calculate
T
dust
= 48.3 K and
λ
peak
= 80
μ
m and see line deficits in all five lines. The ionized gas is less dense than comparable galaxies, with
n
e
< 32 cm
−3
, while ∼20% of the C
ii
158
μ
m emission originates from the ionized phase of the ISM. We also calculate the masses of several phases of the ISM. We find that molecular gas dominates the mass of the ISM in SPT 0346–52, with the molecular gas mass ∼4× higher than the neutral atomic gas mass and ∼100× higher than the ionized gas mass.
Franz Zwicky first discovered “Dunkle Materie,” or “Dark Matter” over 100 years ago, when he realized galaxy clusters must consist predominately of non-luminous matter. Since then, mounting evidence, ...has shown that a paltry 4% of the energy density of the universe is baryonic matter. We realize that the energy density of the universe is, in fact, dominated by dark matter and dark energy. Despite the evidence for dark matter, there is a long-standing discrepancy in the interpretation of results from direct dark matter experiments. The Italian DArk MAtter project (DAMA) claims to have discovered WIMPs, a particular variety of dark matter, since 1999. However, other direct detection experiments, provide results that directly contradict DAMA’s claims. For years, the dark matter community has worked to reconcile the two opposing sets of results through improved experiments in direct detection and alternative Dark Matter models. This thesis outlines the Modulation Experiment, which is designed to identify and determine possible systematic sources of error that could explain the annually modulating signal attributed to Dark Matter by DAMA. We present a dedicated experiment for the long-term measurement of gamma emissions resulting from beta decays that provides high-quality data and allows for the identification of systematic influences. Up to 16 sources are monitored redundantly by 32 3×3” NaI(Tl) detectors in four separate setups across three continents. In each setup, monitoring of environmental and operational conditions facilitates correlation studies. The deadtime-free performance of the data acquisition system is confirmed and monitored by LED pulsers. Waveforms of all events are recorded individually, enabling a study of time-dependent effects spanning microseconds to years, using both time-binned and unbinned analyses. In this thesis, we show that the experiment is successfully acquiring data, and environmental effects are well-understood. Because of the experimental design, the Modulation Experiment is particularly well-suited to monitor decay rates of various isotopes. Though decay rates are generally considered to be Poisson processes, standards offices such as the National Institute of Standards (NIST) and Physikalisch-Technische Bundesanstalt (PTB) have reported annually modulating rates due to an unknown influence. Some scientists hypothesize that these effects may be due to a solar neutrino influence. Furthermore, some scientists have also examined a potential link from solar effects (e.g. flares and storms) to discrepancies in decay rate. However, these effects may simply be the by-products of some seasonal effects. This thesis explores the reported claims of decay rate modulation, and limits annual modulation amplitudes to < 5.95×10-5 for Ti-44, 1.46×10-4 for Co-60, and 1.8×10-4 Cs-137 at a 3σ confidence level. No additional periodicities were found to be statistically significant. The Modulation experiment is beginning to explore the true nature of the impact of systematic effects on the measured decay rate. As data continues to be collected and more setups come online, we will be able to lower statistical uncertainties on measurements the half life, measure or set further limits on time-dependent modulations and search for correlations between locations.
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