Abstract
We present an ALMA 1.3 mm (Band 6) continuum survey of lensed submillimeter galaxies (SMGs) at
z
= 1.0 to ∼3.2 with an angular resolution of ∼0.″2. These galaxies were uncovered by the ...Herschel Lensing Survey and feature exceptionally bright far-infrared continuum emission (
S
peak
≳ 90 mJy) owing to their lensing magnification. We detect 29 sources in 20 fields of massive galaxy clusters with ALMA. Using both the Spitzer/IRAC (3.6/4.5
μ
m) and ALMA data, we have successfully modeled the surface brightness profiles of 26 sources in the rest-frame near- and far-infrared. Similar to previous studies, we find the median dust-to-stellar continuum size ratio to be small (
R
e,dust
/
R
e,star
= 0.38 ± 0.14) for the observed SMGs, indicating that star formation is centrally concentrated. This is, however, not the case for two spatially extended main-sequence SMGs with a low surface brightness at 1.3 mm (≲0.1 mJy arcsec
−2
), in which the star formation is distributed over the entire galaxy (
R
e,dust
/
R
e,star
> 1). As a whole, our SMG sample shows a tight anticorrelation between (
R
e,dust
/
R
e,star
) and far-infrared surface brightness (Σ
IR
) over a factor of ≃1000 in Σ
IR
. This indicates that SMGs with less vigorous star formation (i.e., lower Σ
IR
) lack central starburst and are likely to retain a broader spatial distribution of star formation over the whole galaxies (i.e., larger
R
e,dust
/
R
e,star
). The same trend can be reproduced with cosmological simulations as a result of central starburst and potentially subsequent “inside-out” quenching, which likely accounts for the emergence of compact quiescent galaxies at
z
∼ 2.
Abstract
We present an ALMA-Herschel joint analysis of sources detected by the ALMA Lensing Cluster Survey (ALCS) at 1.15 mm. Herschel/PACS and SPIRE data at 100–500
μ
m are deblended for 180 ALMA ...sources in 33 lensing cluster fields that are detected either securely (141 sources; in our main sample) or tentatively at S/N ≥ 4 with cross-matched HST/Spitzer counterparts, down to a delensed 1.15 mm flux density of ∼0.02 mJy. We performed far-infrared spectral energy distribution modeling and derived the physical properties of dusty star formation for 125 sources (109 independently) that are detected at >2
σ
in at least one Herschel band. A total of 27 secure ALCS sources are not detected in any Herschel bands, including 17 optical/near-IR-dark sources that likely reside at
z
= 4.2 ± 1.2. The 16th, 50th, and 84th percentiles of the redshift distribution are 1.15, 2.08, and 3.59, respectively, for ALCS sources in the main sample, suggesting an increasing fraction of
z
≃ 1 − 2 galaxies among fainter millimeter sources (
f
1150
∼ 0.1 mJy). With a median lensing magnification factor of
μ
=
2.6
−
0.8
+
2.6
, ALCS sources in the main sample exhibit a median intrinsic star formation rate of
94
−
54
+
84
M
⊙
yr
−1
, lower than that of conventional submillimeter galaxies at similar redshifts by a factor of ∼3. Our study suggests weak or no redshift evolution of dust temperature with
L
IR
< 10
12
L
⊙
galaxies within our sample at
z
≃ 0 − 2. At
L
IR
> 10
12
L
⊙
, the dust temperatures show no evolution across
z
≃ 1–4 while being lower than those in the local universe. For the highest-redshift source in our sample (
z
= 6.07), we can rule out an extreme dust temperature (>80 K) that was reported for MACS0416 Y1 at
z
= 8.31.
We present the Magellan/FIRE detection of highly ionized C ivλ1550 and O iiiλ1666 in a deep infrared spectrum of the z = 6.11 gravitationally lensed low-mass galaxy RXC J2248.7-4431-ID3, which has ...previously known Ly . No corresponding emission is detected at the expected location of He iiλ1640. The upper limit on He ii, paired with detection of O iii and C iv, constrains possible ionization scenarios. Production of C iv and O iii requires ionizing photons of 2.5-3.5 Ryd, but once in that state their multiplet emission is powered by collisional excitation at lower energies (∼0.5 Ryd). As a pure recombination line, He ii emission is powered by 4 Ryd ionizing photons. The data therefore require a spectrum with significant power at 3.5 Ryd but a rapid drop toward 4.0 Ryd. This hard spectrum with a steep drop is characteristic of low-metallicity stellar populations, and less consistent with soft AGN excitation, which features more 4 Ryd photons and hence higher He ii flux. The conclusions based on ratios of metal line detections to helium non-detection are strengthened if the gas metallicity is low. RXJ2248-ID3 adds to the growing handful of reionization-era galaxies with UV emission line ratios distinct from the general population in a way that suggests hard ionizing spectra that do not necessarily originate in AGNs.
Abstract
We present a Spitzer/IRAC survey of
H
-faint (
H
160
≳ 26.4, < 5
σ
) sources in 101 lensing cluster fields. Across a CANDELS/Wide-like survey area of ∼648 arcmin
2
(effectively ∼221 arcmin
2
...in the source plane), we have securely discovered 53 sources in the IRAC Channel-2 band (CH2, 4.5
μ
m; median CH2 = 22.46 ± 0.11 AB mag) that lack robust HST/WFC3-IR F160W counterparts. The most remarkable source in our sample, namely ES-009 in the field of Abell 2813, is the brightest
H
-faint galaxy at 4.5
μ
m known so far (CH2 = 20.48 ± 0.03 AB mag). We show that the
H
-faint sources in our sample are massive (median
M
star
= 10
10.3±0.3
M
⊙
), star-forming (median star formation rate
=
100
−
40
+
60
M
⊙
yr
−1
), and dust-obscured (
A
V
= 2.6 ± 0.3) galaxies around a median photometric redshift of
z
= 3.9 ± 0.4. The stellar continua of 14
H
-faint galaxies can be resolved in the CH2 band, suggesting a median circularized effective radius (
R
e,circ
; lensing corrected) of 1.9 ± 0.2 kpc and <1.5 kpc for the resolved and whole samples, respectively. This is consistent with the sizes of massive unobscured galaxies at
z
∼ 4, indicating that
H
-faint galaxies represent the dusty tail of the distribution of a wider galaxy population. Comparing with the ALMA dust continuum sizes of similar galaxies reported previously, we conclude that the heavy dust obscuration in
H
-faint galaxies is related to the compactness of both stellar and dust continua (
R
e,circ
∼ 1 kpc). These
H
-faint galaxies make up
16
−
7
+
13
% of the galaxies in the stellar-mass range of 10
10
− 10
11.2
M
⊙
at
z
= 3 ∼ 5, contributing to
8
−
4
+
8
% of the cosmic star formation rate density in this epoch and likely tracing the early phase of massive galaxy formation.
ABSTRACT
We present initial results from the Cosmic Ultraviolet Baryon Survey (CUBS). CUBS is designed to map diffuse baryonic structures at redshift z ≲ 1 using absorption-line spectroscopy of 15 ...UV-bright QSOs with matching deep galaxy survey data. CUBS QSOs are selected based on their NUV brightness to avoid biases against the presence of intervening Lyman limit systems (LLSs) at zabs < 1. We report five new LLSs of $\log \, N({\mathrm{ H} \,{\small I}})/{{\rm cm^{-2}}}\gtrsim 17.2$ over a total redshift survey path-length of $\Delta \, z_{\mathrm{ LL}}=9.3$, and a number density of $n(z)=0.43_{-0.18}^{+0.26}$. Considering all absorbers with $\log \, N({{\mathrm{ H} \,{\small I}}})/{{\rm cm^{-2}}}\gt 16.5$ leads to $n(z)=1.08_{-0.25}^{+0.31}$ at zabs < 1. All LLSs exhibit a multicomponent structure and associated metal transitions from multiple ionization states such as C ii, C iii, Mg ii, Si ii, Si iii, and O vi absorption. Differential chemical enrichment levels as well as ionization states are directly observed across individual components in three LLSs. We present deep galaxy survey data obtained using the VLT-MUSE integral field spectrograph and the Magellan Telescopes, reaching sensitivities necessary for detecting galaxies fainter than $0.1\, L_*$ at d ≲ 300 physical kpc (pkpc) in all five fields. A diverse range of galaxy properties is seen around these LLSs, from a low-mass dwarf galaxy pair, a co-rotating gaseous halo/disc, a star-forming galaxy, a massive quiescent galaxy, to a galaxy group. The closest galaxies have projected distances ranging from d = 15 to 72 pkpc and intrinsic luminosities from ${\approx} 0.01\, L_*$ to ${\approx} 3\, L_*$. Our study shows that LLSs originate in a variety of galaxy environments and trace gaseous structures with a broad range of metallicities.
Abstract
We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of six radio-loud quasar host galaxies at
z
= 1.4–2.3. We combine the kiloparsec-scale resolution ALMA ...observations with high spatial resolution adaptive optics integral field spectrograph data of the ionized gas. We detect molecular gas emission in five quasar host galaxies and resolve the molecular interstellar medium using the CO (3–2) or CO (4–3) rotational transitions. Clumpy molecular outflows are detected in four quasar host galaxies and a merger system 21 kpc away from one quasar. Between the ionized and cold molecular gas phases, the majority of the outflowing mass is in a molecular phase, while for three out of four detected multiphase gas outflows, the majority of the kinetic luminosity and momentum flux is in the ionized phase. Combining the energetics of the multiphase outflows, we find that their driving mechanism is consistent with energy-conserving shocks produced by the impact of the quasar jets with the gas in the galaxy. By assessing the molecular gas mass to the dynamics of the outflows, we estimate a molecular gas depletion timescale of a few megayears. The gas outflow rates exceed the star formation rates, suggesting that quasar feedback is a major mechanism of gas depletion at the present time. The coupling efficiency between the kinetic luminosity of the outflows and the bolometric luminosity of the quasar of 0.1%–1% is consistent with theoretical predictions. Studying multiphase gas outflows at high redshift is important for quantifying the impact of negative feedback in shaping the evolution of massive galaxies.
Abstract
We report the discovery of giant (50−100 kpc) O
ii
emitting nebulae with MUSE in the field of TXS 0206−048, a luminous quasar at
z
= 1.13. “Down-the-barrel” UV spectra of the quasar show ...absorption at velocities coincident with those of the extended nebulae, enabling new insights into inflows and outflows around the quasar host. One nebula exhibits a filamentary morphology extending over 120 kpc from the halo toward the quasar and intersecting with another nebula surrounding the quasar host with a radius of 50 kpc. This is the longest cool filament observed to date and arises at higher redshift and in a less massive system than those in cool-core clusters. The filamentary nebula has line-of-sight velocities >300 km s
−1
from nearby galaxies but matches that of the nebula surrounding the quasar host where they intersect, consistent with accretion of cool intergalactic or circumgalactic medium or cooling hot halo gas. The kinematics of the nebulae surrounding the quasar host are unusual and complex, with redshifted and blueshifted spiral-like structures. The emission velocities at 5−10 kpc from the quasar match those of inflowing absorbing gas observed in UV spectra of the quasar. Together, the extended nebulae and associated redshifted absorption represent a compelling case of cool, filamentary gas accretion from halo scales into the extended interstellar medium and toward the nucleus of a massive quasar host. The inflow rate implied by the combined emission and absorption constraints is well below levels required to sustain the quasar’s radiative luminosity, suggesting anisotropic or variable accretion.
ABSTRACT
We present a systematic investigation of physical conditions and elemental abundances in four optically thick Lyman-limit systems (LLSs) at z = 0.36–0.6 discovered within the Cosmic ...Ultraviolet Baryon Survey (CUBS). Because intervening LLSs at z < 1 suppress far-UV (ultraviolet) light from background QSOs, an unbiased search of these absorbers requires a near-UV-selected QSO sample, as achieved by CUBS. CUBS LLSs exhibit multicomponent kinematic structure and a complex mix of multiphase gas, with associated metal transitions from multiple ionization states such as C ii, C iii, N iii, Mg ii, Si ii, Si iii, O ii, O iii, O vi, and Fe ii absorption that span several hundred km s−1 in line-of-sight velocity. Specifically, higher column density components (log N(H i)/cm−2≳ 16) in all four absorbers comprise dynamically cool gas with $\langle T \rangle =(2\pm 1) \times 10^4\,$K and modest non-thermal broadening of $\langle b_\mathrm{nt} \rangle =5\pm 3\,$km s−1. The high quality of the QSO absorption spectra allows us to infer the physical conditions of the gas, using a detailed ionization modelling that takes into account the resolved component structures of H i and metal transitions. The range of inferred gas densities indicates that these absorbers consist of spatially compact clouds with a median line-of-sight thickness of $160^{+140}_{-50}$ pc. While obtaining robust metallicity constraints for the low density, highly ionized phase remains challenging due to the uncertain $N\mathrm{(H\, {\small I})}$, we demonstrate that the cool-phase gas in LLSs has a median metallicity of $\mathrm{\alpha /H_{1/2}}=-0.7^{+0.1}_{-0.2}$, with a 16–84 percentile range of α/H = (−1.3, −0.1). Furthermore, the wide range of inferred elemental abundance ratios (C/α, N/α, and Fe/α) indicate a diversity of chemical enrichment histories. Combining the absorption data with deep galaxy survey data characterizing the galaxy environment of these absorbers, we discuss the physical connection between star-forming regions in galaxies and diffuse gas associated with optically thick absorption systems in the z < 1 circumgalactic medium.
The relationship between galaxies and the state/chemical enrichment of the warm-hot intergalactic medium (WHIM) expected to dominate the baryon budget at low-z provides sensitive constraints on ...structure formation and galaxy evolution models. We present a deep redshift survey in the field of 1ES1553+113, a blazar with a unique combination of ultraviolet (UV)+X-ray spectra for surveys of the circumgalactic/intergalactic medium (CGM/IGM). Nicastro et al. reported the detection of two O vii WHIM absorbers at z = 0.4339 and 0.3551 in its spectrum, suggesting that the WHIM is metal rich and sufficient to close the missing baryons problem. Our survey indicates that the blazar is a member of a z = 0.433 group and that the higher-z O vii candidate arises from its intragroup medium. The resulting bias precludes its use in baryon censuses. The z = 0.3551 candidate occurs in an isolated environment 630 kpc from the nearest galaxy (with stellar mass ), which we show is unexpected for the WHIM. Finally, we characterize the galactic environments of broad H i Ly absorbers (Doppler widths of b = 40-80 km s−1; T 4 × 105 K) that provide metallicity-independent WHIM probes. On average, broad Ly absorbers are 2× closer to the nearest luminous (L > 0.25L*) galaxy (700 kpc) than narrow (b < 30 km s−1; T 4 × 105 K) ones (1300 kpc) but 2× further than O vi absorbers (350 kpc). These observations suggest that gravitational collapse heats portions of the IGM to form the WHIM, but with feedback that does not enrich the IGM far beyond galaxy/group halos to levels currently observable in UV/X-ray metal lines.
Pathology in Practice Armwood, Abigail R; Mayer, Jörg; Walth, Gregory B ...
Journal of the American Veterinary Medical Association,
04/2022, Letnik:
260, Številka:
10
Journal Article
PDF
