The ALPINE-ALMA [CII] survey Ginolfi, M; Jones, G C; Béthermin, M ...
Astronomy & astrophysics,
11/2020, Letnik:
643
Journal Article
Recenzirano
Odprti dostop
We present ALMA observations of a merging system at z ∼ 4.57, observed as a part of the ALMA Large Program to INvestigate CII at Early times (ALPINE) survey. Combining ALMA CII158 μm and far-infrared ...continuum data with multi-wavelength ancillary data, we find that the system is composed of two massive (M⋆ ≳ 1010 M⊙) star-forming galaxies experiencing a major merger (stellar mass ratio rmass ≳ 0.9) at close spatial (∼13 kpc; projected) and velocity (Δv < 300 km s−1) separations, and two additional faint narrow CII-emitting satellites. The overall system belongs to a larger scale protocluster environment and is coincident to one of its overdensity peaks. Additionally, ALMA reveals the presence of CII emission arising from a circumgalactic gas structure, extending up to a diameter-scale of ∼30 kpc. Our morpho-spectral decomposition analysis shows that about 50% of the total flux resides between the individual galaxy components, in a metal-enriched gaseous envelope characterised by a disturbed morphology and complex kinematics. Similarly to observations of shock-excited CII emitted from tidal tails in local groups, our results can be interpreted as a possible signature of interstellar gas stripped by strong gravitational interactions, with a possible contribution from material ejected by galactic outflows and emission triggered by star formation in small faint satellites. Our findings suggest that mergers could be an efficient mechanism of gas mixing in the circumgalactic medium around high-z galaxies, and thus play a key role in the galaxy baryon cycle at early epochs.
The ALPINE-ALMA [C II] survey Schaerer, D; Ginolfi, M; Béthermin, M ...
Astronomy and astrophysics (Berlin),
11/2020, Letnik:
643
Journal Article
Recenzirano
Odprti dostop
The C II 158 μm line is one of the strongest IR emission lines, which has been shown to trace the star formation rate (SFR) of galaxies in the nearby Universe, and up to z ∼ 2. Whether this is also ...the case at higher redshift and in the early Universe remains debated. The ALPINE survey, which targeted 118 star-forming galaxies at 4.4 < z < 5.9, provides a new opportunity to examine this question with the first statistical dataset. Using the ALPINE data and earlier measurements from the literature, we examine the relation between the C II luminosity and the SFR over the entire redshift range from z ∼ 4 − 8. ALPINE galaxies, which are both detected in C II and in dust continuum, show good agreement with the local L(CII)–SFR relation. Galaxies undetected in the continuum by ALMA are found to be over-luminous in C II when the UV SFR is used. After accounting for dust-obscured star formation, by an amount of SFR(IR) ≈ SFR(UV) on average, which results from two different stacking methods and SED fitting, the ALPINE galaxies show an L(CII)–SFR relation comparable to the local one. When C II non-detections are taken into account, the slope may be marginally steeper at high-z, although this is still somewhat uncertain. When compared homogeneously, the z > 6 C II measurements (detections and upper limits) do not behave very differently to the z ∼ 4 − 6 data. We find a weak dependence of L(CII)/SFR on the Lyα equivalent width. Finally, we find that the ratio L(CII)/LIR ∼ (1 − 3) × 10−3 for the ALPINE sources, comparable to that of “normal” galaxies at lower redshift. Our analysis, which includes the largest sample (∼150 galaxies) of C II measurements at z > 4 available so far, suggests no or little evolution of the C II–SFR relation over the last 13 Gyr of cosmic time.
The ALPINE-ALMA [CII] survey O. Le Fèvre; Béthermin, M; Faisst, A ...
Astronomy & astrophysics,
11/2020, Letnik:
643
Journal Article
Recenzirano
Odprti dostop
The ALMA-ALPINE CII survey is aimed at characterizing the properties of a sample of normal star-forming galaxies (SFGs). The ALMA Large Program to INvestigate (ALPINE) features 118 galaxies observed ...in the CII-158 μm line and far infrared (FIR) continuum emission during the period of rapid mass assembly, right after the end of the HI reionization, at redshifts of 4 < z < 6. We present the survey science goals, the observational strategy, and the sample selection of the 118 galaxies observed with ALMA, with an average beam minor axis of about 0.85″, or ∼5 kpc at the median redshift of the survey. The properties of the sample are described, including spectroscopic redshifts derived from the UV-rest frame, stellar masses, and star-formation rates obtained from a spectral energy distribution (SED) fitting. The observed properties derived from the ALMA data are presented and discussed in terms of the overall detection rate in CII and FIR continuum, with the observed signal-to-noise distribution. The sample is representative of the SFG population in the main sequence at these redshifts. The overall detection rate in CII is 64% for a signal-to-noise ratio (S/N) threshold larger than 3.5 corresponding to a 95% purity (40% detection rate for S/N > 5). Based on a visual inspection of the CII data cubes together with the large wealth of ancillary data, we find a surprisingly wide range of galaxy types, including 40% that are mergers, 20% extended and dispersion-dominated, 13% compact, and 11% rotating discs, with the remaining 16% too faint to be classified. This diversity indicates that a wide array of physical processes must be at work at this epoch, first and foremost, those of galaxy mergers. This paper sets a reference sample for the gas distribution in normal SFGs at 4 < z < 6, a key epoch in galaxy assembly, which is ideally suited for studies with future facilities, such as the James Webb Space Telescope (JWST) and the Extremely Large Telescopes (ELTs).
Although the properties of most superconducting materials are well described by the theory of Bardeen, Cooper and Schrieffer (BCS), considerable effort has been devoted to the search for exotic ...superconducting systems in which BCS theory does not apply. The transition to the superconducting state in conventional BCS superconductors involves the breaking of gauge symmetry only, whereby the wavefunction describing the Cooper pairs--the paired electron states responsible for superconductivity--adopt a definite phase.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We present the KMOS{sup 3D} survey, a new integral field survey of over 600 galaxies at 0.7 < z < 2.7 using KMOS at the Very Large Telescope. The KMOS{sup 3D} survey utilizes synergies with ...multi-wavelength ground- and space-based surveys to trace the evolution of spatially resolved kinematics and star formation from a homogeneous sample over 5 Gyr of cosmic history. Targets, drawn from a mass-selected parent sample from the 3D-HST survey, cover the star formation-stellar mass (M {sub *}) and rest-frame (U – V) – M {sub *} planes uniformly. We describe the selection of targets, the observations, and the data reduction. In the first-year of data we detect Hα emission in 191 M {sub *} = 3 × 10{sup 9}-7 × 10{sup 11} M {sub ☉} galaxies at z = 0.7-1.1 and z = 1.9-2.7. In the current sample 83% of the resolved galaxies are rotation dominated, determined from a continuous velocity gradient and v {sub rot}/σ{sub 0} > 1, implying that the star-forming ''main sequence'' is primarily composed of rotating galaxies at both redshift regimes. When considering additional stricter criteria, the Hα kinematic maps indicate that at least ∼70% of the resolved galaxies are disk-like systems. Our high-quality KMOS data confirm the elevated velocity dispersions reported in previous integral field spectroscopy studies at z ≳ 0.7. For rotation-dominated disks, the average intrinsic velocity dispersion decreases by a factor of two from 50 km s{sup –1}at z ∼ 2.3 to 25 km s{sup –1}at z ∼ 0.9. Combined with existing results spanning z ∼ 0-3, we show that disk velocity dispersions follow an evolution that is consistent with the dependence of velocity dispersion on gas fractions predicted by marginally stable disk theory.
The ALPINE-ALMA [CII] survey Fudamoto, Y.; Oesch, P. A.; Faisst, A. ...
Astronomy and astrophysics (Berlin),
11/2020, Letnik:
643
Journal Article
Recenzirano
Odprti dostop
We present dust attenuation properties of spectroscopically confirmed star forming galaxies on the main sequence at a redshift of ∼4.4 − 5.8. Our analyses are based on the far infrared continuum ...observations of 118 galaxies at rest-frame 158
μ
m obtained with the Atacama Large Millimeter Array (ALMA) Large Program to INvestigate CII at Early times (ALPINE). We study the connection between the ultraviolet (UV) spectral slope (
β
), stellar mass (
M
⋆
), and infrared excess (IRX =
L
IR
/
L
UV
). Twenty-three galaxies are individually detected in the continuum at > 3.5
σ
significance. We perform a stacking analysis using both detections and nondetections to study the average dust attenuation properties at
z
∼ 4.4 − 5.8. The individual detections and stacks show that the IRX–
β
relation at
z
∼ 5 is consistent with a steeper dust attenuation curve than typically found at lower redshifts (
z
< 4). The attenuation curve is similar to or even steeper than that of the extinction curve of the Small Magellanic Cloud. This systematic change of the IRX–
β
relation as a function of redshift suggests an evolution of dust attenuation properties at
z
> 4. Similarly, we find that our galaxies have lower IRX values, up to 1 dex on average, at a fixed mass compared to previously studied IRX–
M
⋆
relations at
z
≲ 4, albeit with significant scatter. This implies a lower obscured fraction of star formation than at lower redshifts. Our results suggest that dust properties of UV-selected star forming galaxies at
z
≳ 4 are characterised by (i) a steeper attenuation curve than at
z
≲ 4, and (ii) a rapidly decreasing dust obscured fraction of star formation as a function of redshift. Nevertheless, even among this UV-selected sample, massive galaxies (log
M
⋆
/
M
⊙
> 10) at
z
∼ 5 − 6 already exhibit an obscured fraction of star formation of ∼45%, indicating a rapid build-up of dust during the epoch of reionization.
The ALPINE-ALMA [CII] survey Le Fèvre, O.; Béthermin, M.; Faisst, A. ...
Astronomy and astrophysics (Berlin),
11/2020, Letnik:
643
Journal Article
Recenzirano
Odprti dostop
The ALMA-ALPINE CII survey is aimed at characterizing the properties of a sample of normal star-forming galaxies (SFGs). The ALMA Large Program to INvestigate (ALPINE) features 118 galaxies observed ...in the CII-158
μ
m line and far infrared (FIR) continuum emission during the period of rapid mass assembly, right after the end of the HI reionization, at redshifts of 4 <
z
< 6. We present the survey science goals, the observational strategy, and the sample selection of the 118 galaxies observed with ALMA, with an average beam minor axis of about 0.85″, or ∼5 kpc at the median redshift of the survey. The properties of the sample are described, including spectroscopic redshifts derived from the UV-rest frame, stellar masses, and star-formation rates obtained from a spectral energy distribution (SED) fitting. The observed properties derived from the ALMA data are presented and discussed in terms of the overall detection rate in CII and FIR continuum, with the observed signal-to-noise distribution. The sample is representative of the SFG population in the main sequence at these redshifts. The overall detection rate in CII is 64% for a signal-to-noise ratio (S/N) threshold larger than 3.5 corresponding to a 95% purity (40% detection rate for
S
/
N
> 5). Based on a visual inspection of the CII data cubes together with the large wealth of ancillary data, we find a surprisingly wide range of galaxy types, including 40% that are mergers, 20% extended and dispersion-dominated, 13% compact, and 11% rotating discs, with the remaining 16% too faint to be classified. This diversity indicates that a wide array of physical processes must be at work at this epoch, first and foremost, those of galaxy mergers. This paper sets a reference sample for the gas distribution in normal SFGs at 4 <
z
< 6, a key epoch in galaxy assembly, which is ideally suited for studies with future facilities, such as the
James Webb
Space Telescope (JWST) and the Extremely Large Telescopes (ELTs).
The ALPINE-ALMA [C II] survey Schaerer, D.; Ginolfi, M.; Béthermin, M. ...
Astronomy and astrophysics (Berlin),
11/2020, Letnik:
643, Številka:
A3
Journal Article
Recenzirano
Odprti dostop
The C
II
158
μ
m line is one of the strongest IR emission lines, which has been shown to trace the star formation rate (SFR) of galaxies in the nearby Universe, and up to
z
∼ 2. Whether this is ...also the case at higher redshift and in the early Universe remains debated. The ALPINE survey, which targeted 118 star-forming galaxies at 4.4 <
z
< 5.9, provides a new opportunity to examine this question with the first statistical dataset. Using the ALPINE data and earlier measurements from the literature, we examine the relation between the C
II
luminosity and the SFR over the entire redshift range from
z
∼ 4 − 8. ALPINE galaxies, which are both detected in C
II
and in dust continuum, show good agreement with the local
L
(CII)–SFR relation. Galaxies undetected in the continuum by ALMA are found to be over-luminous in C
II
when the UV SFR is used. After accounting for dust-obscured star formation, by an amount of SFR(IR) ≈ SFR(UV) on average, which results from two different stacking methods and SED fitting, the ALPINE galaxies show an
L
(CII)–SFR relation comparable to the local one. When C
II
non-detections are taken into account, the slope may be marginally steeper at high-
z
, although this is still somewhat uncertain. When compared homogeneously, the
z
> 6 C
II
measurements (detections and upper limits) do not behave very differently to the
z
∼ 4 − 6 data. We find a weak dependence of
L
(CII)/SFR on the Ly
α
equivalent width. Finally, we find that the ratio
L
(CII)/
L
IR
∼ (1 − 3) × 10
−3
for the ALPINE sources, comparable to that of “normal” galaxies at lower redshift. Our analysis, which includes the largest sample (∼150 galaxies) of C
II
measurements at
z
> 4 available so far, suggests no or little evolution of the C
II
–SFR relation over the last 13 Gyr of cosmic time.
The ALPINE-ALMA [C II] survey Dessauges-Zavadsky, M.; Ginolfi, M.; Pozzi, F. ...
Astronomy and astrophysics (Berlin),
11/2020, Letnik:
643
Journal Article
Recenzirano
Odprti dostop
The molecular gas content of normal galaxies at z > 4 is poorly constrained because the commonly used molecular gas tracers become hard to detect at these high redshifts. We use the C II 158 μ m ...luminosity, which was recently proposed as a molecular gas tracer, to estimate the molecular gas content in a large sample of main sequence star-forming galaxies at z = 4.4 − 5.9, with a median stellar mass of 10 9.7 M ⊙ , drawn from the ALMA Large Program to INvestigate C II at Early times survey. The agreement between the molecular gas masses derived from C II luminosities, dynamical masses, and rest-frame 850 μ m luminosities extrapolated from the rest-frame 158 μ m continuum supports C II as a reliable tracer of molecular gas in our sample. We find a continuous decline of the molecular gas depletion timescale from z = 0 to z = 5.9, which reaches a mean value of (4.6 ± 0.8) × 10 8 yr at z ∼ 5.5, only a factor of between two and three shorter than in present-day galaxies. This suggests a mild enhancement of the star formation efficiency toward high redshifts. Our estimates also show that the previously reported rise in the molecular gas fraction flattens off above z ∼ 3.7 to achieve a mean value of 63%±3% over z = 4.4 − 5.9. This redshift evolution of the gas fraction is in line with that of the specific star formation rate. We use multi-epoch abundance-matching to follow the gas fraction evolution across cosmic time of progenitors of z = 0 Milky Way-like galaxies in ∼10 13 M ⊙ halos and of more massive z = 0 galaxies in ∼10 14 M ⊙ halos. Interestingly, the former progenitors show a monotonic increase of the gas fraction with redshift, while the latter show a steep rise from z = 0 to z ∼ 2 followed by a constant gas fraction from z ∼ 2 to z = 5.9. We discuss three possible effects, namely outflows, a pause in gas supply, and over-efficient star formation, which may jointly contribute to the gas fraction plateau of the latter massive galaxies.
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