Abstract
We present our determination of the baryon budget for an X-ray-selected XXL sample of 136 galaxy groups and clusters spanning nearly two orders of magnitude in mass (M500 ∼ 1013–1015 M⊙) and ...the redshift range 0 ≲ z ≲ 1. Our joint analysis is based on the combination of Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) weak-lensing mass measurements, XXL X-ray gas mass measurements, and HSC and Sloan Digital Sky Survey multiband photometry. We carry out a Bayesian analysis of multivariate mass-scaling relations of gas mass, galaxy stellar mass, stellar mass of brightest cluster galaxies (BCGs), and soft-band X-ray luminosity, by taking into account the intrinsic covariance between cluster properties, selection effect, weak-lensing mass calibration, and observational error covariance matrix. The mass-dependent slope of the gas mass–total mass (M500) relation is found to be $1.29_{-0.10}^{+0.16}$, which is steeper than the self-similar prediction of unity, whereas the slope of the stellar mass–total mass relation is shallower than unity; $0.85_{-0.09}^{+0.12}$. The BCG stellar mass weakly depends on cluster mass with a slope of $0.49_{-0.10}^{+0.11}$. The baryon, gas mass, and stellar mass fractions as a function of M500 agree with the results from numerical simulations and previous observations. We successfully constrain the full intrinsic covariance of the baryonic contents. The BCG stellar mass shows the larger intrinsic scatter at a given halo total mass, followed in order by stellar mass and gas mass. We find a significant positive intrinsic correlation coefficient between total (and satellite) stellar mass and BCG stellar mass and no evidence for intrinsic correlation between gas mass and stellar mass. All the baryonic components show no redshift evolution.
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 report the detection of a massive neutral gas outflow in the
z
= 2.09 gravitationally lensed dusty star-forming galaxy HATLAS J085358.9+015537 (G09v1.40), seen in absorption with the OH
+
...(1
1
−1
0
) transition using spatially resolved (0.″5 × 0.″4) Atacama Large Millimeter/submillimeter Array (ALMA) observations. The blueshifted OH
+
line is observed simultaneously with the CO(9−8) emission line and underlying dust continuum. These data are complemented by high-angular-resolution (0.″17 × 0.″13) ALMA observations of CH
+
(1−0) and underlying dust continuum, and Keck 2.2
μ
m imaging tracing the stellar emission. The neutral outflow, dust, dense molecular gas, and stars all show spatial offsets from each other. The total atomic gas mass of the observed outflow is 6.7 × 10
9
M
⊙
, >25% as massive as the gas mass of the galaxy. We find that a conical outflow geometry best describes the OH
+
kinematics and morphology and derive deprojected outflow properties as functions of possible inclination (0.°38–64°). The neutral gas mass outflow rate is between 83 and 25,400
M
⊙
yr
−1
, exceeding the star formation rate (788 ± 300
M
⊙
yr
−1
) if the inclination is >3.°6 (mass-loading factor = 0.3–4.7). Kinetic energy and momentum fluxes span (4.4–290) × 10
9
L
⊙
and (0.1–3.7) × 10
37
dyne, respectively (energy-loading factor = 0.013–16), indicating that the feedback mechanisms required to drive the outflow depend on the inclination assumed. We derive a gas depletion time between 29 and 1 Myr, but find that the neutral outflow is likely to remain bound to the galaxy unless the inclination is small and may be reaccreted if additional feedback processes do not occur.
We explore the effects of active galactic nuclei (AGNs) and star formation activity on the infrared (0.3-1000 mu m) spectral energy distributions (SEDs) of luminous infrared galaxies from z = 0.5 to ...4.0. A significant portion (~25%) of our sample is dominated by an AGN (>50% of the mid-IR luminosity) in the mid-IR. Based on the mid-IR classification, we divide our full sample into four sub-samples: z ~ 1 star-forming (SF) sources, z ~ 2 SF sources, AGNs with clear 9.7 mu m silicate absorption, and AGNs with featureless mid-IR spectra. We compare our composite SEDs to local templates and find that local templates do not accurately reproduce the mid-IR features and dust temperatures of our high-redshift systems. High-redshift IR luminous galaxies contain significantly more cool dust than their local counterparts. We find that a full suite of photometry spanning the IR peak is necessary to accurately account for the dominant dust temperature components in high-redshift IR luminous galaxies.
Submillimeter galaxies (SMGs) at are luminous in the far-infrared, and have star formation rates, SFR, of hundreds to thousands of solar masses per year. However, it is unclear whether they are true ...analogs of local ULIRGs or whether the mode of their star formation is more similar to that in local disk galaxies. We target these questions by using Herschel-PACS to examine the conditions in the interstellar medium (ISM) in far-infrared luminous SMGs at -4. We present 70-160 m photometry and spectroscopy of the O iv26 m, Fe ii26 m, S iii33 m, Si ii34 m, O iii52 m, N iii57 m, and O i63 m fine-structure lines and the S(0) and S(1) hydrogen rotational lines in 13 lensed SMGs identified by their brightness in early Herschel data. Most of the 13 targets are not individually spectroscopically detected; we instead focus on stacking these spectra with observations of an additional 32 SMGs from the Herschel archive-representing a complete compilation of PACS spectroscopy of SMGs. We detect O i63 m, Si ii34 m, and N iii57 m at in the stacked spectra, determining that the average strengths of these lines relative to the far-IR continuum are , , and , respectively. Using the O iii52 m/N iii57 m emission line ratio, we show that SMGs have average gas-phase metallicities . By using PDR modeling and combining the new spectral measurements with integrated far-infrared fluxes and existing C ii158 m data, we show that SMGs have average gas densities, n, of and FUV field strengths, (in Habing units: ), consistent with both local ULIRGs and lower luminosity star-forming galaxies.
The Herschel-PACS North Ecliptic Pole Survey Pearson, Chris; Barrufet, Laia; Campos Varillas, Maria del Carmen ...
Publications of the Astronomical Society of Japan,
01/2019, Volume:
71, Issue:
1
Journal Article
Peer reviewed
Open access
Abstract
A detailed analysis of Herschel/Photoconductor Array Camera and Spectrometer (PACS) observations at the North Ecliptic Pole is presented. High-quality maps, covering an area of 0.44 deg2, ...are produced and then used to derive potential candidate source lists. A rigorous quality-control pipeline has been used to create final legacy catalogues in the PACS Green 100 μm and Red 160 μm bands, containing 1384 and 630 sources respectively. These catalogues reach to more than twice the depth of the current archival Herschel/PACS Point Source Catalogue, detecting 400 and 270 more sources in the short- and long-wavelength bands, respectively. Galaxy source counts are constructed that extend down to flux densities of 6 mJy and 19 mJy (50% completeness) in the Green 100 μm and Red 160 μm bands, respectively. These source counts are consistent with previously published PACS number counts in other fields across the sky. The source counts are then compared with a galaxy evolution model which identifies a population of luminous infrared galaxies as responsible for the bulk of the galaxy evolution over the flux range (5–100 mJy) spanned by the observed counts, contributing approximate fractions of 50% and 60% to the cosmic infrared background at 100 μm and 160 μm, respectively.
The XXL Survey Farahi, Arya; Guglielmo, Valentina; Evrard, August E. ...
Astronomy & astrophysics,
12/2018, Volume:
620
Journal Article
Peer reviewed
Open access
Context. An X-ray survey with the XMM-Newton telescope, XMM-XXL, has identified hundreds of galaxy groups and clusters in two 25 deg2 fields. Combining spectroscopic and X-ray observations in one ...field, we determine how the kinetic energy of galaxies scales with hot gas temperature and also, by imposing prior constraints on the relative energies of galaxies and dark matter, infer a power-law scaling of total mass with temperature. Aims. Our goals are: i) to determine parameters of the scaling between galaxy velocity dispersion and X-ray temperature, T300 kpc, for the halos hosting XXL-selected clusters, and; ii) to infer the log-mean scaling of total halo mass with temperature, ⟨lnM200 | T300 kpc, z⟩. Methods. We applied an ensemble velocity likelihood to a sample of >1500 spectroscopic redshifts within 132 spectroscopically confirmed clusters with redshifts z < 0.6 to model, ⟨lnσgal | T300 kpc, z⟩, where σgal is the velocity dispersion of XXL cluster member galaxies and T300 kpc is a 300 kpc aperture temperature. To infer total halo mass we used a precise virial relation for massive halos calibrated by N-body simulations along with a single degree of freedom summarising galaxy velocity bias with respect to dark matter. Results. For the XXL-N cluster sample, we find σgal ∝ T300 kpc0.63±0.05 $\sigma_{\textrm{gal}} \propto {{T_{\textrm{300~kpc}}}^{0.63\pm0.05}$ σgal∝T300 kpc0.63±0.05, a slope significantly steeper than the self-similar expectation of 0.5. Assuming scale-independent galaxy velocity bias, we infer a mean logarithmic mass at a given X-ray temperature and redshift, 〈ln(E(z)M200/1014 M⊙)|T300 kpc, z〉 = πT + αT ln (T300 kpc/Tp) + βT ln (E(z)/E(zp)) $\langle \ln (E(z) M_{200}/10^{14} {{\, M_{\odot}}})|{{T_{\textrm{300~kpc}}},z\rangle=\pi_{T}+\alpha_{T}\ln\left({{T_{\textrm{300~kpc}}}/T_{\textrm{p}}\right)+\beta_{T}\ln\left(E(z)/E(z_{\textrm{p}})\right)$ 〈ln(E(z)M200/1014 M⊙)|T300 kpc,z〉=πT+αTln(T300 kpc/Tp)+βTln(E(z)/E(zp)) using pivot values kTp = 2.2 keV and zp = 0.25, with normalization πT = 0.45 ± 0.24 and slope αT = 1.89 ± 0.15. We obtain only weak constraints on redshift evolution, βT = −1.29 ± 1.14. Conclusions. The ratio of specific energies in hot gas and galaxies is scale dependent. Ensemble spectroscopic analysis is a viable method to infer mean scaling relations, particularly for the numerous low mass systems with small numbers of spectroscopic members per system. Galaxy velocity bias is the dominant systematic uncertainty in dynamical mass estimates.
MS 0451.6−0305 is a rich galaxy cluster whose strong lensing is particularly prominent at submm wavelengths. We combine new Submillimetre Common-User Bolometer Array (SCUBA)-2 data with imaging from ...Herschel Spectral and Photometric Imaging Receiver (SPIRE) and PACS and Hubble Space Telescope in order to try to understand the nature of the sources being lensed. In the region of the ‘giant submm arc’, we uncover seven multiply imaged galaxies (up from the previously known four), of which six are found to be at a redshift of z ∼ 2.9, and possibly constitute an interacting system. Using a novel forward-modelling approach, we are able to simultaneously deblend and fit spectral energy distributions to the individual galaxies that contribute to the giant submm arc, constraining their dust temperatures, far-infrared luminosities, and star formation rates (SFRs). The submm arc first identified by SCUBA can now be seen to be composed of at least five distinct sources, four of these within a galaxy group at z ∼ 2.9. Only a handful of lensed galaxy groups at this redshift are expected on the sky, and thus this is a unique opportunity for studying such systems in detail. The total unlensed luminosity for this galaxy group is (3.1 ± 0.3) × 1012 L⊙, which gives an unlensed SFR of (450 ± 50) M⊙ yr−1. This finding suggests that submm source multiplicity, due to physically associated groupings as opposed to chance alignment, extends to fainter flux densities than previously discovered. Many of these systems may also host optical companions undetected in the submm, as is the case here.
AGN dust tori: the X-ray-infrared connection Rowan-Robinson, Michael; Valtchanov, Ivan; Nandra, Kirpal
Monthly Notices of the Royal Astronomical Society,
08/2009, Volume:
397, Issue:
3
Journal Article
Peer reviewed
Open access
We have combined the well-studied CLASXS Chandra survey in Lockman with the Spitzer SWIRE survey data to study the X-ray-infrared connection for active galactic nuclei (AGN). The sample consists of ...401 X-ray-sources, of which 306 are detected by Spitzer, and a further 257 AGN candidates detected through their dust torus, but not by Chandra. We have used spectroscopic redshifts and classifications from the literature, where available, and photometric redshifts for the remainder. For X-ray sources, the X-ray hardness ratio has been modelled in terms of a power law (Γ= 1.9) with absorption N(H). The optical and infrared data have been modelled in terms of our well-established optical galaxy and quasi-stellar object templates, and infrared templates based on radiative transfer models. This type of analysis gives better insight into the infrared spectral energy distributions, and a better separation of the contribution of starbursts and AGN dust tori, than a simple comparison of 24 μm to optical or X-ray fluxes. We also believe this gives more insight than using a library of fixed ultraviolet-infrared templates. Our estimate of the N(H) distribution is consistent with other studies, but we do find a higher proportion of low absorption objects at z < 0.5 than at z > 0.5. While we find only one X-ray AGN with N(H) > 1024 cm−2, we argue that 10 objects with torus luminosity apparently exceeding the bolometric X-ray to 3 μm luminosity are strong candidates for being heavily absorbed in X-rays. We also estimate that at least half of the infrared-detected AGN dust tori, which are undetected in X-rays, are likely to be Compton thick. Our estimate of the total number of Compton-thick objects in the 0.4 deg2 area is ≥130, corresponding to ≥20 per cent of the combined SWIRE-CLASXS sample (and with an upper limit of 39 per cent). We find no evidence for AGN with no dust tori, and none with a covering factor <1 per cent but there are clear examples of AGN with covering factors of only a few percent and these, though rare, do not fit easily with a unified picture for AGN. The range of dust covering factors is 1–100 per cent, with a mean of 40 per cent, that is a Type 2 fraction of 40 per cent. Measured by the ratio of dust torus luminosity to X-ray or (for Type 1 objects) optical luminosity, the covering factor appears to decrease towards intermediate AGN luminosity, in contradiction to estimates based on ratios of narrow-line and broad-line spectra, but may increase again at low AGN luminosity. We find 7–10 candidate X-ray starbursts in the SWIRE-CLASXS sample, with X-ray luminosities ranging up to LXh= 1044 erg s−1. This is a considerable extension of the luminosity range of X-ray starbursts previously reported, but is consistent with the an extrapolation of the X-ray-infrared relation for starbursts into the realm of hyperluminous infrared galaxies.
Learning to denoise astronomical images with U-nets Vojtekova, Antonia; Lieu, Maggie; Valtchanov, Ivan ...
Monthly Notices of the Royal Astronomical Society,
05/2021, Volume:
503, Issue:
3
Journal Article
Peer reviewed
Open access
ABSTRACT
Astronomical images are essential for exploring and understanding the Universe. Optical telescopes capable of deep observations, such as the Hubble Space Telescope (HST), are heavily ...oversubscribed in the Astronomical Community. Images also often contain additive noise, which makes denoising a mandatory step in post-processing the data before further data analysis. In order to maximize the efficiency and information gain in the post-processing of astronomical imaging, we turn to machine learning. We propose Astro U-net, a convolutional neural network for image denoising and enhancement. For a proof-of-concept, we use HST images from Wide Field Camera 3 instrument UV/visible channel with F555W and F606W filters. Our network is able to produce images with noise characteristics as if they are obtained with twice the exposure time, and with minimum bias or information loss. From these images, we are able to recover $95.9{{\ \rm per\ cent}}$ of stars with an average flux error of $2.26{{\ \rm per\ cent}}$. Furthermore, the images have, on average, 1.63 times higher signal-to-noise ratio than the input noisy images, equivalent to the stacking of at least three input images, which means a significant reduction in the telescope time needed for future astronomical imaging campaigns.
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