19 research outputs found
The Fine Line Between Normal and Starburst Galaxies
Recent literature suggests that there are two modes through which galaxies
grow their stellar mass - a normal mode characterized by quasi-steady star
formation, and a highly efficient starburst mode possibly triggered by
stochastic events such as galaxy mergers. While these differences are
established for extreme cases, the population of galaxies in-between these two
regimes is poorly studied and it is not clear where the transition between
these two modes of star formation occurs. We utilize ALMA observations of the
CO J=3-2 line luminosity in a sample of 20 infrared luminous galaxies that lie
in the intermediate range between normal and starburst galaxies at z ~ 0.25-0.6
in the COSMOS field to examine the gas content and star formation efficiency of
these galaxies. We compare these quantities to the galaxies' deviation from the
well-studied "main sequence" correlation between star formation rate and
stellar mass (MS) and find that at log() < 0.6, a galaxy's
distance to the main sequence is mostly driven by increased gas content, and
not a more efficient star formation process.Comment: 21 pages, 10 figure
Feedback factory : multiple faint radio jets detected in a cluster at z=2
We report the detection of multiple faint radio sources, that we identify as active galactic nucleus (AGN) jets, within CLJ1449+0856 at z = 2 using 3 GHz Very Large Array observations. We study the effects of radio-jet-based kinetic feedback at high redshifts, which has been found to be crucial in low-redshift clusters to explain the observed thermodynamic properties of their intracluster medium (ICM). We investigate this interaction at an epoch featuring high levels of AGN activity and a transitional phase of ICM in regards to the likelihood of residual cold gas accretion. We measure a total flux of 30.6 +/- 3.3 mu Jy from the six detected jets. Their power contribution is estimated to be 1.2 (+/- 0.6) x 10(44) erg s(-1), although this value could be up to 4.7 x 10(44) erg s(-1). This is a factor of similar to 0.25-1.0 of the previously estimated instantaneous energy injection into the ICM of CLJ1449+0856 from AGN outflows and star formation that have already been found to be sufficient in globally offsetting the cooling flows in the cluster core. In line with the already detected abundance of star formation, this mode of feedback being distributed over multiple sites, contrary to a single central source observed at low redshifts, points to accretion of gas into the cluster centre. This also suggests a 'steady state' of the cluster featuring non-cool-core-like behaviour. Finally, we also examine the total infrared-radio luminosity ratio for the known sample of galaxies within the cluster core and find that dense environments do not have any serious consequence on the compliance of galaxies to the infrared-radio correlation.Peer reviewe
LEARNING STYLES IN HYBRID EDUCATION PROCESSES
A documentary review was carried out on the production and publication of research papers related to the study of the variables Learning Styles and Hybrid Education. The purpose of the bibliometric analysis proposed in this paper was to know the main characteristics of the volume of publications registered in the Scopus database during the period 2016-2021, achieving the identification of 92 publications. The information provided by the said platform was organized through tables and figures, categorizing the information by Year of Publication, Country of Origin, Area of Knowledge and Type of Publication. Once these characteristics were described, the position of different authors regarding the proposed topic was referenced by applying qualitative analysis. Among the main findings of this research, it is found that the United States, with 26 publications, was the country with the highest scientific production registered in the name of authors affiliated with institutions of that country. The Knowledge Area that made the greatest contribution to the construction of bibliographic material referring to the study of the different learning styles in hybrid education processes was Computer Science with 49 published documents, and the type of publication that was most used during the above-mentioned period was the conference article, which represents 53% of the total scientific production
The IR Compactness of Dusty Galaxies Set Star-formation and Dust Properties at z~0-2
Surface densities of gas, dust and stars provide a window into the physics of
star-formation that, until the advent of high-resolution
far-infrared/sub-millimeter observations, has been historically difficult to
assess amongst dusty galaxies. To study the link between infrared (IR) surface
densities and dust properties, we leverage the Atacama Large
Millimetre/Submillimetre Array (ALMA) archive to measure the extent of cold
dust emission in 15 IR selected galaxies selected on the basis of
having available mid-IR spectroscopy from Spitzer. We use the mid-IR spectra to
constrain the relative balance between dust heating from star-formation and
active galactic nuclei (AGN), and to measure emission from Polycylic Aromatic
Hydrocarbons (PAHs) -- small dust grains that play a key role in the
photoelectric heating of gas. In general, we find that dust-obscured
star-formation at high IR surface densities exhibits similar properties at low-
and high-redshift, namely: local luminous IR galaxies have comparable PAH
luminosity to total dust mass ratios as high- galaxies, and star-formation
at is more efficient at high IR surface densities despite the fact
that our sample of high galaxies are closer to the main-sequence than local
luminous IR galaxies. High star-formation efficiencies are coincident with a
decline in the PAH/IR luminosity ratio reminiscent of the deficit observed in
far-infrared fine-structure lines. Changes in the gas and dust conditions
arising from high star-formation surface densities might help drive the
star-formation efficiency up. This could help explain high efficiencies needed
to reconcile star-formation and gas volume densities in dusty galaxies at
cosmic noon.Comment: 18 pages, 10 figures, accepted to Ap
A galaxy group candidate at z approximate to 3.7 in the COSMOS field
We report a galaxy group candidate HPC1001 at z approximate to 3.7 in the COSMOS field. This structure was selected as a high galaxy overdensity at z > 3 in the COSMOS2020 catalog. It contains ten candidate members, of which eight are assembled in a 10 '' x 10 '' area with the highest sky density among known protoclusters and groups at z > 3. Four out of ten sources were also detected at 1.2mm with Atacama Large Millimeter Array continuum observations. Photometric redshifts, measured by four independent methods, fall within a narrow range of 3.5 < z < 3.9 and with a weighted average of z = 3.65 +/- 0.07. The integrated far-IR-to-radio spectral energy distribution yields a total UV and IR star formation rate SFR approximate to 900 M-circle dot yr(-1). We also estimated a halo mass of similar to 10(13) M-circle dot for the structure, which at this redshift is consistent with potential cold gas inflow. Remarkably, the most massive member has a specific star formation rate and dust to stellar mass ratio of M-dust/M-* that are both significantly lower than that of star-forming galaxies at this redshift, suggesting that HPC1001 could be a z approximate to 3.7 galaxy group in maturing phase. If confirmed, this would be the earliest structure in maturing phase to date, and an ideal laboratory to study the formation of the earliest quiescent galaxies as well as cold gas accretion in dense environments.Non peer reviewe
Size - Stellar Mass Relation and Morphology of Quiescent Galaxies at in Public Fields
We present the results of a systematic study of the rest-frame optical
morphology of quiescent galaxies at using the Near-Infrared Camera
(NIRCam) onboard . Based on a sample selected by color or
color, we focus on 26 quiescent galaxies with
at with publicly
available data. Their sizes are constrained by fitting the S\'ersic
profile to all available NIRCam images. We see a negative correlation between
the observed wavelength and the size in our sample and derive their size at the
rest-frame taking into account this trend. Our quiescent
galaxies show a significant correlation between the rest-frame size and the stellar mass at . The analytical fit for them at
implies that our size - stellar mass relations
are below those at lower redshifts, with the amplitude of
at . This value agrees with the
extrapolation from the size evolution of quiescent galaxies at in the
literature, implying that the size of quiescent galaxies increases
monotonically from . Our sample is mainly composed of galaxies with
bulge-like structures according to their median S\'ersic index and axis ratio
of and , respectively. On the other hand, there is a
trend of increasing fraction of galaxies with low S\'ersic index, suggesting
might be the epoch of onset of morphological transformation with a
fraction of very notable disky quenched galaxies.Comment: 23 pages, 16 figures, 2 tables; submitted to Ap
ALMA 26 Arcmin Survey of GOODS-S at One-millimeter (ASAGAO): Average Morphology of High- Dusty Star-Forming Galaxies is an Exponential-Disk ()
We present morphological properties of dusty star-forming galaxies at z=1-3
determined with high-resolution (FWHM~0"19) Atacama Large
Milllimeter/submilimeter Array (ALMA) 1-mm band maps of our ASAGAO survey
covering a 26-arcmin^2 area in GOODS-S. In conjunction with the ALMA archival
data, the present sample consists of 42 ALMA sources with a wide rest-frame
far-infrared (FIR) luminosity L_FIR range of ~10^11-10^13 Lo. To obtain an
average rest-frame FIR profile, we perform individual measurements and careful
stacking of the ALMA sources using the uv-visibility method that includes
positional-uncertainty and smoothing-effect evaluations through Monte-Carlo
simulations. We find that the dusty star-forming galaxies have the average
FIR-wavelength Sersic index and effective radius of n_FIR=1.2+/-0.2 and
R_e,FIR=1.0-1.3 kpc, respectively, additionally with a point source at the
center, indicative of the existence of AGN. The average FIR profile agrees with
a morphology of an exponential-disk clearly distinguished from a spheroidal
profile (Sersic index of 4). We also examine the rest-frame optical Sersic
index n_opt and effective radius R_e,opt with the deep Hubble Space Telescope
(HST) images. Interestingly, we obtain n_opt=0.9+/-0.3 (~n_FIR) and
R_e,opt=3.2+/-0.6 kpc (>R_e,FIR), suggesting that the FIR-emitting disk is
embedded within a larger stellar disk. The rest-frame UV and FIR data of HST
and ALMA provide us a radial surface density profile of the total
star-formation rate (SFR), where the FIR SFR dominates over the UV SFR at the
center. Under the simple assumption of a constant SFR, a compact stellar
distribution found in z~1-2 compact quiescent galaxies (cQGs) is well
reproduced, while a spheroidal stellar morphology of cQGs (n_opt=4) cannot,
suggestive of other important mechanisms such as dynamical dissipation.Comment: 13 pages, 6 figures, ApJ in pres
Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries
Abstract
Background
Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres.
Methods
This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries.
Results
In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia.
Conclusion
This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries
How primordial magnetic fields shrink galaxies
As one of the prime contributors to the interstellar medium energy budget, magnetic fields naturally play a part in shaping the evolution of galaxies. Galactic magnetic fields can originate from strong primordial magnetic fields provided these latter remain below current observational upper limits. To understand how such magnetic fields would affect the global morphological
and dynamical properties of galaxies, we use a suite of high-resolution constrained transport magnetohydrodynamic cosmological zoom simulations where we vary the initial magnetic field strength and configuration along with the prescription for stellar feedback. We find that
strong primordial magnetic fields delay the onset of star formation and drain the rotational support of the galaxy, diminishing the radial size of the galactic disc and driving a higher amount of gas towards the centre. This is also reflected in mock UVJ observations by an increase in the light profile concentration of the galaxy. We explore the possible mechanisms
behind such a reduction in angular momentum, focusing on magnetic braking. Finally, noticing that the effects of primordial magnetic fields are amplified in the presence of stellar feedback, we briefly discuss whether the changes we measure would also be expected for galactic magnetic fields of non-primordial origin