Management of infrarenal abdominal aortic aneurysm by open repair versus endovascular repair

Abdominal aortic aneurysms (AAA) are a pathological dilation of the aorta greater than 2.5cm and affect more than 4% of the male population and 1% of women aged 60 years or older. Screening is recommended among men and women older than age 65, and is covered by Medicare for patients with a family history and men with a history of smoking. Due to its asymptomatic nature, AAA is usually found incidentally during another radiological investigation. Many factors are associated with AAA development, but it is most commonly found in conjunction with atherosclerosis. There is currently no pharmacological intervention specifically for AAA, though statin therapy has shown some promise. The aneurysm will invariably grow, with an average rate of expansion of less than 0.5cm per year. As the aneurysm grows larger the chance of the rupture increases significantly with this outcome carrying an extremely high rate of mortality. Surgical intervention is recommended once the diameter reaches 5.5cm in men or about 5cm in women. There are two approaches to the repair of the aorta: the open surgical approach and the endovascular approach. The open surgical procedure replaces the affected portion of the aorta with a graft. The endovascular procedure places an endograft within the intact aneurysm, effectively excluding the affected section of vessel. The endovascular method carries a lower perioperative mortality rate than the open procedure, but over time can require additional surgeries to prevent continued aneurysm expansion due to blood flow in the aneurysm sac. Additionally, lifetime surveillance of the endograft is required to monitor its integrity and effectiveness. Lifestyle changes and possible pharmacological interventions in patients with AAA should focus on cardiovascular health changes to improve overall health and minimize risk factors for continued development of the aneurysm. In patients who will require repair particular attention should be paid to individual risks and preferences. The open repair procedure may be preferable in patients with better overall health and a longer life expectancy, while endovascular repair may be beneficial for more elderly or frail patients. Research and technology in this area are developing quickly, particularly for endovascular procedures, and the near future may see important changes in the risk-benefit analysis of AAA surgical interventions

Unveiling the Primary Quenching Mechanisms in Galaxies through Large Spectroscopic Surveys

Star-forming galaxies can be transformed into passive systems through a multitude of mechanisms that quench star formation, such as the halting of cold gas accretion (known as starvation) and the rapid removal of gas in AGN-driven winds. However, it remains unclear which mechanism is the most significant, primary driver of the star-forming–passive bimodality. Leveraging on the statistical power of the Sloan Digital Sky Survey, we have investigated how galaxy quenching depends on both the internal properties of galaxies (i.e. stellar mass) and external factors (i.e. environment), how galaxy quenching has evolved across cosmic time and how quenching operates within galaxies. Building upon an innovative technique for assessing the relative impact of different quenching mechanisms through comparisons of the levels of chemical enrichment in star-forming, green valley and passive galaxies, we have analysed the chemical properties of tens of thousands of galaxies in the local Universe to unveil the primary quenching mechanisms in galaxies. We find that the significant difference in stellar metallicity between passive galaxies and their star-forming progenitors implies that for galaxies at all masses, quenching must have involved an extended phase of starvation. In order to best match the observed properties of local passive galaxies, some form of gas ejection has to be introduced in our models, with outflows becoming increasingly more important with decreasing stellar mass. Through an analysis of the local population of green valley galaxies, we find that quenching operates more slowly in the local Universe than at high redshift. By separating star-forming, green valley and passive galaxies, we further find that the environment leaves a much weaker imprint on the stellar populations of galaxies than was previously thought. Satellite galaxies are only marginally more metal-rich and older than central galaxies of the same stellar mass, with stellar metallicities that show only a weak dependence on halo mass, local overdensity and projected distance from their central. Finally, we find, using integral field spectroscopy from the SDSS-IV MaNGA galaxy survey, that passive galaxies are substantially more metal-rich than star-forming galaxies at all radii, with the stellar metallicity difference decreasing with increasing radial distance. Therefore, starvation is a primary driver of quenching at all radii in galaxies, playing a prominent role in quenching the central regions of galaxies, but playing an increasingly less important role in quenching their outskirts

Adding Value to JWST Spectra and Photometry: Stellar Population and Star Formation Properties of Spectroscopically Confirmed JADES and CEERS Galaxies at z>7z > 7

In this paper, we discuss measurements of the stellar population and star forming properties for 43 spectroscopically confirmed publicly available high-redshift $z > 7$ JWST galaxies in the JADES and CEERS observational programs. We carry out a thorough study investigating the relationship between spectroscopic features and photometrically derived ones, including from spectral energy distribution (SED) fitting of models, as well as morphological and structural properties. We find that the star formation rates (SFRs) measured from H$\beta$ line emission are higher than those estimated from Bayesian SED fitting and UV luminosity, with ratios SFR$_{H\beta}$/ SFR$_{UV}$ ranging from 2~13. This is a sign that the star formation history is consistently rising given the timescales of H$\beta$ vs UV star formation probes. In addition, we investigate how well equivalent widths (EWs) of H$\beta$ $\lambda$4861, [O III] $\lambda$4959, and [O III] $\lambda$5007 can be measured from photometry, finding that on average the EW derived from photometric excesses in filters is 30% smaller than the direct spectroscopic measurement. We also discover that a stack of the line emitting galaxies shows a distinct morphology after subtracting imaging that contains only the continuum. This gives us a first view of the line or ionized gas emission from $z > 7$ galaxies, demonstrating that this material has a similar distribution, statistically, as the continuum. We also compare the derived SFRs and stellar masses for both parametric and non-parametric star formation histories, where we find that 35% of our sample formed at least 30% of their stellar mass in recent (< 10 Myr) starburst events.Comment: 17 Pages, 13 Figures, 4 Tables, submitted to MNRA

EPOCHS VIII. An Insight into MIRI-selected Galaxies in SMACS-0723 and the Benefits of Deep MIRI Photometry in Revealing AGN and the Dusty Universe

We present the analysis of the stellar population and star formation history of 181 MIRI selected galaxies at redshift 0-3.5 in the massive galaxy cluster field SMACS J0723.3-7327, commonly referred to as SMACS0723, using the James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI). We combine the data with the JWST Near Infrared Camera (NIRCam) catalogue, in conjunction with the Hubble Space Telescope (HST) WFC3/IR and ACS imaging. We find that the MIRI bands capture PAH features and dust emission, significantly enhancing the accuracy of photometric redshift and measurements of the physical properties of these galaxies. The median photo-z's of galaxies with MIRI data are found to have a small 0.1% difference from spectroscopic redshifts and reducing the error by 20 percent. With MIRI data included in SED fits, we find that the measured stellar masses are unchanged, while the star formation rate is systematically lower by 0.1 dex. We also fit the median SED of active galactic nuclei (AGN) and star forming galaxies (SFG) separately. MIRI data provides tighter constraints on the AGN contribution, reducing the typical AGN contributions by ~14 percent. In addition, we also compare the median SED obtained with and without MIRI, and we find that including MIRI data yields steeper optical and UV slopes, indicating bluer colours, lower dust attenuation, and younger stellar populations. In the future, MIRI/MRS will enhance our understanding by providing more detailed spectral information and allowing for the study of specific emission features and diagnostics associated with AGN.Comment: 15 pages, 14 figures and 1 table, submitted to MNRA

The black hole mass metallicity relation and insights into galaxy quenching

One of the most important questions in astrophysics is what causes galaxies to stop forming stars. Previous studies have shown a tight link between quiescence and black hole mass. Other studies have revealed that quiescence is also associated with 'starvation', the halting of gas inflows, which results in the remaining gas being used up rapidly by star formation and in rapid chemical enrichment. In this work we find the final missing link between these two findings. Using a large sample of galaxies, we uncover the intrinsic dependencies of the stellar metallicity on galaxy properties. In the case of the star-forming galaxies, the stellar metallicity is driven by stellar mass. However, for passive galaxies the stellar metallicity is primarily driven by the black hole mass, as traced by velocity dispersion. This result finally reveals the connection between previous studies, where the integrated effect of black hole feedback prevents gas inflows, starving the galaxy, which is seen by the rapid increase in the stellar metallicity, leading to the galaxy becoming passive.Comment: 20 pages, 6 figures, submitted to Nature Astronom

The JWST Hubble Sequence: The Rest-frame Optical Evolution of Galaxy Structure at 1.5 < z < 6.5

© 2023. The Author(s). Published by the American Astronomical Society. This is an open access article distributed under the Creative Commons Attribution License, to view a copy of the license, see: https://creativecommons.org/licenses/by/4.0/We present results on the morphological and structural evolution of a total of 3956 galaxies observed with JWST at 1.5 109 M ⊙ at z > 3 are not dominated by irregular and peculiar structures, either visually or quantitatively, as previously thought. We find a strong dominance of morphologically selected disk galaxies up to z = 6 in this mass range. We also find that the stellar mass and star formation rate densities are dominated by disk galaxies up to z ∼ 6, demonstrating that most stars in the Universe were likely formed in a disk galaxy. We compare our results to theory to show that the fraction of types we find is predicted by cosmological simulations, and that the Hubble Sequence was already in place as early as one billion years after the Big Bang. Additionally, we make our visual classifications public for the community.Peer reviewe

Seeing sharper and deeper: JWST's first glimpse of the photometric and spectroscopic properties of galaxies in the epoch of reionisation

We analyse the photometric and spectroscopic properties of four galaxies in the epoch of reionisation (EoR) within the SMACS 0723 JWST Early Release Observations field. Given the known spectroscopic redshifts of these sources, we investigated the accuracy with which photometric redshifts can be derived using NIRCam photometry alone, finding that F115W imaging is essential to distinguish between z~8 galaxies with high equivalent width (EW) [O III] {\lambda}5007 emission and z~10 Balmer break galaxies. We find that all four sources exhibit strong (> 0.6 mag) F356W-F444W colours, which sit at the extreme end of theoretical predictions from numerical simulations. We find that these galaxies deviate (by roughly 0.5 dex) from the local correlation between [O III] {\lambda}5007/H\beta and [Ne III] {\lambda}3869/[O II], which is consistent with the predictions from simulations of high-redshift galaxies. We measure the [O III] {\lambda}5007 rest-frame equivalent widths both directly from the spectroscopy, and indirectly as inferred from the strong F356W-F444W colours, finding large [O III] {\lambda}5007 EWs of 400-1000 {\AA}. The [O III] {\lambda}5007 and H\beta EWs are consistent with those seen in extreme, intensely star-forming dwarf galaxies in the local Universe. Our structural analysis indicates that these galaxies are resolved, exhibiting irregular shapes with bright clumps and colour gradients. In line with the predictions from the FLARES hydrodynamic simulations, such intense star formation and extreme nebular conditions are likely the norm, rather than the exception, in the EoR. Finally, although star-forming galaxies and AGN often occupy similar regions within the [O III] {\lambda}5007/H\beta-[O II]/H{\delta} plane, we find that AGN exhibit distinct, red colours in the F150W-F200W, F200W-F277W plane.Comment: 14 pages, 8 figure