Galaxy Zoo Green Peas: discovery of a class of compact extremely star-forming galaxies

‘The definitive version is available at www3.interscience.wiley.com '. Copyright Royal Astronomical Society. DOI: 10.1111/j.1365-2966.2009.15383.xWe investigate a class of rapidly growing emission line galaxies, known as 'Green Peas', first noted by volunteers in the Galaxy Zoo project because of their peculiar bright green colour and small size, unresolved in Sloan Digital Sky Survey imaging. Their appearance is due to very strong optical emission lines, namely [O iii]λ5007 Å, with an unusually large equivalent width of up to ∼1000 Å. We discuss a well-defined sample of 251 colour-selected objects, most of which are strongly star forming, although there are some active galactic nuclei interlopers including eight newly discovered narrow-line Seyfert 1 galaxies. The star-forming Peas are low-mass galaxies (M∼ 108.5–1010 M⊙) with high star formation rates (∼10 M⊙ yr−1) , low metallicities (log[O/H]+ 12 ∼ 8.7) and low reddening [ E(B−V) ≤ 0.25 ] and they reside in low-density environments. They have some of the highest specific star formation rates (up to ∼10−8 yr−1 ) seen in the local Universe, yielding doubling times for their stellar mass of hundreds of Myr. The few star-forming Peas with Hubble Space Telescope imaging appear to have several clumps of bright star-forming regions and low surface density features that may indicate recent or ongoing mergers. The Peas are similar in size, mass, luminosity and metallicity to luminous blue compact galaxies. They are also similar to high-redshift ultraviolet-luminous galaxies, e.g. Lyman-break galaxies and Lyα emitters, and therefore provide a local laboratory with which to study the extreme star formation processes that occur in high-redshift galaxies. Studying starbursting galaxies as a function of redshift is essential to understanding the build up of stellar mass in the Universe.Peer reviewe

A deep Chandra, VLA and Spitzer IRAC study of the very low luminosity nucleus of the elliptical NGC821

The relatively nearby (distance=24.1 Mpc) elliptical galaxy NGC821 hosts an extreme example of a quiescent central massive black hole, for which deep Chandra observations revealed a nuclear source for the first time (with L(2-10 keV)/L_Edd ~ 3.6X10^{-8}). We present here a multiwavelength study of this nucleus, including VLA observations that detect a radio counterpart to the Chandra nuclear source at 1.4 GHz, with a flux density of 127 $\mu$m and possibly a flat spectral shape; we also consider new Spitzer IRAC observations and archival HST images. With these data we discuss possible scenarios for the accretion modalities of the sole material that is available for fuelling, i.e., the stellar mass losses steadily replenishing the circumnuclear region. The final stages of accretion could be radiatively inefficient and coupled to a compact nuclear jet/outfow. The stellar mass losses could instead end up in a standard disc only if a Compton-thick AGN is present. Two extended sources detected by Chandra close to the nucleus could be due to several unresolved knots in a jet. If a jet is present, though, its kinetic energy would be only a very small fraction of the energy associated with the rest mass of the material being accreted. Starformation close to the nucleus is not shown by the available data. Deeper NICMOS, radio and far-IR observations should further constrain the accretion process.Comment: 32 pages, 4 figures; minor changes; accepted for publication in ApJ. This is the companion paper of astro-ph/070163

Optimization of quasi-hemispherical CdZnTe detectors by means of first principles simulation

In this paper we present the development of quasi-hemispherical gamma-ray detectors based on CdZnTe. Among the possible single-polarity electrode configurations, such as coplanar, pixelated, or virtual Frisch-grid geometries, quasi-hemispherical detectors are the most cost-effective alternative with comparable raw energy resolution in the high and low energy range. The optimal configuration of the sensor in terms of dimension of the crystals and electrode specifications has been first determined by simulations, and successively validated with experimental measures. Spectra from different sources have been acquired to evaluate the detectors performances. Three types of detectors with different CZT volumes have been fabricated, namely 10 × 10 × 5 mm3, 15 × 15 × 10 mm3 and 20 × 20 × 10 mm3. In the case of 10 × 10 × 5 mm3 crystals, the optimum pixel size determined by our simulation tool was confirmed by experiments: the best spectroscopic resolution of 1.3% at 662 keV has been found for a 750 μm diameter pixel detector. The best energy resolution values obtained for the 15 × 15 × 10 mm3 and 20 × 20 × 10 mm3 detectors were respectively 1.7% and 2.7% at 662 keV

Star formation and figure rotation in the early-type galaxy NGC2974

We present Galaxy Evolution Explorer (GALEX) far (FUV) and near (NUV) ultraviolet imaging of the nearby early-type galaxy NGC2974, along with complementary ground-based optical imaging. In the ultraviolet, the galaxy reveals a central spheroid-like component and a newly discovered complete outer ring of radius 6.2kpc, with suggestions of another partial ring at an even larger radius. Blue FUV-NUV and UV-optical colours are observed in the centre of the galaxy and from the outer ring outward, suggesting young stellar populations (< 1Gyr) and recent star formation in both locations. This is supported by a simple stellar population model which assumes two bursts of star formation, allowing us to constrain the age, mass fraction and surface mass density of the young component pixel by pixel. Overall, the mass fraction of the young component appears to be just under 1per cent (lower limit, uncorrected for dust extinction). The additional presence of a nuclear and an inner ring (radii 1.4 and 2.9kpc, respectively), as traced by [OIII] emission, suggests ring formation through resonances. All three rings are consistent with a single pattern speed of $78\pm6$ km/s/kpc, typical of S0 galaxies and only marginally slower than expected for a fast bar if traced by a small observed surface brightness plateau. This thus suggests that star formation and morphological evolution in NGC2974 at the present epoch are primarily driven by a rotating asymmetry (probably a large-scale bar), despite the standard classification of NGC2974 as an E4 elliptical.Comment: 13 pages, 10 figures, Changed content, Accepted for publication in MNRA

The JCMT Nearby Galaxies Legacy Survey VII: H\alpha{} imaging and massive star formation properties

We present H\alpha{} fluxes, star formation rates (SFRs) and equivalent widths (EWs) for a sample of 156 nearby galaxies observed in the 12CO J=3-2 line as part of the James Clerk Maxwell Telescope Nearby Galaxies Legacy Survey. These are derived from images and values in the literature and from new H\alpha{} images for 72 galaxies which we publish here. We describe the sample, observations and procedures to extract the H\alpha{} fluxes and related quantities. We discuss the SFR properties of our sample and confirm the well-known correlation with galaxy luminosity, albeit with high dispersion. Our SFRs range from 0.1 to 11 Msun yr-1 with a median SFR value for the complete sample of 0.2 Msun yr-1. This median values is somewhat lower than similar published measurements, which we attribute, in part, to our sample being HI-selected and, thus, not biased towards high SFRs as has frequently been the case in previous studies. Additionally, we calculate internal absorptions for the H\alpha{} line, A(H\alpha{}), which are lower than many of those used in previous studies. Our derived EWs, which range from 1 to 880\AA{} with a median value of 27\AA{}, show little dependence with luminosity but rise by a factor of five from early- to late-type galaxies. This paper is the first in a series aimed at comparing SFRs obtained from H\alpha{} imaging of galaxies with information derived from other tracers of star formation and atomic and molecular gas.Comment: Accepted for publication in MNRAS. 47 pages, 18 figure

Accuracy of synovial fluid analysis compared to histology for the identification of calcium pyrophosphate crystals: An ancillary study of the OMERACT US working group - CPPD subgroup

The aim of this study was to evaluate the accuracy of synovial fluid analysis in the identification of calcium pyrophosphate dihydrate crystals compared to microscopic analysis of joint tissues as the reference standard. This is an ancillary study of an international, multicentre cross-sectional study performed by the calcium pyrophosphate deposition disease (CPPD) subgroup of the OMERACT Ultrasound working group. Consecutive patients with knee osteoarthritis (OA) waiting for total knee replacement surgery were enrolled in the study from 2 participating centres in Mexico and Romania. During the surgical procedures, synovial fluid, menisci and hyaline cartilage were collected and analysed within 48 hours from surgery under transmitted light microscopy and compensated polarised light microscopy for the presence/absence of calcium pyrophosphate crystals. All slides were analysed by expert examiners on site, blinded to other findings. A dichotomic score (absence/presence) was used for scoring both synovial fluid and tissues. Microscopic analysis of knee tissues was considered the gold standard. Sensitivity, specificity, accuracy, positive and negative predictive values of synovial fluid analysis in the identification of calcium pyrophosphate crystals were calculated.15 patients (53% female, mean age 68 yo +/- 8.4) with OA of grade 3 or 4 according to Kellgren-Lawrence scoring were enrolled. 12 patients (80%) were positive for calcium pyrophosphate crystals at the synovial fluid analysis and 14 (93%) at the tissue microscopic analysis. The overall diagnostic accuracy of synovial fluid analysis compared with histology for CPPD was 87%, with a sensitivity of 86% and a specificity of 100%, the positive predictive value was 100% and the negative predictive value was 33%.In conclusion synovial fluid analysis proved to be an accurate test for the identification of calcium pyrophosphate dihydrate crystals in patients with advanced OA

POS0230 INTESTINAL MICROBIOTA CHANGES TNF-INHIBITORS INDUCED IN IBD-RELATED SPONDYLOARTHRITIS

Background:the close relationship between joints and gut inflammation has long been known and several data suggest that the dysbiosis could represents the link between Spondyloarthritis (SpA) and Inflammatory Bowel Diseases (IBD). To date, the manipulation of the intestinal microbiota is considered the key to the cure or control of the natural history of several pathologies sustained or favored by dysbiosis. The introduction of biologic drugs, in particular Tumor Necrosis Factor inhibitors (TNFi), revolutionized the management of both these diseases, thanks to the strong inhibition of inflammation and partially indirectly with mechanisms not yet fully clarified. While the impact of conventional drugs on gut microbiota is well known poor data are available about TNFi.Objectives:to investigate the impact of TNFi on gut microbiota.Methods:we included CD or UC patients fulfilling criteria for axial or peripheral SpA (ASAS 2009) on a typical Mediterranean diet, naïve to biologics needing TNFi. Clinical history, physical examination, instrumental examinations, biochemical examination including C-reactive protein (CRP), erhytrocyte sedimentation rate (ESR), HLA-B27 and fecal calprotectin at the baseline and after 6 months were performed. TNFi included infliximab and adalimumab. Fecal samples were collected by patients themselves by 24 hours before the start of the therapy. The processing was performed through metagenomic NGS (next generation sequencing) including the amplification of the V3 and V4 regions of the 16S (V3 and V4) and sequencing on the Illumina MiSeq platform. All patients received the treatment at least until week 24. Clinical disease indices included Visual Analogue Scale (VAS)-pain and Visual Analgue Scale(VAS)-disease activity for all patients, Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) for axial involvement, clinical disease activity index (CDAI) and Health Assessment Questionnaire-Disability Index (HAQ-DI) for peripheral involvement, Harvey-Bradshaw Index for CD (HBI), or partial Mayo (pMAYO) score for UC, were assessed at baseline and at the end of the study. The study was approved by the ethics committee (approval code 0056924).Results:we evaluated 20 patients affected by enteropatic arthritis, naïve for biologic drugs, treated with TNFi. After six months of therapy we observed a significant increase in Lachnospiracae family (Δ +10.3, p 0.04) and in Coprococcus genus (Δ +2.8, p 0.003). We also observed a decrease trend in Proteobacteria (Δ -8.0 p 0.095) and Gammaproteobacteria (Δ -9, p 0.093) and an increase trend in Clostridia (Δ +8.2 p 0.083). We didn't find differences between TNFi responders (SpA improvement or IBD remission achieved) and not responders in terms of alpha and beta-diversity.Conclusion:the decrease of Proteobacteria and the increase of Lachnospiraceae and Coprococcus is consistent with the hypothesis that TNFi therapy, by decreasing inflammation, tends to restore the intestinal eubiosis. However further studies on larger cohort incuding the evaluation of gut virota and micobiota will be necessary to definitively clarify the effects of TNFi on the composition and function of the gut microbiota.References:[1]Bazin T et al. Sci Rep. 2018;8(1):5446.[2]Aden K et al. Gastroenterology. 2019;157(5):1279-1292.e11.Table 1.Comparison between clinical variables between baseline and T6 (six months)Clinical variablesT0T6P_valueFecal Calprotectin(μg/g)- median (IQR)207.5(125.5-446.2)81(50-197.2)0.004CRP(mg/L)- median(IQR)8.2(4.8-20.8)2.9(1-4)0.001ESR(mm/h)- median(IQR)21.5(10.8-34)11(7.8-21)0.003VAS_pain- median(IQR)50(38.8-60)35(10-42.5)0.001VAS_disease- median(IQR)50(38.8-50)37.5(25-42.5)0.006HAQ- mediana(IQR)0.6(0.1-0.8)0.2(0.1-0.6)0.004BASDAI_score- median(IQR)5.2(4.1-5.6)2.8(2.5-4.3)0.013CDAI_activity- median(IQR)13(10.5-16)7(5.2-11)0.004IBD activity n(%) - 011 (55%)20 (100%)0.174IBD activity n(%) - 16 (30%)0 (0%)IBD activity n(%) - 22 (10%)0 (0%)IBD activity n(%) - 31 (5%)0 (0%)Disclosure of Interests:None declared

The ATLAS3D project - XXV: Two-dimensional kinematic analysis of simulated galaxies and the cosmological origin of fast and slow rotators

We present a detailed two-dimensional stellar dynamical analysis of as ample of 44 cosmological hydrodynamical simulations of individual central galaxies with stellar masses of 2 x 1010Msun ∼≤ Mstar ∼≤ 6x 1011Msun. Kinematic maps of the stellar line-of-sight velocity, velocity dispersion, and higher-order Gauss-Hermite moments h3 and h4 are constructed for each central galaxy and for the most massive satellites. The amount of rotation is quantified using the λR-parameter. The velocity, velocity dispersion, h3, and h4 fields of the simulated galaxies show a diversity similar to observed kinematic maps of early-type galaxies in the ATLAS3D survey. This includes fast (regular), slow, and misaligned rotation, hot spheroids with embedded cold disk components as well as galaxies with counter-rotating cores or central depressions in the velocity dispersion. We link the present-day kinematic properties to the individual cosmological formation histories of the galaxies. In general, major galaxy mergers have a significant influence on the rotation properties resulting in both a spin-down as well as a spin-up of the merger remnant. Lower mass galaxies with significant in-situ formation of stars, or with additional gas-rich major mergers - resulting in a spin-up - in their formation history, form elongated fast rotators with a clear anti-correlation of h3 and v/σ. An additional formation path for fast rotators includes gas-poor major mergers leading to a spin-up of the remnants. This formation path does not result in anti-correlated h3 and v/σ. The galaxies most consistent with the rare class of non-rotating round early-type galaxies grow by gas-poor minor mergers alone. In general, more massive galaxies have less in-situ star formation since z ∼ 2, rotate slower and have older stellar populations. (shortened)PostprintPeer reviewe