2,546 research outputs found

    Hubble Frontier Field Free-Form Mass Mapping of the Massive Multiple-Merging Cluster MACSJ0717.5+3745

    Get PDF
    We examine the latest data on the cluster MACSJ0717.5+3745 from the Hubble Frontier Fields campaign. The critically lensed area is the largest known of any lens and very irregular making it a challenge for parametric modelling. Using our Free-Form method we obtain an accurate solution, identify here many new sets of multiple images, doubling the number of constraints and improving the reconstruction of the dark matter distribution. Our reconstructed mass map shows several distinct central substructures with shallow density profiles, clarifying earlier work and defining well the relation between the dark matter distribution and the luminous and X-ray peaks within the critically lensed region. Using our free-form method, we are able to meaningfully subtract the mass contribution from cluster members to the deflection field to trace the smoothly distributed cluster dark matter distribution. We find 4 distinct concentrations, 3 of which are coincident with the luminous matter. The fourth peak has a significant offset from both the closest luminous and X-ray peaks. These findings, together with dynamical data from the motions of galaxies and gas will be important for uncovering the potentially important implications of this extremely massive and intriguing system.Comment: 16 pages, 10 figures, 2 tables. Matches the verson submitted to mnras. New table (A2) included with additional system candidate

    A Rigorous Free-form Lens Model of Abell 2744 to Meet the Hubble Frontier Fields Challenge

    Get PDF
    Hubble Frontier Fields (HFF) imaging of the most powerful lensing clusters provides access to the most magnified distant galaxies. The challenge is to construct lens models capable of describing these complex massive, merging clusters so that individual lensed systems can be reliably identified and their intrinsic properties accurately derived. We apply the free-form lensing method (WSLAP+) to A2744, providing a model independent map of the cluster mass, magnification, and geometric distance estimates to multiply-lensed sources. We solve simultaneously for a smooth cluster component on a pixel grid, together with local deflections by the cluster member galaxies. Combining model prediction with photometric redshift measurements, we correct and complete several systems recently claimed, and identify 4 new systems - totalling 65 images of 21 systems spanning a redshift range of 1.4<z<9.8. The reconstructed mass shows small enhancements in the directions where significant amounts of hot plasma can be seen in X-ray. We compare photometric redshifts with "geometric redshifts", finding a high level of self-consistency. We find excellent agreement between predicted and observed fluxes - with a best-fit slope of 0.999+-0.013 and an RMS of ~0.25 mag, demonstrating that our magnification correction of the lensed background galaxies is very reliable. Intriguingly, few multiply-lensed galaxies are detected beyond z~7.0, despite the high magnification and the limiting redshift of z~11.5 permitted by the HFF filters. With the additional HFF clusters we can better examine the plausibility of any pronounced high-z deficit, with potentially important implications for the reionization epoch and the nature of dark matter.Comment: Accepted for publication in ApJ with newly identified lensed images in complete HFF dat

    A Free-Form Prediction for the Reappearance of Supernova Refsdal in the Hubble Frontier Fields Cluster MACSJ1149.5+2223

    Get PDF
    The massive cluster MACSJ1149.5+2223(z=0.544) displays five very large lensed images of a well resolved spiral galaxy at zspect=1.491z_{\rm spect}=1.491. It is within one of these images that the first example of a multiply-lensed supernova has been detected recently as part of the Grism Lens-Amplified Survey from Space. The depth of this data also reveals many HII regions within the lensed spiral galaxy which we identify between the five counter-images. Here we expand the capability of our free-form method to incorporate these HII regions locally, with other reliable lensed galaxies added for a global solution. This improved accuracy allows us to estimate when the Refsdal supernova will appear within the other lensed images of the spiral galaxy to an accuracy of \sim 7\%. We predict this supernova will reappear in one of the counter-images (RA=11:49:36.025, DEC=+22:23:48.11, J2000) and on November 1st^{st} 2015 (with an estimated error of ±\pm 25 days) it will be at the same phase as it was when it was originally discovered, offering a unique opportunity to study the early phases of this supernova and to examine the consistency of the mass model and the cosmological model that have an impact on the time delay prediction.Comment: 12 images, 11 pages. Mateches accepted version in MNRAS. MNRAS in pres

    A Geometrically Supported z10z\sim10 Candidate Multiply-Imaged by the Hubble Frontier Fields Cluster Abell 2744

    Get PDF
    The deflection angles of lensed sources increase with their distance behind a given lens. We utilize this geometric effect to corroborate the zphot9.8z_{phot}\simeq9.8 photometric redshift estimate of a faint near-IR dropout, triply-imaged by the massive galaxy cluster Abell 2744 in deep Hubble Frontier Fields images. The multiple images of this source follow the same symmetry as other nearby sets of multiple images which bracket the critical curves and have well defined redshifts (up to zspec3.6z_{spec}\simeq3.6), but with larger deflection angles, indicating that this source must lie at a higher redshift. Similarly, our different parametric and non-parametric lens models all require this object be at z4z\gtrsim4, with at least 95\% confidence, thoroughly excluding the possibility of lower-redshift interlopers. To study the properties of this source we correct the two brighter images for their magnifications, leading to a SFR of 0.3M\sim0.3 M_{\odot}/yr, a stellar mass of 4×107M\sim4\times10^{7} M_{\odot}, and an age of 220\lesssim220 Myr (95\% confidence). The intrinsic apparent magnitude is 29.9 AB (F160W), and the rest-frame UV (1500A˚\sim1500 \AA) absolute magnitude is MUV,AB=17.6M_{UV,AB}=-17.6. This corresponds to 0.1Lz=8\sim0.1 L^{*}_{z=8} (0.2Lz=10\sim0.2 L^{*}_{z=10}, adopting dM/dz0.45dM^{*}/dz\sim0.45), making this candidate one of the least luminous galaxies discovered at z10z\sim10.Comment: 7 pages, 4 figures, 1 table; V2: very minor changes, ApJ Letters Accepte

    The Taiwan ECDFS Near-Infrared Survey: Very Bright End of the Luminosity Function at z>7

    Get PDF
    The primary goal of the Taiwan ECDFS Near-Infrared Survey (TENIS) is to find well screened galaxy candidates at z>7 (z' dropout) in the Extended Chandra Deep Field-South (ECDFS). To this end, TENIS provides relatively deep J and Ks data (~25.3 ABmag, 5-sigma) for an area of 0.5*0.5 degree. Leveraged with existing data at mid-infrared to optical wavelengths, this allows us to screen for the most luminous high-z objects, which are rare and thus require a survey over a large field to be found. We introduce new color selection criteria to select a z>7 sample with minimal contaminations from low-z galaxies and Galactic cool stars; to reduce confusion in the relatively low angular resolution IRAC images, we introduce a novel deconvolution method to measure the IRAC fluxes of individual sources. Illustrating perhaps the effectiveness at which we screen out interlopers, we find only one z>7 candidate, TENIS-ZD1. The candidate has a weighted z_phot of 7.8, and its colors and luminosity indicate a young (45M years old) starburst galaxy with a stellar mass of 3.2*10^10 M_sun. The result matches with the observational luminosity function analysis and the semi-analytic simulation result based on the Millennium Simulations, which may over predict the volume density for high-z massive galaxies. The existence of TENIS-ZD1, if confirmed spectroscopically to be at z>7, therefore poses a challenge to current theoretical models for how so much mass can accumulate in a galaxy at such a high redshift.Comment: 14 pages, 11 figures, ApJ accepte

    Radiomics in urolithiasis: Systematic review of current applications, limitations, and future directions

    Get PDF
    Radiomics is increasingly applied to the diagnosis, management, and outcome prediction of various urological conditions. Urolithiasis is a common benign condition with a high incidence and recurrence rate. The purpose of this scoping review is to evaluate the current evidence of the application of radiomics in urolithiasis, especially its utility in diagnostics and therapeutics. An electronic literature search on radiomics in the setting of urolithiasis was conducted on PubMed, EMBASE, and Scopus from inception to 21 March 2022. A total of 7 studies were included. Radiomics has been successfully applied in the field of urolithiasis to differentiate phleboliths from calculi and classify stone types and composition pre-operatively. More importantly, it has also been utilized to predict outcomes and complications after endourological procedures. Although radiomics in urolithiasis is still in its infancy, it has the potential for large-scale implementation. Its greatest potential lies in the correlation with conventional established diagnostic and therapeutic factors

    Comparison of Mortality Outcomes in Acute Myocardial Infarction Patients With or Without Standard Modifiable Cardiovascular Risk Factors

    Get PDF
    Background: Acute myocardial infarction (AMI) cases have decreased in part due to the advent of targeted therapies for standard modifiable cardiovascular disease risk factors (SMuRF). Recent studies have reported that ST-elevation myocardial infarction (STEMI) patients without SMuRF (termed "SMuRF-less") may be increasing in prevalence and have worse outcomes than "SMuRF-positive" patients. As these studies have been limited to STEMI and comprised mainly Caucasian cohorts, we investigated the changes in the prevalence and mortality of both SMuRF-less STEMI and non-STEMI (NSTEMI) patients in a multiethnic Asian population. Methods: We evaluated 23,922 STEMI and 62,631 NSTEMI patients from a national multiethnic registry. Short-term cardiovascular and all-cause mortalities in SMuRF-less patients were compared to SMuRF-positive patients. Results: The proportions of SMuRF-less STEMI but not of NSTEMI have increased over the years. In hospitals, all-cause and cardiovascular mortality and 1-year cardiovascular mortality were significantly higher in SMuRF-less STEMI after adjustment for age, creatinine, and hemoglobin. However, this difference did not remain after adjusting for anterior infarction, cardiopulmonary resuscitation (CPR), and Killip class. There were no differences in mortality in SMuRF-less NSTEMI. In contrast to Chinese and Malay patients, SMuRF-less patients of South Asian descent had a two-fold higher risk of in-hospital all-cause mortality even after adjusting for features of increased disease severity. Conclusion: SMuRF-less patients had an increased risk of mortality with STEMI, suggesting that there may be unidentified nonstandard risk factors predisposing SMuRF-less patients to a worse prognosis. This group of patients may benefit from more intensive secondary prevention strategies to improve clinical outcomes
    corecore