Observations of many Type Ia supernovae (SNe Ia) for multiple epochs per object with the Swift Ultraviolet Optical Telescope instrument have revealed that there exists order to the differences in the ...UV-optical colors of optically normal supernovae (SNe). We examine UV-optical color curves for 23 SNe Ia, dividing the SNe into four groups, and find that roughly one-third of "NUV-blue" SNe Ia have bluer UV-optical colors than the larger "NUV-red" group. Two minor groups are recognized, "MUV-blue" and "irregular" SNe Ia. This finding is promising for extending the cosmological utilization of SNe Ia into the NUV. We generate spectrophotometry of 33 SNe Ia and determine the correct grouping for each. We argue that there is a fundamental spectral difference in the 2900-3500A wavelength range, a region suggested to be dominated by absorption from iron-peak elements. Many NUV-red events also exhibit a low gradient, perhaps suggestive that NUV-blue events are a subset of the larger low-velocity gradient group.
ABSTRACT
The Type Ia supernovae (SNe Ia) 2011by, hosted in NGC 3972, and 2011fe, hosted in M101, are optical ‘twins,’ having almost identical optical light-curve shapes, colours, and ...near-maximum-brightness spectra. However, SN 2011fe had significantly more ultraviolet (UV; 1600 < λ < 2500 Å) flux than SN 2011by before and at peak luminosity. Several theoretical models predict that SNe Ia with higher progenitor metallicity should (1) have additional UV opacity and thus lower UV flux; (2) have an essentially unchanged optical spectral-energy distribution; (3) have a similar optical light-curve shape; and (4) because of the excess neutrons, produce more stable Fe-group elements at the expense of radioactive 56Ni and thus have a lower peak luminosity. Following these predictions, Foley and Kirshner suggested that the difference in UV flux between SNe 2011by and 2011fe was the result of their progenitors having significantly different metallicities. They also measured a large, but insignificant, difference between the peak absolute magnitudes of the SNe (ΔMV, peak = 0.60 ± 0.36 mag), with SN 2011fe being more luminous. We present a new Cepheid-based distance to NGC 3972, substantially improving the precision of the distance measurement for SN 2011by. With these new data, we determine that the SNe have significantly different peak luminosities (ΔMV, peak = 0.335 ± 0.069 mag). Consequently, SN 2011fe produced 38 per cent more 56Ni than SN 2011by, consistent with predictions for progenitor metallicity differences for these SNe, although alternative models may also explain this difference. We discuss how progenitor metallicity differences can contribute to the intrinsic scatter for light-curve-shape-corrected SN luminosities, the use of ‘twin’ SNe for measuring distances, and implications for using SNe Ia for constraining cosmological parameters.
The advent of second-generation sequencing (2GS) has provided a range of significant new challenges for the visualization of sequence assemblies. These include the large volume of data being ...generated, short-read lengths and different data types and data formats associated with the diversity of new sequencing technologies. This article illustrates how Tablet-a high-performance graphical viewer for visualization of 2GS assemblies and read mappings-plays an important role in the analysis of these data. We present Tablet, and through a selection of use cases, demonstrate its value in quality assurance and scientific discovery, through features such as whole-reference coverage overviews, variant highlighting, paired-end read mark-up, GFF3-based feature tracks and protein translations. We discuss the computing and visualization techniques utilized to provide a rich and responsive graphical environment that enables users to view a range of file formats with ease. Tablet installers can be freely downloaded from http://bioinf.hutton.ac.uk/tablet in 32 or 64-bit versions for Windows, OS X, Linux or Solaris. For further details on the Tablet, contact tablet@hutton.ac.uk.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
We present space-based ultraviolet/optical photometry and spectroscopy with the
Swift
Ultra-Violet/Optical Telescope and
Hubble Space Telescope
(
HST
), respectively, along with ground-based ...optical photometry and spectroscopy and near-infrared spectroscopy of supernova SN 2017erp. The optical light curves and spectra are consistent with a normal SN Ia. Compared to previous photometric samples in the near-ultraviolet (NUV), SN 2017erp has UV colors that are redder than NUV-blue SNe Ia corrected to similar optical colors. The chromatic difference between SNe 2011fe and 2017erp is dominated by the intrinsic differences in the UV rather than the expected dust reddening. This chromatic difference is similar to the SALT2 color law, derived from rest-frame ultraviolet photometry of higher redshift SNe Ia. Differentiating between intrinsic UV diversity and dust reddening can have important consequences for determining cosmological distances with rest-frame ultraviolet photometry. This ultraviolet spectroscopic series is the first from
HST
of a normal, albeit reddened, NUV-red SN Ia and is important for analyzing SNe Ia with intrinsically redder NUV colors. We show model comparisons suggesting that metallicity could be the physical difference between NUV-blue and NUV-red SNe Ia, with emission peaks from reverse fluorescence near 3000 Å implying a factor of ∼10 higher metallicity in the upper layers of SN 2017erp compared to SN 2011fe. Metallicity estimates are very model dependent, however, and there are multiple effects in the UV. Further models and UV spectra of SNe Ia are needed to explore the diversity of SNe Ia, which show seemingly independent differences in the near-UV peaks and mid-UV flux levels.
Abstract
Background
Evidence linking breast size to breast cancer risk has been inconsistent, and its interpretation is often hampered by confounding factors such as body mass index (BMI). Here, we ...used linkage disequilibrium score regression and two-sample Mendelian randomization (MR) to examine the genetic associations between BMI, breast size and breast cancer risk.
Methods
Summary-level genotype data from 23andMe, Inc (breast size, n = 33 790), the Breast Cancer Association Consortium (breast cancer risk, n = 228 951) and the Genetic Investigation of ANthropometric Traits (BMI, n = 183 507) were used for our analyses. In assessing causal relationships, four complementary MR techniques inverse variance weighted (IVW), weighted median, weighted mode and MR-Egger regression were used to test the robustness of the results.
Results
The genetic correlation (rg) estimated between BMI and breast size was high (rg = 0.50, P = 3.89x10−43). All MR methods provided consistent evidence that higher genetically predicted BMI was associated with larger breast size odds ratio (ORIVW): 2.06 (1.80–2.35), P = 1.38x10−26 and lower overall breast cancer risk ORIVW: 0.81 (0.74–0.89), P = 9.44x10−6. No evidence of a relationship between genetically predicted breast size and breast cancer risk was found except when using the weighted median and weighted mode methods, and only with oestrogen receptor (ER)-negative risk. There was no evidence of reverse causality in any of the analyses conducted (P > 0.050).
Conclusion
Our findings indicate a potential positive causal association between BMI and breast size and a potential negative causal association between BMI and breast cancer risk. We found no clear evidence for a direct relationship between breast size and breast cancer risk.
Abstract
We report comprehensive multi-wavelength observations of a peculiar Type Ia-like supernova (“SN Ia-pec”) ASASSN-15pz. ASASSN-15pz is a spectroscopic “twin” of SN 2009dc, a so-called ...“Super-Chandrasekhar-mass” SN, throughout its evolution, but it has a peak luminosity
that is
dimmer and comparable to the SN 1991T sub-class of SNe Ia at the luminous end of the normal width-luminosity relation. The synthesized
56
Ni mass of
is also substantially less than that found for several 2009dc-like SNe. Previous well-studied 2009dc-like SNe have generally suffered from large and uncertain amounts of host-galaxy extinction, which is negligible for ASASSN-15pz. Based on the color of ASASSN-15pz, we estimate a host extinction for SN 2009dc of
and confirm its high luminosity (
). The 2009dc-like SN population, which represents ∼1% of SNe Ia, exhibits a range of peak luminosities, and do not fit onto the tight width-luminosity relation. Their optical light curves also show significant diversity of late-time (≳50 days) decline rates. The nebular-phase spectra provide powerful diagnostics to identify the 2009dc-like events as a distinct class of SNe Ia. We suggest referring to these sources using the phenomenology-based “2009dc-like SN Ia-pec” instead of “Super-Chandrasekhar SN Ia,” which is based on an uncertain theoretical interpretation.
Abstract
We present photometry and spectroscopy of SN 2013fs and SN 2013fr in the first ∼100 d post-explosion. Both objects showed transient, relatively narrow H α emission lines characteristic of ...SNe IIn, but later resembled normal SNe II-P or SNe II-L, indicative of fleeting interaction with circumstellar material (CSM). SN 2013fs was discovered within 8 h of explosion; one of the earliest SNe discovered thus far. Its light curve exhibits a plateau, with spectra revealing strong CSM interaction at early times. It is a less luminous version of the transitional SN IIn PTF11iqb, further demonstrating a continuum of CSM interaction intensity between SNe II-P and SNe IIn. It requires dense CSM within 6.5 × 1014 cm of the progenitor, from a phase of advanced pre-SN mass loss beginning shortly before explosion. Spectropolarimetry of SN 2013fs shows little continuum polarization (∼0.5 per cent, consistent with zero), but noticeable line polarization during the plateau phase. SN 2013fr morphed from an SN IIn at early times to an SN II-L. After the first epoch, its narrow lines probably arose from host-galaxy emission, but the bright, narrow H α emission at early times may be intrinsic to the SN. As for SN 2013fs, this would point to a short-lived phase of strong CSM interaction if proven to be intrinsic, suggesting a continuum between SNe IIn and SNe II-L. It is a low-velocity SN II-L like SN 2009kr, but more luminous. SN 2013fr also developed an infrared excess at later times, due to warm CSM dust that requires a more sustained phase of strong pre-SN mass loss.
Abstract
We measured high-quality surface brightness fluctuation (SBF) distances for a sample of 63 massive early-type galaxies using the WFC3/IR camera on the Hubble Space Telescope. The median ...uncertainty on the SBF distance measurements is 0.085 mag, or 3.9% in distance. Achieving this precision at distances of 50–100 Mpc required significant improvements to the SBF calibration and data analysis procedures for WFC3/IR data. Forty-two of the galaxies are from the MASSIVE Galaxy Survey, a complete sample of massive galaxies within ∼100 Mpc; the SBF distances for these will be used to improve the estimates of the stellar and central supermassive black hole masses in these galaxies. Twenty-four of the galaxies are Type Ia supernova hosts, useful for calibrating SN Ia distances for early-type galaxies and exploring possible systematic trends in the peak luminosities. Our results demonstrate that the SBF method is a powerful and versatile technique for measuring distances to galaxies with evolved stellar populations out to 100 Mpc and constraining the local value of the Hubble constant.
The intrinsic colors of Type Ia supernovae (SNe Ia) are important to understanding their use as cosmological standard candles. Understanding the effects of reddening and redshift on the observed ...colors are complicated and dependent on the intrinsic spectrum, the filter curves, and the wavelength dependence of reddening. We present ultraviolet and optical data of a growing sample of SNe Ia observed with the Ultraviolet/Optical Telescope on the Swift spacecraft and use this sample to re-examine the near-UV (NUV) colors of SNe Ia. We find that a small amount of reddening (E(B − V) = 0.2 mag) could account for the difference between groups designated as NUV-blue and NUV-red, and a moderate amount of reddening (E(B − V) = 0.5 mag) could account for the whole NUV-optical differences. The reddening scenario, however, is inconsistent with the mid-UV colors and color evolution. The effect of redshift alone only accounts for part of the variation. Using a spectral template of SN2011fe, we can forward model the effects of redshift and reddening and directly compare those with the observed colors. We find that some SNe are consistent with reddened versions of SN2011fe, but most SNe Ia are much redder in the uvw1 − v color than SN2011fe reddened to the same b − v color. The absolute magnitudes show that two out of five NUV-blue SNe Ia are blue because their near-UV luminosity is high, and the other three are optically fainter. We also show that SN 2011fe is not a "normal" SN Ia in the UV, but has colors placing it at the blue extreme of our sample.
ABSTRACT Ultraviolet (UV) and optical photometry of Type Ia supernovae (SNe Ia) at low redshift have revealed the existence of two distinct color groups, composed of NUV-red and NUV-blue events. The ...color curves differ primarily by an offset, with the NUV-blue color curves bluer than the NUV-red curves by 0.4 mag. For a sample of 23 low-redshift SNe Ia observed with Swift, the NUV-red group dominates by a ratio of 2:1. We compare rest-frame UV/optical spectrophotometry of intermediate- and high-redshift SNe Ia with UVOT photometry and Hubble Space Telescope spectrophotometry of low-redshift SNe Ia, finding that the same two color groups exist at higher redshift, but with the NUV-blue events as the dominant group. Within each red/blue group, we do not detect any offset in color for different redshifts, providing insight into how SN Ia UV emission evolves with redshift. Through spectral comparisons of SNe Ia with similar peak width and phase, we explore the wavelength range that produces the UV/optical color differences. We show that the ejecta velocity of NUV-red supernovae (SNe) is larger than that of NUV-blue objects by roughly 12% on average. This velocity difference can explain some of the UV/optical color difference, but differences in the strengths of spectral features seen in mean spectra require additional explanation. Because of the slightly different colors for these groups, NUV-red SNe will have their extinction underestimated using common techniques. This, in turn, leads to underestimation of the optical luminosity of the NUV-blue SNe Ia, in particular, for the high-redshift cosmological sample. Not accounting for this effect should thus produce a distance bias that increases with redshift and could significantly bias measurements of cosmological parameters.
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