- ID:
- ivo://CDS.VizieR/J/ApJ/897/18
- Title:
- Swift UVOT observation of the radio quasar 3C 273
- Short Name:
- J/ApJ/897/18
- Date:
- 16 Mar 2022 00:38:40
- Publisher:
- CDS
- Description:
- 3C273 is an intensively monitored flat-spectrum radio quasar with both a beamed jet and blue bump together with broad emission lines. The coexistence of the comparably prominent jet and accretion disk leads to complicated variability properties. Recent reverberation mapping monitoring for 3C273 revealed that the optical continuum shows a distinct long-term trend that does not have a corresponding echo in the H{beta} fluxes. We compile multiwavelength monitoring data from the Swift archive and other ground-based programs and clearly find two components of emissions at optical wavelength. One component stems from the accretion disk itself, and the other component can be ascribed to the jet contribution, which also naturally accounts for the nonechoed trend in reverberation mapping data. We develop an approach to decouple the optical emissions from the jet and accretion disk in 3C273 with the aid of multiwavelength monitoring data. By assuming that the disk emission has a negligible polarization in consideration of the low inclination of the jet, the results show that the jet contributes a fraction of ~10% at the minimum and up to ~40% at the maximum to the total optical emissions. This is the first time to provide a physical interpretation of the "detrending" manipulation conventionally adopted in reverberation mapping analysis. Our work also illustrates the importance of appropriately analyzing variability properties in cases of coexisting jets and accretion disks.
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- ID:
- ivo://CDS.VizieR/J/ApJ/749/18
- Title:
- Swift/UVOT observations of 12 nearby SN-Ia
- Short Name:
- J/ApJ/749/18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compare early ultraviolet (UV) observations of Type Ia supernovae (SNe Ia) with theoretical predictions for the brightness of the shock associated with the collision between SN ejecta and a companion star. Our simple method is independent of the intrinsic flux from the SN and treats the flux observed with the Swift/Ultra-Violet Optical Telescope as conservative upper limits on the shock brightness. Comparing this limit with the predicted flux for various shock models, we constrain the geometry of the SN progenitor-companion system. We find the model of a 1 M_{sun}_ red supergiant companion in Roche-lobe overflow to be excluded at a 95% confidence level for most individual SNe for all but the most unfavorable viewing angles. For the sample of 12 SNe taken together, the upper limits on the viewing angle are inconsistent with the expected distribution of viewing angles for red gaint stars as the majority of companions with high confidence. The separation distance constraints do allow main-sequence companions. A better understanding of the UV flux arising from the SN itself as well as continued UV observations of young SNe Ia will further constrain the possible progenitors of SNe Ia.
- ID:
- ivo://CDS.VizieR/J/ApJ/753/22
- Title:
- Swift/UVOT observations of SN 2011fe
- Short Name:
- J/ApJ/753/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the earliest ultraviolet (UV) observations of the bright Type Ia supernova SN 2011fe/PTF11kly in the nearby galaxy M101 at a distance of only 6.4 Mpc. It was discovered shortly after explosion by the Palomar Transient Factory and first observed by Swift/UVOT about a day after explosion. The early UV light is well defined, with ~20 data points per filter in the five days after explosion. These early and well-sampled UV observations form new template light curves for comparison with observations of other SNe Ia at low and high redshift. We report fits from semiempirical models of the explosion and find the time evolution of the early UV flux to be well fitted by the superposition of two parabolic curves. Finally, we use the early UV flux measurements to examine a possible shock interaction with a non-degenerate companion. From models predicting the measurable shock emission, we find that even a solar mass companion at a distance of a few solar radii is unlikely at more than 95% confidence.
- ID:
- ivo://CDS.VizieR/J/ApJ/702/226
- Title:
- Swift/UVOT panchromatic observations of SN 2008D
- Short Name:
- J/ApJ/702/226
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present extensive early photometric (ultraviolet through near-infrared) and spectroscopic (optical and near-infrared) data on supernova (SN) 2008D as well as X-ray data analysis on the associated Swift X-ray transient (XRT) 080109. Our data span a time range of 5hr before the detection of the X-ray transient to 150 days after its detection, and a detailed analysis allowed us to derive constraints on the nature of the SN and its progenitor; throughout we draw comparisons with results presented in the literature and find several key aspects that differ. Our data first established that SN 2008D is a spectroscopically normal SN Ib (i.e., showing conspicuous He lines) and showed that SN 2008D had a relatively long rise time of 18 days and a modest optical peak luminosity. The early-time light curves of the SN are dominated by a cooling stellar envelope (for {Delta}t~0.1-4days, most pronounced in the blue bands) followed by ^56^Ni decay.
- ID:
- ivo://CDS.VizieR/II/339
- Title:
- Swift/UVOT Serendipitous Source Catalog
- Short Name:
- II/339
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The first version of the Swift UVOT serendipitous source catalogue (UVOTSSC) provides positions and magnitudes, as well as errors and upper limits of confirmed sources for observations taken from start of operations in 2005 until October 1st of 2010. The first version of the Swift UVOT Serendipitous Source Catalogue (UVOTSSC) has been produced by processing the image data obtained from the Swift Ultraviolet and Optical Telescope (UVOT) from the beginning of the mission (2005) until 1st of October of 2010. The data processing was performed at the Mullard Space Science Laboratory (MSSL, University College London, U.K.) using Swift FTOOLS from NASA's High Energy Astrophysics Software (HEASoft-6.11), with some customising of the UVOT packages in order to get more complete source detection and properly apply quality flags to those sources that were detected within the UVOT image artefacts. The total number of observations with 17'x17' images used for version 1 of the catalogue is 23,059, giving 6,200,016 sources in total, of which 2,027,265 have multiple entries in the source table because they have been detected in more than one observation. Some sources were only observed in one filter. The total number of entries in the source table is 13,860,568. The S/N ratio for all sources exceeds 5 for at least one UVOT filter, the rest of the filters having a S/N greater than 3.
- ID:
- ivo://CDS.VizieR/J/MNRAS/424/1636
- Title:
- Swift/UVOT sources in NGC4321 (M100)
- Short Name:
- J/MNRAS/424/1636
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the star-forming regions in the spiral galaxy NGC 4321 (M100). We take advantage of the spatial resolution (2.5-arcsec full width at half-maximum) of the Swift/Ultraviolet/Optical Telescope camera and the availability of three ultraviolet (UV) passbands in the region 1600<{lambda}<3000{AA}, in combination with optical and infrared (IR) imaging from Sloan Digital Sky Survey, KPNO/H{alpha} and Spitzer/IRAC, to obtain a catalogue of 787 star-forming regions out to three disc scalelengths. We use a large volume of star formation histories, combined with stellar population synthesis, to determine the properties of the young stellar component and its relationship with the spiral arms.
- ID:
- ivo://CDS.VizieR/J/AJ/158/35
- Title:
- Swift UVOT Stars Survey. III. Galactic open clusters
- Short Name:
- J/AJ/158/35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of the Swift/Ultraviolet-Optical Telescope Stars Survey, we present near-ultraviolet (NUV; 3000-1700 {AA}) point-source photometry for 103 Galactic open clusters. These data, taken over the span of the mission, provide a unique and unprecedented set of NUV point-source photometry on simple stellar populations. After applying a membership analysis fueled mostly by Gaia DR2 (Cat. I/345) proper motions, we find that 49 of these 103 have clear precise color-magnitude diagrams (CMDs) amenable to investigation. We compare the CMDs to theoretical isochrones and find good agreement between the theoretical isochrones and the CMDs. The exceptions are the fainter parts of the main sequence and the red giant branch in the uvw2-uvw1 CMDs, which is most likely due to either the difficulty of correcting for the red leak in the uvw2 filter or limitations in our understanding of UV opacities for cool stars. For the most part, our derived cluster parameters - age, distance, and reddening - agree with the consensus literature, but we find a few clusters that warrant substantial revision from literature values, notably NGC 2304, NGC 2343, NGC 2360, NGC 2396, NGC 2428, NGC 2509, NGC 2533, NGC 2571, NGC 2818, Collinder 220, and NGC 6939. A number of these are clusters in the third Galactic quadrant, where previous studies may have mistaken the disk sequence for the cluster. However, the Gaia DR2 proper motions clearly favor a different sequence. A number of clusters also show white dwarf and blue straggler sequences. We confirm the presence of extended main-sequence turnoffs in NGC 2360 and NGC 2818 and show hints of them in a number of other clusters that may warrant future spectroscopic study. Most of the clusters in the study have low extinction, and the rest are well fit by a "Milky Way-like" extinction law. However, Collinder 220 hints at a possible "LMC-like" extinction law. We finally provide a comprehensive point-source catalog to the community as a tool for future investigation.
- ID:
- ivo://CDS.VizieR/J/AJ/150/129
- Title:
- Swift UVOT stars survey. II. RR Lyrae in M3 and M15
- Short Name:
- J/AJ/150/129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results of a Near-UltraViolet (NUV) survey of RR Lyrae stars from the Ultraviolet Optical Telescope (UVOT) on board the Swift Gamma-ray Burst Mission. It is well-established that RR Lyrae stars have large amplitudes in the far- and near-ultraviolet. We have used UVOT's unique wide-field NUV imaging capability to perform the first systematic NUV survey of variable stars in the Galactic globular clusters M3 and M15. We identify 280 variable stars, comprised of 275 RR Lyrae, 2 anomalous Cepheids, 1 classical Cepheid, 1 SX Phoenicis star, and 1 possible long-period or irregular variable. Only two of these are new discoveries. We compare our results to previous investigations and find excellent agreement in the periods with significantly larger amplitudes in the NUV. We map out, for the first time, an NUV Bailey diagram from globular clusters, showing the usual loci for fundamental mode RRab and first overtone RRc pulsators. We show the unique sensitivity of NUV photometry to both the temperatures and the surface gravities of RR Lyrae stars. Finally, we show evidence of an NUV period-metallicity-luminosity relationship. Future investigations will further examine the dependence of NUV pulsation parameters on metallicity and Oosterhoff classification.
- ID:
- ivo://CDS.VizieR/J/ApJ/866/97
- Title:
- Swift X-ray flash & rich gamma-ray bursts in BAT3
- Short Name:
- J/ApJ/866/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We build a comprehensive sample to statistically describe the properties of X-ray flashes (XRFs) and X-ray riches (XRRs) from the third Swift Burst Alert Telescope (BAT3) catalog of Gamma-ray bursts (GRBs). We obtain 81 XRFs, 540 XRRs, and 394 classical GRBs (C-GRBs). We statistically explore the different properties of the {gamma}-ray prompt emission, the X-ray emission, the X-ray light-curve type, the association with supernovae (SNe), and the host galaxy properties for these sources. We confirm that most XRFs/XRRs are long GRBs with low values of peak energy E_peak_^obs^ and they are low-luminosity GRBs. XRFs, XRRs, and C-GRBs follow the same E_X,iso_-E_{gamma},iso_-E_peak,z_ correlations. Compared to the classical GRBs, XRFs are favorable to have the association with SN explosions. We do not find any significant differences of redshift distribution and host galaxy properties among XRFs, XRRs, and C-GRBs. We also discuss some observational biases and selection effects that may affect our statistical results. The GRB detectors with wide energy range and low energy threshold are expected for the XRF/XRR research in the future.
- ID:
- ivo://CDS.VizieR/J/ApJS/197/31
- Title:
- Swift X-ray observations of classical novae. II.
- Short Name:
- J/ApJS/197/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Swift gamma-ray burst satellite is an excellent facility for studying novae. Its rapid response time and sensitive X-ray detector provides an unparalleled opportunity to investigate the previously poorly sampled evolution of novae in the X-ray regime. This paper presents Swift observations of 52 Galactic/Magellanic Cloud novae. We included the X-Ray Telescope (0.3-10keV) instrument count rates and the UltraViolet and Optical Telescope (1700-8000{AA}) filter photometry. Also included in the analysis are the publicly available pointed observations of 10 additional novae the X-ray archives. This is the largest X-ray sample of Galactic/Magellanic Cloud novae yet assembled and consists of 26 novae with Super Soft X-ray emission, 19 from Swift observations.