- ID:
- ivo://CDS.VizieR/J/AJ/155/201
- Title:
- SweetSpot DR1: 74 SNe Ia in 36 nights on WIYN+WHIRC
- Short Name:
- J/AJ/155/201
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- SweetSpot is a 3 yr National Optical Astronomy Observatory (NOAO) survey program to observe Type Ia supernovae (SNe Ia) in the smooth Hubble flow with the WIYN High-resolution Infrared Camera (WHIRC) on the WIYN 3.5 m telescope. We present data from the first half of this survey, covering the 2011B-2013B NOAO semesters and consisting of 493 calibrated images of 74 SNe Ia observed in the rest-frame near-infrared (NIR) in the range 0.02<z<0.09. Because many observed supernovae require host-galaxy subtraction from templates taken in later semesters, this release contains only the 186 NIR (JHK_s_) data points for the 33 SNe Ia that do not require host-galaxy subtraction. The sample includes four objects with coverage beginning before the epoch of B-band maximum and 27 beginning within 20 days of B-band maximum. We also provide photometric calibration between the WIYN+WHIRC and Two Micron All-Sky Survey (2MASS) systems, along with light curves for 786 2MASS stars observed alongside the SNe Ia. This work is the first in a planned series of three SweetSpot Data Releases. Future releases will include the full set of images from all 3 yr of the survey, including host-galaxy reference images and updated data processing with host-galaxy reference subtraction. SweetSpot will provide a well-calibrated sample that will help improve our ability to standardize distance measurements to SNe Ia, examine the intrinsic optical-NIR colors of SNe Ia at different epochs, explore the nature of dust in other galaxies, and act as a stepping-stone for more distant, potentially space-based surveys.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/222/13
- Title:
- Swift AGN and Cluster Survey (SWCL). II. SDSS
- Short Name:
- J/ApJS/222/13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study 203 (of 442) Swift AGN and Cluster Survey extended X-ray sources located in the SDSS DR8 footprint to search for galaxy over-densities in three-dimensional space using SDSS galaxy photometric redshifts and positions near the Swift cluster candidates. We find 104 Swift clusters with a >3{sigma} galaxy over-density. The remaining targets are potentially located at higher redshifts and require deeper optical follow-up observations for confirmation as galaxy clusters. We present a series of cluster properties including the redshift, brightest cluster galaxy (BCG) magnitude, BCG-to-X-ray center offset, optical richness, and X-ray luminosity. We also detect red sequences in ~85% of the 104 confirmed clusters. The X-ray luminosity and optical richness for the SDSS confirmed Swift clusters are correlated and follow previously established relations. The distribution of the separations between the X-ray centroids and the most likely BCG is also consistent with expectation. We compare the observed redshift distribution of the sample with a theoretical model, and find that our sample is complete for z<~0.3 and is still 80% complete up to z~0.4, consistent with the SDSS survey depth. These analysis results suggest that our Swift cluster selection algorithm has yielded a statistically well-defined cluster sample for further study of cluster evolution and cosmology. We also match our SDSS confirmed Swift clusters to existing cluster catalogs, and find 42, 23, and 1 matches in optical, X-ray, and Sunyaev-Zel'dovich catalogs, respectively, and so the majority of these clusters are new detections.
- ID:
- ivo://CDS.VizieR/J/ApJ/850/74
- Title:
- Swift/BAT AGN Spectroscopic Survey. I.
- Short Name:
- J/ApJ/850/74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first catalog and data release of the Swift-BAT AGN Spectroscopic Survey. We analyze optical spectra of the majority of the detected AGNs (77%, 642/836) based on their 14-195keV emission in the 70-month Swift-BAT all-sky catalog. This includes redshift determination, absorption and emission-line measurements, and black hole mass and accretion rate estimates for the majority of obscured and unobscured AGNs (74%, 473/642), with 340 measured for the first time. With ~90% of sources at z<0.2, the survey represents a significant advance in the census of hard X-ray-selected AGNs in the local universe. In this first catalog paper, we describe the spectroscopic observations and data sets, and our initial spectral analysis. The FWHMs of the emission lines show broad agreement with the X-ray obscuration (~94%), such that Sy 1-1.8 have N_H_<10^21.9^cm^-2^, and Seyfert 2 have N_H_>10^21.9^cm^-2^. Seyfert 1.9, however, show a range of column densities. Compared to narrow-line AGNs in the SDSS, the X-ray-selected AGNs have a larger fraction of dusty host galaxies (H{alpha}/H{beta}>5), suggesting that these types of AGN are missed in optical surveys. Using the [OIII]{lambda}5007/H{beta} and [NII]{lambda}6583/H{alpha} emission-line diagnostic, about half of the sources are classified as Seyferts; ~15% reside in dusty galaxies that lack an H{beta} detection, but for which the upper limits on line emission imply either a Seyfert or LINER, ~15% are in galaxies with weak or no emission lines despite high-quality spectra, and a few percent each are LINERS, composite galaxies, H II regions, or in known beamed AGNs.
- ID:
- ivo://CDS.VizieR/J/ApJS/233/17
- Title:
- Swift/BAT AGN spectroscopic survey. V. X-ray data
- Short Name:
- J/ApJS/233/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Hard X-ray (>=10keV) observations of active galactic nuclei (AGNs) can shed light on some of the most obscured episodes of accretion onto supermassive black holes. The 70-month Swift/BAT all-sky survey, which probes the 14-195keV energy range, has currently detected 838 AGNs. We report here on the broadband X-ray (0.3-150keV) characteristics of these AGNs, obtained by combining XMM-Newton, Swift/XRT, ASCA, Chandra, and Suzaku observations in the soft X-ray band (<=10keV) with 70-month averaged Swift/BAT data. The nonblazar AGNs of our sample are almost equally divided into unobscured (N_H_<10^22^cm^-2^) and obscured (N_H_>=10^22^cm^-2^) AGNs, and their Swift/BAT continuum is systematically steeper than the 0.3-10keV emission, which suggests that the presence of a high-energy cutoff is almost ubiquitous. We discuss the main X-ray spectral parameters obtained, such as the photon index, the reflection parameter, the energy of the cutoff, neutral and ionized absorbers, and the soft excess for both obscured and unobscured AGNs.
- ID:
- ivo://CDS.VizieR/J/ApJS/209/20
- Title:
- Swift GRB catalog with X-ray data
- Short Name:
- J/ApJS/209/20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- When a massive star explodes as a gamma-ray burst (GRB), information about the explosion is retained in the properties of the prompt and afterglow emission. We report on new relations between the prompt and X-ray afterglow emission of Swift-detected GRBs found from Burst Alert Telescope (BAT) and X-Ray Telescope data covering 2004 December to 2013 August (754 in total). These relations suggest that the prompt and afterglow emission are closely linked. In particular, we find very strong correlations between the BAT 15-150keV T_90_ and the break times before and after the plateau phase in the 0.3-10keV X-ray afterglow light curves. We also find a strong anticorrelation between the photon index of the GRB prompt emission and the X-ray spectral slope of the afterglow. Moreover, anticorrelations exist between the rest-frame peak energy in the prompt emission E_peak, z_and the X-ray afterglow decay slope during the plateau phase and the break times after the plateau phase. The rest-frame break times before and after the plateau phase are also anticorrelated with the rest-frame 15-150keV luminosity and the isotropic energy during the prompt emission. A principal component analysis suggests that the GRB properties are primarily driven by the luminosity/energy release in the 15-150keV band. Luminosity functions derived at different redshifts from a log N-log S analysis indicate that the density of bright bursts is significantly lower in the local universe than in the universe at z~3, where the density of bright GRBs peaks. Using cluster analysis, we find that the duration of BAT-detected short GRBs is less than 1s.
- ID:
- ivo://CDS.VizieR/J/ApJ/774/157
- Title:
- Swift GRBs with X-ray afterglows and z<9.5
- Short Name:
- J/ApJ/774/157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gamma-ray bursts (GRBs), which have been observed up to redshifts z~9.5, can be good probes of the early universe and have the potential to test cosmological models. Dainotti's analysis of GRB Swift afterglow light curves with known redshifts and a definite X-ray plateau shows an anti-correlation between the rest-frame time when the plateau ends (the plateau end time) and the calculated luminosity at that time (or approximately an anti-correlation between plateau duration and luminosity) (Dainotti+ 2008MNRAS.391L..79D, 2010ApJ...722L.215D). Here, we present an update of this correlation with a larger data sample of 101 GRBs with good light curves. Since some of this correlation could result from the redshift dependences of these intrinsic parameters, namely, their cosmological evolution, we use the Efron-Petrosian method to reveal the intrinsic nature of this correlation. We find that a substantial part of the correlation is intrinsic and describe how we recover it and how this can be used to constrain physical models of the plateau emission, the origin of which is still unknown. The present result could help to clarify the debated nature of the plateau emission.
- ID:
- ivo://CDS.VizieR/J/ApJS/201/34
- Title:
- Swift-INTEGRAL X-ray (SIX) survey
- Short Name:
- J/ApJS/201/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The supermassive black holes at the center of active galactic nuclei (AGNs) are surrounded by obscuring matter that can block nuclear radiation. Depending on the amount of blocked radiation, the flux from the AGN can be too faint to be detected by currently flying hard X-ray (above 15keV) missions. At these energies only ~1% of the intensity of the cosmic X-ray background (CXB) can be resolved into point-like sources that are AGNs. In this work, we address the question of undetected sources contributing to the CXB with a very sensitive and new hard X-ray survey: the Swift-INTEGRAL X-ray (SIX) survey, which is obtained with the new approach of combining the Swift/BAT and INTEGRAL/IBIS X-ray observations. We merge the observations of both missions, which enhances the exposure time and reduces systematic uncertainties. As a result, we obtain a new survey over a wide sky area of 6200deg^2^ that is more sensitive than the surveys of Swift/BAT or INTEGRAL/IBIS alone. Our sample comprises 113 sources: 86 AGNs (Seyfert-like and blazars), 5 galaxies, 2 clusters of galaxies, 3 Galactic sources, 3 previously detected unidentified X-ray sources, and 14 unidentified sources. The scientific outcome from the study of the sample has been properly addressed to study the evolution of AGNs at redshift below 0.4.
- ID:
- ivo://CDS.VizieR/J/ApJS/248/21
- Title:
- Swift long gamma-ray bursts
- Short Name:
- J/ApJS/248/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The exact relationship between the long gamma-ray burst (LGRB) rate and the cosmic star formation rate (CSFR) is essential for using LGRBs as cosmological probes. In this work, we collect a large sample composed of 371 Swift LGRBs with known redshifts and prompt emission properties. We first compare the rest-frame prompt properties of these bursts in different redshift bins, finding negligible redshift evolution of the luminosity of LGRBs with L_iso_>~10^51^erg/s between z~1 and z~4. Then, by utilizing the CSFR obtained from the large-scale cosmological hydrodynamical simulation, the Illustris simulation, we calculate the cumulative redshift distribution of LGRBs under different metallicity thresholds. After comparing with our sample, we find that the predictions with a moderate threshold between 0.3Z_{sun}_<=Z_th_<=1.0Z_{sun}_ are consistent with the sample between redshift 0<z<3, while at higher redshifts, between 3<z<5, all metallicity thresholds fit the data well. When changing to an empirical model based on observations, the predictions show similar results as well. After comparing with the metallicity distribution of the observed LGRB host galaxies between 0<z<1, we confirm that the production of LGRBs in galaxies with super-solar metallicity is suppressed. Nevertheless, considering that a significant fraction of stars are born in sub-solar metallicity environments at z>~3, we suggest that, as a first approximation, LGRBs can be used as direct tracers of the CSFR in this redshift range.
- 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/216/28
- Title:
- SWXCS III. Cluster catalog from 2005-2012 Swift data
- Short Name:
- J/ApJS/216/28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Swift X-ray Cluster Survey (SWXCS) catalog obtained using archival data from the X-ray telescope (XRT) on board the Swift satellite acquired from 2005 February to 2012 November, extending the first release of the SWXCS. The catalog provides positions, soft fluxes, and, when possible, optical counterparts for a flux-limited sample of X-ray group and cluster candidates. We consider the fields with Galactic latitude |b|>20{deg} to avoid high H I column densities. We discard all of the observations targeted at groups or clusters of galaxies, as well as particular extragalactic fields not suitable to search for faint extended sources. We finally select ~3000 useful fields covering a total solid angle of ~400deg^2^. We identify extended source candidates in the soft-band (0.5-2keV) images of these fields using the software EXSdetect, which is specifically calibrated for the XRT data. Extensive simulations are used to evaluate contamination and completeness as a function of the source signal, allowing us to minimize the number of spurious detections and to robustly assess the selection function. Our catalog includes 263 candidate galaxy clusters and groups down to a flux limit of 7x10^-15^erg/cm2/s in the soft band, and the logN-logS is in very good agreement with previous deep X-ray surveys. The final list of sources is cross-correlated with published optical, X-ray, and Sunyaev-Zeldovich catalogs of clusters. We find that 137 sources have been previously identified as clusters in the literature in independent surveys, while 126 are new detections. Currently, we have collected redshift information for 158 sources (60% of the entire sample).