PS15cey and PS17cke: prospective candidates from the Pan-STARRS Search for kilonovae

ABSTRACT Time domain astronomy was revolutionized with the discovery of the first kilonova, AT2017gfo, in August 2017, which was associated with the gravitational wave signal GW170817. Since this event, numerous wide-field surveys have been optimizing search strategies to maximize their efficiency of detecting these fast and faint transients. With the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS), we have been conducting a volume-limited survey for intrinsically faint and fast-fading events to a distance of D ≃ 200 Mpc. Two promising candidates have been identified from this archival search, with sparse data – PS15cey and PS17cke. Here, we present more detailed analysis and discussion of their nature. We observe that PS15cey was a luminous, fast-declining transient at 320 Mpc. Models of BH–NS mergers with a very stiff equation of state could possibly reproduce the luminosity and decline but the physical parameters are extreme. A more likely scenario is that this was an AT2018kzr-like merger event. PS17cke was a faint and fast-declining event at 15 Mpc. We explore several explosion scenarios of this transient including models of it as a NS–NS and BH–NS merger, the outburst of a massive luminous star, and compare it against other known fast-fading transients. Although there is uncertainty in the explosion scenario due to difficulty in measuring the explosion epoch, we find PS17cke to be a plausible kilonova candidate from the model comparisons.

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Processing GOTO data with the Rubin Observatory LSST Science Pipelines I: Production of coadded frames

Publications of the Astronomical Society of Australia ◽

10.1017/pasa.2020.45 ◽

2021 ◽

Vol 38 ◽

Author(s):

J. R. Mullaney ◽

L. Makrygianni ◽

V. Dhillon ◽

S. Littlefair ◽

K. Ackley ◽

...

Keyword(s):

Gravitational Wave ◽

Time Domain ◽

Wide Area ◽

Wide Field ◽

Process Data ◽

Data Production ◽

The Time Domain ◽

Further Development ◽

High Cadence

Abstract The past few decades have seen the burgeoning of wide-field, high-cadence surveys, the most formidable of which will be the Legacy Survey of Space and Time (LSST) to be conducted by the Vera C. Rubin Observatory. So new is the field of systematic time-domain survey astronomy; however, that major scientific insights will continue to be obtained using smaller, more flexible systems than the LSST. One such example is the Gravitational-wave Optical Transient Observer (GOTO) whose primary science objective is the optical follow-up of gravitational wave events. The amount and rate of data production by GOTO and other wide-area, high-cadence surveys presents a significant challenge to data processing pipelines which need to operate in near-real time to fully exploit the time domain. In this study, we adapt the Rubin Observatory LSST Science Pipelines to process GOTO data, thereby exploring the feasibility of using this ‘off-the-shelf’ pipeline to process data from other wide-area, high-cadence surveys. In this paper, we describe how we use the LSST Science Pipelines to process raw GOTO frames to ultimately produce calibrated coadded images and photometric source catalogues. After comparing the measured astrometry and photometry to those of matched sources from PanSTARRS DR1, we find that measured source positions are typically accurate to subpixel levels, and that measured L-band photometries are accurate to $\sim50$ mmag at $m_L\sim16$ and $\sim200$ mmag at $m_L\sim18$ . These values compare favourably to those obtained using GOTO’s primary, in-house pipeline, gotophoto, in spite of both pipelines having undergone further development and improvement beyond the implementations used in this study. Finally, we release a generic ‘obs package’ that others can build upon, should they wish to use the LSST Science Pipelines to process data from other facilities.

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Detecting the Hadron-Quark Phase Transition with Gravitational Waves

Universe ◽

10.3390/universe5060156 ◽

2019 ◽

Vol 5 (6) ◽

pp. 156 ◽

Cited By ~ 5

Author(s):

Matthias Hanauske ◽

Luke Bovard ◽

Elias Most ◽

Jens Papenfort ◽

Jan Steinheimer ◽

...

Keyword(s):

Phase Transition ◽

Neutron Star ◽

Equation Of State ◽

Gravitational Wave ◽

Compact Star ◽

Binary Neutron Star ◽

Interesting Part ◽

Merger Event ◽

Tidal Deformations ◽

Quark Phase

The long-awaited detection of a gravitational wave from the merger of a binary neutron star in August 2017 (GW170817) marks the beginning of the new field of multi-messenger gravitational wave astronomy. By exploiting the extracted tidal deformations of the two neutron stars from the late inspiral phase of GW170817, it is now possible to constrain several global properties of the equation of state of neutron star matter. However, the most interesting part of the high density and temperature regime of the equation of state is solely imprinted in the post-merger gravitational wave emission from the remnant hypermassive/supramassive neutron star. This regime was not observed in GW170817, but will possibly be detected in forthcoming events within the current observing run of the LIGO/VIRGO collaboration. Numerous numerical-relativity simulations of merging neutron star binaries have been performed during the last decades, and the emitted gravitational wave profiles and the interior structure of the generated remnants have been analysed in detail. The consequences of a potential appearance of a hadron-quark phase transition in the interior region of the produced hypermassive neutron star and the evolution of its underlying matter in the phase diagram of quantum cromo dynamics will be in the focus of this article. It will be shown that the different density/temperature regions of the equation of state can be severely constrained by a measurement of the spectral properties of the emitted post-merger gravitational wave signal from a future binary compact star merger event.

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Discovering strongly lensed QSOs from unresolved light curves

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab241 ◽

2021 ◽

Vol 502 (2) ◽

pp. 2912-2921

Author(s):

Yiping Shu ◽

Vasily Belokurov ◽

N Wyn Evans

Keyword(s):

Time Domain ◽

Time Delays ◽

True Positive Rate ◽

Light Curves ◽

True Positive ◽

Rapid Response System ◽

Response System ◽

Positive Rate ◽

Deep Survey ◽

System 1

ABSTRACT We present a new method of discovering galaxy-scale, strongly lensed QSO systems from unresolved light curves using the autocorrelation function. The method is tested on five rungs of simulated light curves from the Time Delay Challenge 1 that were designed to match the light-curve qualities from existing, ongoing, and forthcoming time-domain surveys such as the Medium Deep Survey of the Panoramic Survey Telescope And Rapid Response System 1, the Zwicky Transient Facility, and the Rubin Observatory Legacy Survey of Space and Time. Among simulated lens systems for which time delays can be successfully measured by current best algorithms, our method achieves an overall true-positive rate of 28–58 per cent for doubly imaged QSOs (doubles) and 36–60 per cent for quadruply imaged QSOs (quads) while maintains ≲10 per cent false-positive rates. We also apply the method to observed light curves of 22 known strongly lensed QSOs, and recover 20 per cent of doubles and 25 per cent of quads. The tests demonstrate the capability of our method for discovering strongly lensed QSOs from major time domain surveys. The performance of our method can be further improved by analysing multifilter light curves and supplementing with morphological, colour, and/or astrometric constraints. More importantly, our method is particularly useful for discovering small-separation strongly lensed QSOs, complementary to traditional imaging-based methods.

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Merging neutron star binaries: equation of state and electrodynamics

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312023459 ◽

2012 ◽

Vol 8 (S291) ◽

pp. 149-154

Author(s):

Dong Lai

Keyword(s):

Neutron Star ◽

Equation Of State ◽

Gravitational Wave ◽

Electromagnetic Radiation ◽

Symmetry Energy ◽

Fast Imaging ◽

Wide Field ◽

Nuclear Symmetry Energy ◽

Imaging Telescopes

AbstractMerging neutron star (NS) binaries may be detected by ground-based gravitational wave (GW) interferometers (e.g. LIGO/VIRGO) within this decade and may also generate electromagnetic radiation detectable by wide-field, fast imaging telescopes that are coming online. The GWs can provide new constraint on the NS equation of state (including mass-radius relation and the related nuclear symmetry energy). This paper reviews various hydrodynamical and electrodynamical processes in coalescing NS binaries, with focus on the pre-merger phase.

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Processing GOTO survey data with the Rubin Observatory LSST Science Pipelines II: Forced Photometry and lightcurves

Publications of the Astronomical Society of Australia ◽

10.1017/pasa.2021.19 ◽

2021 ◽

Vol 38 ◽

Author(s):

L. Makrygianni ◽

J. Mullaney ◽

V. Dhillon ◽

S. Littlefair ◽

K. Ackley ◽

...

Keyword(s):

Gravitational Wave ◽

Sloan Digital Sky Survey ◽

Rapid Response System ◽

Process Data ◽

Repeated Observations ◽

Response System ◽

Sky Survey ◽

Optical Transient ◽

Selection Of ◽

Better Than

Abstract We have adapted the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) Science Pipelines to process data from the Gravitational-wave Optical Transient Observer (GOTO) prototype. In this paper, we describe how we used the LSST Science Pipelines to conduct forced photometry measurements on nightly GOTO data. By comparing the photometry measurements of sources taken on multiple nights, we find that the precision of our photometry is typically better than 20 mmag for sources brighter than 16 mag. We also compare our photometry measurements against colour-corrected Panoramic Survey Telescope and Rapid Response System photometry and find that the two agree to within 10 mmag (1 $\sigma$ ) for bright (i.e., $\sim 14{\rm th} \mathrm{mag}$ ) sources to 200 mmag for faint (i.e., $\sim 18{\rm th} \mathrm{mag}$ ) sources. Additionally, we compare our results to those obtained by GOTO’s own in-house pipeline, gotophoto, and obtain similar results. Based on repeatability measurements, we measure a $5\sigma$ L-band survey depth of between 19 and 20 magnitudes, depending on observing conditions. We assess, using repeated observations of non-varying standard Sloan Digital Sky Survey stars, the accuracy of our uncertainties, which we find are typically overestimated by roughly a factor of two for bright sources (i.e., $< 15{\rm th} \mathrm{mag}$ ), but slightly underestimated (by roughly a factor of 1.25) for fainter sources ( $> 17{\rm th} \mathrm{mag}$ ). Finally, we present lightcurves for a selection of variable sources and compare them to those obtained with the Zwicky Transient Factory and GAIA. Despite the LSST Software Pipelines still undergoing active development, our results show that they are already delivering robust forced photometry measurements from GOTO data.

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Implementation of a Multicenter Rapid Response System in Pediatric Academic Hospitals Is Effective

PEDIATRICS ◽

10.1542/peds.2010-0756d ◽

2011 ◽

Vol 128 (1) ◽

pp. peds.2010-0756d-peds.2010-0756d

Keyword(s):

Rapid Response ◽

Rapid Response System ◽

Response System ◽

Academic Hospitals

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Faculty Opinions recommendation of Effect of a rapid response system for patients in shock on time to treatment and mortality during 5 years.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1102350.559386 ◽

2008 ◽

Author(s):

Patrick Ray

Keyword(s):

Rapid Response ◽

Rapid Response System ◽

Time To Treatment ◽

Response System

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Testing the evolution of correlations between supermassive black holes and their host galaxies using eight strongly lensed quasars

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2992 ◽

2020 ◽

Vol 501 (1) ◽

pp. 269-280

Author(s):

Xuheng Ding ◽

Tommaso Treu ◽

Simon Birrer ◽

Adriano Agnello ◽

Dominique Sluse ◽

...

Keyword(s):

Black Holes ◽

Hubble Space Telescope ◽

High Redshift ◽

Galactic Nuclei ◽

Host Galaxy ◽

Wide Field ◽

Host Galaxies ◽

Field Surveys ◽

Instrumental Resolution ◽

The Moment

ABSTRACT One of the main challenges in using high-redshift active galactic nuclei (AGNs) to study the correlations between the mass of a supermassive black hole ($\mathcal {M}_{\rm BH}$) and the properties of its active host galaxy is instrumental resolution. Strong lensing magnification effectively increases instrumental resolution and thus helps to address this challenge. In this work, we study eight strongly lensed AGNs with deep Hubble Space Telescope imaging, using the lens modelling code lenstronomy to reconstruct the image of the source. Using the reconstructed brightness of the host galaxy, we infer the host galaxy stellar mass based on stellar population models. $\mathcal {M}_{\rm BH}$ are estimated from broad emission lines using standard methods. Our results are in good agreement with recent work based on non-lensed AGNs, demonstrating the potential of using strongly lensed AGNs to extend the study of the correlations to higher redshifts. At the moment, the sample size of lensed AGNs is small and thus they provide mostly a consistency check on systematic errors related to resolution for non-lensed AGNs. However, the number of known lensed AGNs is expected to increase dramatically in the next few years, through dedicated searches in ground- and space-based wide-field surveys, and they may become a key diagnostic of black holes and galaxy co-evolution.

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