We present the discovery of PS18kh, a tidal disruption event discovered at the center of SDSS J075654.53+341543.6 (d 322 Mpc) by the Pan-STARRS Survey for Transients. Our data set includes ...pre-discovery survey data from Pan-STARRS, the All-sky Automated Survey for Supernovae, and the Asteroid Terrestrial-impact Last Alert System as well as high-cadence, multiwavelength follow-up data from ground-based telescopes and Swift, spanning from 56 days before peak light until 75 days after. The optical/UV emission from PS18kh is well-fit as a blackbody with temperatures ranging from T 12,000 K to T 25,000 K and it peaked at a luminosity of L 8.8 × 1043 erg s−1. PS18kh radiated E = (3.45 0.22) × 1050 erg over the period of observation, with (1.42 0.20) × 1050 erg being released during the rise to peak. Spectra of PS18kh show a changing, boxy/double-peaked H emission feature, which becomes more prominent over time. We use models of non-axisymmetric accretion disks to describe the profile of the H line and its evolution. We find that at early times the high accretion rate leads the disk to emit a wind which modifies the shape of the line profile and makes it bell-shaped. At late times, the wind becomes optically thin, allowing the non-axisymmetric perturbations to show up in the line profile. The line-emitting portion of the disk extends from rin ∼ 60rg to an outer radius of rout ∼ 1400rg and the perturbations can be represented either as an eccentricity in the outer rings of the disk or as a spiral arm in the inner disk.
We report the discovery and multiwavelength data analysis of the peculiar optical transient, ATLAS17aeu. This transient was identified in the sky map of the LIGO gravitational wave event GW 170104 by ...our ATLAS and Pan-STARRS coverage. ATLAS17aeu was discovered 23.1 hr after GW 170104 and rapidly faded over the next three nights, with a spectrum revealing a blue featureless continuum. The transient was also detected as a fading X-ray source by Swift and in the radio at 6 and 15 GHz. The gamma-ray burst GRB 170105A was detected by three satellites 19.04 hr after GW 170104 and 4.10 hr before our first optical detection. We analyze the multiwavelength fluxes in the context of the known GRB population and discuss the observed sky rates of GRBs and their afterglows. We find it statistically likely that ATLAS17aeu is an afterglow associated with GRB 170105A, with a chance coincidence ruled out at the 99% confidence or 2.6 . A long, soft GRB within a redshift range of would be consistent with all the observed multiwavelength data. The Poisson probability of a chance occurrence of GW 170104 and ATLAS17aeu is p = 0.04. This is the probability of a chance coincidence in 2D sky location and in time. These observations indicate that ATLAS17aeu is plausibly a normal GRB afterglow at significantly higher redshift than the distance constraint for GW 170104 and therefore a chance coincidence. However, if a redshift of the faint host were to place it within the GW 170104 distance range, then physical association with GW 170104 should be considered.
ABSTRACT
GW190425 is the second of two binary neutron star (BNS) merger events to be significantly detected by the Laser Interferometer Gravitational Wave (GW) Observatory (LIGO), Virgo and the ...Kamioka Gravitational Wave (KAGRA) detector network. With a detection only in LIGO Livingston, the skymap containing the source was large and no plausible electromagnetic counterpart was found in real-time searching in 2019. Here, we summarize Asteroid Terrestrial-Impact Last Alert System (ATLAS) and Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) wide-field optical coverage of the skymap beginning within 1 and 3 h, respectively, of the GW190425 merger time. More recently, a potential coincidence between GW190425 and a fast radio burst FRB 20190425A has been suggested, given their spatial and temporal coincidences. The smaller sky localization area of FRB 20190425A and its dispersion measure led to the identification of a likely host galaxy, UGC 10667 at a distance of 141 ± 10 Mpc. Our optical imaging covered the galaxy 6.0 h after GW190425 was detected and 3.5 h after the FRB 20190425A. No optical emission was detected and further imaging at +1.2 and +13.2 d also revealed no emission. If the FRB 20190425A and GW190425 association were real, we highlight our limits on kilonova emission from a BNS merger in UGC 10667. The model for producing FRB 20190425A from a BNS merger involves a supramassive magnetized neutron star spinning down by dipole emission on the time-scale of hours. We show that magnetar-enhanced kilonova emission is ruled out by optical upper limits. The lack of detected optical emission from a kilonova in UGC 10667 disfavours, but does not disprove, the FRB–GW link for this source.
The rotational state of asteroids is controlled by various physical mechanisms including collisions, internal damping and the Yarkovsky-O'Keefe-Radzievskii-Paddack effect. We have analysed the ...changes in magnitude between consecutive detections of ~60 000 asteroids measured by the Panoramic Survey Telescope and Rapid Response System (PanSTARRS) 1 survey during its first 18 months of operations. We have attempted to explain the derived brightness changes physically and through the application of a simple model. We have found a tendency towards smaller magnitude variations with decreasing diameter for objects of 1 < D < 8 km. Assuming the shape distribution of objects in this size range to be independent of size and composition our model suggests a population with average axial ratios 1 : 0.85 plus or minus 0.13 : 0.71 plus or minus 0.13, with larger objects more likely to have spin axes perpendicular to the orbital plane.
ABSTRACT We present a search for an electromagnetic counterpart of the gravitational-wave source GW151226. Using the Pan-STARRS1 telescope we mapped out 290 square degrees in the optical iP1 filter, ...starting 11.5 hr after the LIGO information release and lasting for an additional 28 days. The first observations started 49.5 hr after the time of the GW151226 detection. We typically reached sensitivity limits of iP1 = 20.3-20.8 and covered 26.5% of the LIGO probability skymap. We supplemented this with ATLAS survey data, reaching 31% of the probability region to shallower depths of m 19. We found 49 extragalactic transients (that are not obviously active galactic nuclei), including a faint transient in a galaxy at 7 Mpc (a luminous blue variable outburst) plus a rapidly decaying M-dwarf flare. Spectral classification of 20 other transient events showed them all to be supernovae. We found an unusual transient, PS15dpn, with an explosion date temporally coincident with GW151226, that evolved into a type Ibn supernova. The redshift of the transient is secure at z = 0.1747 0.0001 and we find it unlikely to be linked, since the luminosity distance has a negligible probability of being consistent with that of GW151226. In the 290 square degrees surveyed we therefore do not find a likely counterpart. However we show that our survey strategy would be sensitive to NS-NS mergers producing kilonovae at DL 100 Mpc, which is promising for future LIGO/Virgo searches.
We report the discovery of an Hr = 3.4 0.1 dwarf planet candidate by the Pan-STARRS Outer Solar System Survey. 2010 JO179 is red with (g − r) = 0.88 0.21, roughly round, and slowly rotating, with a ...period of 30.6 hr. Estimates of its albedo imply a diameter of 600-900 km. Observations sampling the span between 2005 and 2016 provide an exceptionally well determined orbit for 2010 JO179, with a semimajor axis of 78.307 0.009 au; distant orbits known to this precision are rare. We find that 2010 JO179 librates securely within the 21:5 mean-motion resonance with Neptune on 100 Myr timescales, joining the small but growing set of known distant dwarf planets on metastable resonant orbits. These imply a substantial trans-Neptunian population that shifts between stability in high-order resonances, the detached population, and the eroding population of the scattering disk.
Abstract
In Smith et al. we published estimates of the volumetric rate of supernovae within 100 Mpc. These were incorrect and we present the correct values in this corrigendum.
The Pan-STARRS1 Small Area Survey 2 Metcalfe, N; Farrow, D. J; Cole, S ...
Monthly notices of the Royal Astronomical Society,
11/2013, Letnik:
435, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The Panoramic Survey Telescope and Rapid Response System 1 (Pan-STARRS1) survey is acquiring multi-epoch imaging in five bands (g
P1, r
P1, i
P1, z
P1, y
P1) over the entire sky north of declination ...−30° (the 3π survey). In 2011 July a test area of about 70 deg2 was observed to the expected final depth of the main survey. In this, the first of a series of papers targeting the galaxy count and clustering properties of the combined multi-epoch test area data, we present a detailed investigation into the depth of the survey and the reliability of the Pan-STARRS1 analysis software. We show that the Pan-STARRS1 reduction software can recover the properties of fake sources, and show good agreement between the magnitudes measured by Pan-STARRS1 and those from Sloan Digital Sky Survey. We also examine the number of false detections apparent in the Pan-STARRS1 data. Our comparisons show that the test area survey is somewhat deeper than the Sloan Digital Sky Survey in all bands, and, in particular, the z band approaches the depth of the stacked Sloan Stripe 82 data.
ABSTRACT We describe the development and application of a Global Astrometric Solution (GAS) to the problem of Pan-STARRS1 (PS1) astrometry. Current PS1 astrometry is based on differential astrometric ...measurements using 2MASS reference stars, and thus PS1 astrometry inherits the errors of the 2MASS catalog. The GAS, based on a single, least-squares adjustment to approximately 750 k "grid stars" using over 3000 extragalactic objects as reference objects, avoids this catalog-to-catalog propagation of errors to a great extent. The GAS uses a relatively small number of quasi-stellar objects (QSOs, or distant active galactic nuclei) with very accurate (<1 mas) radio positions, referenced to the ICRF2. These QSOs provide a hard constraint in the global least-squares adjustment. Solving such a system provides absolute astrometry for all of the stars simultaneously. The concept is much cleaner than conventional astrometry but is not easy to perform for large catalogs. In this paper, we describe our method and its application to Pan-STARRS1 data. We show that large-scale systematic errors are easily corrected but our solution residuals for position (∼60 mas) are still larger than expected based on simulations (∼10 mas). We provide a likely explanation for the reason the small-scale residual errors are not corrected in our solution as would be expected.
We introduce a new technique to estimate the comet nuclear size frequency distribution (SFD) that combines a cometary activity model with a survey simulation and apply it to 150 long period comets ...(LPC) detected by the Pan-STARRS1 near-Earth object survey. The debiased LPC size-frequency distribution is in agreement with previous estimates for large comets with nuclear diameter ≳1 km but we measure a significant drop in the SFD slope for small objects with diameters <1 km and approaching only 100 m diameter. Large objects have a slope αbig = 0.72 ± 0.09(stat.) ± 0.15(sys.) while small objects behave as αsmall = 0.07 ± 0.03(stat.) ± 0.09(sys.) where the SFD is ∝10αHN and HN represents the cometary nuclear absolute magnitude. The total number of LPCs that are >1 km diameter and have perihelia q < 10 au is 0.46 ± 0.15 × 109 while there are only 2.4 ± 0.5(stat.) ± 2(sys.) × 109 objects with diameters >100 m due to the shallow slope of the SFD for diameters <1 km. We estimate that the total number of ‘potentially active’ objects with diameters ≥1 km in the Oort cloud, objects that would be defined as LPCs if their perihelia evolved to <10 au, is (1.5 ± 1) × 1012 with a combined mass of 1.3 ± 0.9 M⊕. The debiased LPC orbit distribution is broadly in agreement with expectations from contemporary dynamical models but there are discrepancies that could point towards a future ability to disentangle the relative importance of stellar perturbations and galactic tides in producing the LPC population.
•we introduce a new technique to estimate the comet nuclear size frequency distribution (SFD) that combines a cometary activity model with a survey simulation•we applied the technique to 150 long period comets (LPC) detected by the Pan-STARRS1 near-Earth object survey•we find a relatively steep slope for the SFD of large LPCs with diameters >∼3 km and a shallow slope for smaller objects•we estimate that there are (0.46±0.15)×109 active LPCs that are >1 km diameter and have perihelia q<10 au•the total number of ‘active’ objects with diameters ≥1 km in the Oort cloud, objects that would be defined as LPCs if their perihelia evolved to <10 au, is (1.5±1)×1012 with a combined mass of 1.3±0.9 M⊕.
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