Physical Properties of 15 Quasars at z 6.5 Mazzucchelli, C.; Bañados, E.; Venemans, B. P. ...
The Astrophysical journal,
11/2017, Letnik:
849, Številka:
2
Journal Article
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Quasars are galaxies hosting accreting supermassive black holes; due to their brightness, they are unique probes of the early universe. To date, only a few quasars have been reported at (<800 Myr ...after the big bang). In this work, we present six additional quasars discovered using the Pan-STARRS1 survey. We use a sample of 15 quasars to perform a homogeneous and comprehensive analysis of this highest-redshift quasar population. We report four main results: (1) the majority of quasars show large blueshifts of the broad C iv λ1549 emission line compared to the systemic redshift of the quasars, with a median value ∼3× higher than a quasar sample at ; (2) we estimate the quasars' black hole masses ( (0.3-5) × 109 M ) via modeling of the Mg ii λ2798 emission line and rest-frame UV continuum and find that quasars at high redshift accrete their material (with ) at a rate comparable to a luminosity-matched sample at lower redshift, albeit with significant scatter (0.4 dex); (3) we recover no evolution of the Fe ii/Mg ii abundance ratio with cosmic time; and (4) we derive near-zone sizes and, together with measurements for quasars from recent work, confirm a shallow evolution of the decreasing quasar near-zone sizes with redshift. Finally, we present new millimeter observations of the C ii 158 m emission line and underlying dust continuum from NOEMA for four quasars and provide new accurate redshifts and C ii/infrared luminosity estimates. The analysis presented here shows the large range of properties of the most distant quasars.
Pan-STARRS Photometric and Astrometric Calibration Magnier, Eugene. A.; Schlafly, Edward. F.; Finkbeiner, Douglas P. ...
The Astrophysical journal. Supplement series,
11/2020, Letnik:
251, Številka:
1
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Abstract
We present the details of the photometric and astrometric calibration of the Pan-STARRS1 3
π
Survey. The photometric goals were to reduce the systematic effects introduced by the camera and ...detectors, and to place all of the observations onto a photometric system with consistent zero-points over the entire area surveyed, the ≈30,000 deg
2
north of
δ
= −30°. Using external comparisons, we demonstrate that the resulting photometric system is consistent across the sky to between 7 and 12.4 mmag depending on the filter. For bright stars, the systematic error floor for individual measurements is (
σ
g
,
σ
r
,
σ
i
,
σ
z
,
σ
y
) = (14, 14, 15, 15, 18) mmag. The astrometric calibration compensates for similar systematic effects so that positions, proper motions, and parallaxes are reliable as well. The bright-star systematic error floor for individual astrometric measurements is 16 mas. The Pan-STARRS Data Release 2 (DR2) astrometric system is tied to the Gaia DR1 coordinate frame with a systematic uncertainty of ∼5 mas.
We present a systematic search for periodically varying quasar and supermassive black hole binary (SMBHB) candidates in the Pan-STARRS1 Medium Deep Survey (MDS). From ∼9000 color-selected quasars in ...an ∼50 °2 sky area, we initially identify 26 candidates with more than 1.5 cycles of variation. We extend the baseline of observations via our imaging campaign with the Discovery Channel Telescope and the Las Cumbres Observatory network and reevaluate the candidates using a more rigorous, maximum likelihood method. Using a range of statistical criteria and assuming the damped random walk model for normal quasar variability, we identify one statistically significant periodic candidate. We also investigate the capabilities of detecting SMBHBs with the Large Synoptic Survey Telescope using our study with MDS as a benchmark and explore any complementary multiwavelength evidence for SMBHBs in our sample.
We use 1169 Pan-STARRS supernovae (SNe) and 195 low-z (z < 0.1) SNe Ia to measure cosmological parameters. Though most Pan-STARRS SNe lack spectroscopic classifications, in a previous paper we ...demonstrated that photometrically classified SNe can be used to infer unbiased cosmological parameters by using a Bayesian methodology that marginalizes over core-collapse (CC) SN contamination. Our sample contains nearly twice as many SNe as the largest previous SN Ia compilation. Combining SNe with cosmic microwave background (CMB) constraints from Planck, we measure the dark energy equation-of-state parameter w to be −0.989 0.057 (stat+sys). If w evolves with redshift as w(a) = w0 + wa(1 − a), we find w0 = −0.912 0.149 and wa = −0.513 0.826. These results are consistent with cosmological parameters from the Joint Light-curve Analysis and the Pantheon sample. We try four different photometric classification priors for Pan-STARRS SNe and two alternate ways of modeling CC SN contamination, finding that no variant gives a w differing by more than 2% from the baseline measurement. The systematic uncertainty on w due to marginalizing over CC SN contamination, , is the third-smallest source of systematic uncertainty in this work. We find limited (1.6 ) evidence for evolution of the SN color-luminosity relation with redshift, a possible systematic that could constitute a significant uncertainty in future high-z analyses. Our data provide one of the best current constraints on w, demonstrating that samples with ∼5% CC SN contamination can give competitive cosmological constraints when the contaminating distribution is marginalized over in a Bayesian framework.
The Pan-STARRS Data-processing System Magnier, Eugene A.; Chambers, K. C.; Flewelling, H. A. ...
The Astrophysical journal. Supplement series,
11/2020, Letnik:
251, Številka:
1
Journal Article
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Abstract
The Pan-STARRS data-processing system is responsible for the steps needed to downloaded, archive, and process all images obtained by the Pan-STARRS telescopes, including real-time detection ...of transient sources such as supernovae and moving objects including potentially hazardous asteroids. With a nightly data volume of up to 4 TB and an archive of over 4 PB of raw imagery, Pan-STARRS is solidly in the realm of Big Data astronomy. The full data-processing system consists of several subsystems covering the wide range of necessary capabilities. This article describes the Image Processing Pipeline and its connections to both the summit data systems and the outward-facing systems downstream. The latter include the Moving Object Processing System (MOPS) and the public database: the Published Science Products Subsystem.
Abstract
The Pan-STARRS1 (PS1) Science Consortium has carried out a set of imaging surveys using the 1.4 gigapixel GPC1 camera on the PS1 telescope. As this camera is composed of many individual ...electronic readouts and covers a very large field of view, great care was taken to ensure that the many instrumental effects were corrected to produce the most uniform detector response possible. We present the image-detrending steps used as part of the processing of the data contained within the public release of Pan-STARRS1 Data Release 1 (DR1). In addition to the single image processing, the methods used to transform the 375,573 individual exposures into a common sky-oriented grid are discussed, as well as those used to produce both the image stack and difference combination products.
Abstract
Over 3 billion astronomical sources have been detected in the more than 22 million orthogonal transfer CCD images obtained as part of the Pan-STARRS1 3
π
survey. Over 85 billion instances of ...those sources have been automatically detected and characterized by the Pan-STARRS Image Processing Pipeline photometry software,
psphot
. This fast, automatic, and reliable software was developed for the Pan-STARRS project but is easily adaptable to images from other telescopes. We describe the analysis of the astronomical sources by
psphot
in general as well as for the specific case of the third processing version used for the first two public releases of the Pan-STARRS 3
π
Survey data.
ABSTRACT We present a systematic search for periodically varying quasars and supermassive black hole binary (SMBHB) candidates in the Pan-STARRS1 (PS1) Medium Deep Survey's MD09 field. From a ...color-selected sample of 670 quasars extracted from a multi-band deep-stack catalog of point sources, we locally select variable quasars and look for coherent periods with the Lomb-Scargle periodogram. Three candidates from our sample demonstrate strong variability for more than ∼3 cycles, and their PS1 light curves are well fitted to sinusoidal functions. We test the persistence of the candidates' apparent periodic variations detected during the 4.2 years of the PS1 survey with archival photometric data from the SDSS Stripe 82 survey or new monitoring with the Large Monolithic Imager at the Discovery Channel Telescope. None of the three periodic candidates (including PSO J334.2028+1.4075) remain persistent over the extended baseline of 7-14 years, corresponding to a detection rate of <1 in 670 quasars in a search area of 5 deg2. Even though SMBHBs should be a common product of the hierarchal growth of galaxies, and periodic variability in SMBHBs has been theoretically predicted, a systematic search for such signatures in a large optical survey is strongly limited by its temporal baseline and the "red noise" associated with normal quasar variability. We show that follow-up long-term monitoring ( 5 cycles) is crucial to our search for these systems.
ABSTRACT Luminous quasars at can be studied in detail with the current generation of telescopes and provide us with unique information on the first gigayear of the universe. Thus far, these studies ...have been statistically limited by the number of quasars known at these redshifts. Such quasars are rare, and therefore, wide-field surveys are required to identify them, and multiwavelength data are required to separate them efficiently from their main contaminants, the far more numerous cool dwarfs. In this paper, we update and extend the selection for the quasars presented in Bañados et al. (2014) using the Pan-STARRS1 (PS1) survey. We present the PS1 distant quasar sample, which currently consists of 124 quasars in the redshift range that satisfy our selection criteria. Of these quasars, 77 have been discovered with PS1, and 63 of them are newly identified in this paper. We present the composite spectra of the PS1 distant quasar sample. This sample spans a factor of ∼20 in luminosity and shows a variety of emission line properties. The number of quasars at presented in this work almost doubles the previously known quasars at these redshifts, marking a transition phase from studies of individual sources to statistical studies of the high-redshift quasar population, which was impossible with earlier, smaller samples.
THE Pan-STARRS1 PHOTOMETRIC SYSTEM TONRY, J. L; STUBBS, C. W; MAGNIER, E. A ...
The Astrophysical journal,
05/2012, Letnik:
750, Številka:
2
Journal Article
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The Pan-STARRS1 survey is collecting multi-epoch, multi-color observations of the sky north of declination -30 Degree-Sign to unprecedented depths. These data are being photometrically and ...astrometrically calibrated and will serve as a reference for many other purposes. In this paper, we present our determination of the Pan-STARRS1 photometric system: g{sub P1}, r{sub P1}, i{sub P1}, z{sub P1}, y{sub P1}, and w{sub P1}. The Pan-STARRS1 photometric system is fundamentally based on the Hubble Space Telescope Calspec spectrophotometric observations, which in turn are fundamentally based on models of white dwarf atmospheres. We define the Pan-STARRS1 magnitude system and describe in detail our measurement of the system passbands, including both the instrumental sensitivity and atmospheric transmission functions. By-products, including transformations to other photometric systems, Galactic extinction, and stellar locus, are also provided. We close with a discussion of remaining systematic errors.
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