Abstract We report the discovery, spectroscopic confirmation and mass modelling of the gravitationally lensed quasar system PS J0630−1201. The lens was discovered by matching a photometric quasar ...catalogue compiled from Pan-STARRS1 and Wide-field Infrared Survey Explorer photometry to the Gaia data release 1 catalogue, exploiting the high spatial resolution of the latter (full width at half-maximum ∼0.1 arcsec) to identify the three brightest components of the lensed quasar system. Follow-up spectroscopic observations with the William Herschel Telescope confirm the multiple objects are quasars at redshift zq = 3.34. Further follow-up with Keck adaptive optics high-resolution imaging reveals that the system is composed of two lensing galaxies and the quasar is lensed into an ∼2.8 arcsec separation four-image cusp configuration with a fifth image clearly visible, and a 1.0 arcsec arc due to the lensed quasar host galaxy. The system is well modelled with two singular isothermal ellipsoids, reproducing the position of the fifth image. We discuss future prospects for measuring time delays between the images and constraining any offset between mass and light using the faintly detected Einstein arcs associated with the quasar host galaxy.
Aims.
Integral field spectroscopy (IFS) with JWST NIRSpec will significantly improve our understanding of the first quasars, by providing spatially resolved, infrared spectroscopic capabilities that ...cover key rest-frame optical emission lines that have been previously unobservable.
Methods.
Here we present our results from the first two
z
> 6 quasars observed as a part of the Galaxy Assembly with NIRSpec IFS (GA-NIFS) GTO programme, with DELS J0411–0907 at
z
= 6.82 and VDES J0020–3653 at
z
= 6.86.
Results.
By observing the H
β
, O
III
λλ
4959, 5007, and H
α
emission lines in these high-
z
quasars for the first time, we measured accurate black hole masses,
M
BH
= 1.85
−0.8
+2
× 10
9
M
⊙
and 2.9
−1.3
+3.5
× 10
9
M
⊙
, corresponding to Eddington ratios of
λ
Edd
= 0.8
−0.4
+0.7
and 0.4
−0.2
+0.3
for DELS J0411–0907 and VDES J0020–3653, respectively. These provide a key comparison for existing estimates from the more uncertain Mg
II
line. We performed quasar–host decomposition using models of the quasars’ broad lines to measure the underlying host galaxies. We also discovered multiple emission line regions surrounding each of the host galaxies, which are likely companion galaxies undergoing mergers with these hosts. We measured the star formation rates, excitation mechanisms, and dynamical masses of the hosts and companions, measuring the
M
BH
/
M
dyn
ratios at high
z
using these estimators for the first time. DELS J0411–0907 and VDES J0020–3653 both lie above the local black hole–host mass relation, and are consistent with the existing observations of
z
≳ 6 quasar host galaxies with ALMA. We detected ionised outflows in O
III
λλ
4959, 5007 and H
β
from both quasars, with mass outflow rates of 58
−37
+44
and 525
−92
+75
M
⊙
yr
−1
for DELS J0411–0907 and VDES J0020–3653, much larger than their host star formation rates of < 33 and < 54
M
⊙
yr
−1
, respectively.
Conclusions.
This work highlights the exceptional capabilities of the JWST NIRSpec IFU for observing quasars in the early Universe.
We present the discovery and preliminary characterization of a gravitationally lensed quasar with a source redshift zs = 2.74 and image separation of 2.9 arcsec lensed by a foreground zl = 0.40 ...elliptical galaxy. Since optical observations of gravitationally lensed quasars show the lens system as a superposition of multiple point sources and a foreground lensing galaxy, we have developed a morphology-independent multi-wavelength approach to the photometric selection of lensed quasar candidates based on Gaussian Mixture Models (GMM) supervised machine learning. Using this technique and gi multicolour photometric observations from the Dark Energy Survey (DES), near-IR JK photometry from the VISTA Hemisphere Survey (VHS) and WISE mid-IR photometry, we have identified a candidate system with two catalogue components with iAB = 18.61 and iAB = 20.44 comprising an elliptical galaxy and two blue point sources. Spectroscopic follow-up with NTT and the use of an archival AAT spectrum show that the point sources can be identified as a lensed quasar with an emission line redshift of z = 2.739 ± 0.003 and a foreground early-type galaxy with z = 0.400 ± 0.002. We model the system as a single isothermal ellipsoid and find the Einstein radius θE ~ 1.47 arcsec, enclosed mass Menc ~ 4 × 1011 M⊙ and a time delay of ~52 d. The relatively wide separation, month scale time delay duration and high redshift make this an ideal system for constraining the expansion rate beyond a redshift of 1.
We present XMM-Newton X-ray observations and analysis of three DES \(z>6.5\) quasars (VDES J0020\(-\)3653 at \(z=6.824\), VDES J0244\(-\)5008 at \(z=6.724\) and VDES J0224\(-\)4711 at \(z=6.526\)) ...and six other quasars with \(6.438 < z < 6.747\) from the XMM-Newton public archive. Two of the nine quasars are detected at a high (\(>\)4\(\sigma\)) significance level: VDES J0224\(-\)4711(z=6.53) at \(9\sigma\) and PSO J159\(-\)02 (\(z=6.38\)) at \(8\sigma\). They have a photon index of \(\Gamma=1.82^{+0.29}_{-0.27}\) and \(\Gamma=1.94^{+0.31}_{-0.29}\) respectively, which is consistent with the mean value of \(\sim1.9\) found for quasars at all redshifts. The rest-frame \(2-10\) keV luminosity of VDES J0224\(-\)4711, is \(L_{2-10\mathrm{keV}} = (2.92\pm0.43)\times10^{45}\;\mathrm{erg\;s^{-1}}\), which makes this quasar one of the most X-ray luminous quasars at \(z>5.5\) and the most X-ray luminous quasar at \(z>6.5\), with a luminosity 6 times and 2.5 times larger than ULAS J1120+0641 (\(z=7.08\)) and ULAS J1342+0928 (\(z=7.54\)) respectively. The X-ray-to-optical power-law slopes of the nine quasars are consistent with the previously observed anti-correlation of \(\alpha_{ox}\) with UV luminosity \(L_{2500\mathrmÅ}\). We find no evidence for evolution of \(\alpha_{ox}\) with redshift when the anti-correlation with UV luminosity is taken into account. Similar to previous studies at z\(\sim\)6 we have found remarkably consistent X-ray spectral properties between low (z\(\sim\)1) and high-redshift quasars. Our results add further evidence to the picture that the observable properties of high luminosity quasars over the UV to X-ray spectral region have not evolved significantly from \(z\sim7\) to the present day and that quasars comparable to local versions existed 800 million years after the big bang.
A&A 678, A191 (2023) Integral Field Spectroscopy (IFS) with JWST NIRSpec will significantly
improve our understanding of the first quasars, by providing spatially
resolved, infrared spectroscopic ...capabilities which cover key rest-frame
optical emission lines that have been previously unobservable. Here we present
our results from the first two z>6 quasars observed as a part of the Galaxy
Assembly with NIRSpec IFS (GA-NIFS) GTO program, DELS J0411-0907 at z=6.82 and
VDES J0020-3653 at z=6.86. By observing the H$\beta$, OIII, and H$\alpha$
emission lines in these high-z quasars for the first time, we measure accurate
black hole masses, $M_{\rm{BH}}=1.85e9$ and $2.9e9$M$_\odot$, corresponding to
Eddington ratios of $\lambda_{\rm{Edd}}=0.8$ and 0.4 for DELS J0411-0907 and
VDES J0020-3653 respectively. These provide a key comparison for existing
estimates from the more uncertain MgII line. We perform quasar-host
decomposition using models of the quasars' broad lines to measure the
underlying host galaxies. We also discover multiple emission line regions
surrounding each of the host galaxies, which are likely companion galaxies
undergoing mergers with these hosts. We measure the star formation rates,
excitation mechanisms, and dynamical masses of the hosts and companions,
measuring the $M_{\rm{BH}}/M_{\rm{dyn}}$ ratios at high-z using these
estimators for the first time. DELS J0411-0907 and VDES J0020-3653 both lie
above the local black hole--host mass relation, and are consistent with the
existing observations of $z\gtrsim6$ quasar host galaxies with ALMA. We detect
ionized outflows in OIII and H$\beta$ from both quasars, with mass outflow
rates of 58 and 525 M$_{\odot}$/yr for DELS J0411-0907 and VDES J0020-3653,
much larger than their host star formation rates of <33 and <54 M$_\odot$/yr.
This work highlights the exceptional capabilities of the JWST NIRSpec IFU for
observing quasars in the early Universe.
The Vera C. Rubin Observatory will advance many areas of astronomy over the next decade with its unique wide-fast-deep multi-color imaging survey, the Legacy Survey of Space and Time (LSST). The LSST ...will produce approximately 20TB of raw data per night, which will be automatically processed by the LSST Science Pipelines to generate science-ready data products -- processed images, catalogs and alerts. To ensure that these data products enable transformative science with LSST, stringent requirements have been placed on their quality and scientific fidelity, for example on image quality and depth, astrometric and photometric performance, and object recovery completeness. In this paper we introduce faro, a framework for automatically and efficiently computing scientific performance metrics on the LSST data products for units of data of varying granularity, ranging from single-detector to full-survey summary statistics. By measuring and monitoring metrics, we are able to evaluate trends in algorithmic performance and conduct regression testing during development, compare the performance of one algorithm against another, and verify that the LSST data products will meet performance requirements by comparing to specifications. We present initial results using faro to characterize the performance of the data products produced on simulated and precursor data sets, and discuss plans to use faro to verify the performance of the LSST commissioning data products.
We present the discovery of a new \(z \sim 6.8\) quasar discovered with the near-IR VISTA Hemisphere Survey (VHS) which has been spectroscopically confirmed by the ESO New Technology Telescope (NTT) ...and the Magellan telescope. This quasar has been selected by spectral energy distribution (SED) classification using near infrared data from VISTA, optical data from Pan-STARRS, and mid-IR data from WISE. The SED classification algorithm is used to statistically rank two classes; foreground Galactic low-mass stars and high redshift quasars, prior to spectroscopic observation. Forced photometry on Pan-STARRS pixels for VHS J0411-0907 allows to improve the SED classification reduced-\(\chi^2\) and photometric redshift. VHS J0411-0907 (\(z=6.82\), \(y_{AB} = 20.1\) mag, \(J_{AB} = 20.0\) mag) has the brightest J-band continuum magnitude of the nine known quasars at \(z > 6.7\) and is currently the highest redshift quasar detected in the Pan-STARRS survey. This quasar has one of the lowest black hole mass (\(M_{\rm{BH}}= (6.13 \pm 0.51)\times 10^8\:\mathrm{M_{\odot}}\)) and the highest Eddington ratio (\(2.37\pm0.22\)) of the known quasars at \(z>6.5\). The high Eddington ratio indicates that some very high-\(z\) quasars are undergoing super Eddington accretion. We also present coefficients of the best polynomials fits for colours vs spectral type on the Pan-STARRS, VISTA and WISE system for MLT dwarfs and present a forecast for the expected numbers of quasars at \(z>6.5\).
The paper presents the third data release of Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP), a wide-field multi-band imaging survey with the Subaru 8.2m telescope. HSC-SSP has three survey ...layers (Wide, Deep, and UltraDeep) with different area coverages and depths, designed to address a wide array of astrophysical questions. This third release from HSC-SSP includes data from 278 nights of observing time and covers about 670 square degrees in all five broad-band filters at the full depth (\(\sim26\)~mag at \(5\sigma\)) in the Wide layer. If we include partially observed area, the release covers 1,470 square degrees. The Deep and UltraDeep layers have \(\sim80\%\) of the originally planned integration times, and are considered done, as we have slightly changed the observing strategy in order to compensate for various time losses. There are a number of updates in the image processing pipeline. Of particular importance is the change in the sky subtraction algorithm; we subtract the sky on small scales before the detection and measurement stages, which has significantly reduced false detections. Thanks to this and other updates, the overall quality of the processed data has improved since the previous release. However, there are limitations in the data (for example, the pipeline is not optimized for crowded fields), and we encourage the user to check the quality assurance plots as well as a list of known issues before exploiting the data. The data release website is https://hsc-release.mtk.nao.ac.jp/.
We present measurements of the mean and scatter of the IGM Lyman-{\alpha} opacity at 4.9 < z < 6.1 along the lines of sight of 62 quasars at z > 5.7, the largest sample assembled at these redshifts ...to date by a factor of two. The sample size enables us to sample cosmic variance at these redshifts more robustly than ever before. The spectra used here were obtained by the SDSS, DES-VHS and SHELLQs collaborations, drawn from the ESI and X-Shooter archives, reused from previous studies or observed specifically for this work. We measure the effective optical depth of Lyman-{\alpha} in bins of 10, 30, 50 and 70 cMpc h-1, construct cumulative distribution functions under two treatments of upper limits on flux and explore an empirical analytic fit to residual Lyman-{\alpha} transmission. We verify the consistency of our results with those of previous studies via bootstrap re-sampling and confirm the existence of tails towards high values in the opacity distributions, which may persist down to z = 5.2. Comparing our results with predictions from cosmological simulations, we find further strong evidence against models that include a spatially uniform ionizing background and temperature-density relation. We also compare to IGM models that include either a fluctuating UVB dominated by rare quasars or temperature fluctuations due to patchy reionization. Although both models produce better agreement with the observations, neither fully captures the observed scatter in IGM opacity. Our sample of 62 z > 5.7 quasar spectra opens many avenues for future study of the reionisation epoch.
PDF
