We present photometry of the large scale environments of a sample of twelve broad line AGN with $0.06 < z < 0.37$ from deep images in the SDSS $u$, $g$, $r$, and $i$ filters taken with the 90Prime prime focus camera on the Steward Observatory Bok Telescope. We measure galaxy clustering around these AGN using two standard techniques: correlation amplitude (B$_{gq}$) and the two point correlation function. We find average correlation amplitudes for the 10 radio quiet objects in the sample equal to (9$\pm$18, 144$\pm$114, -39$\pm$56, 295$\pm$260) Mpc$^{1.77}$ in ($u$, $g$, $r$, $i$), all consistent with the expectation from galaxy clustering. Using a ratio of the galaxy-quasar cross-correlation function to the galaxy autocorrelation function, we calculate the relative bias of galaxies and AGN, $b_{gq}$. The bias in the $u$ band, $b_{gq}=3.08\pm0.51$ is larger compared to that calculated in the other bands, but it does not correlate with AGN luminosity, black hole mass, or AGN activity via the luminosity of the [OIII] emission line. Thus ongoing nuclear accretion activity is not reflected in the large scale environments from $\sim$10 h$^{-1}$ kpc to $\sim$0.5 h$^{-1}$ Mpc and may indicate a non-merger mode of AGN activity and/or a significant delay between galaxy mergers and nuclear activity in this sample of mostly radio quiet quasars.
Quasi-simultaneous observations of the Flat Spectrum Radio Quasar PKS 2326-502 were carried out in the gamma-ray, X-ray, UV, optical, near-infrared, and radio bands. Thanks to these observations we are able to characterize the spectral energy distribution of the source during two flaring and one quiescent gamma-ray states. These data were used to constrain one-zone leptonic models of the spectral energy distributions of each flare and investigate the physical conditions giving rise to them. While modeling one flare only required changes to the electron spectrum, the other flare needed changes …
Quasar redshifts require the best possible precision and accuracy for a number of applications, such as setting the velocity scale for outflows as well as measuring small-scale quasar-quasar clustering. The most reliable redshift standard in luminous quasars is arguably the narrow [OIII] $λλ$4959,5007 emission line doublet in the rest-frame optical. We use previously published [OIII] redshifts obtained using near-infrared spectra in a sample of 45 high-redshift (z > 2.2) quasars to evaluate redshift measurement techniques based on rest-frame ultraviolet spectra. At redshifts above z = 2.2 the …
We present imaging and spectroscopic observations for six quasars at z>5.9 discovered by the Canada-France High-z Quasar Survey (CFHQS). The CFHQS contains sub-surveys with a range of flux and area combinations to sample a wide range of quasar luminosities at z~6. The new quasars have luminosities 10 to 75 times lower than the most luminous SDSS quasars at this redshift. The least luminous quasar, CFHQS J0216-0455 at z=6.01, has absolute magnitude M_1450=-22.21, well below the likely break in the luminosity function. This quasar is not detected in a deep XMM-Newton survey showing that optical …
Further investigation of data on quasars, especially in the ultraviolet band, yields an amazingly coherent narrative which we present in this paper. Quasars are characterised by strong continuum emission and redshifted emission and absorption lines which includes the famous Lyman $α$ forest. We present irrefutable evidence in support of (1) the entire line spectrum arising in matter located inside the quasar system, (2) the range of redshifts shown by the lines being due to the variable contribution of the gravitational redshift in the observed line velocity, (3) existence of rotating black ho…
The most luminous quasars at high redshift harbour the fastest-growing and most massive black holes in the early Universe. They are exceedingly rare and hard to find. Here, we present our search for the most luminous quasars in the redshift range from $z=4.5$ to $5$ using data from SkyMapper, Gaia and WISE. We use colours to select likely high-redshift quasars and reduce the stellar contamination of the candidate set with parallax and proper motion data. In $\sim$12,500~deg$^2$ of Southern sky, we find 92 candidates brighter than $R_p=18.2$. Spectroscopic follow-up has revealed 21 quasars at $…
We present initial results from the first systematic survey of luminous $z\sim 5.5$ quasars. Quasars at $z \sim$ 5.5, the post-reionization epoch, are crucial tools to explore the evolution of intergalactic medium, quasar evolution and the early super-massive black hole growth. However, it has been very challenging to select quasars at redshifts 5.3 $\le z \le$ 5.7 using conventional color selections, due to their similar optical colors to late-type stars, especially M dwarfs, resulting in a glaring redshift gap in quasar redshift distributions. We develop a new selection technique for $z \sim…
We present a method of selecting quasars up to redshift $\approx$ 6 with random forests, a supervised machine learning method, applied to Pan-STARRS1 and WISE data. We find that, thanks to the increasing set of known quasars we can assemble a training set that enables supervised machine learning algorithms to become a competitive alternative to other methods up to this redshift. We present a candidate set for the redshift range 4.8 to 6.3 which includes the region around z = 5.5 where quasars are difficult to select due to photometric similarity to red and brown dwarfs. We demonstrate that und…
I present timely spectroscopic follow-up of the newly discovered, quadruply lensed quasar PSOJ0147 from the Pan-STARRS 1 survey. The newly acquired optical spectra with GMOS onboard the Gemini north telescope allow us to pin down the redshifts of both the foreground lensing galaxy and the background lensed quasar to be z=0.572 and 2.341, providing firm basis for cosmography with future high cadence photometric monitoring. I also inspect difference spectra from two of the quasar images, revealing the microlensing effect. Long-term spectroscopic follow-ups will shed lights on the structure of th…
Three Hundred Quasars from the Couch: A first look at high-redshift quasar discovery with SPHEREx
Max-Planck-Institut für Astronomie（马克斯·普朗克天文学研究所）；Institute for Theoretical Physics, Heidelberg University（海德堡大学理论物理研究所）；INAF - Osservatorio di Astrofisica e Scienza dello Spazio di Bologna（博洛尼亚天文物理与空间科学研究所（INAF））；Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）；Leiden Observatory, Leiden University（莱顿大学莱顿天文台）；Department of Physics, Broida Hall, University of California, Santa Barbara（加州大学圣塔芭芭拉分校物理系）；Department of Astronomy, University of Michigan（密歇根大学天文学系）
Search for quasar pairs with Gaia astrometric data. II. Photometric redshift prediction with machine learning for the MGQPC catalogue
Institute for Frontier in Astronomy and Astrophysics, Beijing Normal University（北京师范大学前沿天文与天体物理研究院）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；School of Physics and Astronomy, Beijing Normal University（北京师范大学物理与天文学院）
We study the environments of low redshift (z < 0.5) quasars based on a large and homogeneous dataset from the Stripe 82 region of the Sloan Digital Sky Survey (SDSS). We have compared the < 1 Mpc scale envi- ronments of 302 quasars that were resolved in our recent study to those of 288 inactive galaxies with closely matched redshifts. Crucially, the lu- minosities of the inactive galaxies and the quasar host galaxies are also closely matched, unlike in most previous studies. The environmental overdensities were studied by measuring the num- ber density of galaxies within a projected distance o…
A population of quasars at z ~ 2 is determined based on dust luminosities vLv(7.8 um) that includes unobscured, partially obscured, and obscured quasars. Quasars are classified by the ratio vLv(0.25 um)/vLv(7.8 um) = UV/IR, assumed to measure obscuration of UV luminosity by the dust which produces IR luminosity. Quasar counts at rest frame 7.8 um are determined for quasars in the Bootes field of the NOAO Deep Wide Field Survey using 24 um sources with optical redshifts from the AGN and Galaxy Evolution Survey (AGES) or infrared redshifts from the Spitzer Infrared Spectrograph. Spectral energy …
We investigate the properties of the galaxy environment of a sample of 14 low redshift (z $<$ 0.85) quasar physical pairs extracted from SDSS DR10 archives. The pairs have a systemic radial velocity difference $ΔV_\parallel \leqslant$ 600 $km \ s^{-1}$ (based on [OIII]5007 Å\ line) and projected distance $ R_\bot \leqslant$ 600 kpc. The physical association of the pairs is statistically confirmed at a level of $\sim$ 90 %. For most of the images of these quasars we are able to resolve their host galaxies that turn out to be on average similar to those of quasars not in pairs. We also found tha…
We examine the kinematics of the gas in the environments of galaxies hosting quasars at $z\sim2$. We employ 148 projected quasar pairs to study the circumgalactic gas of the foreground quasars in absorption. The sample selects foreground quasars with precise redshift measurements, using emission-lines with precision $\lesssim300\,{\rm km\,s^{-1}}$ and average offsets from the systemic redshift $\lesssim|100\,{\rm km\,s^{-1}}|$. We stack the background quasar spectra at the foreground quasar's systemic redshift to study the mean absorption in \ion{C}{2}, \ion{C}{4}, and \ion{Mg}{2}. We find tha…
Broad line regions (BLRs) in high-redshift quasars provide crucial information of chemical enrichment in the early universe. Here we present a study of BLR metallicities in 33 quasars at redshift $5.7<z<6.4$. Using the near-IR spectra of the quasars obtained from the Gemini telescope, we measure their rest-frame UV emission line flux and calculate flux ratios. We then estimate BLR metallicities with empirical calibrations based on photoionization models. The inferred median metallicity of our sample is a few times the solar value, indicating that the BLR gas had been highly metal-enriched at $…
Extreme deconvolution (XD) of broad-band photometric data can both separate stars from quasars and generate probability density functions for quasar redshifts, while incorporating flux uncertainties and missing data. Mid-infrared photometric colors are now widely used to identify hot dust intrinsic to quasars, and the release of all-sky WISE data has led to a dramatic increase in the number of IR-selected quasars. Using forced-photometry on public WISE data at the locations of SDSS point sources, we incorporate this all-sky data into the training of the XDQSOz models originally developed to se…
High-redshift quasars are important tracers of structure and evolution in the early universe. However, they are very rare and difficult to find when using color selection because of contamination from late-type dwarfs. High-redshift quasar surveys based on only optical colors suffer from incompleteness and low identification efficiency, especially at $z\gtrsim4.5$. We have developed a new method to select $4.7\lesssim z \lesssim 5.4$ quasars with both high efficiency and completeness by combining optical and mid-IR Wide-field Infrared Survey Explorer (WISE) photometric data, and are conducting…
This is the second paper in a series on a new luminous z ~ 5 quasar survey using optical and near-infrared colors. Here we present a new determination of the bright end of the quasar luminosity function (QLF) at z ~ 5. Combined our 45 new quasars with previously known quasars that satisfy our selections, we construct the largest uniform luminous z ~ 5 quasar sample to date, with 99 quasars in the range 4.7 <= z < 5.4 and -29 < M1450 <= -26.8, within the Sloan Digital Sky Survey (SDSS) footprint. We use a modified 1/Va method including flux limit correction to derive a binned QLF, and we model …
BayeSED-GALAXIES I. Performance test for simultaneous photometric redshift and stellar population parameter estimation of galaxies in the CSST wide-field multiband imaging survey
We present SQUEzE, a software package to classify quasar spectra and estimate their redshifts. SQUEzE is a random forest classifier operating on the parameters of candidate emission peaks identified in the spectra. We test the performance of the algorithm using visually inspected data from BOSS as a truth table. Only 4\% of the sample ($\sim$6,800 quasars and $\sim$11,520 contaminants) is needed for converged training in recommended choices of the confidence threshold ($0.2<p_{\rm min}<0.7$). For an operational mode which balances purity and completeness ($p_{\rm min}=0.28$) we recover a purit…
Multiple color selection techniques have been successful in identifying quasars from wide-field broad-band imaging survey data. Among the quasars that have been discovered so far, however, there is a redshift gap at $5 \lesssim {\rm z} \lesssim 5.7$ due to the limitations of filter sets in previous studies. In this work, we present a new selection technique of high redshift quasars using a sequence of medium-band filters: nine filters with central wavelengths from 625 to 1025 nm and bandwidths of 50 nm. Photometry with these medium-bands traces the spectral energy distribution (SED) of a sourc…
We present a new approach to capturing the broad diversity of emission line and continuum properties in quasar spectra. We identify populations of spectrally similar quasars through pixel-level clustering on 12,968 high signal-to-noise spectra from the Sloan Digital Sky Survey (SDSS) in the redshift range of $1.57<z<2.4$. Our clustering analysis finds 396 quasar spectra that are not assigned to any population, 15 misclassified spectra, and six quasars with incorrect redshifts. We compress the quasar populations into a library of 684 high signal-to-noise composite spectra, anchored in redshift …
Being observed only one billion years after the Big Bang, z ~ 7 quasars are a unique opportunity for exploring the early Universe. However, only two z ~ 7 quasars have been discovered in near-infrared surveys: the quasars ULAS J1120+0641 and ULAS J1342+0928 at z = 7.09 and z = 7.54, respectively. The Canada-France High-z Quasar Survey in the Near Infrared (CFHQSIR) has been carried out to search for z ~ 7 quasars using near-infrared and optical imaging from the Canada-France Hawaii Telescope (CFHT). Our data consist of $\rm{\sim 130\,deg^{2}}$ of Wide-field Infrared Camera (WIRCam) Y-band imag…
We report on the discovery of a peculiar Broad Absorption Line (BAL) quasar identified in our Gaia-assisted survey of red quasars. The systemic redshift of this quasar was difficult to establish due to the absence of conspicuous emission lines. Based on deep and broad BAL troughs (at least SiIV, CIV, and AlIII), a redshift of z=2.41 was established under the assumption that the systemic redshift can be inferred from the red edge of the BAL troughs. However, we observe a weak and spatially-extended emission line at 4450 AA most likely due to Lyman-alpha emission, which implies a systemic redshi…
Streamlined Lensed Quasar Identification in Multiband Images via Ensemble Networks
Max-Planck-Institut für Astrophysik（马克斯·普朗克天体物理研究所）；Academia Sinica Institute of Astronomy and Astrophysics (ASIAA)（中央研究院天文及天文物理研究所）；Università degli Studi di Milano（米兰大学）；Purple Mountain Observatory（紫金山天文台）；MIT Kavli Institute for Astrophysics and Space Research（麻省理工学院卡夫利天体物理与空间研究所）；Institut Teknologi Bandung（万隆理工学院）；Technical University of Munich（慕尼黑工业大学）
Detailed studies of relativistic jets in active galactic nuclei (AGN) require high-fidelity imaging at the highest possible resolution. This can be achieved using very long baseline interferometry (VLBI) at radio frequencies, combining worldwide (global) VLBI arrays of radio telescopes with a space-borne antenna on board a satellite. We present multiwavelength images made of the radio emission in the powerful quasar S5 0836+710, obtained using a global VLBI array and the antenna Spektr-R of the RadioAstron mission of the Russian Space Agency, with the goal of studying the internal structure an…
We develop an automated technique to measure quasar redshifts in the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey (SDSS). Our technique is an extension of an earlier Gaussian process method for detecting damped Lyman-alpha absorbers (DLAs) in quasar spectra with known redshifts. We apply this technique to a subsample of SDSS DR12 with BAL quasars removed and redshift larger than 2.15. We show that we are broadly competitive to existing quasar redshift estimators, disagreeing with the PCA redshift by more than 0.5 in only 0.38% of spectra. Our method produces a…
Quasars are powerful systems whose spectrum is rich of metal features that allow us to investigate the chemical evolution of galaxies at very high redshift, even close to the reionization epoch. I review the main observational constraints on the metallicity of quasars host galaxies at high redshift and discuss the implications and issues for models of galaxy evolution in the early universe.
High-redshift quasars typically have their redshift determined from rest-frame ultraviolet (UV) emission lines. However, these lines, and more specifically the prominent C IV $λ1549$ emission line, are typically blueshifted yielding highly uncertain redshift estimates compared to redshifts determined from rest-frame optical emission lines. We present near-infrared spectroscopy of 18 luminous quasars at $2.15 < z < 3.70$ that allows us to obtain reliable systemic redshifts for these sources. Together with near-infrared spectroscopy of an archival sample of 44 quasars with comparable luminositie…
The clustering of quasars on small scales yields fundamental constraints on models of quasar evolution and the buildup of supermassive black holes. This paper describes the first systematic survey to discover high redshift binary quasars. Using color-selection and photometric redshift techniques, we searched 8142 deg^2 of SDSS imaging data for binary quasar candidates, and confirmed them with follow-up spectroscopy. Our sample of 27 high redshift binaries (24 of them new discoveries) at redshifts 2.9 < z < 4.3 with proper transverse separations 10 kpc < R_{\perp} < 650 kpc increases the number…
We report the serendipitous discoveries of companion galaxies to two high-redshift quasars. SDSS J025617.7+001904 is a z=4.79 quasar included in our recent survey of faint quasars in the SDSS Stripe 82 region. The initial MMT slit spectroscopy shows excess Lyman alpha emission extending well beyond the quasar's light profile. Further imaging and spectroscopy with LBT/MODS1 confirms the presence of a bright galaxy (i_AB = 23.6) located 2arcsec (12 kpc projected) from the quasar with strong Lyman alpha emission (EW_0 ~ 100Ang) at the redshift of the quasar, as well as faint continuum. The second…
The observed lensed fraction of high-redshift quasars $(\sim0.2\%)$ is significantly lower than previous theoretical predictions $(\gtrsim4\%)$. We revisit the lensed fraction of high-redshift quasars predicted by theoretical models, where we adopt recent measurements of galaxy velocity dispersion functions (VDFs) and explore a wide range of quasar luminosity function (QLF) parameters. We use both analytical methods and mock catalogs which give consistent results. For ordinary QLF parameters and the depth of current high-redshift quasar surveys $(m_z\lesssim22)$, our model suggests a multiply-…
The broad emission lines commonly seen in quasar spectra have velocity widths of a few per cent of the speed of light, so special- and general-relativistic effects have a significant influence on the line profile. We have determined the redshift of the broad H-beta line in the quasar rest frame (determined from the core component of the [OIII] line) for over 20,000 quasars from the Sloan Digital Sky Survey DR7 quasar catalog. The mean redshift as a function of line width is approximately consistent with the relativistic redshift that is expected if the line originates in a randomly oriented Ke…
We report the results of near-infrared spectroscopic observations of 37 quasars in the redshift range $6.3< z\le7.64$, including 32 quasars at $z>6.5$, forming the largest quasar near-infrared spectral sample at this redshift. The spectra, taken with Keck, Gemini, VLT, and Magellan, allow investigations of central black hole mass and quasar rest-frame ultraviolet spectral properties. The black hole masses derived from the MgII emission lines are in the range $(0.3-3.6)\times10^{9}\,M_{\odot}$, which requires massive seed black holes with masses $\gtrsim10^{3-4}\,M_{\odot}$, assuming Eddington …
Luminous high-redshift quasars can be used to probe of the intergalactic medium (IGM) in the early universe because their UV light is absorbed by the neutral hydrogen along the line of sight. They help us to measure the neutral hydrogen fraction of the high-z universe, shedding light on the end of reionization epoch. In this paper, we present a discovery of a new quasar (PSO J006.1240+39.2219) at redshift $z=6.61\pm0.02$ from Panoramic Survey Telescope & Rapid Response System 1. Including this quasar, there are nine quasars above $z>6.5$ up to date. The estimated continuum brightness is $M_\te…
We investigate the luminosity and redshift dependence of the quasar continuum by means of composite spectrum using a large non-BAL radio-quiet quasar sample drawn from the Sloan Digital Sky Survey. Quasar continuum slopes in the UV-Opt band are measured at two different wavelength ranges, i.e., $α_{\nu12}$ ($1000\sim 2000 \rmÅ$) and $α_{\nu24}$ ($2000 \sim 4000 \rmÅ$) derived from power law fitting. Generally, the UV spectra slope becomes harder (higher $α_ν$) towards higher bolometric luminosity. On the other hand, when quasars are further grouped into luminosity bins, we find both $α_{\nu12}…
We report exploratory \chandra\ observation of the ultraluminous quasar SDSS J010013.02+280225.8 at redshift 6.30. The quasar is clearly detected by \chandra\ with a possible component of extended emission. The rest-frame 2-10 keV luminosity is 9.0$^{+9.1}_{-4.5}$ $\times$ 10$^{45}$ erg s$^{-1}$ with inferred photon index of $Γ$ = 3.03$^{+0.78}_{-0.70}$. This quasar is X-ray bright, with inferred X-ray-to-optical flux ratio \aox\ $=-1.22^{+0.07}_{-0.05}$, higher than the values found in other quasars of comparable ultraviolet luminosity. The properties inferred from this exploratory observatio…
We use the coadded spectra of 32 epochs of Sloan Digital Sky Survey (SDSS) Reverberation Mapping Project observations of 482 quasars with z>1.46 to highlight systematic biases in the SDSS- and BOSS-pipeline redshifts due to the natural diversity of quasar properties. We investigate the characteristics of this bias by comparing the BOSS-pipeline redshifts to an estimate from the centroid of HeII 1640. HeII has a low equivalent width but is often well-defined in high-S/N spectra, does not suffer from self-absorption, and has a narrow component that, when present (the case for about half of our s…
We present high resolution (arcsecond or better) observations made with the Karl G. Jansky Very Large Array of 123 radio-loud quasars with redshifts in the range $2.5 \leq z \leq 5.28$ that form a complete flux limited sample ($\geq 70$ mJy at 1.4 GHz or 5 GHz). Where possible, we used previous high resolution VLA observations (mainly A array at 1.4, 5 and 8 GHz) from the NRAO archive and re-imaged them (43 sources). For the remainder, new observations were made in the A array at 1.4 and 5 GHz. We show images of the 61 resolved sources, and list structural properties of all of them. Optical da…
We characterise the distribution of quasars within dark matter halos using a direct measurement technique for the first time at redshifts as high as $z \sim 1$. Using the Planck Sunyaev-Zeldovich (SZ) catalogue for galaxy groups and the Sloan Digital Sky Survey (SDSS) DR12 quasar dataset, we assign host clusters/groups to the quasars and make a measurement of the mean number of quasars within dark matter halos as a function of halo mass. We find that a simple power-law fit of $\log\left <N\right> = (2.11 \pm 0.01) \log (M) -(32.77 \pm 0.11)$ can be used to model the quasar fraction in dark mat…
The wavelength dependence of atmospheric refraction causes differential chromatic refraction (DCR), whereby objects imaged at different optical/UV wavelengths are observed at slightly different positions in the plane of the detector. Strong spectral features induce changes in the effective wavelengths of broad-band filters that are capable of producing significant positional offsets with respect to standard DCR corrections. We examine such offsets for broad-emission-line (type 1) quasars from the Sloan Digital Sky Survey (SDSS) spanning 0<z<5 and an airmass range of 1.0 to 1.8. These offsets a…
Galaxy mergers occur frequently in the early universe and bring multiple supermassive black holes (SMBHs) into the nucleus, where they may eventually coalesce. Identifying post-merger-scale (i.e., <~a few kpc) dual SMBHs is a critical pathway to understanding their dynamical evolution and successive mergers. While serendipitously discovering kpc-scale dual SMBHs at z<1 is possible, such systems are elusive at z>2, but critical to constraining the progenitors of SMBH mergers. The redshift z~2 also marks the epoch of peak activity of luminous quasars, hence probing this spatial regime at high re…
Sorbonne Université（索邦大学）；Université Paris Diderot（巴黎狄德罗大学）；CNRS/IN2P3（法国国家科学研究中心/国家核物理与粒子物理研究所）
We introduce QuasarNET, a deep convolutional neural network that performs classification and redshift estimation of astrophysical spectra with human-expert accuracy. We pose these two tasks as a \emph{feature detection} problem: presence or absence of spectral features determines the class, and their wavelength determines the redshift, very much like human-experts proceed. When ran on BOSS data to identify quasars through their emission lines, QuasarNET defines a sample $99.51\pm0.03$\% pure and $99.52\pm0.03$\% complete, well above the requirements of many analyses using these data. QuasarNET…
Most galaxy evolutionary models require quasar feedback to regulate star formation in their host galaxies. In particular, at high redshift, models expect that feedback associated with quasar-driven outflows is so efficient that the gas in the host galaxy is largely swept away or heated up, hence suppressing star formation in massive galaxies. We observationally investigate this phenomenon by using VLT-SINFONI integral field spectroscopy of the luminous quasar 2QZJ002830.4-281706 at z=2.4. The spectra sample the optical emission lines redshifted into the near-IR. The [OIII]5007 emission-line ki…
We propose and apply a new test of Einstein's Equivalence Principle (EEP) based on the gravitational redshift induced by the central super massive black hole of quasars in the surrounding accretion disk. Specifically, we compare the observed gravitational redshift of the Fe III$λλ$2039-2113 emission line blend in quasars with the predicted values in a wide, uncharted, cosmic territory ($0 \lesssim z_{cosm}\lesssim3$). For the first time we measure, with statistical uncertainties comparable or better than those of other classical methods outside the Solar System, the ratio between the observed …
