scholarly journals The near and mid-infrared photometric properties of known redshift z ≥ 5 quasars

2020 ◽  
Vol 494 (1) ◽  
pp. 789-803 ◽  
Author(s):  
Nicholas P Ross ◽  
Nicholas J G Cross
Keyword(s):  
Near Infrared ◽  
Signal To Noise Ratio ◽  
High Redshift ◽  
Infrared Camera ◽  
Sloan Digital Sky Survey ◽  
Wide Field ◽  
Photometric Variability ◽  
Infrared Telescope ◽  
Black Hole Accretion ◽  
Very High

ABSTRACT We assemble a catalogue of 488 spectroscopically confirmed very high (z ≥ 5.00) redshift quasars (VHzQ) and report their near- (ZYJHKs/K) and mid- (WISE W1234) infrared properties. 97 per cent of the VHzQ sample is detected in one or more near-infrared (NIR) band, with lack of coverage rather than lack of depth being the reason for the non-detections. 389 (80 per cent) of the very high redshift quasars are detected at 3.4 μm in the W1 band from the unWISE catalogue and all of the z ≥ 7 quasars are detected in both unWISE W1 and W2. Using archival Wide Field Camera (WFCAM)/United Kingdom Infrared Telescope (UKIRT) and VISTA Infrared Camera (VIRCAM)/Visible and Infrared Survey Telescope for Astronomy (VISTA) data we check for photometric variability that might be expected from super-Eddington accretion. We find 28 of the quasars have sufficient NIR measurements and signal-to-noise ratio to look for variability. Weak variability was detected in multiple bands of Sloan Digital Sky Survey (SDSS) J0959+0227, and very marginally in the Y-band of MMT J0215-0529. Only one quasar, SDSS J0349+0034, shows significant differences between WFCAM and VISTA magnitudes in one band. With supermassive black hole accretion likely to be redshift invariant up to very high redshift, further monitoring of these sources is warranted. All the data, analysis codes and plots used and generated here can be found at: github.com/d80b2t/VHzQ.

scholarly journals Near-infrared time-series photometry in the field of Cygnus OB2 association

2020 ◽  
Vol 640 ◽  
pp. A128
Author(s):  
J. Roquette ◽  
S. H. P. Alencar ◽  
J. Bouvier ◽  
M. G. Guarcello ◽  
B. Reipurth
Keyword(s):  
Near Infrared ◽  
Color Space ◽  
Variable Stars ◽  
Wide Field ◽  
Photometric Variability ◽  
Circumstellar Material ◽  
Infrared Telescope ◽  
The United Kingdom ◽  
Low Mass ◽  
Cold Spots

We present the results of a J, H, and K photometric variability survey of the central 0.78 square degrees of the young OB association Cygnus OB2. We used data observed with the Wide-Field CAMera at the United Kingdom Infrared Telescope in 2007 (spanning 217 days) to investigate the light curves of 5083 low mass candidate members in the association and explore the occurrence and main characteristics of their near-infrared variability. We identified 2529 stars (∼50% of the sample) with significant variability with time-scales ranging from days to months. We classified the variable stars into the following three groups according to their light curve morphology: periodic variability (1697 stars), occultation variability (124 stars), and other types of variability (726 stars). We verified that the disk-bearing stars in our sample are significantly more variable in the near-infrared than diskless stars, with a steep increase in the disk-fraction among stars with higher variability amplitude. We investigated the trajectories described by variable stars in the color-space and measured slopes for 335 stars describing linear trajectories. Based on the trajectories in the color-space, we inferred that the sample analyzed is composed of a mix of young stars presenting variability due to hot and cold spots, extinction by circumstellar material, and changes in the disk emission in the near-infrared. We contemplated using the use of near-infrared variability to identify disk-bearing stars and verified that 53.4% of the known disk-bearing stars in our sample could have been identified as such based solely on their variability. We present 18 newly identified disk-bearing stars and 14 eclipsing binary candidates among CygOB2 lower-mass members.

scholarly journals The CFHQSIR survey: a Y-band extension of the CFHTLS-Wide survey

2018 ◽  
Vol 616 ◽  
pp. A55 ◽  
Author(s):  
S. Pipien ◽  
S. Basa ◽  
J.-G. Cuby ◽  
J.-C. Cuillandre ◽  
C. Willott ◽  
...  
Keyword(s):  
Near Infrared ◽  
High Redshift ◽  
Infrared Camera ◽  
Point Sources ◽  
Optical Data ◽  
Wide Field ◽  
Correlated Noise ◽  
Aperture Diameter ◽  
Photometric Calibration ◽  
Multi Wavelength

Context. The Canada–France–Hawaii Telescope Legacy Survey (CFHTLS) has been conducted over a 5-yr period at the CFHT with the MegaCam instrument, totaling 450 nights of observations. The Wide Synoptic Survey is one component of the CFHTLS, covering 155 square degrees in four patches of 23 to 65 square degrees through the whole MegaCam filter set (u*, g’, r’, i’, z’) down to i’AB = 24.5. Aims. With the motivation of searching for high-redshift quasars at redshifts above 6.5, we extend the multi-wavelength CFHTLS-Wide data in the Y -band down to magnitudes of ~22.5 for point sources (5σ). Methods. We observed the four CFHTLS-Wide fields (except one quarter of the W3 field) in the Y -band with the Wide-field InfraRed Camera (WIRCam) at the CFHT. Each field was visited twice, at least three weeks apart. Each visit consisted of two dithered exposures. The images are reduced with the Elixir software used for the CFHTLS and modified to account for the properties of near-InfraRed (IR) data. Two series of image stacks are subsequently produced: four-image stacks for each WIRCam pointing, and one-square-degree tiles matched to the format of the CFHTLS data release. Photometric calibration is performed on stars by fitting stellar spectra to their CFHTLS photometric data and extrapolating their Y -band magnitudes. Results. After corrections accounting for correlated noise, we measure a limiting magnitude of YAB ≃ 22.4 for point sources (5σ) in an aperture diameter of 0.′′93, over 130 square degrees. We produce a multi-wavelength catalogue combining the CFHTLS-Wide optical data with our CFHQSIR (Canada–France High-z quasar survey in the near-InfraRed) Y -band data. We derive the Y -band number counts and compare them to the Vista Deep Extragalactic Observations survey (VIDEO). We find that the addition of the CFHQSIR Y -band data to the CFHTLS optical data increases the accuracy of photometric redshifts and reduces the outlier rate from 13.8% to 8.8% in the redshift range 1.05 ≲ z ≲ 1.2.

scholarly journals IRTS: Infrared Telescope in Space

1990 ◽  
Vol 123 ◽  
pp. 215-222
Author(s):  
Toshio Matsumoto
Keyword(s):  
Focal Plane ◽  
Near Infrared ◽  
Space Shuttle ◽  
Spectroscopic Measurement ◽  
Small Space ◽  
Valuable Data ◽  
Infrared Telescope ◽  
Wide Wavelength Range ◽  
Infrared Sources ◽  
Very High

AbstractIRTS is a small cryogenically cooled telescope onboard the small space platform SFU (Space Flyer Unit). SFU will be launched with the new Japanese HII rocket on January 1994 and retrieved by the space shuttle.The IRTS telescope has an aperture of only 15 cm diameter, but is optimized to observe diffuse extended infrared sources. Four focal plane instruments are being developed under collaboration between Japan and the U.S.A. IRTS covers a wide wavelength range from near-infrared to submillimeter region, and has a capability for the spectroscopic measurement. Due to newly developed detectors, the sky will be surveyed with very high sensitivities. IRTS will provide valuable data on cosmology, galactic structure, cosmic dust, etc.

scholarly journals Substellar and low-mass dwarf identification with near-infrared imaging space observatories

2018 ◽  
Vol 620 ◽  
pp. A132 ◽  
Author(s):  
B. W. Holwerda ◽  
J. S. Bridge ◽  
R. Ryan ◽  
M. A. Kenworthy ◽  
N. Pirzkal ◽  
...  
Keyword(s):  
Near Infrared ◽  
Infrared Imaging ◽  
High Redshift ◽  
Brown Dwarfs ◽  
Wide Field ◽  
Space Telescope ◽  
Low Mass ◽  
Space Observatories ◽  
Broad Type ◽  
Selection Of

Aims. We aim to evaluate the near-infrared colors of brown dwarfs as observed with four major infrared imaging space observatories: the Hubble Space Telescope (HST), the James Webb Space Telescope (JWST), the Euclid mission, and the WFIRST telescope. Methods. We used the SPLAT SPEX/ISPEX spectroscopic library to map out the colors of the M-, L-, and T-type dwarfs. We have identified which color–color combination is optimal for identifying broad type and which single color is optimal to then identify the subtype (e.g., T0-9). We evaluated each observatory separately as well as the narrow-field (HST and JWST) and wide-field (Euclid and WFIRST) combinations. Results. The Euclid filters perform equally well as HST wide filters in discriminating between broad types of brown dwarfs. WFIRST performs similarly well, despite a wider selection of filters. However, subtyping with any combination of Euclid and WFIRST observations remains uncertain due to the lack of medium, or narrow-band filters. We argue that a medium band added to the WFIRST filter selection would greatly improve its ability to preselect brown dwarfs its imaging surveys. Conclusions. The HST filters used in high-redshift searches are close to optimal to identify broad stellar type. However, the addition of F127M to the commonly used broad filter sets would allow for unambiguous subtyping. An improvement over HST is one of two broad and medium filter combinations on JWST: pairing F140M with either F150W or F162M discriminates very well between subtypes.

scholarly journals Probing the cold magnetised Universe with SPICA-POL (B-BOP)

2019 ◽  
Vol 36 ◽  
Author(s):  
Ph. André ◽  
A. Hughes ◽  
V. Guillet ◽  
F. Boulanger ◽  
A. Bracco ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Dynamic Range ◽  
Signal To Noise Ratio ◽  
European Space Agency ◽  
Dust Emission ◽  
Far Infrared ◽  
High Dynamic Range ◽  
Wide Field ◽  
Infrared Telescope ◽  
Nearby Galaxies

Abstract Space Infrared Telescope for Cosmology and Astrophysics (SPICA), the cryogenic infrared space telescope recently pre-selected for a ‘Phase A’ concept study as one of the three remaining candidates for European Space Agency (ESA's) fifth medium class (M5) mission, is foreseen to include a far-infrared polarimetric imager [SPICA-POL, now called B-fields with BOlometers and Polarizers (B-BOP)], which would offer a unique opportunity to resolve major issues in our understanding of the nearby, cold magnetised Universe. This paper presents an overview of the main science drivers for B-BOP, including high dynamic range polarimetric imaging of the cold interstellar medium (ISM) in both our Milky Way and nearby galaxies. Thanks to a cooled telescope, B-BOP will deliver wide-field 100–350 $\mu$ m images of linearly polarised dust emission in Stokes Q and U with a resolution, signal-to-noise ratio, and both intensity and spatial dynamic ranges comparable to those achieved by Herschel images of the cold ISM in total intensity (Stokes I). The B-BOP 200 $\mu$ m images will also have a factor $\sim $ 30 higher resolution than Planck polarisation data. This will make B-BOP a unique tool for characterising the statistical properties of the magnetised ISM and probing the role of magnetic fields in the formation and evolution of the interstellar web of dusty molecular filaments giving birth to most stars in our Galaxy. B-BOP will also be a powerful instrument for studying the magnetism of nearby galaxies and testing Galactic dynamo models, constraining the physics of dust grain alignment, informing the problem of the interaction of cosmic rays with molecular clouds, tracing magnetic fields in the inner layers of protoplanetary disks, and monitoring accretion bursts in embedded protostars.

scholarly journals Highly accreting quasars: The SDSS low-redshift catalog

2018 ◽  
Vol 620 ◽  
pp. A118 ◽  
Author(s):  
C. A. Negrete ◽  
D. Dultzin ◽  
P. Marziani ◽  
D. Esparza ◽  
J. W. Sulentic ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
Signal To Noise Ratio ◽  
High Redshift ◽  
Galactic Nuclei ◽  
Host Galaxy ◽  
Central Engine ◽  
Composite Spectra ◽  
Order Of Magnitude ◽  
Distance Indicators ◽  
Very High

Context. The most highly accreting quasars are of special interest in studies of the physics of active galactic nuclei (AGNs) and host galaxy evolution. Quasars accreting at high rates (L/LEdd ∼ 1) hold promise for use as “standard candles”: distance indicators detectable at very high redshift. However, their observational properties are still largely unknown. Aims. We seek to identify a significant number of extreme accretors. A large sample can clarify the main properties of quasars radiating near L/LEdd ∼ 1 (in this paper they are designated as extreme Population A quasars or simply as extreme accretors) in the Hβ spectral range for redshift ≲0.8. Methods. We use selection criteria derived from four-dimensional Eigenvector 1 (4DE1) studies to identify and analyze spectra for a sample of 334 candidate sources identified from the SDSS DR7 database. The source spectra were chosen to show a ratio RFeII between the FeII emission blend at λ4570 and Hβ, RFeII > 1. Composite spectra were analyzed for systematic trends as a function of Fe II strength, line width, and [OIII] strength. We introduced tighter constraints on the signal-to-noise ratio (S/N) and RFeII values that allowed us to isolate sources most likely to be extreme accretors. Results. We provide a database of detailed measurements. Analysis of the data allows us to confirm that Hβ shows a Lorentzian function with a full width at half maximum (FWHM) of Hβ ≤ 4000 km s−1. We find no evidence for a discontinuity at 2000 km s−1 in the 4DE1, which could mean that the sources below this FWHM value do not belong to a different AGN class. Systematic [OIII] blue shifts, as well as a blueshifted component in Hβ are revealed. We interpret the blueshifts as related to the signature of outflowing gas from the quasar central engine. The FWHM of Hβ is still affected by the blueshifted emission; however, the effect is non-negligible if the FWHM Hβ is used as a “virial broadening estimator” (VBE). We emphasize a strong effect of the viewing angle on Hβ broadening, deriving a correction for those sources that shows major disagreement between virial and concordance cosmology luminosity values. Conclusions. The relatively large scatter between concordance cosmology and virial luminosity estimates can be reduced (by an order of magnitude) if a correction for orientation effects is included in the FWHM Hβ value; outflow and sample definition yield relatively minor effects.

scholarly journals The Science Case for PILOT II: the Distant Universe

2009 ◽  
Vol 26 (4) ◽  
pp. 397-414 ◽  
Author(s):  
J. S. Lawrence ◽  
M. C. B. Ashley ◽  
A. Bunker ◽  
R. Bouwens ◽  
D. Burgarella ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Redshift ◽  
High Sensitivity ◽  
Infrared Light ◽  
Wide Field ◽  
Atmospheric Conditions ◽  
Large Area ◽  
Optical Telescope ◽  
Infrared Telescope ◽  
Scientific Potential

AbstractPILOT (the Pathfinder for an International Large Optical Telescope) is a proposed 2.5-m optical/infrared telescope to be located at Dome C on the Antarctic plateau. The atmospheric conditions at Dome C deliver a high sensitivity, high photometric precision, wide-field, high spatial resolution, and high-cadence imaging capability to the PILOT telescope. These capabilities enable a unique scientific potential for PILOT, which is addressed in this series of papers. The current paper presents a series of projects dealing with the distant (redshift >1) Universe, that have been identified as key science drivers for the PILOT facility. The potential for PILOT to detect the first populations of stars to form in the early Universe, via infrared projects searching for pair-instability supernovae and gamma-ray burst afterglows, is investigated. Two projects are proposed to examine the assembly and evolution of structure in the Universe: an infrared survey searching for the first evolved galaxies at high redshift, and an optical survey aimed at characterising moderate-redshift galaxy clusters. Finally, a large-area weak-lensing survey and a program to obtain supernova infrared light-curves are proposed to examine the nature and evolution of dark energy and dark matter.

scholarly journals GALACTICNUCLEUS: A high angular resolution JHKs imaging survey of the Galactic centre

2018 ◽  
Vol 610 ◽  
pp. A83 ◽  
Author(s):  
F. Nogueras-Lara ◽  
A. T. Gallego-Calvente ◽  
H. Dong ◽  
E. Gallego-Cano ◽  
J. H. V. Girard ◽  
...  
Keyword(s):  
Near Infrared ◽  
Angular Resolution ◽  
Infrared Camera ◽  
Stellar Model ◽  
Galactic Centre ◽  
High Angular Resolution ◽  
Wide Field ◽  
Photometric Calibration ◽  
Solar Metallicity

Context. The Galactic centre (GC) is of fundamental astrophysical interest, but existing near-infrared surveys fall short covering it adequately, either in terms of angular resolution, multi-wavelength coverage, or both. Here we introduce the GALACTICNUCLEUS survey, a JHKs imaging survey of the centre of the Milky Way with a 0.2″ angular resolution. Aims. The purpose of this paper is to present the observations of Field 1 of our survey, centred approximately on SgrA* with an approximate size of 7.95′ × 3.43′. We describe the observational set-up and data reduction pipeline and discuss the quality of the data. Finally, we present the analysis of the data. Methods. The data were acquired with the near-infrared camera High Acuity Wide field K-band Imager (HAWK-I) at the ESO Very Large Telescope (VLT). Short readout times in combination with the speckle holography algorithm allowed us to produce final images with a stable, Gaussian PSF (point spread function) of 0.2″ FWHM (full width at half maximum). Astrometric calibration is achieved via the VISTA Variables in the Via Lactea (VVV) survey and photometric calibration is based on the SIRIUS/Infrared Survey Facility telescope (IRSF) survey. The quality of the data is assessed by comparison between observations of the same field with different detectors of HAWK-I and at different times. Results. We reach 5σ detection limits of approximately J = 22, H = 21, and Ks = 20. The photometric uncertainties are less than 0.05 at J ≲ 20, H ≲ 17, and Ks ≲ 16. We can distinguish five stellar populations in the colour-magnitude diagrams; three of them appear to belong to foreground spiral arms, and the other two correspond to high- and low-extinction star groups at the GC. We use our data to analyse the near-infrared extinction curve and find some evidence for a possible difference between the extinction index between J − H and H − Ks. However, we conclude that it can be described very well by a power law with an index of αJHKs = 2.30 ± 0.08. We do not find any evidence that this index depends on the position along the line of sight, or on the absolute value of the extinction. We produce extinction maps that show the clumpiness of the ISM (interstellar medium) at the GC. Finally, we estimate that the majority of the stars have solar or super-solar metallicity by comparing our extinction-corrected colour-magnitude diagrams with isochrones with different metallicities and a synthetic stellar model with a constant star formation.

scholarly journals Near-infrared variability in dusty white dwarfs: tracing the accretion of planetary material

2020 ◽  
Vol 494 (2) ◽  
pp. 2861-2874 ◽  
Author(s):  
Laura K Rogers ◽  
Siyi Xu (许偲艺) ◽  
Amy Bonsor ◽  
Simon Hodgkin ◽  
Kate Y L Su ◽  
...  
Keyword(s):  
Time Scales ◽  
White Dwarf ◽  
White Dwarfs ◽  
Near Infrared ◽  
Dust Emission ◽  
Infrared Emission ◽  
Wide Field ◽  
Infrared Telescope ◽  
Infrared Monitoring ◽  
K Band

ABSTRACT The inwards scattering of planetesimals towards white dwarfs is expected to be a stochastic process with variability on human time-scales. The planetesimals tidally disrupt at the Roche radius, producing dusty debris detectable as excess infrared emission. When sufficiently close to the white dwarf, this debris sublimates and accretes on to the white dwarf and pollutes its atmosphere. Studying this infrared emission around polluted white dwarfs can reveal how this planetary material arrives in their atmospheres. We report a near-infrared monitoring campaign of 34 white dwarfs with infrared excesses with the aim to search for variability in the dust emission. Time series photometry of these white dwarfs from the United Kingdom Infrared Telescope (Wide Field Camera) in the J-, H-, and K-bands was obtained over baselines of up to 3 yr. We find no statistically significant variation in the dust emission in all three near-infrared bands. Specifically, we can rule out variability at ∼1.3 per cent for the 13 white dwarfs brighter than 16th mag in K-band, and at ∼10 per cent for the 32 white dwarfs brighter than 18th mag over time-scales of 3 yr. Although to date two white dwarfs, SDSS J095904.69−020047.6 and WD 1226+110, have shown K-band variability, in our sample we see no evidence of new K-band variability at these levels. One interpretation is that the tidal disruption events that lead to large variabilities are rare occur on short time-scales, and after a few years the white dwarfs return to being stable in the near-infrared.

scholarly journals Multifrequency filter search for high redshift sources and lensing systems in Herschel-ATLAS

2019 ◽  
Vol 622 ◽  
pp. A106
Author(s):  
A. Manjón-García ◽  
D. Herranz ◽  
J. M. Diego ◽  
L. Bonavera ◽  
J. González-Nuevo
Keyword(s):  
Signal To Noise Ratio ◽  
High Redshift ◽  
Simulated Data ◽  
Galaxy Cluster ◽  
Point Sources ◽  
Sloan Digital Sky Survey ◽  
Large Area ◽  
Redshift Range ◽  
Photometric Redshift ◽  
Area Survey

We present a new catalog of high-redshift candidate Herschel sources. Our sample is obtained after applying a multifrequency filtering method (“matched multifilter”), which is designed to improve the signal-to-noise ratio of faint extragalactic point sources. The method is tested against already-detected sources from the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) and used to search for new high-redshift candidates. The multifilter technique also produces an estimation of the photometric redshift of the sources. When compared with a sample of sources with known spectroscopic redshift, the photometric redshift returned from the multifilter is unbiased in the redshift range 0.8 <  z <  4.3. Using simulated data we reproduced the same unbiased result in roughly the same redshift range and determined the error (and bias above z ≈ 4) in the photometric redshifts. Based on the multifilter technique, and a selection based on color, flux, and agreement of fit between the observed photometry and assumed SED, we find 370 robust candidates to be relatively bright high-redshift sources. A second sample with 237 objects focuses on the faint end at high-redshift. These 237 sources were previously near the H-ATLAS detection limit but are now confirmed with our technique as high significance detections. Finally, we look for possible lensed Herschel sources by cross-correlating the first sample of 370 objects with two different catalogs of known low-redshift objects, the redMaPPer Galaxy Cluster Catalog and a catalog of galaxies with spectroscopic redshift from the Sloan Digital Sky Survey Data Release 14. Our search renders a number of candidates to be lensed systems from the SDSS cross-correlation but none from the redMaPPeR confirming the more likely galactic nature of the lenses.

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