Identification of AKARI infrared sources by the Deep HSC Optical Survey: construction of a new band-merged catalogue in the North Ecliptic Pole Wide field

ABSTRACT The North Ecliptic Pole field is a natural deep-field location for many satellite observations. It has been targeted many times since it was surveyed by the AKARI space telescope with its unique wavelength coverage from the near- to mid-infrared (mid-IR). Many follow-up observations have been carried out, making this field one of the most frequently observed areas with a variety of facilities, accumulating abundant panchromatic data from the X-ray to the radio wavelength range. Recently, a deep optical survey with the Hyper Suprime-Cam (HSC) at the Subaru telescope covered the NEP-Wide (NEPW) field, which enabled us to identify faint sources in the near- and mid-IR bands, and to improve the photometric redshift (photo-z) estimation. In this work, we present newly identified AKARI sources by the HSC survey, along with multiband photometry for 91 861 AKARI sources observed over the NEPW field. We release a new band-merged catalogue combining various photometric data from the GALEX UV to submillimetre (sub-mm) bands (e.g. Herschel/SPIRE, JCMT/SCUBA-2). About ∼20 000 AKARI sources are newly matched to the HSC data, most of which seem to be faint galaxies in the near- to mid-infrared AKARI bands. This catalogue is motivating a variety of current research, and will be increasingly useful as recently launched (eROSITA/ART-XC) and future space missions (such as JWST, Euclid, and SPHEREx) plan to take deep observations in the NEP field.

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Identification of AGN in the XMM-Newton X-ray survey of the SMC

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833663 ◽

2019 ◽

Vol 622 ◽

pp. A29 ◽

Cited By ~ 6

Author(s):

Chandreyee Maitra ◽

Frank Haberl ◽

Valentin D. Ivanov ◽

Maria-Rosa L. Cioni ◽

Jacco Th. van Loon

Keyword(s):

Near Infrared ◽

Spectral Characteristics ◽

Selection Criterion ◽

Galactic Nuclei ◽

Seyfert Galaxies ◽

Mid Infrared ◽

X Ray ◽

Stellar Density ◽

Narrow Emission

Context. Finding active galactic nuclei (AGN) behind the Magellanic Clouds (MCs) is difficult because of the high stellar density in these fields. Although the first AGN behind the Small Magellanic Cloud (SMC) were reported in the 1980s, it is only recently that the number of AGN known behind the SMC has increased by several orders of magnitude. Aims. The mid-infrared colour selection technique has proven to be an efficient means of identifying AGN, especially obscured sources. The X-ray regime is complementary in this regard and we use XMM-Newton observations to support the identification of AGN behind the SMC. Methods. We present a catalogue of AGN behind the SMC by correlating an updated X-ray point-source catalogue from our XMM-Newton survey of the SMC with previously identified AGN from the literature as well as a list of candidates obtained from the ALLWISE mid-infrared colour-selection criterion. We studied the properties of the sample with respect to their redshifts, luminosities, and X-ray spectral characteristics. We also identified the near-infrared counterpart of the sources from the VISTA observations. Results. The redshift and luminosity distributions of the sample (where known) indicate that we detect sources ranging from nearby Seyfert galaxies to distant and obscured quasars. The X-ray hardness ratios are compatible with those typically expected for AGN, and the VISTA colours and variability are also consistent with AGN. A positive correlation was observed between the integrated X-ray flux (0.2–12 keV) and the ALLWISE and VISTA magnitudes. We further present a sample of new candidate AGN and candidates for obscured AGN. Together these make an interesting subset for further follow-up studies. An initial spectroscopic follow-up of 6 out of the 81 new candidates showed that all six sources are active galaxies, although two have narrow emission lines.

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EROSITA: AGN SCIENCE, BACKGROUND DETERMINATION, AND OPTICAL FOLLOW-UP SPECTROSCOPY

Acta Polytechnica ◽

10.14311/ap.2013.53.0793 ◽

2013 ◽

Vol 53 (A) ◽

pp. 793-798

Author(s):

Thomas Boller

Keyword(s):

Small Sample ◽

Scientific Success ◽

X Ray ◽

Photometric Redshift ◽

Sky Survey ◽

Extended Sources ◽

Small Sample Sizes ◽

Primary Instrument ◽

The Ideal

More than 20 years after the highly impacting ROSAT all-sky survey in the soft X-ray spectral range, we are close to the next major X-ray all/sky surveys with eROSITA. eROSITA will be the primary instrument on-board the Russian “Spectrum–Roentgen–Gamma” (SRG) satellite which will be launched from Baikonur in 2014 and placed in an L2 orbit. It will perform the first imaging all-sky survey in the medium energy X-ray range up to 10 keV with an unprecedented spectral and angular resolution. The eROSITA all sky X-ray survey will take place in a very different context than the ROSAT survey. There is now a wealth of complete, ongoing and planned surveys of the sky in broad range of wavelengths from the gamma, X-ray to the radio. A significant amount of science can be accomplished through the multi-frequency study of the eROSITA AGN and cluster sample, including optical confirmation and photometric redshift estimation of the eROSITA extended sources and AGNs. Optical spectroscopy has been, and will for the foreseeable future be, one of the main tools of astrophysics allowing studies of a large variety of astronomical objects over many fields of research. The fully capitalize on the eROSITA potential, a dedicated spectroscopic follow-up program is needed. 4MOST is the ideal instrument to secure the scientific success of the eROSITA X-ray survey and to overcome the small sample sizes together with selection biases that plagued past samples. The aim is to have the instrument commissioned in 2017, well matched to the data releases of eROSITA and Gaia. The design and implementation of the 4MOST facility simulator aimed to optimize the science output for eROSITA is described in necessary details.

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Can we quickly flag ultra-long gamma-ray bursts?

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz1036 ◽

2019 ◽

Vol 486 (2) ◽

pp. 2471-2476 ◽

Cited By ~ 4

Author(s):

B Gendre ◽

Q T Joyce ◽

N B Orange ◽

G Stratta ◽

J L Atteia ◽

...

Keyword(s):

Gamma Ray ◽

High Energy ◽

Gamma Ray Bursts ◽

Wide Field ◽

Exact Nature ◽

X Ray ◽

Central Engine ◽

Long Duration ◽

Limited Coverage

Abstract Ultra-long gamma-ray bursts are a class of high-energy transients lasting several hours. Their exact nature is still elusive, and several models have been proposed to explain them. Because of the limited coverage of wide-field gamma-ray detectors, the study of their prompt phase with sensitive narrow-field X-ray instruments could help in understanding the origin of ultra-long GRBs. However, the observers face a true problem in rapidly activating follow-up observations, due to the challenging identification of an ultra-long GRB before the end of the prompt phase. We present here a comparison of the prompt properties available after a few tens of minutes of a sample of ultra-long GRBs and normal long GRBs, looking for prior indicators of the long duration. We find that there is no such clear prior indicator of the duration of the burst. We also found that statistically, a burst lasting at least 10 and 20 minutes has respectively $28{{\ \rm per\ cent}}$ and $50{{\ \rm per\ cent}}$ probability to be an ultralong event. These findings point towards a common central engine for normal long and ultra-long GRBs, with the collapsar model privileged.

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The Evolution of Galaxies and Groups in Cluster Environments at 0.3 < z < 0.6

Proceedings of the International Astronomical Union ◽

10.1017/s1743921306006260 ◽

2006 ◽

Vol 2 (S235) ◽

pp. 220-220

Author(s):

I. H. Li ◽

H. K. C. Yee ◽

B. C. Hsieh ◽

D. G. Gilbank ◽

M. D. Gladders

Keyword(s):

Evolutionary Status ◽

Wide Field ◽

Training Set ◽

Cluster Galaxies ◽

Galaxy Groups ◽

Photometric Redshift ◽

Probability Densities ◽

Galaxy Populations ◽

Intermediate Redshift

We investigate the dependence of galaxy populations on environment. Our samples are selected from the follow-up of Red-Sequence Cluster Survey (RCS) catalogs using wide-field BVRz' imaging for 60 intermediate redshift (0.3 < z < 0.6) clusters. Galaxy redshifts are estimated using an empirical photometric redshift technique with a training set of 3996 galaxies to z 1.4. To obtain photometric redshift probability density for each galaxy, we bootstrap the training set galaxies to estimate the fitting uncertainties and apply Monte-Carlo method to simulate galaxy magnitudes errors. In order to find galaxy groups using photometric redshift, we develop a modified friends-of-friends algorithm, ‘Probability Friends-of-Friends Algorithm (pFOF)’, where photometric redshift redshift probability densities of individual galaxies are used to determine member galaxies of a group. We calculate the red galaxy fraction to infer the evolutionary status of cluster galaxies and also for galaxies in groups selected in the same redshift space as the clusters.

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A new RASS galaxy cluster catalogue with low contamination extending to z ∼ 1 in the DES overlap region

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz1463 ◽

2019 ◽

Vol 488 (1) ◽

pp. 739-769 ◽

Cited By ~ 11

Author(s):

M Klein ◽

S Grandis ◽

J J Mohr ◽

M Paulus ◽

T M C Abbott ◽

...

Keyword(s):

Matched Filter ◽

Galaxy Cluster ◽

Galactic Nuclei ◽

Mass Function ◽

Optical Data ◽

X Ray ◽

Sky Survey ◽

Infrared Sources ◽

Step Selection

ABSTRACT We present the MARD-Y3 catalogue of between 1086 and 2171 galaxy clusters (52 per cent and 65 per cent new) produced using multicomponent matched filter (MCMF) follow-up in 5000 deg2 of DES-Y3 optical data of the ∼20 000 overlapping ROSAT All-Sky Survey source catalogue (2RXS) X-ray sources. Optical counterparts are identified as peaks in galaxy richness as a function of redshift along the line of sight towards each 2RXS source within a search region informed by an X-ray prior. All peaks are assigned a probability fcont of being a random superposition. The clusters lie at 0.02 < z < 1.1 with more than 100 clusters at z > 0.5. Residual contamination is 2.6 per cent and 9.6 per cent for the cuts adopted here. For each cluster we present the optical centre, redshift, rest frame X-ray luminosity, M500 mass, coincidence with NWAY infrared sources, and estimators of dynamical state. About 2 per cent of MARD-Y3 clusters have multiple possible counterparts, the photo-z’s are high quality with σΔz/(1 + z) = 0.0046, and ∼1 per cent of clusters exhibit evidence of X-ray luminosity boosting from emission by cluster active galactic nuclei. Comparison with other catalogues (MCXC, RM, SPT-SZ, Planck) is performed to test consistency of richness, luminosity, and mass estimates. We measure the MARD-Y3 X-ray luminosity function and compare it to the expectation from a fiducial cosmology and externally calibrated luminosity- and richness–mass relations. Agreement is good, providing evidence that MARD-Y3 has low contamination and can be understood as a simple two step selection – X-ray and then optical – of an underlying cluster population described by the halo mass function.

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Effectiveness of WISE colour-based selection techniques to uncover obscured AGN

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314003792 ◽

2013 ◽

Vol 9 (S304) ◽

pp. 209-212

Author(s):

S. Mateos

Keyword(s):

Sloan Digital Sky Survey ◽

Spectral Energy ◽

Wide Field ◽

Mid Infrared ◽

Selection Technique ◽

X Ray ◽

Sky Survey ◽

Two Samples ◽

Optical Surveys

AbstractWe present a highly reliable and efficient mid-infrared colour-based selection technique for luminous active galactic nuclei (AGN) using the Wide-field Infrared Survey Explorer (WISE) survey. Our technique is designed to identify objects with red mid-infrared power-law spectral energy distributions. We studied the dependency of our mid-infrared selection on the AGN intrinsic luminosity and the effectiveness of our technique to uncover obscured AGN missed in X-ray surveys. To do so we used two samples of luminous AGN independently selected in hard X-ray and optical surveys. We used the largest catalogue of 887 [OIII] λ5007-selected type 2 quasars (QSO2s) at z≲0.83 in the literature from the Sloan Digital Sky Survey (SDSS), and the 258 hard (>4.5 keV) X-ray-selected AGN from the Bright Ultrahard XMM-Newton Survey (BUXS). The effectiveness of our mid-infrared selection technique increases with the AGN luminosity. At high luminosities and at least up to z~1 our technique is very effective at identifying both Compton-thin and Compton-thick AGN.

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Subaru/HSC deep optical imaging of infrared sources in the AKARI North Ecliptic Pole-Wide field

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3080 ◽

2020 ◽

Vol 500 (4) ◽

pp. 5024-5042

Author(s):

Nagisa Oi ◽

Tomotsugu Goto ◽

Hideo Matsuhara ◽

Yousuke Utsumi ◽

Rieko Momose ◽

...

Keyword(s):

Optical Imaging ◽

Thermal Emission ◽

Spectral Energy Distribution ◽

Broad Band ◽

Spectral Energy ◽

Wide Field ◽

Star Forming ◽

The North ◽

Almost All ◽

Infrared Sources

ABSTRACT We present a five-broad-band (grizy) photometric catalogue of Subaru/Hyper Suprime-Cam (HSC) optical imaging observations at around the North Ecliptic Pole (NEP) where the AKARI infrared (IR) satellite conducted a large survey (NEP-Wide survey). The observations cover almost all the NEP-Wide survey field down to the depth of 28.1, 26.8, 26.3, 25.5, and 25.0 mag (5σ) at grizy, respectively. The five-band HSC catalogue contains about 2.6 million objects, and 70 959 AKARI NEP-Wide counterpart sources are identified in the catalogue. We added existing supplementary catalogues from the u band to the far-IR band, and estimated photo-z for the AKARI-HSC sources. We achieved σΔz/(1 + zs) = 0.06 and an outlier rate of 13.4 per cent at z = 0.2–1.5. Using the spectral energy distribution (SED) template fitting, we classified the AKARI-HSC galaxies into four categories, namely quiescent, star-forming, Type1 active galactic nucleus (AGN), and Type2 AGN, in each redshift bin. At z > 1, the mean SED of star-forming galaxies in mid-IR (3–10 μm) range is significantly different from that of spiral galaxies in the nearby Universe, indicating that many of star-forming galaxies at z > 1 contain a heat source capable of heating dust to temperatures that radiate thermal emission in the mid-IR range. Furthermore, we estimated the number fraction of AGNs (fAGN) in each bin of redshift and IR luminosity (LIR), and examined the dependence of redshift and LIR. In log(LIR/L⊙) = 11.0–14.0, the fAGN shows a significant increase with increasing redshift, regardless of the LIR bins. In contrast, the fAGN shows a slight increase against LIR at z < 1 and no increase with increasing LIR at z > 1.

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The Deepest Chandra View of RBS 797: Evidence for Two Pairs of Equidistant X-ray Cavities

The Astrophysical Journal ◽

10.3847/2041-8213/ac374c ◽

2021 ◽

Vol 923 (2) ◽

pp. L25

Author(s):

F. Ubertosi ◽

M. Gitti ◽

F. Brighenti ◽

G. Brunetti ◽

M. McDonald ◽

...

Keyword(s):

Radial Distance ◽

Galaxy Cluster ◽

Age Difference ◽

X Ray ◽

The North ◽

The Galaxy ◽

Centrally Symmetric ◽

First Results ◽

East West

Abstract We present the first results of a deep Chandra observation of the galaxy cluster RBS 797 whose previous X-ray studies revealed two pronounced X-ray cavities in the east–west (E–W) direction. Follow-up VLA radio observations of the central active galactic nucleus (AGN) uncovered different jet and lobe orientations, with radio lobes filling the E–W cavities and perpendicular jets showing emission in the north–south (N–S) direction over the same scale (≈30 kpc). With the new ∼427 ks total exposure, we report the detection of two additional, symmetric X-ray cavities in the N–S direction at nearly the same radial distance as the E–W ones. The newly discovered N–S cavities are associated with the radio emission detected at 1.4 and 4.8 GHz in archival VLA data, making RBS 797 the first galaxy cluster found to have four equidistant, centrally symmetric, radio-filled cavities. We derive the dynamical and radiative ages of the four cavities from X-ray and radio data, respectively, finding that the two outbursts are approximately coeval, with an age difference of ⪅10 Myr between the E–W and N–S cavities. We discuss two scenarios for the origin of the two perpendicular, equidistant cavity systems: either the presence of a binary AGN that is excavating coeval pairs of cavities in perpendicular directions or a fast (<10 Myr) jet reorientation event that produced subsequent, misaligned outbursts.

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Colour–magnitude diagrams of transiting exoplanets – III. A public code, nine strange planets, and the role of phosphine

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2350 ◽

2020 ◽

Vol 499 (1) ◽

pp. 505-519 ◽

Cited By ~ 2

Author(s):

Georgina Dransfield ◽

Amaury H M J Triaud

Keyword(s):

Theoretical Models ◽

Wide Field ◽

Bulk Properties ◽

Mid Infrared ◽

James Webb Space Telescope ◽

Water Band ◽

Selection Of ◽

Low Irradiation

ABSTRACT Colour–magnitude diagrams provide a convenient way of comparing populations of similar objects. When well populated with precise measurements, they allow quick inferences to be made about the bulk properties of an astronomic object simply from its proximity on a diagram to other objects. We present here a python toolkit that allows a user to produce colour–magnitude diagrams of transiting exoplanets, comparing planets to populations of ultra-cool dwarfs, of directly imaged exoplanets, to theoretical models of planetary atmospheres, and to other transiting exoplanets. Using a selection of near- and mid-infrared colour–magnitude diagrams, we show how outliers can be identified for further investigation, and how emerging subpopulations can be identified. Additionally, we present evidence that observed differences in the Spitzer’s 4.5 μm flux, between irradiated Jupiters and field brown dwarfs, might be attributed to phosphine, which is susceptible to photolysis. The presence of phosphine in low-irradiation environments may negate the need for thermal inversions to explain eclipse measurements. We speculate that the anomalously low 4.5 μm flux of the nightside of HD 189733b and the daysides of GJ 436b and GJ 3470b might be caused by phosphine absorption. Finally, we use our toolkit to include Hubble Wide Field Camera 3 spectra, creating a new photometric band called the ‘Water band’ (WJH band) in the process. We show that the colour index [WJH − H] can be used to constrain the C/O ratio of exoplanets, showing that future observations with James Webb Space Telescope and Ariel will be able to distinguish these populations if they exist, and select members for future follow-up.

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