Papers by Tadafumi Takata
HYPER SUPRIME-CAM Subaru戦略プログラムの第2データリリース
Publications of the Astronomical Society of Japan, 2019
VizieR Online Data Catalog: XMM-Newton 13 H deep field (Loaring+
yCat, Apr 1, 2006
Catalog of galaxies behind the Milky Way. Vol. 2: l = 230 to 250 degrees
CoKyo, 1991
Monthly Notices of the Royal Astronomical Society, 2005
We present the results of a deep X-ray survey conducted with XMM-Newton, centred on the UK ROSAT ... more We present the results of a deep X-ray survey conducted with XMM-Newton, centred on the UK ROSAT 13 H deep field area. This region covers 0.18 deg 2 and is the first of two areas covered with XMM-Newton as part of an extensive multi-wavelength survey designed to study the nature and evolution of the faint X-ray source population. We have produced detailed Monte-Carlo simulations to obtain a quantitative characterisation of the source detection procedure and to assess the reliability of the resultant sourcelist. We use the simulations to establish a likelihood threshold above which we expect less than 7 (3%) of our sources to be spurious. We present the final catalogue of 225 sources. Within the central 9 ′ , 68 per cent of source positions are accurate to 2 ′′ making optical follow-up relatively straightforward. We construct the N(> S) relation in four energy bands: 0.2-0.5 keV, 0.5-2 keV, 2-5 keV and 5-10 keV. In all but our highest energy band we find that the source counts can be represented by a double powerlaw with a bright end slope consistent with the Euclidean case and a break around 10 −14 erg cm −2 s −1. Below this flux the counts exhibit a flattening. Our source counts reach densities of 700, 1300, 900 and 300 deg −2 at fluxes of 4.1×10 −16 , 4.5×10 −16 , 1.1×10 −15 and 5.3×10 −15 erg cm −2 s −1 in the 0.2-0.5, 0.5-2, 2-5 and 5-10 keV energy bands respectively. We have compared our source counts with those in the two Chandra deep fields and Lockman hole and find our source counts to be amongst the highest of these fields in all energy bands. We resolve > 51% (> 50%) of the X-ray background emission in the 1-2 keV (2-5 keV) energy bands.
Publications of the Astronomical Society of Japan, 2000
The results of deep-imaging observations of a candidate of an absorbed QSO at z = 0.653, AX J1318... more The results of deep-imaging observations of a candidate of an absorbed QSO at z = 0.653, AX J131831+3341, are presented. AX J131831+3341 was found during the course of optical follow-up observations of the ASCA Large Sky Survey, and has an X-ray luminosity of 10 45 erg s −1 (2-10 keV), which corresponds to those of QSOs. Its optical spectrum shows no significant broad Hβ emission line, suggesting that the object is an absorbed QSO. Deep R and V band images reveal the presence of a point-like nucleus and an asymmetric extended component. The nuclear component has a blue color, and the optical magnitude is much fainter than that expected from the observed X-ray flux for typical type-1 AGNs. These photometric properties and the presence of broad Mg II 2800Å emission can be explained simultaneously if the observed nuclear light is dominated by scattered nuclear light, though there is a possibility that the nuclear component is a slightly absorbed nucleus if its intrinsic X-ray to optical flux ratio is the largest among X-ray selected AGNs. The size of the extended component, which is thought to be the host galaxy of the QSO, is larger than those of normal disk galaxies at z = 0 − 0.75, and the absolute magnitude is similar to those of the brightest host galaxies of QSOs at redshifts smaller than 0.5. The V − R and R − I colors of the component are consistent with a 1 Gyr-old stellar population model without absorption. galaxies: active-galaxies: individual (AX J131831+3341)-galaxies: photometry-quasars headings
Massive red galaxies around a submilimeter bright high redshift radio galaxy
Unveiling Sub-mm Galaxies(II)
Databases in Subaru telescope
The Astronomical Journal, 2012
We derived the luminosity function (LF) of dwarf galaxies in the Coma Cluster down to M R = −10 a... more We derived the luminosity function (LF) of dwarf galaxies in the Coma Cluster down to M R = −10 at three fields located at the center, intermediate, and outskirt. The LF (−19 < M R < −10) shows no significant differences among the three fields. It shows a clear dip at M R ∼ −13, and is composed of two distinct components of different slopes; the bright component with −19 < M R < −13 has a flatter slope than the faint component with −13 < M R < −10 which has a steep slope. The bright component (−19 < M R < −13) consists of mostly red extended galaxies including few blue galaxies whose colors are typical of late-type galaxies. On the other hand, the faint component (−13 < M R < −10) consists of largely PSF-like compact galaxies. We found that both these compact galaxies and some extended galaxies are present in the center while only compact galaxies are seen in the outskirt. In the faint component, the fraction of blue galaxies is larger in the outskirt than in the center. We suggest that the dwarf galaxies in the Coma Cluster, which make up the two components in the LF, are heterogeneous with some different origins.
The Astronomical Journal, 2005
We have carried out near-infrared JHK spectroscopy of a gravitationally lensed submillimeter gala... more We have carried out near-infrared JHK spectroscopy of a gravitationally lensed submillimeter galaxy SMM J14011+0252 at z = 2.565, using OHS and CISCO on the Subaru telescope. This object consists of two optical components, J1 and J2, which are lensed by the cluster Abell 1835. J1 suffers additional strong lensing by a foreground galaxy at z = 0.25 in the cluster. The rest-frame optical Hα, Hβ, and [O ii]λ3727 lines are detected in both J1 and J2, and [N ii]λλ6548, 6583 lines are also detected in J1. A diagnosis of emission-line ratios shows that the excitation source of J1 is stellar origin, consistent with previous X-ray observations. The continua of J1 and J2 show breaks at rest-frame 4000Å, indicating relatively young age. Combined with optical photometry, we have carried out model spectrum fitting of J2 and find that it is a very young (∼50 Myr) galaxy of rather small mass (∼ 10 8 M ⊙) which suffers some amount of dust extinction. A new gravitational lensing model is constructed to assess both magnification factor and contamination from the lensing galaxy of the component J1, using HST-F 702W image. We have found that J1 suffers strong lensing with magnification of ∼ 30, and its stellar mass is estimated to be 10 9 M ⊙. These results suggest that SMM J14011+0252 is a major merger system at high redshift that undergoes intense star formation, but not a formation site of a giant elliptical. Still having plenty of gas, it will transform most of the gas into stars and will evolve into a galaxy of 10 10 M ⊙. Therefore, this system is possibly an ancestor of a less massive galaxy such as a mid-sized elliptical or a spiral at the present.
Multiwavelength …, 2004
We present the X-ray source catalog in the Subaru/XMM-Newton deep survey. A continuous area of 1.... more We present the X-ray source catalog in the Subaru/XMM-Newton deep survey. A continuous area of 1.14 deg 2 centered at R.A. = 02h18m and Dec. =-05d is mapped by seven pointings with XMM-Newton covering the 0.2-10 keV band. From the combined images of the EPIC pn and MOS cameras, we detect 866, 1114, 645, and 136 sources with sensitivity limits of 6 × 10 −16 , 8 × 10 −16 , 3 × 10 −15 , and 5 × 10 −15 erg cm −2 s −1 in the 0.5-2, 0.5-4.5, 2-10, and 4.5-10 keV bands, respectively, with detection likelihood ≥7 (corresponding to a confidence level of 99.91%). The catalog consists of 1245 sources in total including 32 extended-source candidates. The averaged log N-log S relations are in good agreement with previous results, bridging the flux range between Chandra deep surveys and brighter surveys. The log N-log S relations show significant spatial variation among pointings on a scale of 0.2 deg 2. Analyzing the auto correlation function, we detect significant clustering signals from the 0.5-2 keV band sample, which can be fit with a power law form (θ/θ c) −0.8 with a correlation length of θ c = 5.9 ′′+1.0 ′′ −0.9 ′′ when the integral constraint term is included. In the 2-10 keV band, however, the clustering is not significant with a 90% upper limit of θ c < 1.5 ′′ .
Publications of the Astronomical Society of Japan, 2000
Publications of the Astronomical Society of Japan, 2000
We present high spatial resolution images of the gravitational-lens system PG 1115+080 taken with... more We present high spatial resolution images of the gravitational-lens system PG 1115+080 taken with the near-infrared camera (CISCO) on the Subaru telescope. The FWHM of the combined image is 0. ′′ 32 in the K ′-band, yielding spatial resolution of 0. ′′ 14 after a deconvolution procedure. This is a first detection of an extended emission adjacent to the A1/A2 components, indicating the presence of a fairly bright emission region with a characteristic angular radius of ∼ 5 mas (40 pc). The near-infrared image of the Einstein ring was extracted in both the J and K ′ bands. The J − K ′ color is found to be significantly redder than that of a synthetic model galaxy with an age of 3 Gyr, the age of the universe at the quasar redshift.
Evolution of Elliptical Galaxies at Formula Revealed from a Large, Multicolor Sample of Extremely Red Objects
Publications of the Astronomical Society of Japan, 2003
Publications of the Astronomical Society of Japan, 2001
Deep narrow-and broad-band near-infrared imaging observations of the central 2 × 2 region of the ... more Deep narrow-and broad-band near-infrared imaging observations of the central 2 × 2 region of the SSA 22 field were made with the near-infrared camera (CISCO) attached to the Subaru Telescope. Using a narrow-band filter centered at 2.033 µm, [O III] λ 5007 emitters at z ∼ 3.06 ± 0.02 were searched to examine star-forming activities in an over-density region where a clustering of Lyman Break Galaxies (LBGs) and Lyman α emitter candidates around z = 3.09 was reported, though the targeted redshift is slightly different from that of the peak of the over-density region. Although one emitter candidate at z = 3.06 was detected, it is likely to be located at a redshift of between 1 and 2 judged based on multi-band photometry. Another emission-line object was detected in another narrowband filter ("off band" filter) centered at 2.120 µm, which is identified with a galaxy at z = 0.132 (the emission line is Paschen α). The K-band imaging data revealed the presence of 12 Extremely Red Objects (EROs) with I 814 −K ≥ 4. The distribution of the EROs does not seem to coincide with that of Lyman Break Galaxies or Lyman α emitters at z ∼ 3. The magnitudes and colors of the EROs are not consistent with those of passively evolving massive elliptical galaxies at z ∼ 3. Candidates for counterparts of the submm sources detected with SCUBA are found; no EROs around the submm sources are found in our magnitude limit.
Publications of the Astronomical Society of Japan, 2003
We performed deep K-band imaging observations of 2 massive clusters, MS 0451.6−0305 at z = 0.55 a... more We performed deep K-band imaging observations of 2 massive clusters, MS 0451.6−0305 at z = 0.55 and MS 0440.5 + 0204 at z = 0.19, for searching counterparts of the faint sub-mm sources behind these clusters, which would provide one of the deepest extremely red object (ERO) samples. Comparing our near-infrared images with optical images taken by the Hubble Space Telescope and by the Subaru Telescope, we identified 13 EROs in these fields. The sky distributions of EROs are consistent with the previous results, that there is a sign of strong clustering among detected EROs. Also, the surface density with corrected lensing amplification factors in both clusters are in good agreement with that derived from previous surveys. We found 7 EROs and 3 additional very red objects in a small area (∼ 0.6 arcmin 2) of the MS 0451.6−0305 field around an extended SCUBA source. Many of their optical and near-infrared colors are consistent with dusty star-forming galaxies at high redshifts (z ∼ 1.0-4.0), and they may be constituting a cluster of dusty starburst galaxies and/or lensed star-forming galaxies at high redshift. Their red J − K colors and faint optical magnitudes suggest they are relatively old massive stellar systems with ages (> 300 mega years) suffering from dust obscuration. We also found a surface-density enhancement of EROs around the SCUBA source in the MS 0440.5 + 0204 field.
Publications of the Astronomical Society of Japan, 2011
We present the result of projected cross correlation analysis of AGNs and galaxies at redshifts f... more We present the result of projected cross correlation analysis of AGNs and galaxies at redshifts from 0.3 to 3.0. The Japanese Virtual Observatory (JVO) was used to obtain the Subaru Suprime-Cam images and UKIDSS catalog data around AGNs. We investigated 1,809 AGNs, which is about ten times larger a sample than that used in previous studies on AGN-galaxy clustering at redshifts larger than 0.6. 90% of the AGN samples are optically-selected AGN from the SDSS and 2dF catalogs. The galaxy samples at low redshift includes many redder objects from UKIDSS survey, while at higher redshift they are mainly blue galaxies from Suprime-Cam. We found significant excess of galaxies around the AGNs at redshifts from 0.3 to 1.8. For the low redshift samples (z < 0.9), we obtained correlation length of r 0 =5-6 h −1 Mpc (γ = 1.8), which indicates that the AGNs at this redshift range reside in a similar environment around typical local galaxies. We also found that AGNs at higher redshift ranges reside in a denser environment than lower redshift AGNs; For z = 1.3 ∼ 1.8 AGNs, the cross correlation length was measured as 11 +6 −3 h −1 Mpc (γ = 1.8). Considering that our galaxies sample is based on optical observations with Suprime-Cam at the redshift range, it is expected that blue star-forming galaxies comprise the majority of objects that are observed to be clustered around the AGNs. It is successfully demonstrated that the use of the archive through the Virtual Observatory system can provide a powerful tool for investigating the small scale environment of the intermediate redshift AGNs.
Monthly Notices of the Royal Astronomical Society, 2003
We present the results of a Chandra ACIS-I survey of a high-latitude region at 13 h +38 • which w... more We present the results of a Chandra ACIS-I survey of a high-latitude region at 13 h +38 • which was earlier observed with ROSAT and which has recently been observed by XMM-Newton for 200 ks. XMM-Newton will provide good-quality X-ray spectra for over 200 sources with fluxes around the knee of the log N / log S, which are responsible for the bulk of the X-ray background. The main aim of the Chandra observations is to provide arcsecond, or better, positions, and hence reliable identifications, for the XMM-Newton sources. The ACIS-I observations were arranged in a mosaic of four 30-ks pointings, covering almost all of the 15-arcmin radius XMM-Newton/ROSAT field. We detect 214 Chandra sources above a Cash likelihood statistic of 25, which approximates to 5σ significance, to a limiting flux of ∼1.3 × 10 −15 erg cm −2 s −1 (0.5-7 keV). Optical counterparts are derived from a Subaru SuprimeCam image reaching to R ∼ 27. The very large majority of the Chandra sources have an optical counterpart, with the distribution peaking at 23 < R < 24, although 14 have no counterpart to R = 27. The fraction of X-ray sources with no identification brighter than R = 27 is similar to that found in deeper Chandra surveys. The majority of the identifications are with galaxies. As found in other Chandra surveys, there is a very wide range of optical magnitudes for a given X-ray flux, implying a range of emission mechanisms, and many sources have high L X /L opt ratios, implying absorption at moderate redshift. Comparison with the earlier ROSAT survey shows that the accuracy of the ROSAT positions agrees very well with the predictions from simulations by M c Hardy et al. and that the large majority of the identifications were correct.
Superwind-Driven Intense H_2 Emission in NGC 6240
Publications of The Astronomical Society of Japan, 2000
We have performed a long-slit K-band spectroscopic observation of the luminous infrared galaxy NG... more We have performed a long-slit K-band spectroscopic observation of the luminous infrared galaxy NGC 6240. Spatially extended H_2 emission is detected over 3.3 kpc around the two nuclei. The peak position of the H_2 v=1-0 S(1) emission is located at ~ 0.3''-0.'' north of the southern nucleus. Based on line-ratio analyses, we suggest that the excitation mechanism of H_2 is pure thermal at most positions. We find the following three velocity components in the H_2 emission around the southern nucleus and its south region: a blue-shifted component (\approx -250 km s^{-1} with respect to V_sys), which is recognized as a distinct C-shape distortion in the velocity field around the southern nucleus; a high-velocity blue-shifted ``wing'' component (\sim -1000 km s^{-1} with respect to V_sys); and a component indicating possible line splitting of \sim 500 km s^{-1}. We show that these kinematic properties can be reproduced by expanding motion of a shell-like struc...
Subaru Deep Near-Infrared Imaging of the Field of a Possible Proto-Cluster Near the Radio Galaxy 53W002 at z= 2.4
PUBLICATIONS- …, 2001
We present the results of deep K-and J-band imaging of the field of a proto-cluster region near t... more We present the results of deep K-and J-band imaging of the field of a proto-cluster region near the radio galaxy 53W002 at z= 2. 390 with the Subaru Telescope. The data were analyzed together with deep optical and nearinfrared (NIR) images taken with the Hubble ...
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Papers by Tadafumi Takata