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Register a new userBlack hole mass and Eddington ratio distribution functions of X-ray selected broad-line AGNs at z~1.4 in the Subaru XMM-Newton Deep Field
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In order to investigate the growth of super-massive black holes (SMBHs), we construct the black hole mass function (BHMF) and Eddington ratio distribution function (ERDF) of X-ray-selected broad-line AGNs at z~1.4 in the Subaru XMM-Newton Deep Survey field. In this redshift range, a significant part of the accretion growth of SMBHs is thought to be taking place. Black hole masses of X-ray-selected broad-line AGNs are estimated using the width of the broad MgII line and the 3000A monochromatic luminosity. We supplement the MgII FWHM values with the Ha FWHM obtained from our NIR spectroscopic survey. Using the black hole masses of broad-line AGNs at redshifts between 1.18 and 1.68, the binned broad-line AGN BHMF and ERDF are calculated using the Vmax method. To properly account for selection effects that impact the binned estimates, we derive the corrected broad-line AGN BHMF and ERDF by applying the Maximum Likelihood method, assuming that the ERDF is constant regardless of the black hole mass. We do not correct for the non-negligible uncertainties in virial BH mass estimates. If we compare the corrected broad-line AGN BHMF with that in the local Universe, the corrected BHMF at z~1.4 has a higher number density above 10^8 Msolar but a lower number density below that mass range. The evolution may be indicative of a down-sizing trend of accretion activity among the SMBH population. The evolution of broad-line AGN ERDF from z=1.4 to 0 indicates that the fraction of broad-line AGNs with accretion rate close to the Eddington-limit is higher at higher redshifts.
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We present the results of a search for galaxy clusters in Subaru-XMM Deep Field. We reach a depth for a total cluster flux in the 0.5-2 keV band of 2x10^{-15} ergs cm^{-2} s^{-1} over one of the widest XMM-Newton contiguous raster surveys, covering an area of 1.3 square degrees. Cluster candidates are identified through a wavelet detection of extended X-ray emission. The red sequence technique allows us to identify 57 cluster candidates. We report on the progress with the cluster spectroscopic follow-up and derive their properties based on the X-ray luminosity and cluster scaling relations. In addition, 3 sources are identified as X-ray counterparts of radio lobes, and in 3 further sources, X-ray counterpart of radio lobes provides a significant fraction of the total flux of the source. In the area covered by NIR data, our identification success rate achieves 86%. We detect a number of radio galaxies within our groups and for a luminosity-limited sample of radio galaxies we compute halo occupation statistics using a marked cluster mass function. We compare the cluster detection statistics in the SXDF with the predictions of concordance cosmology and current knowledge of the X-ray cluster properties, concluding that a reduction of concordance sigma_8 value by 5% is required in order to match the prediction of the model and the data. This conclusion still needs verification through the completion of cluster follow-up.
We conducted a deep narrowband NB973 (FWHM = 200 A centered at 9755 A) survey of z=7 Lyman alpha emitters (LAEs) in the Subaru/XMM-Newton Deep Survey Field, using the fully depleted CCDs newly installed on the Subaru Telescope Suprime-Cam, which is twice more sensitive to z=7 Lyman alpha at ~ 1 micron than the previous CCDs. Reaching the depth 0.5 magnitude deeper than our previous survey in the Subaru Deep Field that led to the discovery of a z=6.96 LAE, we detected three probable z=7 LAE candidates. Even if all the candidates are real, the Lyman alpha luminosity function (LF) at z=7 shows a significant deficit from the LF at z=5.7 determined by previous surveys. The LAE number and Lyman alpha luminosity densities at z=7 is ~ 7.7-54% and ~5.5-39% of those at z=5.7 to the Lyman alpha line luminosity limit of L(Ly-alpha) >~ 9.2 x 10^{42} erg s^{-1}. This could be due to evolution of the LAE population at these epochs as a recent galaxy evolution model predicts that the LAE modestly evolves from z=5.7 to 7. However, even after correcting for this effect of galaxy evolution on the decrease in LAE number density, the z=7 Lyman alpha LF still shows a deficit from z=5.7 LF. This might reflect the attenuation of Lyman alpha emission by neutral hydrogen remaining at the epoch of reionization and suggests that reionization of the universe might not be complete yet at z=7. If we attribute the density deficit to reionization, the intergalactic medium (IGM) transmission for Lyman alpha photons at z=7 would be 0.4 <= T_{Ly-alpha}^{IGM} <= 1, supporting the possible higher neutral fraction at the earlier epochs at z > 6 suggested by the previous surveys of z=5.7-7 LAEs, z ~ 6 quasars and z > 6 gamma-ray bursts.
We present measurements of the X-ray observables of the intra-cluster medium (ICM), including luminosity $L_X$, ICM mass $M_{ICM}$, emission-weighted mean temperature $T_X$, and integrated pressure $Y_X$, that are derived from XMM-Newton X-ray observations of a Sunyaev-Zeldovich Effect (SZE) selected sample of 59 galaxy clusters from the South Pole Telescope SPT-SZ survey that span the redshift range of $0.20 < z < 1.5$. We constrain the best-fit power law scaling relations between X-ray observables, redshift, and halo mass. The halo masses are estimated based on previously published SZE observable to mass scaling relations, calibrated using information that includes the halo mass function. Employing SZE-based masses in this sample enables us to constrain these scaling relations for massive galaxy clusters ($M_{500}geq 3 times10^{14}$ $M_odot$) to the highest redshifts where these clusters exist without concern for X-ray selection biases. We find that the mass trends are steeper than self-similarity in all cases, and with $geq 2.5{sigma}$ significance in the case of $L_X$ and $M_{ICM}$. The redshift trends are consistent with the self-similar expectation, but the uncertainties remain large. Core-included scaling relations tend to have steeper mass trends for $L_X$. There is no convincing evidence for a redshift-dependent mass trend in any observable. The constraints on the amplitudes of the fitted scaling relations are currently limited by the systematic uncertainties on the SZE-based halo masses, however the redshift and mass trends are limited by the X-ray sample size and the measurement uncertainties of the X-ray observables.
We present a stellar mass-metallicity relation at z~1.4 with an unprecedentedly large sample of ~340 star-forming galaxies obtained with FMOS on the Subaru Telescope. We observed K-band selected galaxies at 1.2 < z_{ph} < 1.6 in the SXDS/UDS fields with M_{*} > 10^{9.5} M_{sun}, and expected F(Halpha) > 5 times 10^{-17} erg s^{-1} cm^{-2}. Among the observed ~1200 targets, 343 objects show significant Halpha emission lines. The gas-phase metallicity is obtained from [NII]lambda 6584/Halpha line ratio, after excluding possible active galactic nuclei (AGNs). Due to the faintness of the [NII]lambda 6584 lines, we apply the stacking analysis and derive the mass-metallicity relation at z~1.4. Our results are compared to past results at different redshifts in the literature. The mass-metallicity relation at z~1.4 is located between those at z~0.8 and z~2.2; it is found that the metallicity increases with decreasing redshift from z~3 to z~0 at fixed stellar mass. Thanks to the large size of the sample, we can study the dependence of the mass-metallicity relation on various galaxy physical properties. The average metallicity from the stacked spectra is close to the local FMR in the higher metallicity part but >0.1 dex higher in metallicity than the FMR in the lower metallicity part. We find that galaxies with larger E(B-V), B-R, and R-H colours tend to show higher metallicity by ~0.05 dex at fixed stellar mass. We also find relatively clearer size dependence that objects with smaller half light radius tend to show higher metallicity by ~0.1 dex at fixed stellar mass, especially in the low mass part.
We present multi-object spectroscopy of galaxies in the immediate (Mpc-scale) environments of four low-power (L_1.4 GHz < 10^25 W/Hz) radio galaxies at z~0.5, selected from the Subaru/XMM-Newton Deep Field. We use the spectra to calculate velocity dispersions and central redshifts of the groups the radio galaxies inhabit, and combined with XMM-Newton (0.3-10 keV) X-ray observations investigate the L_X--sigma_v and T_X--sigma_v scaling relationships. All the radio galaxies reside in moderately rich groups -- intermediate environments between poor groups and rich clusters, with remarkably similar X-ray properties. We concentrate our discussion on our best statistical example that we interpret as a low-power (FRI) source triggered within a sub-group, which in turn is interacting with a nearby group of galaxies, containing the bulk of the X-ray emission for the system -- a basic scenario which can be compared to more powerful radio sources at both high (z>4) and low (z<0.1) redshifts. This suggests that galaxy-galaxy interactions triggered by group mergers may play an important role in the life-cycle of radio galaxies at all epochs and luminosities.
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