Relativistic Iron lines at high redshifts

The shape and the intensity of the 6.4 keV iron line bring unique information on the geometrical and physical properties of the supermassive black hole and the surrounding accreting gas at the very center of Active Galactic Nuclei. While there are convincing evidences of a relativistically broadened iron line in a few nearby bright objects, their properties at larger distances are basically unknown. We have searched for the presence of iron line by fully exploiting Chandra observations in the deep fields. The line is clearly detected in the average spectra of about 250 sources stacked in several redshift bins over the range z=0.5-4.0. We discuss their average properties with particular enphasys on the presence and intensity of a broad component.Comment: 6 pages, 4 figures. To appear in the proceedings of "Relativistic Astrophysics and Cosmology - Einstein's Legacy" (Eds.: B. Aschenbach, V. Burwitz, G. Hasinger, and B. Leibundgut), 7 - 11 November 2005, Munich, German

SMA Observations on faint submillimeter galaxies with S 850 < 2 mJy: ultra dusty low-luminosity galaxies at high redshift

We obtained Submillimeter Array (SMA) observations of eight faint (intrinsic 850 μm fluxes < 2 mJy) submillimeter galaxies (SMGs) discovered in SCUBA images of the massive lensing cluster fields A370, A2390, and A1689 and detected five. In total, we obtain five SMA detections, all of which have de-lensed fluxes <1 mJy with estimated total infrared luminosities 1010-1012 L ☉, comparable to luminous infrared galaxies and normal star-forming galaxies. Based on the latest number counts, these galaxies contribute ~70% of the 850 μm extragalactic background light and represent the dominant star-forming galaxy population in the dusty universe. However, only 40$^{+30}_{-16}$% of our faint SMGs would be detected in deep optical or near-infrared surveys, which suggests many of these sources are at high redshifts (z gsim 3) or extremely dusty, and they are not included in current star formation history estimates

SO(3) Gauge Symmetry and Neutrino-Lepton Flavor Physics

Based on the SO(3) gauge symmetry for three family leptons and general see-saw mechanism, we present a simple scheme that allows three nearly degenerate Majorana neutrino masses needed for hot dark matter. The vacuum structure of the spontaneous SO(3) symmetry breaking can automatically lead to a maximal CP-violating phase. Thus the current neutrino data on both the atmospheric neutrino anomaly and solar neutrino deficit can be accounted for via maximal mixings without conflict with the current data on the neutrinoless double beta decay. The model also allows rich interesting phenomena on lepton flavor violations.Comment: 10 pages, Revtex, no figures, minor changes and references added, the version to appear in Phys. Rev.

The Host Galaxies of X-ray Quasars Are Not Strong Star Formers

We use ultradeep SCUBA-2 850 μm observations (~0.37 mJy rms) of the 2 Ms Chandra Deep Field-North (CDF-N) and 4 Ms Chandra Deep Field-South X-ray fields to examine the amount of dusty star formation taking place in the host galaxies of high-redshift X-ray active galactic nuclei (AGNs). Supplementing with COSMOS, we measure the submillimeter fluxes of the 4–8 keV sources at $z\gt 1$, finding little flux at the highest X-ray luminosities but significant flux at intermediate luminosities. We determine graybody and MIR luminosities by fitting spectral energy distributions to each X-ray source and to each radio source in an ultradeep Karl G. Jansky Very Large Array (VLA) 1.4 GHz (11.5 μJy at $5\sigma$) image of the CDF-N. We confirm the far-infrared (FIR)-radio and mid-infrared (MIR)-radio correlations to z = 4 using the non-X-ray detected radio sources. Both correlations are also obeyed by the X-ray less luminous AGNs but not by the X-ray quasars. We interpret the low FIR luminosities relative to the MIR for the X-ray quasars as being due to a lack of star formation, while the MIR stays high due to the AGN contribution. We find that the FIR luminosity distributions are highly skewed and the means are dominated by a small number of high-luminosity galaxies. Thus, stacking or averaging analyses will overestimate the level of star formation taking place in the bulk of the X-ray sample. We conclude that most of the host galaxies of X-ray quasars are not strong star formers, perhaps because their star formation is suppressed by AGN feedback

HST ultraviolet spectral energy distributions for three ultraluminous infrared galaxies

We present HST Faint Object Camera ultraviolet (230 nm and 140 nm) images of three ultraluminous infrared galaxies (ULIG: L_ir > 10^12 L_sun) selected from the IRAS Revised Bright Galaxy Sample. The purpose is to estimate spectral energy distributions (SEDs) to facilitate the identification of similar objects at high redshift in deep optical, infrared, and submm surveys. All three galaxies (VII Zw031 = IRAS F12112+0305, and IRAS F22491-1808) were well detected at 230 nm. Two of the three were marginally detected at 140 nm. The fluxes, together with ground-based optical and infrared photometry, are used to compute SEDs over a wide wavelength range. The measured SEDs drop from the optical to the ultraviolet, but the magnitude of the drop ranges from a factor of ~3 in IRAS F22491-1808 to a factor of ~100 in VIIZw031. This is most likely due to different internal extinctions. Such an interpretation is also suggested by extrapolating to ultraviolet wavelengths the optical internal extinction measured in VIIZw031. K-corrections are calculated to determine the colors of the sample galaxies as seen at high redshifts. Galaxies like VIIZw031 have very low observed rest-frame UV fluxes which means that such galaxies at high redshift will be extremely red or even missing in optical surveys. On the other hand, galaxies like IRAS F12112+0305 and IRAS F22491-1808, if seen at high redshift, would be sufficiently blue that they would not easily be distinguished from normal field galaxies, and therefore, identified as ULIGs. The implication is then that submillimeter surveys may be the only means of properly identifying the majority of ULIGs at high redshift.Comment: AJ in press, TeX, 23 pages, 7 tab, 17 figs available also (at higher resolution) from http://www.ast.cam.ac.uk~trentham/ufigs.htm

Faint submillimeter galaxy counts at 450 μm

We present the results of SCUBA-2 observations at 450 μm and 850 μm of the field lensed by the massive cluster A370. With a total survey area >100 arcmin2 and 1σ sensitivities of 3.92 and 0.82 mJy beam–1 at 450 and 850 μm, respectively, we find a secure sample of 20 sources at 450 μm and 26 sources at 850 μm with a signal-to-noise ratio (S/N) > 4. Using the latest lensing model of A370 and Monte Carlo simulations, we derive the number counts at both wavelengths. The 450 μm number counts probe a factor of four deeper than the counts recently obtained from the Herschel Space Telescope at similar wavelengths, and we estimate that ~47%-61% of the 450 μm extragalactic background light resolved into individual sources with 450 μm fluxes greater than 4.5 mJy. The faint 450 μm sources in the 4σ sample have positional accuracies of 3 arcsec, while brighter sources (S/N >6σ) are good to 1.4 arcsec. Using a deep radio map (1σ ~ 6 μJy) we find that the percentage of submillimeter sources having secure radio counterparts is 85% for 450 μm sources with intrinsic fluxes >6 mJy and 67% for 850 μm sources with intrinsic fluxes >4 mJy. We also find that 67% of the >4σ 450 μm sources are detected at 850 μm, while the recovery rate at 450 μm of >4σ 850 μm sources is 54%. Combined with the source redshifts estimated using millimetric flux ratios, the recovered rate is consistent with the scenario where both 450 μm and 20 cm emission preferentially select lower redshift dusty sources, while 850 μm emission traces a higher fraction of dusty sources at higher redshifts. We identify potential counterparts in various wavelengths from X-ray to mid-infrared and measure the multiwavelength photometry, which we then use to analyze the characteristics of the sources. We find three X-ray counterparts to our robust submillimeter sample (S/N > 5), giving an active galactic nucleus fraction for our 450 (850) μm sample of 3/8 (3/9) or 38% (33%). We also find a correlation between the Ks band and the 850 μm/20 cm flux ratio

Is there a maximum star formation rate in high-redshift galaxies?

We use the James Clerk Maxwell Telescope's SCUBA-2 camera to image a 400 arcmin2 area surrounding the GOODS-N field. The 850 μm rms noise ranges from a value of 0.49 mJy in the central region to 3.5 mJy at the outside edge. From these data, we construct an 850 μm source catalog to 2 mJy containing 49 sources detected above the 4σ level. We use an ultradeep (11.5 μJy at 5σ) 1.4 GHz image obtained with the Karl G. Jansky Very Large Array together with observations made with the Submillimeter Array to identify counterparts to the submillimeter galaxies. For most cases of multiple radio counterparts, we can identify the correct counterpart from new and existing Submillimeter Array data. We have spectroscopic redshifts for 62% of the radio sources in the 9' radius highest sensitivity region (556/894) and 67% of the radio sources in the GOODS-N region (367/543). We supplement these with a modest number of additional photometric redshifts in the GOODS-N region (30). We measure millimetric redshifts from the radio to submillimeter flux ratios for the unidentified submillimeter sample, assuming an Arp 220 spectral energy distribution. We find a radio-flux-dependent K – z relation for the radio sources, which we use to estimate redshifts for the remaining radio sources. We determine the star formation rates (SFRs) of the submillimeter sources based on their radio powers and their submillimeter fluxes and find that they agree well. The radio data are deep enough to detect star-forming galaxies with SFRs >2000 M ☉ yr–1 to z ~ 6. We find galaxies with SFRs up to ~6000 M ☉ yr–1 over the redshift range z = 1.5-6, but we see evidence for a turn-down in the SFR distribution function above 2000 M ☉ yr–1

Sources of CP Violation in the Two-Higgs Doublet Model

Assuming CP violation arises solely through the Higgs potential, we develop the most general two-Higgs doublet model. There is no discrete symmetry that distinguishes the two Higgs bosons. It is assumed that an approximate global family symmetry sufficiently suppresses flavor-changing neutral scalar interactions. In addition to a CKM phase, neutral boson mixing, and superweak effects, there can be significant CP violation due to charged Higgs boson exchange. The value of $\epsilon'/\epsilon$ due to this last effect could be as large as in the standard model.Comment: 8 pages, RevTex, (appear in Phys. Rev. Lett. 73, (1994) 1762 ), CMU-HEP94-1

Spin Measurements in Cascade Decays at the LHC

We systematically study the possibility of determining the spin of new particles after their discovery at the LHC. We concentrate on angular correlations in cascade decays. Motivated by constraints of electroweak precision tests and the potential of providing a Cold Dark Matter candidate, we focus on scenarios of new physics in which some discrete symmetry guarantees the existence of stable neutral particles which escape the detector. More specifically, we compare supersymmetry with another generic scenario in which new physics particles have the same spin as their Standard Model partners. A survey of possibilities of observing spin correlations in a broad range of decay channels is carried out, with interesting ones identified. Rather than confining ourselves to one "collider friendly" benchmark point (such as SPS1a), we describe the parameter region in which any particular decay channel is effective. We conduct a more detailed study of chargino's spin determination in the decay channel $\tilde{q}\to q + \tilde{C}^\pm \to q + W^\pm + LSP$. A scan over the chargino and neutralino masses is performed. We find that as long as the spectrum is not too degenerate the prospects for spin determination in this channel are rather good.Comment: 36 pages, references added, 1 figure modifie

Global Analysis with SNO: Toward the Solution of the Solar Neutrino Problem

We perform a global analysis of the latest solar neutrino data including the SNO result on the CC-event rate. This result further favors the LMA solution of the solar neutrino problem. The best fit values of parameters we find are: \Delta m^2 = (4.8 - 5.0)10^{-5} eV^2, tan^2 \theta = 0.35 - 0.38, f_B = 1.08 - 1.12, and f_{hep} = 1 - 4. With respect to this best fit the LOW solution is accepted at 90% C.L.. The Vacuum oscillation solution with \Delta m^2 = 1.4 10^{-10} eV^2, gives good fit of the data provided that the boron neutrino flux is substantially smaller than the SSM flux (f_B \sim 0.5). The SMA solution is accepted only at 3\sigma level. We find that vacuum oscillations to sterile neutrino, VAC(sterile), with f_B \sim 0.5 also give rather good global fit of the data. All other sterile solutions are strongly disfavored. We check the quality of the fit by constructing the pull-off diagrams of observables. Predictions for the day-night asymmetry, spectrum distortion and NC/CC ratio at SNO are calculated. In the best fit points of the global solutions we find: A_{DN}^{CC} \approx (7 - 8)% for LMA, \sim 3% for LOW, and (2 - 3)% for SMA. It will be difficult to see the distortion of the spectrum expected for LMA as well as LOW solutions. However, future SNO spectral data can significantly affect the VAC and SMA solutions. We also calculate expectations for the BOREXINO rate.Comment: 35 pages, latex, 9 figures; results of analysis slightly changed due to different treatment of the hep neutrino flux; predictions for NC/CC ratio and Borexino rate adde