Large scale outflows from z ~ 0.7 starburst galaxies identified via ultra-strong MgII quasar absorption lines

(Abridged) Star formation-driven outflows are a critical phenomenon in theoretical treatments of galaxy evolution, despite the limited ability of observations to trace them across cosmological timescales. If the strongest MgII absorption-line systems detected in the spectra of background quasars arise in such outflows, "ultra-strong" MgII (USMgII) absorbers would identify significant numbers of galactic winds over a huge baseline in cosmic time, in a manner independent of the luminous properties of the galaxy. To this end, we present the first detailed imaging and spectroscopic study of the fields of two USMgII absorber systems culled from a statistical absorber catalog, with the goal of understanding the physical processes leading to the large velocity spreads that define such systems. Each field contains two bright emission-line galaxies at similar redshift (dv < 300 km/s) to that of the absorption. Lower-limits on their instantaneous star formation rates (SFR) from the observed OII and Hb line fluxes, and stellar masses from spectral template fitting indicate specific SFRs among the highest for their masses at z~0.7. Additionally, their 4000A break and Balmer absorption strengths imply they have undergone recent (~0.01 - 1 Gyr) starbursts. The concomitant presence of two rare phenomena - starbursts and USMgII absorbers - strongly implies a causal connection. We consider these data and USMgII absorbers in general in the context of various popular models, and conclude that galactic outflows are generally necessary to account for the velocity extent of the absorption. We favour starburst driven outflows over tidally-stripped gas from a major interaction which triggered the starburst as the energy source for the majority of systems. Finally, we discuss the implications of these results and speculate on the overall contribution of such systems to the global SFR density at z~0.7.Comment: 15 pages, 6 figure, accepted for publication by MNRA

Controlling passively-quenched single photon detectors by bright light

Single photon detectors based on passively-quenched avalanche photodiodes can be temporarily blinded by relatively bright light, of intensity less than a nanowatt. I describe a bright-light regime suitable for attacking a quantum key distribution system containing such detectors. In this regime, all single photon detectors in the receiver Bob are uniformly blinded by continuous illumination coming from the eavesdropper Eve. When Eve needs a certain detector in Bob to produce a click, she modifies polarization (or other parameter used to encode quantum states) of the light she sends to Bob such that the target detector stops receiving light while the other detector(s) continue to be illuminated. The target detector regains single photon sensitivity and, when Eve modifies the polarization again, produces a single click. Thus, Eve has full control of Bob and can do a successful intercept-resend attack. To check the feasibility of the attack, 3 different models of passively-quenched detectors have been tested. In the experiment, I have simulated the intensity diagrams the detectors would receive in a real quantum key distribution system under attack. Control parameters and side effects are considered. It appears that the attack could be practically possible.Comment: Experimental results from a third detector model added. Minor corrections and edits made. 11 pages, 10 figure

The z=0.0912 and z=0.2212 damped Ly alpha galaxies along the sight line toward the quasar OI 363

New optical and infrared observations along the sight line toward the quasar OI 363 (0738+313) are presented and discussed. Excluding quasars selectively observed because they were known to be located behind gas-rich galaxies and systems which lack confirming UV spectroscopic observations of the actual Ly alpha Line, this sight line presently contains the two lowest redshift classical damped Lya (DLA) quasar absorption-line systems found in survey mode (i.e., with N-H I >2 x 10(20) atoms cm(-2)), one at z(abs) = 0.0912 and the other at z(abs) = 0.2212. Our new observations suggest identfications for the DLA galaxy counterparts of these absorption-line systems. The z = 0.09 DLA galaxy appears to be an extended low surface brightness galaxy which is easily visible only in infrared images and shows possible rich morphological structure. Assuming there is no contribution from the quasar host galaxy, we place an upper limit on the K-band luminosity of the z = 0.09 DLA galaxy of L-K less than or equal to 0.13L*(K) (for a cosmology with H-0 = 65 km s(-1) Mpc(-1), Omega = 1, and Lambda = 0). More realistically, a subtraction of the quasar nuclear and host light yields L(K)approximate to0.08L*(K). The impact parameter between the galaxy and quasar sight line is very small, b <3.6 kpc

The rotating wind of the quasar PG 1700+518

Original article can be found at: http://www.nature.com/nature/archive/index.html Copyright Nature Publishing Group DOI: 10.1038/nature06319Peer reviewe