A Narrowband Imaging Survey for High Redshift Galaxies in the Near Infrared

A narrowband imaging survey of 276 square minutes of arc was carried out at near infrared wavelengths to search for emission line objects at high redshifts. Most of the fields contained a known quasar or radio galaxy at a redshift that placed one of the strong, restframe optical emission lines (H-alpha, [O III], H-beta, or [O II]) in the bandpass of the narrowband filter. The area weighted line flux limit over the entire survey was 3.4x10e-16 erg/cm2/s (3-sigma), while the most sensitive limits reached 1.4x10e-16 erg/cm2/s. Integrating the volume covered by all four optical emission lines in each image yields a total comoving volume surveyed of 1.4x10e5 cubic megaparsecs. Considering only H-alpha emission in the K band (2.05 < z < 2.65), where the survey is most sensitive, the survey covered a comoving volume of 3.0x10e4 cubic megaparsecs to a volume-weighted average star formation rate of 112 M-solar/yr (for Ho = 50 km/s/Mpc, Omega = 1). This is the most extensive near-infrared survey which is deep enough to have a reasonable chance at detecting strong line emission from an actively star-forming population of galaxies, when d against simple models of galaxy formation. One emission line candidate was identified in this survey, and subsequently confirmed spectroscopically.Comment: To appear in the Astronomical Journal, November 1996. 23 pages, including 2 tables and 7 figure

Taking stock of SLSN and LGRB host galaxy comparison using a complete sample of LGRBs

Long gamma-ray bursts (LGRBs) and superluminous supernovae (SLSNe) are both explosive transients with very massive progenitor stars. Clues about the nature of the progenitors can be found by investigating environments in which such transients occur. While studies of LGRB host galaxies have a long history, dedicated observational campaigns have only recently resulted in a high enough number of photometrically and spectroscopically observed SLSN hosts to allow statistically significant analysis of their properties. In this paper we make a comparison of the host galaxies of hydrogen-poor (H-poor) SLSNe and the Swift/BAT6 sample of LGRBs. In contrast to previous studies we use a complete sample of LGRBs and we address a special attention to the comparison methodology and the selection of SLSN sample whose data have been compiled from the available literature. At intermediate redshifts (0.3 < z < 0.7) the two classes of transients select galaxies whose properties (stellar mass, luminosity, star-formation rate, specific star-formation rate and metallicity) do not differ on average significantly. Moreover, the host galaxies of both classes of objects follow the fundamental metallicity relation and the fundamental plane of metallicity. In contrast to previous studies we show that at intermediate redshifts the emission line equivalent widths of the two populations are essentially the same and that the previous claims regarding the higher fraction of SLSN hosts among the extreme emission line galaxies with respect to LGRBs are mostly due to a larger fraction of strong-line emitters among SLSN hosts at z < 0.3, where samples of LGRB hosts are small and poorly defined.Comment: 7 pages, 4 figures, accepted to Astronomy & Astrophysic

Is there any evidence that ionised outflows quench star formation in type 1 quasars at z<1?

The aim of this paper is to test the basic model of negative AGN feedback. According to this model, once the central black hole accretes at the Eddington limit and reaches a certain critical mass, AGN driven outflows blow out gas, suppressing star formation in the host galaxy and self-regulating black hole growth. We consider a sample of 224 quasars selected from the SDSS at z<1 observed in the infrared band by Herschel. We evaluate the star formation rate in relation to several outflow signatures traced by the [OIII]4959,5007 and [OII]3726,3729 emission lines in about half of the sample with high quality spectra. Most of the quasars show asymmetric and broad wings in [OIII], which we interpret as outflow signatures. We separate the quasars in two groups, ``weakly'' and ``strongly'' outflowing, using three different criteria. When we compare the mean star formation rate in five redshift bins in the two groups, we find that the SFRs are comparable or slightly larger in the strongly outflowing quasars. We estimate the stellar mass from SED fitting and the quasars are distributed along the star formation main sequence, although with a large scatter. The scatter from this relation is uncorrelated with respect to the kinematic properties of the outflow. Moreover, for quasars dominated in the infrared by starburst or by AGN emission, we do not find any correlation between the star formation rate and the velocity of the outflow, a trend previously reported in the literature for pure starburst galaxies. We conclude that the basic AGN negative feedback scenario seems not to agree with our results. Although we use a large sample of quasars, we did not find any evidence that the star formation rate is suppressed in the presence of AGN driven outflows on large scale. A possibility is that feedback is effective over much longer timescales than those of single episodes of quasar activity.Comment: 18 pages, new version that implements the suggestions of the referee and matches the AA published versio

Intravenous immunoglobulin treatment in a type 3 von Willebrand disease patient with alloantibodies and a life-threatening gastrointestinal bleed

Non peer reviewe

New Clues on the Nature of Extremely Red Galaxies

We present near-infrared VLT-UT1+ISAAC spectroscopy of a sample of 9 extremely red galaxies (ERGs) with R-K>5 and K<19.0. Neither strong emission lines (F_lim<1-5 10^{-16} erg s^{-1}cm^{-2}) nor continuum breaks are detected. From near-infrared spectrophotometry, complemented with broad-band optical and near-IR photometry, we estimate ``spectro-photometric'' redshifts to be in the range of 0.8<z_sphot<1.8. We derive upper limits on the star formation rates in range of SFR<6-30h_50^{-2} M_solar yr^{-1}. Two of the observed ERGs are dusty starburst candidates because they require strong dust reddening to reproduce their global spectral energy distributions. The other ERGs are consistent with being dustless old passively evolved spheroidals at z>0.8. We discuss the general implications of our findings in relation with the problem of the formation of early type galaxies.Comment: 6 pages, 2 figures. Astronomy & Astrophysics (Letters), in pres

On the fraction of intermediate-mass close binaries that explode as type-Ia supernovae

Type-Ia supernovae (SNe-Ia) are thought to result from a thermonuclear runaway in white dwarfs (WDs) that approach the Chandrasekhar limit, either through accretion from a companion or a merger with another WD. I compile observational estimates of the fraction eta of intermediate-mass stars that eventually explode as SNe-Ia, supplement them with several new estimates, and compare them self-consistently. The estimates are based on five different methods, each utilising some observable related to the SN-Ia rate, combined with assumptions regarding the IMF: the ratio of SN-Ia to core-collapse rates in star-forming galaxies; the SN-Ia rate per unit star-formation rate; the SN-Ia rate per unit stellar mass; the iron to stellar mass ratio in galaxy clusters; and the abundance ratios in galaxy clusters. The five methods indicate that a fraction in the range eta~2-40% of all stars with initial masses of 3-8 M_sun (the generally assumed SN-Ia progenitors) explode as SNe-Ia. A fraction of eta~15% is consistent with all five methods for a range of plausible IMFs. Considering also the binarity fraction among such stars, the mass ratio distribution, the separation distribution, and duplicity (every binary can produce only one SN-Ia explosion), this implies that nearly every intermediate mass close binary ends up as a SN-Ia, or possibly more SNe-Ia than progenitor systems. Theoretically expected fractions are generally one to two orders of magnitude lower. The problem could be solved: if all the observational estimates are in error; or with a ``middle-heavy'' IMF; or by some mechanism that strongly enhances the efficiency of binary evolution toward SN-Ia explosion; or by a non-binary origin for SNe-Ia.Comment: MNRAS, accepted versio

Discovery of strong CIV absorption in the highest redshift quasar

We report the near-IR detection of a prominent CIV absorption in the rest-frame UV spectrum of the most distant known QSO, SDSS J104433.04-012502.2, at z=5.80. This QSO was recently observed with XMM-Newton and it was found to be notably X-ray weak. The equivalent width of the CIV absorption feature (~10 A) strongly supports the idea that the X-ray faintness of this QSO is due to heavy absorption by gas with a column density N_H > 10^{24} cm^-2. The shape of the CIV feature suggests that this is a Broad Absorption Line QSO. Although absorbed by a huge column of gas, the observed continuum in the 0.9-2.4um range (~1300-3500 A rest frame) exactly matches the template of unabsorbed QSOs without invoking any reddening (E(B-V)<0.08 mag), indicating that dust in the absorbing gas is either absent or composed of large grains.Comment: 4 pages, 2 figures, accepted for publication in A&A Letter

Super star clusters and Supernovae in interacting LIRGs unmasked by NIR adaptive optics

We report on an on-going near-IR adaptive optics survey targeting interacting luminous IR galaxies. High-spatial resolution NIR data are crucial to enable interpretation of kinematic, dynamical and star formation (SF) properties of these very dusty objects. Whole progenitor nuclei in the interactions can be missed if only optical HST imaging is used. Here we specifically present the latest results regarding core-collapse supernovae found within the highly extincted nuclear regions of these galaxies. Direct detection and study of such highly obscured CCSNe is crucial for revising the optically-derived SN rates used for providing an independent measurement of the SF history of the Universe. We also present thus-far the first NIR luminosity functions of super star cluster (SSC) candidates. The LFs can then be used to constrain the formation and evolution of SSCs via constraints based on initial mass functions and cluster disruption models.Comment: 6 pages. To appear in proceedings of 'Galaxies and their Masks' (Namibia, April 2010), published by Springer, New York, eds. D.L. Block, K.C. Freeman, I. Puerar