Related papers: Broad Ly alpha Emission from Three Nearby BL Lacer…

Weak spectral features in BL Lacertae objects (BL Lac) often provide a unique opportunity to probe the inner region of this rare type of active galactic nucleus. We present a Hubble Space Telescope/Cosmic Origins Spectrograph observation of…

The power mechanism and accretion geometry for low-power FR1 radio galaxies is poorly understood in comparison to Seyfert galaxies and QSOs. In this paper we use the diagnostic power of the Lya recombination line observed using the Cosmic…

Deep narrow-band surveys have revealed a large population of faint Lyman-alpha (Lya) emitters (LAEs) in the distant Universe, but relatively little is known about the most luminous sources ($L_{Ly\alpha}>10^{42.7}$ erg/s;…

Aims: We present optical spectroscopy of a sample of BL Lac objects, to determine their redshift, to study their broad emission line properties and to characterize their close environment. Methods: Twelve objects were observed using the ESO…

BL Lac objects are low--power active nuclei exhibiting a variety of peculiar properties that are caused by the presence of a relativistic jet and orientation effects. We present here adaptive optics near-IR images at high spatial resolution…

BL Lac objects are active nuclei, hosted in massive elliptical galaxies, the emission of which is dominated by a relativistic jet closely aligned with the line of sight. This implies the existence of a parent population of sources with a…

A combined analysis of the profiles of the main broad quasar emission lines in both Hubble Space Telescope and optical spectra shows that while the profiles of the strong UV lines are quite similar, there is frequently a strong increase in…

[abbreviated] We present a census of Ly\alpha\ emission at $z\gtrsim7$ utilizing deep near infrared HST grism spectroscopy from the first six completed clusters of the Grism Lens-Amplified Survey from Space (GLASS). In 24/159…

The Faint Object Spectrograph on the Hubble Space Telescope was used to obtain spectra of the central region of M87. These spectra cover the wavelength range 1140 - 1606 Angstrom and have a resolution of about 1 Angstrom. The nuclear…

We report observations from the Hubble Space Telescope (HST) and the VLA on the galactic environment, metallicity, and D/H in strong low-redshift Lya absorption systems toward the bright BL Lac object PKS 2155-304. GHRS/G160M spectra at 20…

(Abridged) We detect the large-scale structure of Lya emission in the Universe at redshifts z=2-3.5 by measuring the cross-correlation of Lya surface brightness with quasars in SDSS/BOSS. We use a million spectra targeting Luminous Red…

Lya nebulae, or "Lya blobs", are extended (up to ~100 kpc), bright (L[Lya] > 10^43 erg/s) clouds of Lya emitting gas that tend to lie in overdense regions at z ~ 2--5. The origin of the Lya emission remains unknown, but recent theoretical…

We investigate the large-scale structure of Lyman-alpha emission intensity in the Universe at redshifts z=2-3.5 using cross-correlation techniques. Our Lya emission samples are spectra of BOSS Luminous Red Galaxies from Data Release 12 with…

[Abridged] With VLT/X-shooter, we obtain optical and NIR spectra of six Ly-alpha blobs at z~2.3. Using three measures --- the velocity offset between the Lya line and the non-resonant [OIII] or H-alpha line (Dv_Lya), the offset of stacked…

Relativistic jets of radio loud active galactic nuclei (AGN) produce highly directed, intense beams of radiation. A fraction of this beamed radiation scatters on the thermal plasma generally surrounding an AGN. The morphology of the…

We present Chandra observations of the X-ray environment of a sample of 6 BL Lacertae objects. The improved sensitivity of the ACIS experiment allows us to separate the core X-ray emission from the contribution of diffuse emission from the…

We present new far-ultraviolet spectra from the Cosmic Origins Spectrograph (HST/COS) of the BL Lac object 1ES1553+113 covering the wavelength range 1135-1795 A. The data show a smooth continuum with a wealth of narrow absorption features…

We report the observation of a further asymmetric, extended Lyman alpha emitting halo at z=2.63, from our ultra-deep, long-slit spectroscopic survey of faint high redshift emitters, undertaken with Magellan LDSS3 in the GOODS-S field. The…

Ly$\alpha$ emission nebulae are ubiquitous around high-z galaxies and are tracers of the gaseous environment on scales out to >100 kpc. High-z radio galaxies (HzRGs, type-2 radio-loud quasars) host large scale nebulae observed in the…

This paper concerns the relationship of BLLacs and flat spectrum weak emission-line galaxies. We compare the weak emission-line galaxies and the BLLacs in a sample of 57 flat spectrum objects (Marcha et al. 1996), using high-frequency radio…