Search

Aims. We examine the physical conditions of ionised gas in the central kiloparsec(s) of nearby Seyfert galaxies. Our aim is a detailed two-dimensional mapping of optical spectroscopic properties, searching for features in the emission structure and in gas kinematics which would be common to all the active galactic nuclei (AGN) or their class, and which would help us to understand the origin and nature of the circumnuclear gas, and its role in the AGN.

The long and relatively faint gamma-ray burst GRB 060605 detected by Swift/BAT lasted about 20 s. Its afterglow could be observed with Swift/XRT for nearly 1 day, while Swift/UVOT could detect the afterglow during the first 6 h after the event. Here, we report on integral field spectroscopy of its afterglow performed with PMAS/PPak mounted at the Calar Alto 3.5 m telescope. In addition, we report on a detailed analysis of XRT and UVOT data and on the results of deep late-time VLT observations that reveal the GRB host galaxy. We find that the burst occurred at a redshift of $z = 3.773$, possibly associated with a faint, RC= 26.4 ±0.3 host. Based on the optical and X-ray data, we deduce information on the SED of the afterglow, the position of the cooling frequency in the SED, the nature of the circumburst environment, its collimation factor, and its energetics. We find that the GRB fireball was expanding into a constant-density medium and that the explosion was collimated with a narrow half-opening angle of about 2.4 degrees. The initial Lorentz factor of the fireball was about 250; however, its beaming-corrected energy release in the gamma-ray band was comparably low. The optical, X-ray afterglow, on the other hand, was rather luminous. Finally, we find that the data are consistent within the error bars with an achromatic evolution of the afterglow during the suspected jet break time at about 0.27 days after the burst.

Aims. In this article we study the morphology, kinematics and ionization properties of the giant ionized gas nebulae surrounding two high redshift radio galaxies, 4C 40.36 (z= 2.27) and 4C 48.48 (z= 2.34).

Aims. We searched for the presence of extended emission-line regions (EELRs) around low-redshift QSOs.

Aims.We performed an integral field spectroscopic study for the HII galaxy IIZw70 to investigate the interplay between its ionized interstellar medium (ISM) and the massive star formation.

Aims.We search for galaxy counterparts to damped Lyman-αabsorbers (DLAs) at $z > 2$towards nine quasars, which have 14 DLAs and 8 sub-DLAs in their spectra.

Aims.We present a low-resolution spectroscopic survey of the Orion nebula. The data are released for public use. We show the possible applications of this dataset analyzing some of the main properties of the nebula.

Context.Quasars trace the most massive structures at high redshifts and their presence may influence the evolution of the massive host galaxies.

Powerful radio galaxies and radio-loud quasars at high redshifts are frequently associated with extended emission-line regions (EELRs). Here we investigate the [$\ion{O}{ii}$] EELR around the quasar 3C 196 at $z=0.871$using integral field spectroscopy. We also detect extended [$\ion{Ne}{ii}$] emission at a distance of about 30 kpc from the core. The emission is aligned with the radio hot spots and shows a redshifted and a blueshifted component with a velocity difference of ~800 km s-1. The alignment effect and large velocities support the hypothesis that the EELR is caused by a jet-cloud interaction, which is furthermore indicated by the presence of a pronounced bend in the radio emission at the location of the radio hot spots. We also report observations of two other systems which do not show as clear indications of interactions. We find a weaker alignment of an [$\ion{O}{ii}$] EELR from the $z=0.927$quasar 3C 336, while no EELR is found around the core-dominated quasar OI 363 at $z=0.63$.

We present optical integral field observations of the H II region containing the ultraluminous X-ray source Holmberg II X-1. We confirm the existence of an X-ray ionized nebula as the counterpart of the source owing to the detection of an extended He II $\lambda4686$region ($21\times 47$pc) at the ChandraACIS-S position. An extended blue object with a size of $11\times 14$pc is coincident with the X-ray/He II $\lambda4686$region, which could indicate that it is either a young stellar complex or a cluster. We have derived an X-ray to optical luminosity ratio of $L_{\rm X}/L_{B}\ge170$, and presumable it is $L_{\rm X}/L_{B}\sim300{-}400$using the recent HST ACS data. We find a complex velocity dispersion at the position of the ULX. In addition, there is a radial velocity variation in the X-ray ionized region found in the He II emission of $\pm50$km s-1on spatial scales of 2–3″. We believe that the putative black hole not only ionizes the surrounding HII gas, but also perturbs it dynamically (via jets or the accretion disk wind). The spatial analysis of the public ChandraACIS-S data reveals a point-like X-ray source and gives marginal indication of an extended component (≪15% of the total flux). The XMM-NewtonEPIC-PN spectrum of HoII X-1 is best fitted with an absorbed power law in addition to either a thermal thick plasma or a thermal thin plasma or a multi-colour disk black body (MCD). In all cases, the thermal component shows a relatively low temperature ($kT\sim0.14{-}0.22$keV). Finally we discuss the optical/X-ray properties of HoII X-1 with regards to the possible nature of the source. The existence of an X-ray ionized nebula coincident with the ULX and the soft X-ray component with a cool accretion disk favours the interpretation as an intermediate-mass black hole (IMBH). However, the complex velocity behaviour at the position of the ULX indicates a dynamical influence of the black hole on the local HII gas.

We report the first results of a study of a sample of 20 galaxy mergers/interacting systems, using the VIMOS and PMAS integral field spectrographs. For each object, we extracted the integrated spectrum of the central regions
and analyzed the ionization state using classical diagnostic diagrams [CITE]. There is evidence of AGN ionization in 4 of the objects, i.e. 20% of the sample, a considerably higher fraction than found in previous studies (~4%).
 An increase of the nuclear activity with the far infrared temperature may account for the difference.

The spectrum of the quasar PHL 1226is known to have a strong $\ion{Mg}{ii}$and sub-damped Lymanα(sub-DLA) absorption line system with $N(\ion{H}{i})=(5\pm2)\times10^{19}$cm-2at $z=0.1602$. Using integral field spectra from the Potsdam Multi Aperture Spectrophotometer (PMAS) we investigate a galaxy at an impact parameter of 6$\farcs$4 which is most probably responsible for the absorption lines. A fainter galaxy at a similar redshift and a slightly larger distance from the QSO is known to exist, but we assume that the absorption is caused by the more nearby galaxy. From optical Balmer lines we estimate an intrinsic reddening consistent with 0, and a moderate star formation rate of 0.5 M$_{\normalsize\odot}$$\>\rm yr^{-1}$is inferred from the Hαluminosity. Using nebular emission line ratios we find a solar oxygen abundance $12+\log\textrm{(O/H)}=8.7\pm0.1$and a solar nitrogen to oxygen abundance ratio $\log\textrm{(N/O)}=-1.0\pm0.2$. This abundance is larger than those of all known sub-DLA systems derived from analyses of metal absorption lines in quasar spectra. On the other hand, the properties are compatible with the most metal rich galaxies responsible for strong $\ion{Mg}{ii}$absorption systems. These two categories can be reconciled if we assume an abundance gradient similar to local galaxies. Under that assumption we predict abundances $12+\log\textrm{(O/H)}=7.1$and $\log\textrm{(N/O)}=-1.9$for the sub-DLA cloud, which is similar to high redshift DLA and sub-DLA systems. We find evidence for a rotational velocity of ~200 km s-1over a length of ~7 kpc. From the geometry and kinematics of the galaxy we estimate that the absorbing cloud does not belong to a rotating disk, but could originate in a rotating halo.

The quasar HE 0047-1756, at $z=1.67$, is found to be split into two images $1\farcs44$apart by an intervening galaxy acting as a gravitational lens. The flux ratio for the two components is roughly 3.5:1, depending slightly upon wavelength. The lensing galaxy is seen on images obtained in the i(800 nm) and Ksbands (2.1 μm); there is also a nearby faint object which may be responsible for some shear. The spectra of the two quasar images are nearly identical, but the emission line ratio between the two components scale differently from the continuum. Moreover, the fainter component has a bluer continuum slope than the brighter one. We argue that these small differences are probably due to microlensing. There is evidence for a partial Einstein ring emanating from the brighter image toward the fainter one.

This paper presents observations of an extended Lyman-αemission nebula surrounding the galaxy responsible for the Damped Lyman-αAbsorption (DLA) line in the spectrum of the quasar Q2233+131. With the Potsdam Multi Aperture Spectrophotometer (PMAS) we measure the properties of the extended Lyαemission in an area of $3\arcsec$$\times$$5\arcsec$having a total line flux of (2.8 ±0.3) $\times$10-16erg cm-2s-1, which at redshift $z=3.15$corresponds to a luminosity of ($2.4_{-0.2}^{+0.3})\times10^{43}$erg s-1and a size of 23 $\times$38 kpc. The location of the emission is spatially coincident with the previously detected DLA galaxy, but extends significantly beyond its limb. We argue that the Lyαemission is likely to be caused by an outflow from the DLA galaxy, presumably powered by star formation. In the case of negligible dust extinction, the Lyαluminosity indicates a star-formation rate of 19 ±$10~M_{\odot}$yr-1consistent with that derived from the UV continuum flux from the parent galaxy. The wind velocity indicated by the integral field spectra is of the order of several hundred km s-1. We find no indication of emission originating in a rotating disk.

We present K-band images of 31 radio quasars selected from the B3-VLA quasar sample. A new method has been developed to detect and restore the host galaxies of these quasars. We have detected the host galaxies of 16 of them. Using these data together with previous data from the B3-VLA quasars (Carballo et al. [CITE], hereafter Paper I) and literature data from other samples, we have analyzed a sample of 69 hosts of radio quasars, covering a redshift range between $0

We present observations of the Type Ia supernova SN 2002er during the brightening phase. The observations were performed with the Potsdam Multi Aperture Spectrophotometer (PMAS) integral field instrument. Due to the $8\arcsec\times8\arcsec$field of view of the spectrograph an accurate background subtraction was possible. Results from analyses of the evolution of absorption features in comparisons with other SNe show that SN 2002eris a fairly bright Type Ia supernova with a peak brightness of $M_B=-19.6\pm0.1$.

We have conducted a NIR study of the environments of seven radio-loud quasars at redshifts $1. In present paper we describe deep $K$ band images obtained for the fields of $\sim6\times6$ arcmin around the quasars with 3$\sigma$ limiting magnitudes of $K\sim20.5$. These fields were previously studied using deep $B$ and $R$ band images (Sánchez & González-Serrano 1999). Using optical and NIR data together, a significant excess of galaxies has been found whose optical-NIR colours, luminosity, spatial scale, and number of galaxies are compatible with clusters at the redshift of the quasar. We have selected a sample of cluster candidates analyzing the $R-K$ vs. $K$ diagram. A ~25% of the candidates present red optical-NIR colours and an ultraviolet excess. This population has been also found in clusters around quasars at the same redshifts (Tanaka et al. 2000; Haines et al. 2001). These galaxies seem to follow a mixed evolution: a main passive evolution plus late star formation processes. The quasars do not inhabit the core of the clusters, being found in the outer regions. This result agrees with the hypothesis that the origin/feeding mechanism of the nuclear activity is merging processes. The quasars inhabit the region where a collision is most likely to produce a merger.

The metallicities of active galactic nuclei (AGN) are usually well above solar in their narrow-line regions, often reaching up to several times solar in their broad-line regions independent of redshift. Low-metallicity AGN are rare objects that have so far always been associated with low-mass galaxies hosting low-mass black holes (MBH106M⊙). We present integral field spectroscopy data of the low-redshift (z= 0.212) quasi-stellar object (QSO) HE 2158 − 0107 for which we find strong evidence of sub-solar NLR metallicities associated with a massive black hole (MBH~ 3 × 108M⊙). The QSO is surrounded by a large extended emission-line region reaching out to 30 kpc from the QSO in a tail-like geometry. We present optical and near-infrared images and investigate the properties of the host galaxy. The host of HE 2158 − 0107 is most likely a very compact bulge-dominated galaxy with a size of re~ 1.4 kpc. The multi-colour spectral energy distribution (SED) of the host is quite blue, indicative of a significant young age stellar population formed within the last 1 Gyr. A 3σupper limit of Lbulge,H< 4.5 × 1010L⊙ ,Hfor the H-band luminosity and a corresponding stellar mass upper limit of Mbulge< 3.4 × 1010M⊙show that the host is offset from the local black hole-bulge relations. This is independently supported by the kinematics of the gas. Although the stellar mass of the host galaxy is lower than expected, it cannot explain the exceptionally low metallicity of the gas. We suggest that the extended emission-line region and the galaxy growth are caused by the infall of nearly pristine gas from the environment of the QSO host. Minor mergers of low-metallicity dwarf galaxies or the theoretically predicted smooth accretion of cold (~ 104K) gas are both potential drivers behind that process. Because the metallicity of the gas in the QSO narrow-line region is much lower than expected, we suspect that the external gas has already reached the galaxy centre and may even contribute to the current feeding of the black hole. HE 2158 − 0107 appears to represent a particular phase of substantial black hole and galaxy growth that can be observationally linked with the accretion of external material from its environment.

Aims.Integral field spectroscopy (IFS) is a powerful approach to studying nearby galaxies since it enables a detailed analysis of their resolved physical properties. Here we present our study of a sample of nearby galaxies selected to exploit the two-dimensional information provided by the IFS.

Lyαemitters (LAEs) are seen everywhere in the redshift domain from local to z~ 7. Far-infrared (FIR) counterparts of LAEs at different epochs could provide direct clues on dust content, extinction, and spectral energy distribution (SED) for these galaxies. We search for FIR counterparts of LAEs that are optically detected in the GOODS-North field at redshift z~ 2.2 using data from the HerschelSpace Telescope with the Photodetector Array Camera and Spectrometer (PACS). The LAE candidates were isolated via color-magnitude diagram using the medium-band photometry from the ALHAMBRA Survey, ancillary data on GOODS-North, and stellar population models. According to the fitting of these spectral synthesis models and FIR/optical diagnostics, most of them seem to be obscured galaxies whose spectra are AGN-dominated. From the analysis of the optical data, we have observed a fraction of AGN or composite over source total number of ~0.75 in the LAE population at z~ 2.2, which is marginally consistent with the fraction previously observed at z= 2.25 and even at low redshift (0.2