The merging/AGN connection: A case for 3D spectroscopy

We discuss an ongoing study of the connection between galaxy merging/interaction and AGN activity, based on integral field spectroscopy. We focus on the search for AGN ionization in the central regions of mergers, previously not classified as AGNs. We present here the science case, the current status of the project, and plans for future observations.Comment: 4 pages, 3 figure, Euro3D Science Workshop, Cambridge, May 2003, AN, accepte

A 2D multiwavelength study of the ionized gas and stellar population in the Giant HII Region NGC 588

We present an analysis of NGC588 based on IFS data with PMAS, together with Spitzer images at 8 mi and 24 mi. The extinction distribution in the optical shows complex structure, with maxima correlating in position with those of the emission at 24 mi and 8 mi. The Ha luminosity absorbed by the dust within the GHIIR reproduces the structure observed in the 24 mi image, supporting the use of this band as a tracer of recent star formation. A velocity difference of ~50 km/s was measured between the areas of high and low surface brightness, which would be expected if NGC588 were an evolved GHIIR. Line ratios used in the BPT diagnostic diagrams show a larger range of variation in the low surface brightness areas. The ranges are ~0.5 to 1.2 dex for [NII]/Ha, 0.7 to 1.7 dex for [SII]/Ha, and 0.3 to 0.5 dex for [OIII]/Hb. Ratios corresponding to large ionization parameter (U) are found between the peak of the emission in Hb and the main ionizing source decreasing radially outwards within the region. Differences between the integrated and local values of the U tracers can be as high as ~0.8 dex. [OII]/Hb and [OIII]/[OII] yield similar local values for U and consistent with those expected from the integrated spectrum of an HII region ionized by a single star. The ratio [SII]/Ha departs significantly from the range predicted by this scenario, indicating the complex ionization structure in GHIIRs. There is a significant scatter in derivations of Z using strong line tracers as a function of position, caused by variations in the degree of ionization. The scatter is smaller for N2O3 which points to this tracer as a better Z tracer than N2. The comparison between integrated and local line ratio values indicates that measurements of the line ratios of GHIIR in galaxies at distances >~25 Mpc may be dominated by the ionization conditions in their low surface brightness areas.AM-I, EP-M and JMV acknowledge partial funding through research projects AYA2007-67965-C03-02 from the Spanish PNAYA and CSD2006-00070 1st Science with GTC of the MICINN. MR is supported by a Marie Curie Intra European Fellowship within the 7th European Community Framework Programme. CK, as a Humboldt Fellow, acknowledges support from the Alexander von Humboldt Foundation, Germany

PINGS: the PPAK IFS Nearby Galaxies Survey

We present the PPAK Integral Field Spectroscopy (IFS) Nearby Galaxies Survey: PINGS, a 2-dimensional spectroscopic mosaicking of 17 nearby disk galaxies in the optical wavelength range. This project represents the first attempt to obtain continuous coverage spectra of the whole surface of a galaxy in the nearby universe. The final data set comprises more than 50000 individual spectra, covering in total an observed area of nearly 80 arcmin^2. In this paper we describe the main astrophysical issues to be addressed by the PINGS project, we present the galaxy sample and explain the observing strategy, the data reduction process and all uncertainties involved. Additionally, we give some scientific highlights extracted from the first analysis of the PINGS sample.Comment: Accepted for publication in MNRAS, 26 pages, 14 figures (some in low resolution), 3 table

Warp or lag? The ionized and neutral hydrogen gas in the edge-on dwarf galaxy UGC 1281

The properties of gas in the halos of galaxies constrain global models of the interstellar medium. Kinematical information is of particular interest since it is a clue to the origin of the gas. Until now mostly massive galaxies have been investigated for their halo properties. Here we report on deep HI and H{\alpha} observations of the edge-on dwarf galaxy UGC 1281 in order to determine the existence of extra-planar gas and the kinematics of this galaxy. This is the first time a dwarf galaxy is investigated for its gaseous halo characteristics. We have obtained H{\alpha} integral field spectroscopy using PPAK at Calar Alto and deep HI observations with the WSRT of this edge-on dwarf galaxy. These observations are compared to 3D models in order to determine the distribution of HI in the galaxy. We find that UGC 1281 has H{\alpha} emission up to 25"(655 pc) in projection above the plane and in general a low H{\alpha} flux. Compared to other dwarf galaxies UGC 1281 is a normal dwarf galaxy with a slowly rising rotation curve that flattens off at 60 km/s and a central depression in its HI distribution. Its HI extends 70" (1.8 kpc) in projection from the plane. This gas can be explained by either a warp partially in the line-of-sight warp or a purely edge-on warp with rotational velocities that decline with a vertical gradient of 10.6 \pm 3.7 km/s/kpc. The line-of-sight warp model is the preferred model as it is conceptually simpler. In either model the warp starts well within the optical radius.Comment: Accepted for publication in MNRAS. 16 pages, 14 figure

The merging/AGN connection II. Ionization of the circumnuclear regions

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 (Veilleux & Osterbrock 1987). 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%Comment: 4 pages, 2 figures, accepted for publishing in A&A Letter

Astronomical optical frequency comb generation and test in a fiber-fed MUSE spectrograph

We here report on recent progress on astronomical optical frequency comb generation at innoFSPEC-Potsdam and present preliminary test results using the fiber-fed Multi Unit Spectroscopic Explorer (MUSE) spectrograph. The frequency comb is generated by propagating two free-running lasers at 1554.3 and 1558.9 nm through two dispersionoptimized nonlinear fibers. The generated comb is centered at 1590 nm and comprises more than one hundred lines with an optical-signal-to-noise ratio larger than 30 dB. A nonlinear crystal is used to frequency double the whole comb spectrum, which is efficiently converted into the 800 nm spectral band. We evaluate first the wavelength stability using an optical spectrum analyzer with 0.02 nm resolution and wavelength grid of 0.01 nm. After confirming the stability within 0.01 nm, we compare the spectra of the astro-comb and the Ne and Hg calibration lamps: the astro-comb exhibits a much larger number of lines than lamp calibration sources. A series of preliminary tests using a fiber-fed MUSE spectrograph are subsequently carried out with the main goal of assessing the equidistancy of the comb lines. Using a P3d data reduction software we determine the centroid and the width of each comb line (for each of the 400 fibers feeding the spectrograph): equidistancy is confirmed with an absolute accuracy of 0.4 pm

The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX): Description and Early Pilot Survey Results

The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) will outfit the 10 m HET with a new wide field and an array of 150 integral-field spectrographs to survey a 420 sq. deg. area in the north Galactic cap. Each fiber-coupled unit spectrograph will cover 350-550 nm, simultaneously. This instrument, called VIRUS, will produce ~34,000 spectra per exposure, and will open up the emission-line universe to large surveys for the first time. The survey will detect 0.8 million Lyman-alpha emitting (LAE) galaxies with 1.9<z<3.5 and more than a million [OII] emitting galaxies with z<0.5. The 3-D map of LAE galaxies in 9 cubic Gpc volume will be used to measure the expansion history at this early epoch using baryonic acoustic oscillations and the shape of the power spectrum. The aim of HETDEX is to provide a direct detection of dark energy at z~3. The measurement will constrain the evolution of dark energy and will also provide 0.1%-level accuracy on the curvature of the Universe, ten times better than current. The prototype of the VIRUS unit spectrograph (VIRUS-P) is a powerful instrument in its own right. Used on the McDonald 2.7 m, it covers the largest area of any integral field spectrograph, and reaches wavelengths down to 340 nm. VIRUS-P is being used for a pilot survey to better measure the properties of LAE galaxies in support of HETDEX. We report initial results from this survey.Comment: 4 pages, 1 Postscript figure. Paper presented at conference "Panoramic Views of the Universe", Hayama, Japan, December 2007 (ASP Conference Series, in press

Mapping the properties of blue compact dwarf galaxies: integral field spectroscopy with PMAS

(Abridged) We perform integral field spectroscopy of a sample of Blue compact dwarf (BCD) galaxies with the aim of analyzing their morphology, the spatial distribution of some of their physical properties (excitation, extinction, and electron density) and their relationship with the distribution and evolutionary state of the stellar populations. Integral field spectroscopy observations of the sample galaxies were carried out with the Potsdam Multi-Aperture Spectrophotometer (PMAS) at the 3.5 m telescope at Calar Alto Observatory. An area 16 arcsec x 16 arcsec in size was mapped with a spatial sampling of 1 arcsec x 1 arcsec. We obtained data in the 3590-6996 Angstroms spectral range, with a linear dispersion of 3.2 Angstroms per pixel. From these data we built two-dimensional maps of the flux of the most prominent emission lines, of two continuum bands, of the most relevant line ratios, and of the gas velocity field. Integrated spectra of the most prominent star-forming regions and of whole objects within the FOV were used to derive their physical parameters and the gas metal abundances. Six galaxies display the same morphology both in emission line and in continuum maps; only in two objects, Mrk 32 and Tololo 1434+032, the distributions of the ionized gas and of the stars differ considerably. In general the different excitation maps for a same object display the same pattern and trace the star-forming regions, as expected for objects ionized by hot stars; only the outer regions of Mrk 32, I Zw 123 and I Zw 159 display higher [SII]/Halpha values, suggestive of shocks. Six galaxies display an inhomogeneous dust distribution. Regarding the kinematics, Mrk 750, Mrk 206 and I Zw 159 display a clear rotation pattern, while in Mrk 32, Mrk 475 and I Zw 123 the velocity fields are flat.Comment: 27 pages, 11 figures; Accepted for publication in A&