H. Hippelein

Max Planck Institute for Astronomy, Heidelburg, Baden-Württemberg, Germany

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Publications (86)222.62 Total impact

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    ABSTRACT: Optical data in B, R, i, and z were collected with LAICA at the prime-focus of the Calar Alto 3.5 m-telescope. In addition, we used the Wide-Field-Imager (WFI) at the 2.2 m-telescope on La Silla during MPG-time to obtain B and R images. Observations started in July 2002 with LAICA, in December 2002 with WFI, and in September 2003 with OMEGA2000. By August 2008, data collection was complete. (1 data file).
    VizieR Online Data Catalog. 07/2010;
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    ABSTRACT: Aims: We describe a survey for distant clusters of galaxies that identified clusters as local overdensities in the 3D galaxy distribution. Methods: Optical and near-IR imaging in B, R, i, z, and H are used to derive photometric redshifts for objects as faint as m* + 1 at a redshift of 1.5. We outline the astrometric and photometric data reduction. The 3D cluster search, based on the photometric redshifts, is described. Results: On the basis of the first fully reduced 1 square degree of data, we demonstrate that the objectives of HIROCS have been achieved. Four representative clusters from the list of candidates are presented. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC) and on observations collected at the European Southern Observatory, Chile, during Max-Planck-time.
    Astronomy and Astrophysics 04/2010; · 4.48 Impact Factor
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    ABSTRACT: We present deep diffraction-limited far-infrared (FIR) strip maps of a sample of 63 galaxies later than S0 and brighter than BT = 16.8, selected from the Virgo Cluster Catalogue of Binggeli, Sandage, & Tammann. The ISOPHOT instrument on board the Infrared Space Observatory was used to achieve sensitivities typically an order of magnitude deeper than IRAS in the 60 and 100 μm bands and to reach the confusion limit at 170 μm. The averaged 3 σ upper limits for integrated flux densities of point sources at 60, 100, and 170 μm are 43, 33, and 58 mJy, respectively. A total of 63.5% are detected at all three wavelengths. The highest detection rate (85.7%) is in the 170 μm band. In many cases the galaxies are resolved, allowing the scale length of the infrared disks to be derived from the oversampled brightness profiles in addition to the spatially integrated emission. The data presented should provide the basis for a variety of statistical investigations of the FIR spectral energy distributions of gas-rich galaxies in the local universe spanning a broad range in star formation activity and morphological types, including dwarf systems and galaxies with rather quiescent star formation activity.
    The Astrophysical Journal Supplement Series 12/2008; 139(1):37. · 14.14 Impact Factor
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    ABSTRACT: We present a deep, wide-field photometric survey of the newly discovered Hercules dwarf spheroidal galaxy (dSph), based on data from the Large Binocular Telescope. Images in B, V, and r were obtained with the Large Binocular Camera covering a 23' × 23' field of view to a magnitude of ~25.5 (5 σ). This permitted the construction of color-magnitude diagrams that reach approximately 1.5 mag below the Hercules main-sequence turnoff. Three-filter photometry allowed us to preferentially select probable Hercules member stars and to examine the structure of this system at a previously unattained level. We find that the Hercules dwarf is highly elongated (3 : 1), considerably more so than any other dSph satellite of the Milky Way, except the disrupting Sagittarius dwarf. Although we cannot rule out that the unusual structure is intrinsic to Hercules as an equilibrium system, our results suggest tidal disruption as a likely cause of this highly elliptical structure. Given the relatively large galactocentric distance of this system (132 ± 12 kpc), signs of tidal disruption would require the Hercules dwarf to be on a highly eccentric orbit around the Milky Way.
    The Astrophysical Journal 12/2008; 668(1):L43. · 6.28 Impact Factor
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    ABSTRACT: We present the first high-redshift galaxy cluster candidate sample from the HIROCS survey found in the COSMOS field. It results from a combination of public COSMOS with proprietary H-band data on a 0.66 square degree part of the COSMOS field and comprises 12 candidates in the redshift range 1.23 < z < 1.55. We find an increasing fraction of blue cluster members with increasing redshift. Many of the blue and even some of the reddest member galaxies exhibit disturbed morphologies as well as signs of interaction. Comment: 5 pages, 5 figures, in print format, accepted for publication by A&A Letters
    09/2007;
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    ABSTRACT: We present a deep, wide-field photometric survey of the newly-discovered Hercules dwarf spheroidal galaxy, based on data from the Large Binocular Telescope. Images in B, V and r were obtained with the Large Binocular Camera covering a 23' times 23' field of view to a magnitude of ~25.5 (5 sigma). This permitted the construction of colour-magnitude diagrams that reach approximately 1.5 magnitudes below the Hercules main sequence turnoff. Three-filter photometry allowed us to preferentially select probable Hercules member stars, and examine the structure of this system at a previously unattained level. We find that the Hercules dwarf is highly elongated (3:1), considerably more so than any other dSph satellite of the Milky Way except the disrupting Sagittarius dwarf. While we cannot rule out that the unusual structure is intrinsic to Hercules as an equilibrium system, our results suggest tidal disruption as a likely cause of this highly elliptical structure. Given the relatively large Galactocentric distance of this system (132 +/- 12 kpc), signs of tidal disruption would require the Hercules dwarf to be on a highly eccentric orbit around the Milky Way.
    07/2007;
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    ABSTRACT: Because of an error in entering proof corrections, the term Mtot(t) is incorrectly identified as the gas mass in the text immediately following equation (3). The sentence following this equation should correctly read: ``The mass of the gas in the model galaxy at a time t, Mgas(t), is equal to M(t)-M*(t), where M*(t) is the mass locked up into stars at the time t.'' Regarding equation (3), it should be noted that Mtot(t)=Mtot except for those time steps t at which Mtot(t) is set to an appropriate smaller value by the Pègase2 code in order to prevent the mass in stars produced at that time step t from exceeding the mass of gas of the model galaxy at that time. The Press sincerely regrets this error.
    The Astrophysical Journal 05/2006; 643(1):584-584. · 6.28 Impact Factor
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    ABSTRACT: The Calar Alto Deep Imaging Survey (CADIS) [5] combines a deep emission line survey employing an imaging Fabry-Perot-Interferometer ( F lim = 3 x 10-20 Wm-2) with a moderately deep multi-band survey ( 400 £ l £ 2300400 \le \lambda \le 2300 nm, Rlim @ 24R_{lim}\simeq 24 ). One of its major goals is the search for Ly- a\alpha galaxies in three redshift windows around z @ 4.8z \simeq 4.8 , 5.7 and 6.6. Six extragalactic fields of 11 11 []¢11 \times 11 \Box^\prime each are surveyed. About 300 emission line galaxies are detected in every field, >~98\gtrsim 98 % of them being foreground galaxies at z < 1.4. The Ly- a\alpha candidates are selected by means of the absence of flux below the Lyman limit (B-band “dropouts”) and the non-detection of secondary emission lines. In this way foreground contamination is kept <~50\lesssim 50 %. Although spectroscopic verification is still pending, the candidate lists alone place upper limit to the abundance of Ly- a\alpha galaxies. From the comparison with Ly- a\alpha surveys at z @ 3.5z \simeq 3.5 we conclude that bright Ly- a\alpha galaxies become such rare beyond z = 5 that a non-evolving population seems virtually excluded.
    02/2006: pages 102-106;
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    ABSTRACT: The 1<z<2 redshift window hosts the peak of the star formation and metal production rates. Studies of the metal content of the star forming galaxies at these epochs are however sparse. We report VLT-ISAAC near-infrared spectroscopy for a sample of five [OII]-selected, M_B,AB<-21.5, z~1.4 galaxies, by which we measured Hbeta and [OIII]5007 emission line fluxes from J-band spectra, and Halpha line fluxes plus upper limits for [NII]6584 fluxes from H-band spectra. The z~1.4 galaxies are characterized by the high [OIII]/[OII] line ratios, low extinction and low metallicity that are typical of lower luminosity CADIS galaxies at 0.4<z<0.7, and of more luminous Lyman Break Galaxies at z~3, but not seen in CFRS galaxies at 0.4<z<0.9. This type of spectrum (e.g., high [OIII]/[OII]) is seen in progressively more luminous galaxies as the redshift increases. These spectra are caused by a combination of high ionisation parameter q and lower [O/H]. Pegase2 chemical evolution models are used to relate the observed metallicities and luminosities of z~1.4 galaxies to galaxy samples at lower and higher redshift. Not surpringsingly, we see a relationship between redshift and inferred chemical age. We suppose that the metal-enriched reservoirs of star forming gas that we are probing at intermediate redshifts are being mostly consumed to build up both the disk and the bulge components of spiral galaxies. Finally, our analysis of the metallicity-luminosity relation at 0<z<1.5 suggests that the period of rapid chemical evolution may take place progressively in lower mass systems as the universe ages. These results are consistent with a ``downsizing'' type picture in the sense that particular signatures (e.g., high [OIII]/[OII] or low [O/H]) are seen in progressively more luminous (massive) systems at higher redshifts. Comment: Accepted for publication in ApJ
    The Astrophysical Journal 11/2005; · 6.28 Impact Factor
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    ABSTRACT: Not Available
    Astronomische Nachrichten 08/2005; · 1.12 Impact Factor
  • Minor Planet Circulars. 06/2005; 54355:11.
  • Astronomische Nachrichten - ASTRON NACHR. 01/2005; 326:523-524.
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    ABSTRACT: We present preliminary results from a programme to obtain multi-object near-infrared spectroscopy of galaxies at redshifts 0.7 < z < 1.5. We are using the instrument CIRPASS (the Cambridge Infra-Red PAnoramic Survey Spectrograph), in multi-object mode, to survey Halpha in galaxies at z~ 1. We aim to address the true star formation history of the Universe at this epoch: potentially the peak period of star formation activity. Halpha is the same star formation measure used at low redshift, and hence we can trace star formation without the systematic uncertainties of using different calibrators in different redshift bins, or the extreme dust extinction in the rest-ultraviolet (rest-UV). CIRPASS has been successfully demonstrated in multi-object mode on the Anglo-Australian Telescope (AAT) and the William Herschel Telescope (WHT). Here we present preliminary results from one of our fields, the Hubble Deep Field North, observed with the WHT. With 150 fibres deployed over an unvignetted field of ~15 arcmin, we have several detections of Halpha from star-forming galaxies at 0.8 < z < 1.0 and present spectra of the seven brightest of these. By pre-selecting galaxies with redshifts such that Halpha will appear between the OH sky lines, we can detect star formation rates of 5h-270 Msolar yr-1(5sigma in 3 hours, OmegaM= 0.3, OmegaLambda= 0.7). It appears that star formation rates inferred from Halpha are, on average, a factor of more than two higher than those based on the UV continuum alone.
    Monthly Notices of the Royal Astronomical Society 10/2004; · 5.23 Impact Factor
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    ABSTRACT: As a step towards our understanding of galaxy evolution and for testing predictions of cosmological models we started a survey for galaxy clusters intending to identify candidates out to redshifts of ~1.5: HIROCS (= Heidelberg InfraRed/Optical Cluster Survey) is a multi-color survey (B, R, i, z and H) covering 11 square degrees in four fields on the sky. Our survey aims at a 5sigma detection of an L*+1 elliptical galaxy at z = 1.5. Classification of all objects and determination of photometric redshifts is done by the multi-color-classification scheme developed for the CADIS and COMBO-17 surveys. Cluster identification will be done by identifying overdensities in 3D-space (RA, DEC, zphot). First tests of our cluster finding algorithm on fields observed within CADIS and COMBO-17 revealed several cluster candidates.
    Proceedings of the International Astronomical Union 07/2004;
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    C. Maier, K. Meisenheimer, H. Hippelein
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    ABSTRACT: The emission line survey within the Calar Alto Deep Imaging Survey (CADIS) detects galaxies with very low continuum brightness by using an imaging Fabry-Perot interferometer. With spectroscopic follow-up observations of MB>~-19 CADIS galaxies using FORS2 at the VLT and DOLORES at TNG we obtained oxygen abundances of 5 galaxies at z~0.4 and 10 galaxies at z~0.64. Combining these measurements with published oxygen abundances of galaxies with MB<~-19 we find evidence that a metallicity-luminosity relation exists at medium redshift, but it is displaced to lower abundances and higher luminosities compared to the metallicity-luminosity relation in the local universe. Comparing the observed metallicities and luminosities of galaxies at z<3 with Pegase2 chemical evolution models we have found a favoured scenario in which the metallicity of galaxies increases by a factor of ~2 between z~0.7 and today, and their luminosity decreases by ~0.5-0.9mag. Comment: Accepted for publication in A&A; 12 pages, 9 figures
    Astronomy and Astrophysics 02/2004; · 4.48 Impact Factor
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    ABSTRACT: We present an outline of a survey for distant clusters of galaxies to be conducted at the Max-Planck-Institut für Astronomie in Heidelberg. The survey will use multi-colour optical and near-infrared wide-field cameras to isolate clusters up to redshifts of about 1.5 using the clustering of galaxies in 3D-space, i. e. RA, DEC and redshift.
    Astronomy and Astrophysics 01/2004; · 4.48 Impact Factor
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    ABSTRACT: Galaxies at high redshift with a strong Ly-Alpha emission line trace massive star formation in the absence of dust, and can therefore be regarded as a prime signature of the first major starburst in galaxies. We report results of the Ly-Alpha search within the Calar Alto Deep Imaging Survey (CADIS). With imaging Fabry-Perot interferometer CADIS can detect emission lines in three waveband windows free of night-sky emission lines at 700nm, 820nm, and 920nm. The typical flux detection limit for Ly-Alpha emission redshifted into these windows, Flim > 3X10^(-20) Wm^(-2), corresponds to (unobscured) star formation rates of >10Msun/yr at z=6. Candidate Ly-Alpha-emitting galaxies are selected from the total emission line sample, which contains more than 97% of objects at z<1.2, by the absence of flux below the Lyman limit (B-band "dropouts"), and the non-detection of secondary emission lines in narrow band filters. We have detected 5 bright Ly-Alpha-emitting galaxy candidates at z ~ 4.8, and 11 candidates at z ~ 5.7. For two of four observed Ly-Alpha candidates, one candidate at z ~ 4.8, and the other at z ~ 5.7, the emission line detected with the Fabry-Perot has been verified spectroscopically at the VLT. When compared to Ly-Alpha surveys at z<3.5 even the upper limits set by our list of candidates show that bright Ly-Alpha galaxies are significantly rarer at z>5 than the assumption of a non-evolving population would predict. Therefore we conclude that the Ly-Alpha bright phase of primeval star formation episodes reached its peak at redshifts between 3 and 6. Comment: Accepted for publication in A&A; 15 pages, 4 figures
    Astronomy and Astrophysics 02/2003; · 4.48 Impact Factor
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    ABSTRACT: The emission line survey within the Calar Alto Deep Imaging Survey (CADIS) detects emission line galaxies by a scan with an imaging Fabry-Perot interferometer. It covers 5 fields of > 100 square arcmin each in three wavelengths windows centered on lambda ~ 700, 820, and 920nm, and reaches to a typical limiting line flux of 3 x 10^(-20) W m^(-2). This is the deepest emission line survey covering a field of several 100 square arcmin. Galaxies between z = 0.25 and z = 1.4 are detected by prominent emission lines (from Halpha to [OII]372.7) falling into the FP scans. Additional observations with a dozen medium band filters allow to establish the line identification and thus the redshift of the galaxies to better than sigma(z) =0.001. On the basis of a total of more than 400 emission line galaxies detected in Halpha (92 galaxies), [OIII]500.7 (124 galaxies), or [OII]372.7 (222 galaxies) we measure the instantaneous star formation rate (SFR) in the range 0.24 < z < 1.21. With this purely emission line selected sample we are able to reach much fainter emission line galaxies than previous, continuum-selected samples. Thus completeness corrections are much less important. Our results substantiates the indications from previous studies (based on small galaxy samples) that the SFR decreases by a factor of ~20 between z = 1.2 and today. In fact, for a Omega(m) = 0.3, Omega(Lambda) = 0.7 cosmology, we find an exponential decline rho(SFR) proportional to exp(-lookback_time) / 2.6Gyr). The inferred SF density is in perfect agreement with that deduced from the FIR emission of optically selected galaxies which is explained by a large overlap between both populations. We show that self-consistent extinction corrections of both our emission lines and the UV continua lead to consistent results for the SF density. Comment: accepted for publication in A&A
    Astronomy and Astrophysics 02/2003; · 4.48 Impact Factor
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    ABSTRACT: We present preliminary results from the CIRPASS instrument (Parry et al. 2000 SPIE 4008, 1193) -- a near-infrared fiber-fed spectrograph which was successfully commissioned in its multi-object spectroscopy (MOS) mode on the 4-m Anglo Australian Telescope in October 2002. The high resolving power of λ / Δ λ FWHM&approx; 5000 enables us to work effectively in the low-background regions between the OH sky lines in the J- and H-bands (1.0-1.7 μ m). CIRPASS-MOS has 150 fibres each of 1.6'' diameter, deployable over a 40'-wide area. A natural project for CIRPASS-MOS is tracing star formation at z ∼ 1 using robust indicators such as Hα , redshifted into the near-infrared. We demonstrated this capability in our AAT observations last October, by observing some galaxies from the Calar Alto Deep Imaging Survey (CADIS) selected from a narrow redshift interval at z=0.88 by their [Oriptsize II] 3727 Å line emission observed in extensive Fabry-Perot observations (Hippelein et al. 2003, astro-ph/0302116). The Hα is found at &approx; 1.247 μ m in a very clean (OH line-free) region of the night-sky spectrum, and we were able to detect Hα for a number of these galaxies. We demonstrated that CIRPASS achieved its design sensitivity: in a stacked 12-hour exposure we detected lines as faint as 4x 10-17 ergs cm-2 s-1 at 10 σ (for Δ vFWHM ∼ 300 km/s). This corresponds to an Hα flux at z ∼ 1 equivalent to an unobscured star formation rate of 2 h70}-2 M{sun yr-1 at z=1 (Ω M=0.3, Ω Λ =0.7), comparable to the star formation rate of the Milky Way today. We also successfully targeted a number of galaxies with photometric redshifts z ∼ 1, and broad-band colours indicating star formation. We are currently installing a 2kx 2k detector on CIRPASS, which will double the wavelength coverage to 2100 Å , and hence our ability to successfully target photometrically-selected galaxies over a range of redshifts will be greatly increased. Bibtex entry for this abstract Preferred format for this abstract (see
    Bulletin of the American Astronomical Society, v.202, 716-– + (2003). 01/2003;
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    ABSTRACT: The Sc galaxy M 33 has been mapped with ISOPHOT in the far-infrared, at 60, 100, and 170 $\mu$m. The spatial resolution of these FIR maps allows the separation of spiral arms and interarm regions and the isolation of a large number of star-forming regions. The spectral energy distribution in the FIR indicates a superposition of two components, a warm one originating from dust at ~45 K, and a cold one, at ~16 K. The warm component is concentrated towards the spiral arms and the star-forming regions, and is likely heated by the UV radiation from OB stars. The cold component is more smoothly distributed over the disk, and heated by the diffuse interstellar radiation. For the about 60 star-forming regions detected the H$\alpha$/FIR flux ratio increases significantly with the distance from the galaxy center, probably due to decreasing extinction. An anti-correlation of $F_{{\rm H}a} / F_{60}$ with $F_{170}$ suggests the intrinsic extinction to be related to the cold dust surface brightness according to $A_V / S_{170} \sim 0.03$ mag MJy$^{-1}$ sr. For the total galaxy the star formation rate (SFR) derived from the FIR is in agreement with that derived from the de-extincted H$\alpha$ emission. For individual star-forming regions, a consistency between SFRs derived from the optical and from the FIR requires only a fraction of the UV radiation to be absorbed locally. The individual star-forming regions also show a local radio-FIR correlation. This local correlation is, however, due to quite different components than to those that lead to the well-known global radio-FIR correlation for entire galaxies.
    http://dx.doi.org/10.1051/0004-6361:20030769. 01/2003;