Publications (58)24.26 Total impact
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Article: Herschel/PACS far-infrared photometry of two z>4 quasars
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ABSTRACT: We present Herschel far-infrared (FIR) observations of two sub-mm bright quasars at high redshift: SDSS J1148+5251 (z=6.42) and BR 1202-0725 (z=4.69) obtained with the PACS instrument. Both objects are detected in the PACS photometric bands. The Herschel measurements provide additional data points that constrain the FIR spectral energy distributions (SEDs) of both sources, and they emphasise a broad range of dust temperatures in these objects. For lambda_rest ~< 20mu, the two SEDs are very similar to the average SEDs of quasars at low redshift. In the FIR, however, both quasars show excess emission compared to low-z QSO templates, most likely from cold dust powered by vigorous star formation in the QSO host galaxies. For SDSS J1148+5251 we detect another object at 160mu with a distance of ~10 arcseconds from the QSO. Although no physical connection between the quasar and this object can be shown with the available data, it could potentially confuse low-resolution measurements, thus resulting in an overestimate of the FIR luminosity of the z=6.42 quasar. Comment: 4 pages, 3 figures, accepted for publication in the A&A special issue on Herschel05/2010; -
Article: The ISOPHOT 170 micron serendipity survey (ISOSS) catalog of optically identified galaxies.
Astronomische Nachrichten 07/2005; 326:531-531. · 1.01 Impact Factor -
Article: The European Large Area ISO Survey – VIII. 90‐μm final analysis and source counts
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ABSTRACT: We present a re-analysis of the European Large Area Infrared Space Observatory (ISO) Survey (ELAIS) 90-μm observations carried out with ISOPHOT, an instrument on board the ISO of the European Space Agency. With more than 12 deg2, the ELAIS survey is the largest area covered by ISO in a single programme and is about one order of magnitude deeper than the IRAS 100-μm survey. The data analysis is presented and was mainly performed with the phot interactive analysis software but using the pairwise method of Stickel et al. for signal processing from edited raw data to signal per chopper plateau. The ELAIS 90-μm catalogue contains 237 reliable sources with fluxes larger than 70 mJy and is available in the electronic version of this article. Number counts are presented and show an excess above the no-evolution model prediction. This confirms the strong evolution detected at shorter (15 μm) and longer (170 μm) wavelengths in other ISO surveys. The ELAIS counts are in agreement with previous works at 90 μm and in particular with the deeper counts extracted from the Lockman hole observations. Comparison with recent evolutionary models show that the models of Franceschini et al. and Guiderdoni et al. (which includes a heavily extinguished population of galaxies) give the best fit to the data. Deeper observations are nevertheless required to discriminate better between the model predictions in the far-infrared, and are scheduled with the Spitzer Space Telescope, which has already started operating, and will also be performed by ASTRO-F.Monthly Notices of the Royal Astronomical Society 12/2004; 354(3):924 - 934. · 4.90 Impact Factor -
Article: The European Large Area ISO Survey VIII: 90-micron final analysis and source counts
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ABSTRACT: We present a re--analysis of the European Large Area ISO Survey (ELAIS) 90mum observations carried out with ISOPHOT, an instrument on board the ESA's Infrared Space Observatory (ISO). With more than 12 sq. deg., the ELAIS survey is the largest area covered by ISO in a single program and is about one order of magnitude deeper than the IRAS 100mum survey. The data analysis is presented and was mainly performed with the Phot Interactive Analysis software but using the pairwise method of Stickel et al. (2003) for signal processing from ERD (Edited Raw Data) to SCP (Signal per Chopper Plateau). The ELAIS 90mum catalogue contains 229 reliable sources with fluxes larger than 70 mJy and is available at www.blackwell-synergy.com. Number counts are presented and show an excess above the no-evolution model prediction. This confirms the strong evolution detected at shorter(15mum) and longer (170mum) wavelengths in other ISO surveys. The ELAIS counts are in agreement with previous works at 90mum and in particular with the deeper counts extracted from the Lockman hole observations. Comparison with recent evolutionary models show that the models of Franceschini et al. and Guiderdoni et al. which includes a heavily-extinguished population of galaxies give the best fit to the data. Deeper observations are nevertheless required to better discriminate between the model predictions in the far-infrared and are scheduled with the Spitzer Space Telescope which already started operating and will also be performed by ASTRO-F. Comment: 13 pages, 10 figures, MNRAS, in press10/2004; -
Article: The European Large Area ISO Survey IX: the 90 micron luminosity function from the Final Analysis sample
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ABSTRACT: We present the 90 micron luminosity function of the Final Analysis of the European Large Area ISO Survey (ELAIS), extending the sample size of our previous analysis (paper IV) by about a factor of 4. Our sample extends to z=1.1, around 50 times the comoving volume of paper IV, and 10^{7.7} < h^{-2}L/Lsun < 10^{12.5}. From our optical spectroscopy campaigns of the northern ELAIS 90 mircon survey (7.4 deg^2 in total, to S(90um)>70mJy), we obtained redshifts for 61% of the sample (151 redshifts) to B<21 identified at 7 microns, 15 microns, 20cm or with bright (B<18.5) optical identifications. The selection function is well-defined, permitting the construction of the 90 micron luminosity function of the Final Analysis catalogue in the ELAIS northern fields, which is in excellent agreement with our Preliminary Analysis luminosity function in the ELAIS S1 field from paper IV. The luminosity function is also in good agreement with the IRAS-based prediction of Serjeant & Harrison (2004), which if correct requires luminosity evolution of (1+z)^{3.4 +/- 1.0} for consistency with the source counts. This implies an evolution in comoving volume averaged star formation rate at z<~1 consistent with that derived from rest-frame optical and ultraviolet surveys. Comment: MNRAS accepted. 7 pages, 5 figures. Uses BoxedEPS (included)01/2004; -
Article: The spiral galaxy M33 mapped in the FIR by ISOPHOT: A spatially resolved study of the warm and cold dust
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ABSTRACT: The Sc galaxy M33 has been mapped with ISOPHOT in the far-infrared, at 60, 100, and 170mue. 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 ~45K, and a cold one, at ~16K. 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_Ha/F_60 with F_170 suggests the intrinsic extinction to be related to the cold dust surface brightness according to A_V/S_170~0.03mag/MJy*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. Comment: 10 pages, 9 figures; the full resolution images of Fig.1 can be obtained by anonymous ftp from ftp.mpia.de /pub/iso-arch06/2003; -
Article: A very young star forming region detected by the ISOPHOT Serendipity Survey
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ABSTRACT: We present a multi-wavelength study of the star forming region ISOSS J 20298+3559, which was identified by a cross-correlation of cold compact sources from the 170 micron ISOPHOT Serendipity Survey (ISOSS) database coinciding with objects detected by the MSX, 2MASS and IRAS infrared surveys. ISOSS J 20298+3559 is associated with a massive dark cloud complex (M ~ 760 M$_{\odot}$) and located in the Cygnus X giant molecular cloud. We derive a distance of 1800 pc on the basis of optical extinction data. The low average dust temperature (T ~ 16 K) and large mass (M ~ 120 M$_{\odot}$) of the dense inner part of the cloud, which has not been dispersed, indicates a recent begin of star formation. The youth of the region is supported by the early evolutionary stage of several pre- and protostellar objects discovered across the regio n: I) Two candidate Class 0 objects with masses of 8 and 3.5 M$_{\odot}$, II) a gravitationally bound, cold (T ~ 12 K) and dense (n(H$_{2}$) \~ 2 x 10$^{5}$ cm$^{-3}$) cloud core with a mass of 50 M$_{\odot}$ and III) a Herbig B2 star with a mass of 6.5 M$_{\odot}$ and a bolometric luminosity of 2200 L$_{\odot}$, showing evidence for ongoing accretion and a stellar age of less than 40000 years. The dereddened SED of the Herbig star is well reproduced by an accretion disc + star model. The externally heated cold cloud core is a good candidate for a massive pre-protostellar object. The star formation efficiency in the central cloud region is about 14 %. Comment: 14 pages, 14 figures, 7 tables. Accepted for publication in Astronomy & Astrophysics09/2002; -
Article: Solar System Objects in the ISOPHOT 170 micron Serendipity Survey
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ABSTRACT: The ISOPHOT Serendipity Survey (ISOSS) covered approximately 15 % of the sky at a wavelength of 170 micron while the ISO satellite was slewing from one target to the next. By chance ISOSS slews went over many solar system objects (SSOs). We identified the comets, asteroids and planets in the slews through a fast and effective search procedure based on N-body ephemeris and flux estimates. The detections were analysed from a calibration and scientific point of view. Through the measurements of the well-known asteroids Ceres, Pallas, Juno and Vesta and the planets Uranus and Neptune it was possible to improve the photometric calibration of ISOSS and to extend it to higher flux regimes. We were also able to establish calibration schemes for the important slew end data. For the other asteroids we derived radiometric diameters and albedos through a recent thermophysical model. The scientific results are discussed in the context of our current knowledge of size, shape and albedos, derived from IRAS observations, occultation measurements and lightcurve inversion techniques. In all cases where IRAS observations were available we confirm the derived diameters and albedos. For the five asteroids without IRAS detections only one was clearly detected and the radiometric results agreed with sizes given by occultation and HST observations. Four different comets have clearly been detected at 170 micron and two have marginal detections. The observational results are presented to be used by thermal comet models in the future. The nine ISOSS slews over Hale-Bopp revealed extended and asymmetric structures related to the dust tail. We attribute the enhanced emission in post-perihelion observations to large particles around the nucleus. The signal patterns are indicative of a concentration of the particles in trail direction. Comment: 15 pages, 6 figures, 6 tables; Accepted for publication in Astronomy and Astrophysics03/2002; -
Article: Extending the limits of globule detection -- ISOPHOT Serendipity Survey Observations of interstellar clouds
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ABSTRACT: A faint $I_{\rm 170}=4$ MJysr$^{-1}$ bipolar globule was discovered with the ISOPHOT 170 $\mu$m Serendipity Survey (ISOSS). ISOSS J 20246+6541 is a cold ($T_{\rm d}\approx 14.5$ K) FIR source without an IRAS pointsource counterpart. In the Digitized Sky Survey B band it is seen as a 3\arcmin size bipolar nebulosity with an average excess surface brightness of $\approx 26$ mag/$\square $\arcsec . The CO column density distribution determined by multi-isotopic, multi-level CO measurements with the IRAM-30m telescope agrees well with the optical appearance. An average hydrogen column density of $\approx 10^{21}$cm$^{-2}$ was derived from both the FIR and CO data. Using a kinematic distance estimate of 400 pc the NLTE modelling of the CO, HCO$^+$, and CS measurements gives a peak density of $\approx 10^4$cm$^{-3}$. The multiwavelength data characterise ISOSS 20246+6541 as a representative of a class of globules which has not been discovered so far due to their small angular size and low 100$\mu $m brightness. A significant overabundance of $^{13}$CO is found $X(^{13}CO) \ge 150\times X(C^{18}O)$. This is likely due to isotope selective chemical processes. Comment: 5 pages, 3 figures02/2002; -
Article: Far-Infrared Emission from Intracluster Dust in Abell Clusters
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ABSTRACT: The ISOPHOT instrument aboard ISO has been used to observe extended FIR emission of six Abell clusters. The raw profiles of the I_(120 um) / I_(180 um) surface brightness ratio including zodiacal light show a bump towards Abell 1656 (Coma), dips towards Abell 262 and Abell 2670, and are without clear structure towards Abell 400, Abell 496, and Abell 4038. After subtraction of the zodiacal light, the bump towards Abell 1656 is still present, while the dips towards Abell 262 and Abell 2670 are no longer noticable. This indicates a localized excess of emitting material outside the Galaxy towards Abell 1656, while the behavior in Abell 262 and Abell 2670 can be reconciled with galactic cirrus structures localized on the line-of-sight to these clusters. The excess towards Abell 1656 (Coma) is interpreted as thermal emission from intracluster dust distributed in the hot X-ray emitting intracluster medium. The absence of any signature for intracluster dust in five clusters and the rather low inferred dust mass in Abell 1656 indicates that intracluster dust is likely not responsible for the excess X-ray absorption seen in cooling flow clusters. These observations thereby represent a further unsuccessful attempt in detecting the presumed final stage of the cooling flow material, in accord with quite a number of previous studies in other wavelengths regions. Finally, the observed dimming of the high-redshift supernovae is unlikely be attributable to extinction caused by dust in the intracluster or even a presumed intercluster medium. Comment: 16 pages, 32 figures, accepted for publication in Astronomy & Astrophysics12/2001; -
Article: The ISOPHOT 170 Micron Serendipity Sky Survey : A Plea to FIRST
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ABSTRACT: The ISOPHOT Serendipity Survey utilized the slew time between ISO's pointed observations with strip scanning measurements of the sky in the far-infrared (FIR) at 170 microns. The integral 170 micron fluxes for compact sources derived from the slews are put on an absolute flux level by using a number of galaxies as calibrator sources observed with ISOPHOT's photometric mapping mode, supplemented by Serendipity Survey observations of two planets and two asteroids with available model fluxes. A first group of 115 well-observed sources with a high signal-to-noise ratio in all four detector pixels having a galaxy association were extracted from the slew data with low (I100 μ m <= 15 MJy/sr) cirrus background. For all but a few galaxies, the 170 micron fluxes are determined for the first time, which represents a significant increase in the number of galaxies with measured FIR fluxes beyond the IRAS 100 microns limit. The large fraction of sources with a high F170 μ m / F100 μ m flux ratio indicates that a very cold (T < 20 K) dust component is present in many galaxies. The typical mass of the coldest dust component is MDust = 107.5 ± 0.5 Msun, a factor 2 - 10 larger than that derived from IRAS fluxes alone. As a consequence, the gas-to-dust ratios are much closer to the canonical value for the Milky Way. A similar Serendipity Survey with FIRST has the prospects of delivering FIR data with a much higher angular resolution (PACS) or at longer wavelengths (SPIRE) than ISOPHOT, thereby providing either crucial information for the identification of compact sources in confused regions or extending the spectral coverage for a large number of sources and finding rare classes of very cold FIR emitters.06/2001; 460:109. -
Article: ISO FIRBACK Source Catalog at 170um (Dole+, 2001)
VizieR Online Data Catalog. 05/2001; 337:20364. -
Article: FIRBACK: III. Catalog, Source counts, and cosmological implications of the 170 micron ISO Deep survey
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ABSTRACT: The FIRBACK (Far Infrared BACKground) survey is one of the deepest imaging surveys carried out at 170 microns with ISOPHOT onboard ISO, and is aimed at the study of the structure of the Cosmic Far Infrared Background. This paper provides the analysis of resolved sources. After a validated process of data reduction and calibration, we perform intensive simulations to optimize the source extraction, measure the confusion noise (sigma_c = 45 mJy), and give the photometric and astrometric accuracies. 196 galaxies with flux S > 3 sigma_c are detected in the area of 3.89 square degrees. Counts of sources with flux S > 4 sigma_c present a steep slope of 3.3 +/- 0.6 on a differential "logN-logS" plot between 180 and 500 mJy. As a consequence, the confusion level is high and will impact dramatically on future IR deep surveys. This strong evolution, compared with a slope of 2.5 from Euclidian geometry, is in line with models implying a strongly evolving Luminous Infrared Galaxy population. The resolved sources account for less than 10% of the Cosmic Infrared Background at 170 microns, which is expected to be resolved into sources in the 1 to 10 mJy range. Comment: Accepted for publication in A&A. 16 pages, includes new aa.cls. Tables 7 to 13 included here will appear on the electronic version of A&A and at the CDS. Paper, catalog and images (with better quality) also available at http://wwwfirback.ias.u-psud.fr and http://mips.as.arizona.edu/~hdole/firback03/2001; -
Article: ISOPHOTs Extragalactic Surveys in the Far Infrared
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ABSTRACT: Several deep surveys were performed in the wavelength range 90 ... 200 μm. The resulting source counts are compatible with models of strong galaxy evolution. The largest survey was obtained serendipitously by scanning the sky between pointed observations at 175 μm. It allows statistical conclusions on the cold dust content of galaxies in the local universe. Several surveys on luminous galaxies (ULIRGs, quasars) deliver templates of the far infrared spectra of distant objects.Proceedings of the International Astronomical Union 12/2000; 204:247. -
Article: ISOPHOT Serendipity Survey observations of interstellar clouds I. Detection of the Coldest Cores in Chamaeleon
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ABSTRACT: ISOPHOT Serendipity Survey (ISOSS) observations at 170 \um\ reveal cold dust clouds in the nearby star forming region Chamaeleon. The distribution of the ISOSS/IRAS based T(I170/I100) colour temperature have been studied in a nearby low-mass star forming region. T(I170/I100) separates the obscured and intercloud regions as seen from a comparison to optical extinction data. The interstellar medium in Chamaeleon-Musca appears to be cold with dust colour temperatures of ~ 16.3 K for intercloud regions, and <= 14.5 K for obscured clouds. The cold clouds account for 3 % of the area. ISOSS found 9 very cold cores with colour temperatures as low as Tdust <~ 12.5 K in an 11°ee x 8°ee sized region. All \CeiO\ cores of the Chamaeleon main clouds which were crossed by ISOSS slews were also detected. Of these 11 (73 %) are cold with T_dust <= 15 K, 6 (40 %) are associated with very cold cores. The very cold cores have high gas column densities, N(Htwo )>1021 cm-2, and 7 out of 9 have low gas kinetic temperatures as indicated by Tex(CeiO ) 8 K. The physical parameters of the very cold cores agree with the results of radiative transfer calculations of a spherical model cloud heated from outside by one third of the the solar neighbourhood ISRF intensity. A check of the photometric calibration of ISOSS against ISOPHOT AOT PHT22 maps and DIRBE interpolated 170 \um\ values showed an agreement of +/- 10 % and +/- 20 %, respectively. We expect to discover in total more than 100 very cold cores in the Galaxy by ISOSS.Astronomy and Astrophysics 11/2000; 364:769-779. · 4.59 Impact Factor -
Article: The ISOPHOT 170 μ m serendipity survey. I. Compact sources with galaxy associations
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ABSTRACT: The first set of compact sources observed in the ISOPHOT 170 μm Serendipity Survey is presented. From the slew data with low (I100 μm <= 15 MJy/sr) cirrus background, 115 well-observed sources with a high signal-to-noise ratio in all detector pixels having a galaxy association were extracted. Of the galaxies with known optical morphologies, the vast majority are classified as spirals, barred spirals, or irregulars. The 170 μm fluxes measured from the Serendipity slews have been put on an absolute flux level by using calibration sources observed additionally with the photometric mapping mode of ISOPHOT. For all but a few galaxies, the 170 μm fluxes are determined for the first time, which represents a significant increase in the number of galaxies with measured Far-Infrared (FIR) fluxes beyond the IRAS 100 μm limit. The 170 μm fluxes cover the range 2 <~ F170 μm la 100 Jy. Formulae for the integrated FIR fluxes F40-220μm and the total infrared fluxes F1-1000μm incorporating the new 170 μm fluxes are provided. The large fraction of sources with a high F170 μm / F100 μm flux ratio indicates that a cold (TDust la 20 K) dust component is present in many galaxies. The detection of such a cold dust component is crucial for the determination of the total dust mass in galaxies, and, in cases with a large F170 μm / F100 μm flux ratio, increases the dust mass by a significant factor. The typical mass of the coldest dust component is MDust = 107.5 +/- 0.5 Msun , a factor 2-10 larger than that derived from IRAS fluxes alone. As a consequence, the majority of the derived gas-to-dust ratios are much closer to the canonical value of ~ 160 for the Milky Way. By relaxing the selection criteria, it is expected that the Serendipity Survey will eventually lead to a catalog of 170 μm fluxes for ~ 1000 galaxies. Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) and with the participation of ISAS and NASA. Members of the Consortium on the ISOPHOT Serendipity Survey (CISS) are MPIA Heidelberg, ESA ISO SOC Villafranca, AIP Potsdam, IPAC Pasadena, Imperial College London.Astronomy and Astrophysics 06/2000; 359:865-875. · 4.59 Impact Factor -
Article: The extragalactic background and its fluctuations in the far-infrared wavelengths
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ABSTRACT: A Cosmic Far-InfraRed Background (CFIRB) has long been predicted that would traces the intial phases of galaxy formation. It has been first detected by Puget et al.(1996) using COBE data and has been later confirmed by several recent studies (Fixsen et al. 1998, Hauser et al. 1998, Lagache et al. 1999). We will present a new determination of the CFIRB that uses for the first time, in addition to COBE data, two independent gas tracers: the HI survey of Leiden/Dwingeloo (hartmann, 1998) and the WHAM H$_{\alpha}$ survey (Reynolds et al 1998). We will see that the CFIRB above 100 micron is now very well constrained. The next step is to see if we can detect its fluctuations. To search for the CFIRB fluctuations, we have used the FIRBACK observations. FIRBACK is a deep cosmological survey conducted at 170 micron with ISOPHOT (Dole et al., 2000). We show that the emission of unresolved extra-galactic sources clearly dominates, at arcminute scales, the background fluctuations in the lowest galactic emission regions. This is the first detection of the CFIRB fluctuations.03/2000; -
Article: FIRBACK Source Counts and Cosmological Implications
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ABSTRACT: FIRBACK is a one of the deepest surveys performed at 170 microns with ISOPHOT onboard ISO, and is aimed at the study of cosmic far infrared background sources. About 300 galaxies are detected in an area of four square degrees, and source counts present a strong slope of 2.2 on an integral "logN-logS" plot, which cannot be due to cosmological evolution if no K-correction is present. The resolved sources account for less than 10% of the Cosmic Infrared Background at 170 microns. In order to understand the nature of the sources contributing to the CIB, and to explain deep source counts at other wavelengths, we have developed a phenomenological model, which constrains in a simple way the luminosity function evolution with redshift, and fits all the existing deep source counts from the mid-infrared to the submillimetre range. Images, materials and papers available on the FIRBACK web: http://wwwfirback.ias.u-psud.fr wwwfirback.ias.u-psud.fr Comment: proceedings of "ISO Surveys of a Dusty Universe", eds. D. Lemke, M. Stickel, K. Wilke, Ringberg, 8-12 Nov 1999, to appear in Springer 'Lecture Notes of Physics'. 8 pages, 7 eps figures, .sty included02/2000; -
Conference Proceeding: FIRBACK Cosmological Survey With ISO: Observing the Cosmic Infrared Background at 170 microns
ISO Beyond Point Sources: Studies of Extended Infrared Emission; 01/2000 -
Article: FIRBACK Far Infrared Survey with ISO: Data Reduction, Analysis and First Results
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ABSTRACT: FIRBACK is one of the deepest cosmological surveys performed in the far infrared, using ISOPHOT. We describe this survey, its data reduction and analysis. We present the maps of fields at 175 microns. We point out some first results: source identifications with radio and mid infrared, and source counts at 175 microns. These two results suggest that half of the FIRBACK sources are probably at redshifts greater than 1. We also present briefly the large follow-up program.03/1999;
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1997–2010
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Max Planck Institute for Astronomy
Heidelberg, Baden-Wuerttemberg, Germany
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