Catherine J. Cesarsky

The Great Observatories Origins Deep Survey: Initial Results from Optical and Near-Infrared Imaging

This special issue of the Astrophysical Journal Letters is dedicated to presenting initial results from the Great Observatories Origins Deep Survey (GOODS) that are primarily, but not exclusively, based on multiband imaging data obtained with the Hubble Space Telescope and the Advanced Camera for Surveys (ACS). The survey covers roughly 320 arcmin2 in the ACS F435W, F606W, F814W, and F850LP bands, divided into two well-studied fields. Existing deep observations from the Chandra X-Ray Observatory and ground-based facilities are supplemented with new, deep imaging in the optical and near-infrared from the European Southern Observatory and from the Kitt Peak National Observatory. Deep observations with the Space Infrared Telescope Facility are scheduled. Reduced data from all facilities are being released worldwide within 3-6 months of acquisition. Together, this data set provides two deep reference fields for studies of distant normal and active galaxies, supernovae, and faint stars in our own Galaxy. This Letter serves to outline the survey strategy and describe the specific data that have been used in the accompanying letters, summarizing the reduction procedures and sensitivity limits.

The Atacama Pathfinder EXperiment (APEX) - a new submillimeter facility for southern skies -

APEX, the Atacama Pathfinder EXperiment, has been successfully commissioned and is operational. This novel submillimeter telescope is located at 5107 m altitude on Llano de Chajnantor in the Chilean High Andes, on what is considered one of the world’s outstanding sites for submillimeter astronomy. The primary reflector with 12 m diameter has been carefully adjusted by means of holography. Its surface smoothness of only 17–18 µm makes APEX suitable for observations up to 200 µm, through all atmospheric submm windows accessible from the ground. First scientific results will be presented in the accompanying papers of this special issue.

The bulk of the cosmic infrared background resolved by ISOCAM

We have computed the 15 microns integrated galaxy light produced by ISOCAM galaxies above a sensitivity limit of 50 microJy. It sets a lower limit to the 15 microns extragalactic background light of (2.4+/-0.5) nW/m^2/Hz. The redshift distribution of the ISOCAM galaxies is inferred from the spectroscopically complete sample of galaxies in the Hubble Deep Field North (HDFN). We demonstrate that mid (MIR) and far (FIR) infrared luminosities correlate for local star forming galaxies and that this correlation is consistent with the radio-FIR one up to z ~ 1. From these correlations, about 75 % of the ISOCAM galaxies are found to belong to the class of luminous infrared galaxies (L[IR]>= 10^11 Lsol), with star formation rates of the order of ~ 100 Msol/yr. The cross-correlation with the deepest X-ray surveys from the Chandra and XMM-Newton observatories in the HDFN and Lockman Hole respectively, indicates that at most 20 % of the 15 microns integrated galaxy light is due to active galactic nuclei (AGNs) unless a large population of AGNs was missed by Chandra and XMM-Newton. The contribution of ISOCAM galaxies to the peak of the cosmic infrared background (CIRB) at 140 microns was computed from the MIR-FIR correlations for star forming galaxies and from the spectral energy distribution of the Seyfert 2, NGC 1068, for AGNs. We find that the galaxies unveiled by ISOCAM surveys are responsible for the bulk of the CIRB, i.e (16+/-5) nW/m^2/Hz as compared to the (25+/-7) nW/m^2/Hz measured with the COBE satellite, with less than 10 % due to AGNs. Since the CIRB contains most of the light radiated over the history of star formation in the universe, this means that a large fraction of present-day stars must have formed during a dusty starburst event similar to those revealed by ISOCAM.Deep extragalactic surveys with ISOCAM revealed the presence of a large density of faint mid-infrared (MIR) sources. We have computed the 15m integrated galaxy light produced by these galaxies above a sensitivity limit of 50 Jy. It sets a lower limit to the 15m extragalactic background light of (2:4 0:5) nW m 2 sr 1 .T he redshift distribution of the ISOCAM galaxies is inferred from the spectroscopically complete sample of galaxies in the Hubble Deep Field North (HDFN). It peaks around z 0.8 in agreement with studies in other elds. The rest-frame 15m and bolometric infrared (8{1000m) luminosities of ISOCAM galaxies are computed using the correlations that we establish between the 6.75, 12, 15m and infrared (IR) luminosities of local galaxies. The resulting IR luminosities were double-checked using radio (1.4 GHz) flux densities from the ultra-deep VLA and WSRT surveys of the HDFN on a sample of 24 galaxies as well as on a sample of 109 local galaxies in common between ISOCAM and the NRAO VLA Sky Survey (NVSS). This comparison shows for the rst time that MIR and radio luminosities correlate up to z 1. This result validates the bolometric IR luminosities derived from MIR luminosities unless both the radio-far infrared (FIR) and the MIR-FIR correlations become invalid around z 1. The fraction of IR light produced by active nuclei was computed from the cross-correlation with the deepest X-ray surveys from the Chandra and XMM-Newton observatories in the HDFN and Lockman Hole respectively. We nd that at most 20% of the 15m integrated galaxy light is due to active galactic nuclei (AGNs) unless a large population of AGNs was missed by Chandra and XMM-Newton. About 75% of the ISOCAM galaxies are found to belong to the class of luminous infrared galaxies (LIR 10 11 L). They exhibit star formation rates of the order of100 M yr 1 . The comoving density of infrared light due to these luminous IR galaxies was more than 40 times larger at z 1 than today. The contribution of ISOCAM galaxies to the peak of the cosmic infrared background (CIRB) at 140m was computed from the MIR-FIR correlations for star forming galaxies and from the spectral energy distribution of the Seyfert 2, NGC 1068, for AGNs. We nd that the galaxies unveiled by ISOCAM surveys are responsible for the bulk of the CIRB, i.e. (16 5) nW m 2 sr 1 as compared to the (25 7) nW m 2 sr 1 measured with the COBE satellite, with less than 10% due to AGNs. Since the CIRB contains most of the light radiated over the history of star formation in the universe, this means that a large fraction of present-day stars must have formed during a dusty starburst event similar to those revealed by ISOCAM.

Extragalactic Results from the Infrared Space Observatory

▪ Abstract More than a decade ago the IRAS satellite opened the realm of external galaxies for studies in the 10 to 100 μm band and discovered emission from tens of thousands of normal and active galaxies. With the 1995–1998 mission of the Infrared Space Observatory1, the next major steps in extragalactic infrared astronomy became possible: detailed imaging, spectroscopy, and spectrophotometry of many galaxies detected by IRAS, as well as deep surveys in the mid- and far-IR. The spectroscopic data reveal a wealth of detail about the nature of the energy source(s) and about the physical conditions in galaxies. ISOs surveys for the first time explore the infrared emission of distant, high-redshift galaxies. ISOs main theme in extragalactic astronomy is the role of star formation in the activity and evolution of galaxies.

The great observatories origins deep survey - VLT/VIMOS spectroscopy in the GOODS-south field

We present the full data set of the VIMOS spectroscopic campaign of the ESO/GOODS program in the CDFS, which complements the FORS2 ESO/GOODS spectroscopic campaign. The GOODS/VIMOS spectroscopic campaign is structured in two separate surveys using two different VIMOS grisms. The VIMOS Low Resolution Blue (LR-Blue) and Medium Resolution (MR) orange grisms have been used to cover different redshift ranges. The LR-Blue campaign is aimed at observing galaxies mainly at 1.8 3.5. The full GOODS/VIMOS spectroscopic campaign consists of 20 VIMOS masks. This release adds 8 new masks to the previous release (12 masks, Popesso et al. 2009). In total we obtained 5052 spectra, 3634 from the 10 LR-Blue masks and 1418 from the 10 MR masks. A significant fraction of the extracted spectra comes from serendipitously observed sources: ~21% in the LR-Blue and ~16% in the MR masks. We obtained 2242 redshifts in the LR-Blue campaign and 976 in the MR campaign for a total success rate of 62% and 69% respectively, which increases to 66% and 73% if only primary targets are considered. The typical redshift uncertainty is estimated to be ~0.0012 (~255 km/s) for the LR-Blue grism and ~0.00040 (~120 km/s) for the MR grism. By complementing our VIMOS spectroscopic catalog with all existing spectroscopic redshifts publicly available in the CDFS, we compiled a redshift master catalog with 7332 entries, which we used to investigate large scale structures out to z~3.7. We produced stacked spectra of LBGs in a few bins of equivalent width (EW) of the Ly-alpha and found evidence for a lack of bright LBGs with high EW of the Ly-alpha. Finally, we obtained new redshifts for 12 X-ray sources of the CDFS and extended-CDFS.

ISOCAM observations of the rho Ophiuchi cloud: Luminosity and mass functions of the pre-main sequence embedded cluster

We present the results of the first extensive mid-infrared (IR) imaging survey of the rho Ophiuchi embedded cluster, performed with the ISOCAM camera on board the ISO satellite. The main molecular cloud L1688, as well as L1689N and L1689S, have been completely surveyed for point sources at 6.7 and 14.3 micron. A total of 425 sources are detected including 16 Class I, 123 Class II, and 77 Class III young stellar objects (YSOs). Essentially all of the mid-IR sources coincide with near-IR sources, but a large proportion of them are recognized for the first time as YSOs. Our dual-wavelength survey allows us to identify essentially all the YSOs with IR excess in the embedded cluster down to Fnu ~ 10 - 15 mJy. It more than doubles the known population of Class II YSOs and represents the most complete census to date of newly formed stars in the rho Ophiuchi central region. The stellar luminosity function of the complete sample of Class II YSOs is derived with a good accuracy down to L= 0.03 Lsun. A modeling of this lumino- sity function, using available pre-main sequence tracks and plausible star for- mation histories, allows us to derive the mass distribution of the Class II YSOs which arguably reflects the IMF of the embedded cluster. We estimate that the IMF in rho Ophiuchi is well described by a two-component power law with a low- mass index of -0.35+/-0.25, a high-mass index of -1.7 (to be compared with the Salpeter value of -1.35), and a break occurring at M = 0.55+/-0.25 Msun. This IMF is flat with no evidence for a low-mass cutoff down to at least 0.06 Msun.

SPECTROSCOPIC OBSERVATIONS OF LYMAN BREAK GALAXIES AT REDSHIFTS ∼4, 5, AND 6 IN THE GOODS-SOUTH FIELD*

We report on observations of Lyman break galaxies (LBGs) selected from the Great Observatories Origins Deep Survey at mean redshifts z ~ 4, 5, and 6 (B 435-, V 606-, and i 775-band dropouts, respectively), obtained with the red-sensitive FORS2 spectrograph at the ESO VLT. This program has yielded spectroscopic identifications for 114 galaxies (~60% of the targeted sample), of which 51 are at z ~ 4, 31 at z ~ 5, and 32 at z ~ 6. We demonstrate that the adopted selection criteria are effective, identifying galaxies at the expected redshift with minimal foreground contamination. Of the 10% interlopers, 83% turn out to be Galactic stars. Once selection effects are properly accounted for, the rest-frame ultraviolet (UV) spectra of the higher redshift LBGs appear to be similar to their counterparts at z ~ 3. As at z ~ 3, LBGs at z ~ 4 and z ~ 5 are observed with Ly? both in emission and in absorption; when in absorption, strong interstellar lines are also observed in the spectra. The stacked spectra of Ly? absorbers and emitters also show that the former have redder UV spectra and stronger but narrower interstellar lines, a fact also observed at z ~ 2 and 3. At z ~ 6, sensitivity issues bias our sample toward galaxies with Ly? in emission; nevertheless, these spectra appear to be similar to their lower redshift counterparts. As in other studies at similar redshifts, we find clear evidence that brighter LBGs tend to have weaker Ly? emission lines. At fixed rest-frame UV luminosity, the equivalent width of the Ly? emission line is larger at higher redshifts. At all redshifts where the measurements can be reliably made, the redshift of the Ly? emission line turns out to be larger than that of the interstellar absorption lines (ISLs), with a median velocity difference ?V ~ 400 km s?1 at z ~ 4 and 5, consistent with results at lower redshifts. This shows that powerful, large-scale winds are common at high redshift. In general, there is no strong correlation between the morphology of the UV light and the spectroscopic properties. However, galaxies with deep ISLs and strong Ly? absorption appear to be more diffuse than galaxies with Ly? in emission.

The AGN contribution to mid-infrared surveys X-ray counterparts of the mid-IR sources in the Lockman Hole and HDF-N

We provide constraints on the AGN contribution to the mid-IR extragalactic background light from a correlation analysis of deep X-ray and mid-IR observations in two regions centred on the Lockman Hole and Hubble Deep Field North (HDF-N). The Lockman region, of more than 200 square arcminutes, was observed by ISOCAM and XMM-Newton to a depth of 0.3 mJy at 15 µm (resolving more than 30% of the mid-IR background). In the same area XMM-Newton reached flux limits of 1.4 × 10 −15 erg cm −2 s −1 in the 2-10 keV energy band and 2.4 × 10 −15 erg cm −2 s −1 in the 5-10 keV energy band, resolving about 80% of the 2-10 keV and 60% of the 5-10 keV backgrounds (the deepest observation in this hard band to date). Among the 76 galaxies detected by XMM-Newton, 24 show mid-IR emission, but the relative percentage of X-ray sources with mid-IR counterparts increases with the band energy: from 30% of the 0.5-2 keV sources up to 63% of the 5-10 keV sources. In contrast, only a small fraction of the mid-IR sources (around 10%) show X-ray emission within the sensitivity limits of XMM-Newton observations. The region centred on the HDF-N has been observed by ISOCAM (24 square arcminutes) to a depth of 0.05 mJy (more than 60% of the mid-IR background is resolved at this limit) and covered with a 1 Msec exposure by Chandra. In this case, 25% of the mid-IR sources are detected in the X-ray, while 30-40% of the X-ray sources show mid-IR emission. Under the assumption that all XMM sources except stars or galaxy clusters are AGN-dominated, AGNs contribute (15 ± 5)% of the total mid-IR flux in the Lockman Hole. For the HDF-N we have assumed that AGN-dominated sources are luminous X-ray sources and sources with SEDs from radio to X-ray wavelengths typical of local AGNs, in which case we find that (18 ± 7)% of the mid-IR flux are due to AGN emission. If we put together all the existing information from the deepest HDF-N data to the bright large-area sample in the ELAIS S1 region observed with BeppoSAX (for a total of 50 X-ray-mid-IR matched sources) using the median mid-IR to X-ray spectral indices as a function of the X-ray flux, we find an AGN contribution to the 15 µm background of (17 ± 2)%. Since the IR spectra of typical AGNs peak around 20 µm while starburst spectra peak at significantly longer infrared wavelengths, this figure may be considered as an upper limit to the AGN contribution to the CIRB energy density. We conclude that the population of IR luminous galaxies detected in the ISOCAM deep surveys, and the CIRB sources themselves, are mainly constituted by dust-obscured starbursts.

New spectroscopic redshifts from the CDFS and a test of the cosmological relevance of the GOODS-South field

(Abbrev.) This paper prepares a series of papers analysing the Intermediate MAss Galaxy Evolution Sequence (IMAGES) up to z=1. Intermediate mass galaxies (MJ <=-20.3) are selected from the Chandra Deep Field South (CDFS) for which we identify a serious lack of spectroscopically determined redshifts..... We have spectroscopically identified 691 objects including 580 gal., 7 QSOs, and 104 stars. This study provides 531 new redshifts in the CDFS. It confirms the presence of several large scale structures in the CDFS. To test the impact of these structures in the GOODS-South field, we ... compare the evolution of rest-frame U, B, V and K galaxy luminosity densities to that derived from the CFRS. The CDFS field shows a significant excess of luminosity densities in the z=0.5-0.75 range, which increases with the wavelength, reaching up to 0.5 dex at 2.1 um. Stellar mass and specific star formation evolutions might be significantly affected by the presence of the peculiar large scale structures at z= 0.668 and at z= 0.735, that contain a significant excess of evolved, massive galaxies when compared to other fields. This leads to a clear warning to results based on the CDFS/GOODS South fields, especially those related to the evolution of red luminosity densities, i.e. stellar mass density and specific star formation rate. Photometric redshift techniques, when applied to that field, are producing quantities which are apparently less affected by cosmic variance (0.25 dex at 2.1 um), however at the cost of the difficulty in disentangling between evolutionary and cosmic variance effects.

The Great Observatories Origins Deep Survey - VLT/ISAAC near-infrared imaging of the GOODS-South field

Aims. We present the final public data release of the VLT /ISAAC near-infrared imaging survey in the GOODS-South field . The survey covers an area of 172.5, 159.6 and 173.1 arcmin 2 in the J, H, and Ks bands, respectively. For point sources total limiting magnitudes of J = 25: 0, H = 24: 5, and Ks = 24: 4 (5� , AB) are reached within 75% of the survey area. Thus these observations are significantly deeper than the previous EIS Deep Public Surve y which covers the same region. The image quality is characterized by a point spread function ranging between 0.34 00 and 0.65 00 FWHM. The images are registered to a common astrometric grid defined by the GSC 2 with an accuracy of�0: 06 00 RMS over the whole field. The overall photometric accuracy, i ncluding all systematic effects, adds up to 0.05 mag. The data are publicly available from the ESO science archive facility. Methods. We describe the data reduction, the calibration, and the quality control process. The final data set is characterized in t erms of astrometric and photometric properties, including the PSF and the curve of growth. We establish an empirical model for the sky background noise in order to quantify the variation of limiting depth and statistical photometric errors over the surve y area. We define a catalog of Ks-selected sources which contains JHKs photometry for 7079 objects. Differential aperture corrections were applied to the color measurements in order to avoid possible biases as a result of the variation of the PSF. We briefly discuss the resu lting color distributions in the context of available redshift data. Fu rthermore, we estimate the completeness fraction and relative contamination due to spurious detections for source catalogs extracted fr om the survey data. For this purpose, an empirical study based on a deep Ks image of the Hubble Ultra Deep Field is combined with extensive image simulations. Results. With respect to previous deep near-infrared surveys, the surface density of faint galaxies has been established with unprecedented accuracy by virtue of the unique combination of depth and area of this survey. We derived galaxy number counts over eight magnitudes in flux up to J = 25: 25, H = 25: 0, Ks = 25: 25 (in the AB system). Very similar faint-end logarithmic slopes between 0.24 and 0.27 mag −1 were measured in the three bands. We found no evidence for a significant change in the slope of the logarithmic galaxy number counts at the faint end.