N. Bavouzet

French National Centre for Scientific Research, Paris, Ile-de-France, France

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Publications (11)33.8 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: PSF fitting photometry allows a simultaneously fit of a PSF profile on the sources. Many routines use PSF fitting photometry, including IRAF/allstar, Strarfinder, and Convphot. These routines are in general complex to use and slow. FASTPHOT is optimized for prior extraction (the position of the sources is known) and is very fast and simple.
    Astrophysics Source Code Library. 02/2013;
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    ABSTRACT: This IDL library is designed to be used on astronomical images. Its main aim is to stack data to allow a statistical detection of faint signal, using a prior. For instance, you can stack 160um data using the positions of galaxies detected at 24um or 3.6um, or use WMAP sources to stack Planck data. It can estimate error bars using bootstrap, and it can perform photometry (aperture photometry, or PSF fitting, or other that you can plug). The IAS Stacking Library works with gnomonic projections (RA---TAN), and also with HEALPIX projection.
    Astrophysics Source Code Library. 02/2013;
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    ABSTRACT: The Cosmic Far-Infrared Background (CIB) at wavelengths around 160 {\mu}m corresponds to the peak intensity of the whole Extragalactic Background Light, which is being measured with increasing accuracy. However, the build up of the CIB emission as a function of redshift, is still not well known. Our goal is to measure the CIB history at 70 {\mu}m and 160 {\mu}m at different redshifts, and provide constraints for infrared galaxy evolution models. We use complete deep Spitzer 24 {\mu}m catalogs down to about 80 {\mu}Jy, with spectroscopic and photometric redshifts identifications, from the GOODS and COSMOS deep infrared surveys covering 2 square degrees total. After cleaning the Spitzer/MIPS 70 {\mu}m and 160 {\mu}m maps from detected sources, we stacked the far-IR images at the positions of the 24 {\mu}m sources in different redshift bins. We measured the contribution of each stacked source to the total 70 and 160 {\mu}m light, and compare with model predictions and recent far-IR measurements made with Herschel/PACS on smaller fields. We have detected components of the 70 and 160 {\mu}m backgrounds in different redshift bins up to z ~ 2. The contribution to the CIB is maximum at 0.3 <= z <= 0.9 at 160{\mu}m (and z <= 0.5 at 70 {\mu}m). A total of 81% (74%) of the 70 (160) {\mu}m background was emitted at z < 1. We estimate that the AGN relative contribution to the far-IR CIB is less than about 10% at z < 1.5. We provide a comprehensive view of the CIB buildup at 24, 70, 100, 160 {\mu}m. IR galaxy models predicting a major contribution to the CIB at z < 1 are in agreement with our measurements, while our results discard other models that predict a peak of the background at higher redshifts. Our results are available online http://www.ias.u-psud.fr/irgalaxies/ .
    Astronomy and Astrophysics 09/2010; · 5.08 Impact Factor
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    ABSTRACT: Context. The instrument BLAST (Balloon-borne Large-Aperture Submillimeter Telescope) performed the first deep and wide extragalactic survey at 250, 350 and 500 mum. The extragalactic number counts at these wavelengths are important constraints for modeling the evolution of infrared galaxies. Aims: We estimate the extragalactic number counts in the BLAST data, which allow a comparison with the results of the P(D) analysis of Patanchon et al. (2009). Methods: We use three methods to identify the submillimeter sources. 1) Blind extraction using an algorithm when the observed field is confusion-limited and another one when the observed field is instrumental-noise-limited. The photometry is computed with a new simple and quick point spread function (PSF) fitting routine (FASTPHOT). We use Monte-Carlo simulations (addition of artificial sources) to characterize the efficiency of this extraction, and correct the flux boosting and the Eddington bias. 2) Extraction using a prior. We use the Spitzer 24 mum galaxies as a prior to probe slightly fainter submillimeter flux densities. 3) A stacking analysis of the Spitzer 24 mum galaxies in the BLAST data to probe the peak of the differential submillimeter counts. Results: With the blind extraction, we reach 97 mJy, 83 mJy and 76 mJy at 250 mum, 350 mum and 500 mum respectively with a 95% completeness. With the prior extraction, we reach 76 mJy, 63 mJy, 49 mJy at 250 mum, 350 mum and 500 mum respectively. With the stacking analysis, we reach 6.2 mJy, 5.2 mJy and 3.5 mJy at 250 mum, 350 mum and 500 mum respectively. The differential submillimeter number counts are derived, and start showing a turnover at flux densities decreasing with increasing wavelength. Conclusions: There is a very good agreement with the P(D) analysis of Patanchon et al. (2009). At bright fluxes (>100 mJy), the Lagache et al. (2004) and Le Borgne et al. (2009) models slightly overestimate the observed counts, but the data agree very well near the peak of the differential number counts. Models predict that the galaxy populations probed at the peak are likely z ~ 1.8 ultra-luminous infrared galaxies. unknown author type, collab
    Astronomy and Astrophysics 01/2010; 516. · 5.08 Impact Factor
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    ABSTRACT: We report the detection of correlated anisotropies in the cosmic far-infrared background at 160 μm. We measure the power spectrum in the SWIRE Lockman Hole field. It reveals unambiguously a strong excess above cirrus and Poisson contributions, at spatial scales between 5' and 30', interpreted as the signature of infrared galaxy clustering. Using our model of infrared galaxy evolution, we derive a linear bias b = 1.74 ± 0.16. It is a factor 2 higher than the bias measured for the local IRAS galaxies. Our model indicates that galaxies dominating the 160 μm correlated anisotropies are at z ~ 1. This implies that infrared galaxies at high redshifts are biased tracers of mass, unlike in the local universe.
    The Astrophysical Journal 12/2008; 665(2):L89. · 6.73 Impact Factor
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    ABSTRACT: We present observations aimed at exploring both the nature of Lya emitting nebulae (Lya blobs) at z=2.38 and the way they trace large scale structure (LSS), by exploring their proximity to maximum starbursts through submillimeter emission. Our most important objectives are to make a census of associated submillimeter galaxies (SMGs), check their properties, and look for a possible overdensity in the protocluster J2142-4426 at z=2.38. We used the newly commissioned Large APEX Bolometer Camera (LABoCa) on the Atacama Pathfinder EXperiment (APEX) telescope, in its Science Verification phase, to carry out a deep 10'x10' map at 870 micron, and we performed multiple checks of the quality of data processing and source extraction. Our map, the first published deep image, confirms the capabilities of APEX/LABoCa as the most efficient current equipment for wide and deep submm mapping. Twenty-two sources were securely extracted with 870 micron flux densities in the range 3-21 mJy, rms noise 0.8-2.4 mJy, and far-IR luminosities probably in the range ~5-20 x 10(12) Lo. Only one of the four 50 kpc-extended Lya blobs has a secure 870 micron counterpart. The 870 micron source counts in the whole area are marginally higher than in the SHADES SCUBA survey, with a possible over-density around this blob. The majority of the 3.6-24 micron SEDs of the submillimeter sources indicate they are starburst dominated, with redshifts mostly >2. However, there is evidence of a high-z AGN in ~30% of the sources. Comment: 14 pages, 9 figures, accepted for publication in A&A, fixed author list
    Astronomy and Astrophysics 03/2008; 485(3):645-655. · 5.08 Impact Factor
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    ABSTRACT: Luminous Infrared Galaxies (LIRGs) are primary contributors to the energy production at redshift ~1. They are responsible for the dramatic increase of the star formation density from z=0 to z=1. Establishing proper spectral energy distribution for this class of sources to characterize the physics of the high star formation activity is one of the challenge of the coming decade. We have obtained IRS low resolution spectra of a sample of 40 LIRGs at 0.1
    Spitzer Proposal. 03/2008;
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    ABSTRACT: Aims.We present the observed correlations between rest-frame 8, 24, 70 and 160 $\mu$m monochromatic luminosities and measured total infrared luminosities $L_{\rm IR}$ of galaxies detected by Spitzer.Methods.Our sample consists of 372 star-forming galaxies with individual detections and flux measurements at 8, 24, 70 and 160 $\mu$m. We have spectroscopic redshifts for 93% of these sources, and accurate photometric redshifts for the remainder. We also used a stacking analysis to measure the IR fluxes of fainter sources at higher redshifts.Results.We show that the monochromatic mid and far-infrared luminosities are strongly correlated with the total infrared luminosity and our stacking analysis confirms that these correlations also hold at higher redshifts. We provide relations between monochromatic luminosities and total infrared luminosities $L_{\rm IR}$ that should be reliable up to $z\sim2$ ($z\sim1.1$) for ULIRGs (LIRGs). In particular, we can predict $L_{\rm IR}$ with accuracies of 37% and 54% from the 8 and 24 $\mu$m fluxes, while the best tracer is the 70 $\mu$m flux. Combining bands leads to slightly more accurate estimates. For example, combining the 8 and 24 $\mu$m luminosities predicts $L_{\rm IR}$ with an accuracy of 34%. Our results are generally compatible with previous studies, and the small changes are probably due to differences in the sample selection criteria. We can rule out strong evolution in dust properties with redshift up to $z\sim 1$. Finally, we show that infrared and sub-millimeter observations are complementary means of building complete samples of star-forming galaxies, with the former being more sensitive for $z \la 2$ and the latter at higher $z \ga 2$.
    Astronomy and Astrophysics 12/2007; · 5.08 Impact Factor
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    ABSTRACT: We present the rest-frame 8 micron luminosity function (LF) at redshifts z=1 and ~2, computed from Spitzer 24 micron-selected galaxies in the GOODS fields over an area of 291 sq. arcmin. Using classification criteria based on X-ray data and IRAC colours, we identify the AGN in our sample. The rest-frame 8 micron LF for star-forming galaxies at redshifts z=1 and ~2 have the same shape as at z~0, but with a strong positive luminosity evolution. The number density of star-forming galaxies with log_{10}(nu L_nu(8 micron))>11 increases by a factor >250 from redshift z~0 to 1, and is basically the same at z=1 and ~2. The resulting rest-frame 8 micron luminosity densities associated with star formation at z=1 and ~2 are more than four and two times larger than at z~0, respectively. We also compute the total rest-frame 8 micron LF for star-forming galaxies and AGN at z~2 and show that AGN dominate its bright end, which is well-described by a power-law. Using a new calibration based on Spitzer star-forming galaxies at 0<z<0.6 and validated at higher redshifts through stacking analysis, we compute the bolometric infrared (IR) LF for star-forming galaxies at z=1 and ~2. We find that the respective bolometric IR luminosity densities are (1.2+/-0.2) x 10^9 and (6.6^{+1.2}_{-1.0}) x 10^8 L_sun Mpc^{-3}, in agreement with previous studies within the error bars. At z~2, around 90% of the IR luminosity density associated with star formation is produced by luminous and ultraluminous IR galaxies (LIRG and ULIRG), with the two populations contributing in roughly similar amounts. Finally, we discuss the consistency of our findings with other existing observational results on galaxy evolution.
    The Astrophysical Journal 01/2007; 660(1). · 6.73 Impact Factor
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    ABSTRACT: We have used the Mambo instrument on the IRAM 30m telescope to observe at 1.2mm 63 Spitzer-selected z>1 hyperluminous infrared galaxy candidates (HLIRGs) with starburst-dominated mid-infrared (MIR) spectral energy distributions from the SWIRE Legacy survey. The primary selection criteria are a peak in the IRAC 5.8μm band due to the rest frame near-infrared spectrum of evolved stars, a bright detection at 24μm, and very faint optical counterparts. The detection rate with Mambo is very high at 45%, and both the detection rate and the average 1.2mm/24μm flux ratio are much higher than found for previous Spitzer MIR-selected samples, due to the fact that earlier samples favored systems with AGN-dominated MIR emission. Our sample, on the other hand, shows systematically lower 1.2mm/24μm ratios than a sample of Spitzer-detected submillimeter-selected galaxies (SMGs) in a similar redshift range. Thus Spitzer MIR selection complements submillimeter selection of high redshift starburst-dominated HLIRGs, finding a population with substantially different SED shapes. The large MIR/submillimeter flux ratios probably indicate exceptionally luminous 7.7μm PAH emission, based on Spitzer IRS spectra for a subset of these objects (Weedman et al. 2007).
    11/2006; 38:1171.
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    ABSTRACT: Aims. We present observations aimed at exploring both the nature of Ly$\alpha$ emitting nebulae (“Ly$\alpha$ blobs”) at $z=2.38$ and the way they trace large scale structure (LSS), by exploring their proximity to “maximum starbursts” through submillimeter emission. Our most important objectives are to make a census of associated submillimeter galaxies (SMGs), check their properties, and look for a possible overdensity in the protocluster J2142-4426 at $z=2.38$.Methods. We used the newly commissioned Large APEX Bolometer Camera (LABoCa) on the Atacama Pathfinder EXperiment (APEX) telescope, in its Science Verification phase, to carry out a deep $10\arcmin \times 10\arcmin$ map at 870 ${\mu {\rm m}}$, and we performed multiple checks of the quality of data processing and source extraction.Results. Our map, the first published deep image, confirms the capabilities of APEX/LABoCa as the most efficient current equipment for wide and deep submm mapping. Twenty-two sources were securely extracted with 870 ${\mu {\rm m}}$ flux densities in the range 3–21 mJy, rms noise ~0.8–2.4 mJy, and far-IR luminosities probably in the range ${\sim}$5–$20\times 10^{12}$ $L_\odot$. Only one of the four 50 kpc-extended Ly$\alpha$ blobs has a secure 870 ${\mu {\rm m}}$  counterpart. The 870 ${\mu {\rm m}}$ source counts in the whole area are marginally higher than in the SHADES SCUBA survey, with a possible over-density around this blob. The majority of the 3.6–24 ${\mu {\rm m}}$SEDs of the submillimeter sources indicate they are starburst dominated, with redshifts mostly $\gtrsim$2. However, there is evidence of a high-z AGN in ~30% of the sources.
    http://dx.doi.org/10.1051/0004-6361:200809500.

Publication Stats

216 Citations
33.80 Total Impact Points

Institutions

  • 2010
    • French National Centre for Scientific Research
      • Institut d'astrophysique spatiale (IAS)
      Paris, Ile-de-France, France
  • 2007–2008
    • Université Paris-Sud 11
      • Institut d'Astrophysique Spatiale
      Paris, Ile-de-France, France