arXiv subjects

D. Burgarella

Publications and source records attributed to D. Burgarella.

At least 145 records · Page 8Linked to original sources

arXiv2008

The Wide-field High-resolution Infrared TElescope (WHITE)

The Wide-field High-resolution Infrared TElescope (WHITE) will be dedicated in the first years of its life to carrying out a few (well focused in terms of science objectives and time) legacy surveys. WHITE would have an angular resolution of ~0.3'' homogeneous over ~0.7 sq. deg. in the wavelength range 1 - 5 um, which means that we will very efficiently use all the available observational time during night time and day time. Moreover, the deepest observations will be performed by summing up shorter individual frames. We will have a temporal information that can be used to study variable objects. The three key science objectives of WHITE are : 1) A complete survey of the Magellanic Clouds to make a complete census of young stellar objects in the clouds and in the bridge and to study their star formation history and the link with the Milky Way. The interaction of the two clouds with our Galaxy might the closest example of a minor merging event that could be the main driver of galaxy evolution in the last 5 Gyrs. 2) The building of the first sample of dusty supernovae at z<1.2 in the near infrared range (1-5 um) to constrain the equation of state from these obscured objects, study the formation of dust in galaxies and build the first high resolution sample of high redshift galaxies observed in their optical frame 3) A very wide weak lensing survey over that would allow to estimate the equation of state in a way that would favourably compete with space projects.

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arXiv2007

Lyman Break Galaxies at z~1 and the evolution of the dust attenuation in star-forming galaxies with the redshift

Ultraviolet (UV) galaxies have been selected from GALEX. The presence of a FUV-dropout in their spectral energy distributions proved to be a very complete (83.3%) but not very efficient (21.4%) tool for identifying Lyman Break Galaxies (LBGs) at z~1. We divide the LBG sample into two sub-classes: red LBGs (RLBGs) detected at 24 micron which are mainly Luminous IR Galaxies (LIRGs) and blue LBGs (BLBGs) undetected at 24 microns down to 83 microJy. Two of the RLBGs are also detected at 70 micron. The median SED of the RLBGs is similar (above lambda~1 micron) to the dusty starburst HR10. However, unlike local (U)LIRGs, RLBGs are UV bright objects. We suggest that these objects contain a large amount of dust but that some bare stellar populations are also directly visible. The median SED of the BLBGs is consistent with their containing the same stellar population as the RLBGs but with a lower dust content. The luminosity function of our LBG sample at z~1 is similar to the luminosity function of NUV-selected galaxies at the same redshift. The integrated luminosity densities of z~1 LBGs and NUV-selected galaxies are very consistent. We show that star formation rates (SFRs) estimated from UV measurements and corrected using the IRX-beta method provide average total SFR_TOT in agreement with SFR_UV + SFR_dust. However, IRX-beta-based SFR_TOT shows a large dispersion. Summing up the detected UV (1150A rest-frame) and IR-based star formation rates of the detected objects, we find that only one third of the total (i.e. UV + dust) LBG SFR resides in BLBGs and two thirds in RLBGs, even though most LBGs at z~1 are BLBGs. On the other hand, the total SFR of LBGs accounts for only 11% of the total SFR at z~1. Finally, we observe a regular decrease of L_TIR / L_FUV from z=0 to z~2 for UV-selected samples.

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arXiv2007

UV to IR SEDs of UV selected galaxies in the ELAIS fields: evolution of dust attenuation and star formation activity from z=0.7 to z=0.2

We study the ultraviolet to far-infrared (hereafter UV-to-IR) SEDs of a sample of intermediate redshift (0.2 < z < 0.7) UV-selected galaxies from the ELAIS-N1 and ELAIS-N2 fields by fitting a multi-wavelength dataset to a library of GRASIL templates. Star formation related properties of the galaxies are derived from the library of models by using the Bayesian statistics. We find a decreasing presence of galaxies with low attenuation and low total luminosity as redshift decreases, which does not hold for high total luminosity galaxies. In addition the dust attenuation of low mass galaxies increases as redshift decreases, and this trend seems to disappear for galaxies with M* > 10^11 M_sun. This result is consistent with a mass dependent evolution of the dust to gas ratio, which could be driven by a mass dependent efficiency of star formation in star forming galaxies. The specific star formation rates (SSFR) decrease with increasing stellar mass at all redshifts, and for a given stellar mass the SSFR decreases with decreasing redshift. The differences in the slope of the M*--SSFR relation found between this work and others at similar redshift could be explained by the adopted selection criteria of the samples which, for a UV selected sample, favours blue, star forming galaxies.

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arXiv2007

The ultraviolet properties of Luminous Infrared Galaxies at z ~ 0.7: is there any evolution in their dust attenuation?

The TIR and FUV luminosity functions of galaxies and the related luminosity densities rho(TIR) and rho(FUV) are known to evolve from z=0 to z~1 but with a different rate: the galaxy populations appear brighter in the past at both wavelengths but the evolution in TIR is larger than in FUV. It leads to an increase of the ratio of TIR to FUV luminosity densities rho(TIR)/rho(FUV) which can be interpreted as a global increase of the dust attenuation from z=0 to z~1. Our aim is to understand the origin of this increase. We focus on infrared galaxies with L(TIR>10^{11} Lsun at z~0.7 observed by SPITZER/MIPS and we measure their UV emission at 2310 A from GALEX. These Luminous InfraRed Galaxies (LIRGs) represent the bulk of the TIR luminosity density at intermediate redshift. Some evolution of L(TIR)/L(FUV) and therefore of dust attenuation is found for these galaxies: LIRGs at z=0.7 span a larger range of L(TIR)/L(FUV) ratios than at z=0 and their mean dust attenuation at FUV is found ~0.5 mag lower than for their local counterparts. The decrease of dust attenuation is found lower than that reported in other studies for bright galaxies selected in UV rest-frame at z=1 and 2. From a semi-quantitative analysis we find that the slight decrease of dust attenuation for LIRGs at z=0.7 remains consistent with the increase of rho(TIR)/rho(FUV) with redshift.

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arXiv2007

Lyman Break Galaxies and Luminous IR Galaxies at z ~ 1

We use deep GALEX images of CDFS in UV to define the first large sample of 420 Lyman Break Galaxies at z~1. We use a PSF fitting to estimate UV magnitudes on these deep crowded images. Deep Spitzer IRAC and MIPS provide the first detection of a large sample of Lyman Break Galaxies in the mid- to far-infrared range. We are therefore able to study and compare the UV and TIR emission of Lyman Break Galaxies. We find that about 15% of the LBG sample are strong emitters at 24 microns (Red LBGs). Most of them are Luminous IR Galaxies (LIRGs) while the rest (Blue LBGs) are undetected at the 83 microJy level of MIPS GTO image. We find that Blue LBGs have a Spectral Energy Distribution similar to high redshift Lyman Break Galaxies. Finally, the dust-to-FUV ratio of this sample is compared with similar ratios at z=1 and z~2. This work suggests an evolution (decrease) of the dust-to-FUV ratio with the redshift.

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arXiv2006

531 new spectroscopic redshifts from the CDFS and a test on 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.

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arXiv2006

Wide Field Astronomy at Dome C: two IR surveys complementary to SNAP

Surveys provide a wealth of data to the astronomical community that are used well after their completion. In this paper, we propose a project that would take the maximum benefit of Dome C in Antarctica by performing two surveys, in the wavelength range from 1-5 micron, complementary to SNAP space surveys. The first one over 1000 sq. deg. (1 KdF) for 4 years and the second one over 15 sq. deg (SNAP-IR) for the next 4 years at the same time as SNAP 0.35-1.7 microns survey. By using a Ground-Layer Adaptive Optics system, we would be able to recover, at the ice level and over at least half a degree in radius, the 300 mas angular resolution available above the 30-m high turbulent layer. Such a survey, combining a high angular resolution with high sensitivities in the NIR and MIR, should also play the role of a pre-survey for JWST and ALMA.

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arXiv2006

An Ultraviolet-to-Radio Broadband Spectral Atlas of Nearby Galaxies

The ultraviolet-to-radio continuum spectral energy distributions are presented for all 75 galaxies in the Spitzer Infrared Nearby Galaxies Survey (SINGS). A principal component analysis of the sample shows that most of the sample's spectral variations stem from two underlying components, one representative of a galaxy with a low infrared-to-ultraviolet ratio and one representative of a galaxy with a high infrared-to-ultraviolet ratio. The influence of several parameters on the infrared-to-ultraviolet ratio is studied (e.g., optical morphology, disk inclination, far-infrared color, ultraviolet spectral slope, and star formation history). Consistent with our understanding of normal star-forming galaxies, the SINGS sample of galaxies in comparison to more actively star-forming galaxies exhibits a larger dispersion in the infrared-to-ultraviolet versus ultraviolet spectral slope correlation. Early type galaxies, exhibiting low star formation rates and high optical surface brightnesses, have the most discrepant infrared-to-ultraviolet correlation. These results suggest that the star formation history may be the dominant regulator of the broadband spectral variations between galaxies. Finally, a new discovery shows that the 24 micron morphology can be a useful tool for parametrizing the global dust temperature and ultraviolet extinction in nearby galaxies. The dust emission in dwarf/irregular galaxies is clumpy and warm accompanied by low ultraviolet extinction, while in spiral galaxies there is typically a much larger diffuse component of cooler dust and average ultraviolet extinction. For galaxies with nuclear 24 micron emission, the dust temperature and ultraviolet extinction are relatively high compared to disk galaxies.

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arXiv2006

The Local Universe as Seen in Far-Infrared and in Far-Ultraviolet: A Global Point of View on the Local Recent Star Formation

We select far-infrared (FIR-60 microns) and far-ultraviolet (FUV-1530 A) samples of nearby galaxies in order to discuss the biases encountered by monochromatic surveys (FIR or FUV). Very different volumes are sampled by each selection and much care is taken to apply volume corrections to all the analyses. The distributions of the bolometric luminosity of young stars are compared for both samples: they are found to be consistent with each other for galaxies of intermediate luminosities but some differences are found for high (>5 10^{10} L_sun) luminosities. The shallowness of the IRAS survey prevents us from securing comparison at low luminosities (<2 10^9 L_sun). The ratio of the total infrared (TIR) luminosity to the FUV luminosity is found to increase with the bolometric luminosity in a similar way for both samples up to 5 10^{10} L_sun. Brighter galaxies are found to have a different behavior according to their selection: the L_TIR/L_FUV ratio of the FUV-selected galaxies brighter than 5 10^{10} L_sun reaches a plateau whereas L_TIR/L_FUV continues to increase with the luminosity of bright galaxies selected in FIR. The volume-averaged specific star formation rate (SFR per unit galaxy stellar mass, SSFR) is found to decrease toward massive galaxies within each selection. The SSFR is found to be larger than that measured for optical and NIR-selected sample over the whole mass range for the FIR selection, and for masses larger than 10^{10} M_sun for the FUV selection. Luminous and massive galaxies selected in FIR appear as active as galaxies with similar characteristics detected at z ~ 0.7.

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arXiv2006

Galaxy luminosity function per morphological type up to z=1.2

We have computed the evolution of the rest-frame B-band luminosity function (LF) for bulge and disk-dominated galaxies since z=1.2. We use a sample of 605 spectroscopic redshifts with I_{AB}<24 in the Chandra Deep Field South from the VIMOS-VLT Deep Survey, 3555 galaxies with photometric redshifts from the COMBO-17 multi-color data, coupled with multi-color HST/ACS images from the Great Observatories Origin Deep Survey. We split the sample in bulge- and disk-dominated populations on the basis of asymmetry and concentration parameters measured in the rest-frame B-band. We find that at z=0.4-0.8, the LF slope is significantly steeper for the disk-dominated population (α=-1.19 \pm 0.07) compared to the bulge-dominated population (α=-0.53 \pm 0.13). The LF of the bulge-dominated population is composed of two distinct populations separated in rest-frame color: 68% of red (B-I)_{AB}>0.9 and bright galaxies showing a strongly decreasing LF slope α=+0.55 \pm 0.21, and 32% of blue (B-I)_{AB}<0.9 and more compact galaxies which populate the LF faint-end. We observe that red bulge-dominated galaxies are already well in place at z~1, but the volume density of this population is increasing by a factor 2.7 between z~1 and z~0.6. It may be related to the building-up of massive elliptical galaxies in the hierarchical scenario. In addition, we observe that the blue bulge-dominated population is dimming by 0.7 magnitude between z~1 and z~0.6. Galaxies in this faint and more compact population could possibly be the progenitors of the local dwarf spheroidal galaxies.

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arXiv2006

Star formation in the nearby universe: the ultraviolet and infrared points of view

This work presents the main ultraviolet (UV) and far-infrared (FIR) properties of two samples of nearby galaxies selected from the GALEX ($λ= 2315$Å, hereafter NUV) and IRAS ($λ= 60μ$m) surveys respectively. They are built in order to get detection at both wavelengths for most of the galaxies. Star formation rate (SFR) estimators based on the UV and FIR emissions are compared. Systematic differences are found between the SFR estimators for individual galaxies based on the NUV fluxes corrected for dust attenuation and on the total IR luminosity. A combined estimator based on NUV and IR luminosities seems to be the best proxy over the whole range of values of SFR. Although both samples present similar average values of the birthrate parameter b, their star-formation-related properties are substantially different: NUV-selected galaxies tend to show larger values of $b$ for lower masses, SFRs and dust attenuations, supporting previous scenarios for the star formation history (SFH). Conversely, about 20% of the FIR-selected galaxies show high values of $b$, SFR and NUV attenuation. These galaxies, most of them being LIRGs and ULIRGs, break down the downsizing picture for the SFH, however their relative contribution per unit volume is small in the local Universe. Finally, the cosmic SFR density of the local Universe is estimated in a consistent way from the NUV and IR luminosities.

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arXiv2006

Ultraviolet-to-Far Infrared Properties of Lyman Break Galaxies and Luminous Infrared Galaxies at z ~ 1

We present the first large, unbiased sample of Lyman Break Galaxies (LBGs) at z ~ 1. Far ultraviolet-dropout (1530 A) galaxies in the Chandra Deep Field South have been selected using GALEX data. This first large sample in the z ~ 1 universe provides us with a high quality reference sample of LBGs. We analyzed the sample from the UV to the IR using GALEX, SPITZER, ESO and HST data. The morphology (obtained from GOODS data) of 75 % of our LBGs is consistent with a disk. The vast majority of LBGs with an IR detection are also Luminous Infrared Galaxies (LIRGs). As a class, the galaxies not detected at 24 microns are an order of magnitude fainter relative to the UV compared with those detected individually, suggesting that there may be two types of behavior within the sample. For the IR-bright galaxies, there is an apparent upper limit for the UV dust attenuation and this upper limit is anti-correlated with the observed UV luminosity. Previous estimates of dust attenuations based on the ultraviolet slope are compared to new ones based on the FIR/UV ratio (for LBGs detected at 24 microns), which is usually a more reliable estimator. Depending on the calibration we use to estimate the total IR luminosity, beta-based attenuations A_{FUV} are larger by 0.2 to 0.6 mag. than the ones estimated from FIR/UV ratio. Finally, for IR-bright LBGs, median estimated beta-based SFRs are 2-3 times larger than the total SFRs estimated as SFR_{TOT} = SFR_{UV} + SFR_{IR} while IR-based SFRs provide values below SFR_{TOT} by 15 - 20 %. We use a stacking method to statistically constrain the 24 microns flux of LBGs non individually detected. The results suggest that these LBGs do not contain large amounts of dust.

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arXiv2005

GALEX Detection of Lyman Break Galaxies at z=1 in the CDFS

The first large sample of Lyman Break Galaxies (LBGs) at z~1 is selected from GALEX Far-UV and Near-UV images of the Chandra Deep Field South. This multi-wavelength study is based on the wealth of data available in this field: SPITZER-MIPS to estimate total IR luminosities and dust attenuations, redshifts from COMBO-17, EIS and GOODS to check the validity of dropout identifications and GOODS to derive the morphology of about 40 of our LBGs. The advantages of this "nearby" LBG sample are that images reach fainter fluxes and surface brightnesses, allowing a deeper detection at all wavelengths and a better morphological analysis. Moreover, the 24-mic fluxes (i.e. 12-mic rest-frame) permit a good estimation of dust attenuations and total IR luminosities. The main results are that the vast majority of our LBGs are also Luminous Infrared Galaxies (LIRGs). The morphology of 75% of our LBGs is consistent with a disk. Previous estimates of dust attenuations based on the ultraviolet slope are likely to be too large by a factor of about 2, which implies that estimated star formation rates were too large by the same amount. This sample in the z~1 universe provides us with a high quality reference sample of LBGs.

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arXiv2005

Spectroscopy and Stellar Populations of Star-forming Galaxies at z~3 in the Hubble Deep Field - South

We present results of VLT/FORS2 spectroscopy of galaxies at z~3 in the Hubble Deep Field-South (HDF-S). A sample of galaxies was drawn from the photo-z catalogue based on the HST/WFPC2 optical images and the deep near-infrared images obtained with VLT/ISAAC as a part of the FIRES project. We selected galaxies with photometric redshift between 2.5 and 4. Most of the selected galaxies are bright in rest-frame UV wavelengths and satisfy color selection criteria of Lyman break galaxies (LBGs) at z~3. The number of target galaxies with I(AB)<25.0 was 15. We identified new 5 firm and 2 probable redshifts in addition to confirmations of previously known 6 galaxies at z~3. We found 6 among these 13 galaxies lie at a quite narrow redshift range at z = 2.80+-0.01. We examined stellar populations of the galaxies with spectroscopic redshifts through comparisons of their optical and near-IR photometry data with template spectra generated by a population synthesis code. The ages from the onset of star formation for these star-forming galaxies with I<=25.0 are typically 50-200 Myr, and their stellar masses are between (0.5-5) x 10^10 M_sun, consistent with previous studies. We also compared these SED fitting results with those for distant red galaxies (DRGs) at z>2 discovered by FIRES. DRGs have larger stellar masses, larger dust attenuation than our UV-luminous LBG sample, and their star formation rates are often comparable to LBGs. These trends suggest that majority of DRGs are indeed the most massive systems at the redshift and are still in the active star-forming phase. Unless the number density of DRGs is much smaller than LBGs, estimates based on UV selected sample could miss substantial part of stellar mass density at z~3.

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arXiv2005

GALEX UV Spectroscopy and Deep Imaging of LIRGs in the ELAIS S1 field

The ELAIS S1 field was observed by GALEX in both its Wide Spectroscopic and Deep Imaging Survey modes. This field was previously observed by the Infrared Space Observatory and we made use of the catalogue of multi-wavelength data published by the ELAIS consortium to select galaxies common to the two samples. Among the 959 objects with GALEX spectroscopy, 88 are present in the ELAIS catalog and 19 are galaxies with an optical spectroscopic redshift. The distribution of redshifts covers the range $0<z<1.6$. The selected galaxies have bolometric IR luminosities $10<Log(L_{IR})<13$ (deduced from the $15 μm$ flux using ISOCAM) which means that we cover a wide range of galaxies from normal to Ultra Luminous IR Galaxies. The mean ($σ$) UV luminosity (not corrected for extinction) amounts to $Log(λ.L_{1530}) = 9.8 (0.6)$ $L_\sun$ for the low-z ($z \le 0.35$) sample. The UV slope $β$ (assuming $f_λ\propto λ^β$) correlates with the GALEX FUV-NUV color if the sample is restricted to galaxies below $z < 0.1$. Taking advantage of the UV and IR data, we estimate the dust attenuation from the IR/UV ratio and compare it to the UV slope $β$. We find that it is not possible to uniquely estimate the dust attenuation from $β$ for our sample of galaxies. These galaxies are highly extinguished with a median value $A_{FUV} = 2.7 \pm 0.8$. Once the dust correction applied, the UV- and IR-based SFRs correlate. For the closest galaxy with the best quality spectrum, we see a feature consistent with being produced by a bump near 220nm in the attenuation curve.

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arXiv2005

VLT narrow-band photometry in the Lyman continuum of two galaxies at z~3: Limits to the escape of ionizing flux

We have performed narrow-band imaging observations with the Very Large Telescope, aimed at detecting the Lyman continuum (LC) flux escaping from galaxies at z~3. We do not find any significant LC flux from our sample of two galaxies in the Hubble Deep Field South, at z=3.170 and 3.275. The corresponding lower limits on the F_{1400}/F_{900} flux density (per Hz) ratio are 15.6 and 10.2 (3-sigma confidence level). After correction for the intergalactic hydrogen absorption, the resulting limits on the relative escape fraction of the LC are compared with those obtained by different approaches, at similar or lower redshifts. One of our two objects has a relative escape fraction lower than the detection reported by Steidel et al. in a composite spectrum of z~3 galaxies. A larger number of objects is required to reach a significant conclusion. Our comparison shows the potential of narrow-band imaging for obtaining the best limit on the relative escape fraction at z~3. Stacking a significant number of galaxies observed through a narrow-band filter would provide constraint on the galactic contribution to the cosmic reionization.

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arXiv2005

Mid-infrared luminosity as an indicator of the total infrared luminosity of galaxies

The infrared (IR) emission plays a crucial role for understanding the star formation in galaxies hidden by dust. We first examined four estimators of the IR luminosity of galaxies, L_fir (Helou et al. 1988), L_tir (Dale et al. 2001), revised version of L_tir (Dale & Helou 2002) (we denote L_tir2), and L_ir (Sanders & Mirabel 1996) by using the observed SEDs of well-known galaxies. We found that L_ir provides excellent estimates of the total IR luminosity for a variety of galaxy SEDs. The performance of L_tir2 was also found to be very good. Using L_ir, we then statistically analyzed the IRAS PSCz galaxy sample (Saunders et al. 2000) and found useful formulae relating the MIR monochromatic luminosities [L(12um) and L(25um)], and L_ir. For this purpose we constructed a subsample of 1420 galaxies with all IRAS four band (12, 25, 60, and 100um) flux densities. We found linear relations between L_ir and MIR luminosities, L(12um) and L(25um). The prediction error with 95-% confidence level is a factor of 4-5. Hence, these formulae are useful for the estimation of the total IR luminosity only from 12um or 25um observations. We further tried to make an `interpolation' formula for galaxies at 0<z<1. For this purpose we construct the formula of the relation between 15-um luminosity and the total IR luminosity. We conclude that the 15-um formula can be used as an estimator of the total IR luminosity from 24um observation of galaxies at z \simeq 0.6.

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arXiv2004

Recent star formation in nearby galaxies from GALEX imaging:M101 and M51

The GALEX (Galaxy Evolution Explorer) Nearby Galaxies Survey is providing deep far-UV and near-UV imaging for a representative sample of galaxies in the local universe. We present early results for M51 and M101, from GALEX UV imaging and SDSS optical data in five bands. The multi-band photometry of compact stellar complexes in M101 is compared to population synthesis models, to derive ages, reddening, reddening-corrected luminosities and current/initial masses. The GALEX UV photometry provides a complete census of young compact complexes on a approximately 160pc scale. A galactocentric gradient of the far-UV - near-UV color indicates younger stellar populations towards the outer parts of the galaxy disks, the effect being more pronounced in M101 than in M51.

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