Roger Leiton

We study the star-formation activity in a sample of ∼ 56,000 brightest cluster galaxies (BCGs) at 0.05 < z < 0.42 using optical and infra-red data from SDSS and WISE. We estimate stellar masses and star-formation rates (SFR) through SED fitting and study the evolution of the SFR with redshift as well as the effects of BCG stellar mass, cluster halo mass and cooling time on star formation. Our BCGs have SFR = 1.4 × 10−3 − 275.2 [$\rm M_{\odot }$/yr] and sSFR = 5 × 10−15 − 6 × 10−10 [yr−1] . We find that star-forming BCGs are more abundant at higher redshifts and have higher SFR than at lower redshifts. The fraction of star-forming BCGs (fSF) varies from 30 per cent to 80 per cent at 0.05 < z < 0.42. Despite the large values of fSF, we show that only 13 per cent of the BCGs lie on the star-forming main sequence for field galaxies at the same redshifts. We also find that fSF depends only weakly on $\rm M_{200}$, while it sharply decreases with $\rm M_{*}$. We finally find t...

Aims. We use high-resolution continuum images obtained with the Atacama Large Millimeter Array (ALMA) to probe the surface density of star formation in z ~ 2 galaxies and study the different physical properties between galaxies within and above the star-formation main sequence of galaxies. Methods. We use ALMA images at 870 μm with 0.2 arcsec resolution in order to resolve star formation in a sample of eight star-forming galaxies at z ~ 2 selected among the most massive Herschel galaxies in the GOODS-South field. This sample is supplemented with eleven galaxies from the public data of the 1.3 mm survey of the Hubble Ultra-Deep Field, HUDF. We derive dust and gas masses for the galaxies, compute their depletion times and gas fractions, and study the relative distributions of rest-frame ultraviolet (UV) and far-infrared (FIR) light. Results. ALMA reveals systematically dense concentrations of dusty star formation close to the center of the stellar component of the galaxies. We identif...

Historically, GHz radio emission has been used extensively to characterize the star-formation activity in galaxies. In this work, we look for empirical relationships amongst the radio luminosity, the infrared luminosity, and the CO-based molecular gas mass. We assemble a sample of 278 nearby galaxies with measurements of radio continuum and total infrared emission, and the 12CO J = 1–0 emission line. We find a correlation between the radio continuum and the CO emission line (with a scatter of 0.36 dex), in a large sample of different kinds of galaxies. Making use of this correlation, we explore the evolution of the molecular gas mass function and the cosmological molecular gas mass density in six redshift bins up to z = 1.5. These results agree with previous semi-analytic predictions and direct measurements: the cosmic molecular gas density increases up to z = 1.5. In addition, we find a single plane across five orders of magnitude for the explored luminosities, with a scatter of 0....

David Elbaz-The main sequence from stars to galaxies • Is the SFR-M ★ scaling-law or "main sequence" of star forming galaxies probing the bulk of the formation of present-day stars ? • Can we learn information on micro (pc-scale) and/or macro (Mpc-scale) physics ? • self-regulation vs infall • Does the main sequence reflect a true "universality" of star-formation ? • role of starbursts and mergers Questions The main sequence from stars to galaxies pc kpc Mpc

Submillimeter/millimeter observations of dusty star-forming galaxies with the Atacama Large Millimeter/submillimeter Array (ALMA) have shown that dust continuum emission generally occurs in compact regions smaller than the stellar distribution. However, it remains to be understood how systematic these findings are. Studies often lack homogeneity in the sample selection, target discontinuous areas with inhomogeneous sensitivities, and suffer from modest uv coverage coming from single array configurations. GOODS-ALMA is a 1.1 mm galaxy survey over a continuous area of 72.42 arcmin2 at a homogeneous sensitivity. In this version 2.0, we present a new low resolution dataset and its combination with the previous high resolution dataset from the survey, improving the uv coverage and sensitivity reaching an average of σ = 68.4 μJy beam−1. A total of 88 galaxies are detected in a blind search (compared to 35 in the high resolution dataset alone), 50% at S/Npeak ≥ 5 and 50% at 3.5 ≤ S/Npeak ≤...

Aims. We present a 69 arcmin2 ALMA survey at 1.1 mm, GOODS-ALMA, matching the deepest HST-WFC3 H-band part of the GOODS-South field. Methods. We tapered the 0″24 original image with a homogeneous and circular synthesized beam of 0″60 to reduce the number of independent beams – thus reducing the number of purely statistical spurious detections – and optimize the sensitivity to point sources. We extracted a catalog of galaxies purely selected by ALMA and identified sources with and without HST counterparts down to a 5σ limiting depth of H = 28.2 AB (HST/WFC3 F160W). Results. ALMA detects 20 sources brighter than 0.7 mJy at 1.1 mm in the 0″60 tapered mosaic (rms sensitivity σ ≃ 0.18 mJy beam−1) with a purity greater than 80%. Among these detections, we identify three sources with no HST nor Spitzer-IRAC counterpart, consistent with the expected number of spurious galaxies from the analysis of the inverted image; their definitive status will require additional investigation. We detect a...

The sample of high-redshift galaxies analyzed here consists of galaxies observed in the two Great Observatories Origins Deep Survey (GOODS) fields in the Northern and Southern hemispheres. Observations with the Herschel Space Observatory were obtained as part of the open time key program GOODS-Herschel (PI Elbaz), for a total time of 361.3h. PACS observations at 100 and 160um cover the whole GOODS-north field of 10'x16' and part of GOODS-south, i.e., 10'x10' (but reaching the largest depths over ~64arcmin^2). When considering the total observing times of 124h in GOODS-N and 206.3h in GOODS-S (including 2.6 and 5h of overheads), the PACS GOODS-Herschel observations reach a total integration time per sky position of 2.4h in GOODS-N and of 15.1h in GOODS-S, i.e., 6.3 times longer. Due to the larger beam size and observing configuration, the SPIRE observations of GOODS-N cover a field of 900 arcmin2, hence largely encompassing the central 10'x16', for a total obs...

Cutri, RM; Aguilera, C.; Bennet, E.; Brehmer, G.; Dembicky, J.; Guerra, A.; Leiton, R.; Ragan, R.; Saa, O.; Ugarte, P.; Vasquez, J.; Young, J.; Skrutskie, MF; van Dyk, S.; Beichman, CA; Carpenter, JM; Chester, T.; Cambresy, L.; Evans, T.; Fowler, J.; Gizis, J.; Howard, E.; ...

Extragalactic surveys provide significant statistical data for the study of crucial galaxy parameters used to constrain galaxy evolution, e.g. stellar mass (M$_*$) and star formation rate (SFR), under different environmental conditions. These quantities are derived using manual or automatic methods for galaxy detection and flux measurement in imaging data at different wavelengths. The reliability of these automatic measurements, however, is subject to mis-identification and poor fitting due to the morphological irregularities present in resolved nearby galaxies (e.g. clumps, tidal disturbances, star-forming regions) and its environment (galaxies in overlap). Our aim is to provide accurate multi-wavelength photometry (from the UV to the IR, including GALEX, SDSS, and WISE) in a sample of $\sim$ 600 nearby (z<0.1) isolated mergers, as well as estimations of M$_*$ and SFR. We performed photometry following a semi-automated approach using SExtractor, confirming by visual inspection t...

We characterize the ionized gas outflows in 15 low-redshift star-forming galaxies, a Valparaíso ALMA/APEX Line Emission Survey (VALES) subsample, using MUSE integral field spectroscopy and GAMA photometric broadband data. We measure the emission-line spectra by fitting a double-component profile, with the second and broader component related to the outflowing gas. This interpretation is in agreement with the correlation between the observed star-formation rate (SFR) surface density (ΣSFR) and the second-component velocity dispersion (σ2nd), expected when tracing the feedback component. By modeling the broadband spectra with spectral energy distribution fitting and obtaining the star-formation histories of the sample, we observe a small decrease in SFR between 100 and 10 Myr in galaxies when the outflow Hα luminosity contribution is increased, indicating that the feedback somewhat inhibits the star formation within these timescales. The observed emission-line ratios are best reproduc...

Context. We report new H I observations of four z ∼ 0.05 VALES galaxies undertaken during the commissioning phase of the Five-hundred-meter Aperture Spherical Radio Telescope (FAST). Aims. FAST is the largest single-dish telescope in the world, with a 500 m aperture and a 19-Beam receiver. Exploiting the unprecedented sensitivity provided by FAST, we aim to study the atomic gas content, via the H I 21 cm emission line, in low-z star formation galaxies taken from the Valparaíso ALMA/APEX Line Emission Survey (VALES). Together with previous Atacama Large Millimeter/submillimeter Array (ALMA) CO(J = 1−0) observations, the H I data provides crucial information to measure the gas mass and dynamics. Methods. As a pilot H I galaxy survey, we targeted four local star-forming galaxies at z ∼ 0.05. In particular, one of them has already been detected in H I by the Arecibo Legacy Fast ALFA survey (ALFALFA), allowing a careful comparison. We use an ON-OFF observing approach that allowed us to r...

Context. Most of the massive star-forming galaxies are found to have “inside-out” stellar mass growth modes, which means the inner parts of the galaxies mainly consist of the older stellar population, while the star forming in the outskirt of the galaxy is still ongoing. Aims. The high-resolution HST images from Hubble Deep UV Legacy Survey and Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey projects with the unprecedented depth in both F275W and F160W bands are the perfect data sets to study the forming and formed stellar distribution directly. Methods. We selected the low redshift (0.05 <  zspec <  0.3) galaxy sample from the GOODS-North field where the HST F275W and F160W images are available. Then we measured the half light radius in F275W and F160W bands, which are the indicators of the star formation and stellar mass. Results. By comparing the F275W and F160W half light radius, we find the massive galaxies are mainly follow the “inside-out” growth mode, wh...

Optical emission line observations of the Magellanic Clouds provide an important view of the ionized component of the interstellar medium (ISM), one which is crucial for the study of the relationships between stars and the ISM, from star formation in HII regions to stellar death as traced by planetary nebulae (PNe) and supernova remnants (SNRs). Early photographic surveys of the

Stars, gas and dust in galaxies: Exploring the Links ASP Conference Series, Vol. 221, 2000 Alloin, Olsen and Galaz (eds.) The UM/CTIO Magellanic Cloud Emission-line Survey R. Chris Smith Roger Leiton Sergio Pizarro Cerro Tololo Inter-American Observatory, La Serena, ...

We present the optical identification of several new supernova remnants (SNRs) in the Large Magellanic Cloud. These SNRs have been identified by the ratios shown in optical emission-line images from the Magellanic Cloud Emission-line Survey. For several of these candidates, we have obtained long slit resolution spectroscopy to confirm the high [S II]/Halpha ratios. We present the list of candidates, discuss the characteristics of these new objects, and also include some preliminary measurements of expansion velocities, electron and ambient densities based on the optical data we have obtained.

As the ejected atmospheres of more common low to intermediate mass stars, planetary nebulae (PNe) represent an important constituent of the interstellar medium (ISM), reflecting the evolutionary histories of the progenitor giant stars and chemically-enriching the ambient ISM. Large samples of PNe are required for the study of general characteristics and evolutionary trends, especially when trying to determine the breakdown of PNe in terms of excitation class, chemical abundances, and other properties. The Galactic PN sample suffers from incompleteness due to interstellar absorption along the line-of-sight and uncertain distance measurements. The Large Magellanic Cloud (LMC), with its low foreground absorption and relative proximity, offers an ideal laboratory to investigate the physical properties of a large sample of PNe. In this work, we present a flux-calibrated set of planetary nebulae (PNe) candidates over the central 8x8 degrees of the LMC using data from the Magellanic Cloud ...

The interstellar medium (ISM) is no longer thought to be a quiescent distribution of gas, but rather a dynamic and complex interaction of the ambient gas and dust with stellar winds, HII regions, planetary nebulae (PNe), supernovae (SNe), supernova remnants ( ...

Optical emission line observations of the Magellanic Clouds provide an important view of the ionized component of the interstellar medium (ISM), one which is crucial for the study of the relationships between stars and the ISM, from star formation in HII regions to stellar death as traced by ...

We have completed the Magellanic Cloud Emission Line Survey, an optical emission line survey of these two nearby galaxies which, together with parallel surveys at other wavelengths, provides the foundation upon which to build a deeper understanding of the ISM in the Clouds (and ...

Cutri, RM; Aguilera, C.; Bennet, E.; Brehmer, G.; Dembicky, J.; Guerra, A.; Leiton, R.; Ragan, R.; Saa, O.; Ugarte, P.; Vasquez, J.; Young, J.; Skrutskie, MF; van Dyk, S.; Beichman, CA; Carpenter, JM; Chester, T.; Cambresy, L.; Evans, T.; Fowler, J.; Gizis, J.; Howard, E.; ...

Cutri, RM; Aguilera, C.; Bennet, E.; Brehmer, G.; Dembicky, J.; Guerra, A.; Leiton, R.; Ragan, R.; Saa, O.; Ugarte, P.; Vasquez, J.; Young, J.; Skrutskie, MF; van Dyk, S.; Beichman, CA; Carpenter, JM; Chester, T.; Cambresy, L.; Evans, T.; Fowler, J.; Gizis, J.; Howard, E.; ...

Aims: We present a 69 arcmin2 ALMA survey at 1.1 mm, GOODS-ALMA, matching the deepest HST-WFC3 H-band part of the GOODS-South field.
Methods: We tapered the 0″24 original image with a homogeneous and circular synthesized beam of 0″60 to reduce the number of independent beams - thus reducing the number of purely statistical spurious detections - and optimize the sensitivity to point sources. We extracted a catalog of galaxies purely selected by ALMA and identified sources with and without HST counterparts down to a 5σ limiting depth of H = 28.2 AB (HST/WFC3 F160W).
Results: ALMA detects 20 sources brighter than 0.7 mJy at 1.1 mm in the 0″60 tapered mosaic (rms sensitivity σ ≃ 0.18 mJy beam-1) with a purity greater than 80%. Among these detections, we identify three sources with no HST nor Spitzer-IRAC counterpart, consistent with the expected number of spurious galaxies from the analysis of the inverted image; their definitive status will require additional investigation. We detect additional three sources with HST counterparts either at high significance in the higher resolution map, or with different detection-algorithm parameters ensuring a purity greater than 80%. Hence we identify in total 20 robust detections.
Conclusions: Our wide contiguous survey allows us to push further in redshift the blind detection of massive galaxies with ALMA with a median redshift of z = 2.92 and a median stellar mass of M⋆ = 1.1 × 1011 M☉. Our sample includes 20% HST-dark galaxies (4 out of 20), all detected in the mid-infrared with Spitzer-IRAC. The near-infrared based photometric redshifts of two of them (z ̃ 4.3 and 4.8) suggest that these sources have redshifts z > 4. At least 40% of the ALMA sources host an X-ray AGN, compared to ̃14% for other galaxies of similar mass and redshift. The wide area of our ALMA survey provides lower values at the bright end of number counts than single-dish telescopes affected by confusion.

Context. Dust and its emission is increasingly being used to constrain the evolutionary stage of a galaxy. A comprehensive characterization of dust, best achieved in nearby bright galaxies, is thus a highly useful resource.
Aims: We aim to characterize the relationship between dust properties (mass, luminosity, and temperature) and their relationships with galaxy-wide properties (stellar, atomic, and molecular gas mass, and star formation mode). We also aim to provide equations to accurately estimate dust properties from limited observational datasets.
Methods: We assemble a sample of 1630 nearby (z < 0.1) galaxies - over a large range of stellar masses (M∗), star formation rates (SFR) and specific star formation rates (sSFR = SFR/M∗) - for which comprehensive and uniform multi-wavelength observations are available from WISE, IRAS, Planck, and/or SCUBA. The characterization of dust emission comes from spectral energy distribution (SED) fitting using Draine & Li (2007, ApJ, 657, 810) dust models, which we parametrize using two components (warm at 45-70 K and cold at 18-31 K). The subsample of these galaxies with global measurements of CO and/or HI are used to explore the molecular and/or atomic gas content of the galaxies.
Results: The total infrared luminosity (LIR), dust mass (Mdust), and dust temperature of the cold component (Tcold) form a plane that we refer to as the dust plane. A galaxy's sSFR drives its position on the dust plane: starburst (high sSFR) galaxies show higher LIR , Mdust , and Tcold compared to main sequence (typical sSFR) and passive galaxies (low sSFR). Starburst galaxies also show higher specific dust masses (Mdust/M∗) and specific gas masses (Mgas/M∗). We confirm earlier findings of an anti-correlation between the dust to stellar mass ratio and M∗ . We also find different anti-correlations depending on sSFR; the anti-correlation becomes stronger as the sSFR increases, with the spread due to different cold dust temperatures. The dust mass is more closely correlated with the total gas mass (atomic plus molecular) than with the individual atomic and molecular gas masses. Our comprehensive multiwavelength data allows us to define several equations to accurately estimate LIR , Mdust , and Tcold from one or two monochromatic luminosities in the infrared and/or sub-millimeter.
Conclusions: It is possible to estimate the dust mass and infrared luminosity from a single monochromatic luminosity within the Rayleigh-Jeans tail of the dust emission, with errors of 0.12 and 0.20 dex, respectively. These errors are reduced to 0.05 and 0.10 dex, respectively, if the dust temperature of the cold component is used. The dust mass is better correlated with the total ISM mass (MISM ∝Mdust0.7). For galaxies with stellar masses 8.5 < log(M∗/M⊙) < 11.9, the conversion factor between the single monochromatic luminosity at 850 μm and the total ISM mass (α850 μm) shows a large scatter (rms = 0.29 dex) and a weak correlation with the LIR . The star formation mode of a galaxy shows a correlation with both the gas mass and dust mass: the dustiest (high Mdust /M∗) galaxies are gas-rich and show the highest SFRs.

We introduce the ALMA Redshift 4 Survey (AR4S), a systematic ALMA survey of all the known galaxies with stellar mass (M*) larger than 5e10 Msun at 3.5<z<5 in the GOODS--South, UDS and COSMOS CANDELS fields. The sample we analyze in this paper is composed of 96 galaxies observed with ALMA at 890um (180um rest-frame) with an on-source integration time of 1.3 min per galaxy. We detect 32% of the sample at more than 3 sigma significance. Using the stacked ALMA and Herschel photometry, we derive an average dust temperature of 40+/-2 K for the whole sample, and extrapolate the Lir and SFR for all our galaxies based on their ALMA flux. We then use a forward modeling approach to estimate their intrinsic sSFR distribution, deconvolved of measurement errors and selection effects: we find a linear relation between SFR and M*, with a median sSFR=2.8+/-0.8 Gyr and a dispersion around that relation of 0.28+/-0.13 dex. This latter value is consistent with that measured at lower redshifts, which is proof that the main sequence of star-forming galaxies was already in place at z=4, at least among massive galaxies. These new constraints on the properties of the main sequence are in good agreement with the latest predictions from numerical simulations, and suggest that the bulk of star formation in galaxies is driven by the same mechanism from z=4 to the present day, i.e., over at least 90% of the cosmic history. We also discuss the consequences of our results on the population of early quiescent galaxies. This paper is part of a series that will employ these new ALMA observations to explore the star formation and dust properties of the massive end of the z=4 galaxy population.

We present a new method to search for candidate z~>2 Herschel 500{\mu}m sources in the GOODS-North field, using a S500{\mu}m/S24{\mu}m "color deconfusion" technique. Potential high-z sources are selected against low-redshift ones from their large 500{\mu}m to 24{\mu}m flux density ratios. By effectively reducing the contribution from low-redshift populations to the observed 500{\mu}m emission, we are able to identify counterparts to high-z 500{\mu}m sources whose 24{\mu}m fluxes are relatively faint. The recovery of known z~4 starbursts confirms the efficiency of this approach in selecting high-z Herschel sources. The resulting sample consists of 34 dusty star-forming galaxies at z~>2. The inferred infrared luminosities are in the range 1.5x10^12-1.8x10^13 Lsun, corresponding to dust-obscured star formation rates (SFRs) of ~260-3100 Msun/yr for a Salpeter IMF. Comparison with previous SCUBA 850{\mu}m-selected galaxy samples shows that our method is more efficient at selecting high-z dusty galaxies with a median redshift of z=3.07+/-0.83 and 10 of the sources at z~>4. We find that at a fixed luminosity, the dust temperature is ~5K cooler than that expected from the Td-LIR relation at z<1, though different temperature selection effects should be taken into account. The radio-detected subsample (excluding three strong AGN) follows the far-infrared/radio correlation at lower redshifts, and no evolution with redshift is observed out to z~5, suggesting that the far-infrared emission is star formation dominated. The contribution of the high-z Herschel 500{\mu}m sources to the cosmic SFR density is comparable to that of SMG populations at z~2.5 and at least 40% of the extinction-corrected UV samples at z~4 (abridged).

We propose a new method of pushing Herschel to its faintest detection limits using universal trends in the redshift evolution of the far infrared over 24μm colours in the well-sampled GOODS-North field. An extension to other fields with less multi-wavelength information is presented. This method is applied here to raise the contribution of individually detected Herschel sources to the cosmic infrared background (CIRB) by a factor 5 close to its peak at 250μm and more than 3 in the 350μm and 500μm bands. We produce realistic mock Herschel images of the deep PACS and SPIRE images of the GOODS-North field from the GOODS-Herschel Key Program and use them to quantify the confusion noise at the position of individual sources, i.e., estimate a "local confusion noise". Two methods are used to identify sources with reliable photometric accuracy extracted using 24μm prior positions. The clean index (CI), previously defined but validated here with simulations, which measures the presence of bright 24μm neighbours and the photometric accuracy index (PAI) directly extracted from the mock Herschel images. After correction for completeness, thanks to our mock Herschel images, individually detected sources make up as much as 54% and 60% of the CIRB in the PACS bands down to 1.1 mJy at 100μm and 2.2 mJy at 160μm and 55, 33, and 13% of the CIRB in the SPIRE bands down to 2.5, 5, and 9 mJy at 250μm, 350μm, and 500μm, respectively. The latter depths improve the detection limits of Herschel by factors of 5 at 250μm, and 3 at 350μm and 500μm as compared to the standard confusion limit. Interestingly, the dominant contributors to the CIRB in all Herschel bands appear to be distant siblings of the Milky Way (z∼0.96 for λ<300μm) with a stellar mass of M⋆∼9×10^10M⊙.