Firedec: a two-channel finite-resolution image deconvolution algorithm

Cantale, N.; Courbin, F.; Tewes, M.; Jablonka, P.; Meylan, G.

doi:10.1051/0004-6361/201424003

Cited by 38 publications

(44 citation statements)

References 43 publications

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“…In practice, the shape of the target PSF is chosen to be a circular Gaussian. The description of the new algorithm is presented in Cantale et al (2016). The new features, which specifically benefited from the deconvolution of the EDisCS data, are an efficient regularization strategy, a new minimization, and a proper noise treatment.…”

Section: Image Deconvolutionmentioning

confidence: 99%

Disc colours in field and cluster spiral galaxies at 0.5 ≲z≲ 0.8

Cantale

Jablonka

Courbin

et al. 2016

A&A

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We present a detailed study of the colours of late-type galaxy discs for ten of the EDisCS galaxy clusters with 0.5 z 0.8. Our cluster sample contains 172 spiral galaxies, and our control sample is composed of 96 field disc galaxies. We deconvolved their ground-based V and I images obtained with FORS2 at the VLT with initial spatial resolutions between 0.4 and 0.8 arcsec to achieve a final resolution of 0.1 arcsec with 0.05 arcsec pixels, which is close to the resolution of the ACS at the HST. After removing the central region of each galaxy to avoid pollution by the bulges, we measured the V − I colours of the discs. We find that 50% of cluster spiral galaxies have disc V − I colours redder by more than 1σ of the mean colours of their field counterparts. This is well above the 16% expected for a normal distribution centred on the field disc properties. The prominence of galaxies with red discs depends neither on the mass of their parent cluster nor on the distance of the galaxies to the cluster cores. Passive spiral galaxies constitute 20% of our sample. These systems are not abnormally dusty. They are are made of old stars and are located on the cluster red sequences. Another 24% of our sample is composed of galaxies that are still active and star forming, but less so than galaxies with similar morphologies in the field. These galaxies are naturally located in the blue sequence of their parent cluster colour-magnitude diagrams. The reddest of the discs in clusters must have stopped forming stars more than ∼5 Gyr ago. Some of them are found among infalling galaxies, suggesting preprocessing. Our results confirm that galaxies are able to continue forming stars for some significant period of time after being accreted into clusters, and suggest that star formation can decline on seemingly long (1 to 5 Gyr) timescales.

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Section: Image Deconvolutionmentioning

confidence: 99%

Disc colours in field and cluster spiral galaxies at 0.5 ≲z≲ 0.8

Cantale

Jablonka

Courbin

et al. 2016

A&A

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“…LSST will also have very precise photometric redshifts and good image quality and this technique should be possible for lower redshift samples where the ground-based seeing results in sufficient physical resolution. Finally deconvolution methods such as in Cantale et al (2016a) can be applied to ground-based imaging surveys making it possible to carry out analysis on these surveys to much larger distances.…”

Section: Discussionmentioning

confidence: 99%

Tidal Interactions and Mergers in Intermediate-redshift EDisCS Clusters

Deger

Rudnick

Kelkar

et al. 2018

ApJ

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We study the fraction of tidal interactions and mergers with well identified observability timescales (f TIM ) in group, cluster, and accompanying field galaxies and its dependence on redshift (z), cluster velocity dispersion (σ) and environment analyzing HST-ACS images and catalogs from the ESO Distant Cluster Survey (EDisCS). Our sample consists of 11 clusters, 7 groups, and accompanying field galaxies at 0.4 ≤ z ≤ 0.8. We derive f TIM using both a visual classification of galaxy morphologies and an automated method, the G − M 20 method. We calibrate this method using the visual classifications that were performed on a subset of our sample. We find marginal evidence for a trend between f TIM and z, in that higher z values correspond to higher f TIM . However, we also cannot rule out the null hypothesis of no correlation at higher than 68% confidence. No trend is present between f TIM and σ. We find that f TIM shows suggestive peaks in groups, and tentatively in clusters at R > 0.5 × R 200 , implying that f TIM gets boosted in these intermediate density environments. However, our analysis of the local densities of our cluster sample does not reveal a trend between f TIM and density, except for a potential enhancement at the very highest densities. We also perform an analysis of projected radius-velocity phase space for our cluster members. Our results reveal that tidal interactions and mergers (TIM), and undisturbed galaxies only have a 6% probability of having been drawn from the same parent population in their velocity distribution and 37% in radii, in agreement with the modest differences obtained in f TIM at the clusters.

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“…We carried out the photometric measurements using the deconvolution photometry with the so-called MCS image deconvolution algorithm (Magain et al 1998;Cantale et al 2016). This algorithm first computes a deconvolution kernel from the images of stars.…”

Section: Observations and Photometrymentioning

confidence: 99%

COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses

Courbin

Bonvin

Buckley-Geer

et al. 2018

A&A

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We present time-delay measurements for the new quadruple imaged quasar DES J0408−5354, the first quadruple imaged quasar found in the Dark Energy Survey (DES). Our result is made possible by implementing a new observational strategy using almost daily observations with the MPIA 2.2 m telescope at La Silla observatory and deep exposures reaching a signal-to-noise ratio of about 1000 per quasar image. This data quality allows us to catch small photometric variations (a few mmag rms) of the quasar, acting on temporal scales much shorter than microlensing, and hence making the time delay measurement very robust against microlensing. In only seven months we very accurately measured one of the time delays in DES J0408−5354: ∆t(AB) = −112.1 ± 2.1 days (1.8%) using only the MPIA 2.2 m data. In combination with data taken with the 1.2 m Euler Swiss telescope, we also measured two delays involving the D component of the system ∆t(AD) = −155.5 ± 12.8 days (8.2%) and ∆t(BD) = −42.4 ± 17.6 days (41%), where all the error bars include systematics. Turning these time delays into cosmological constraints will require deep Hubble Space Telescope (HST) imaging or ground-based adaptive optics (AO), and information on the velocity field of the lensing galaxy.

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Firedec: a two-channel finite-resolution image deconvolution algorithm

Cited by 38 publications

References 43 publications

Disc colours in field and cluster spiral galaxies at 0.5 ≲z≲ 0.8

Disc colours in field and cluster spiral galaxies at 0.5 ≲z≲ 0.8

Tidal Interactions and Mergers in Intermediate-redshift EDisCS Clusters

COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses

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