Parametric Strong Gravitational Lensing Analysis of Abell 1689

(Abridged) We measure the mass distribution of galaxy cluster Abell 1689 within 0.3 Mpc/h_70 of the cluster centre using its strong lensing effect on 32 background galaxies. The multiple images are based on those of Broadhurst et al. 2005 with some modifications. The cluster profile is explored further out to ~2.5 Mpc/h_70 with weak lensing shear measurements from Broadhurst et al. 2005b. The masses of ~200 cluster galaxies are measured with Fundamental Plane in order to accurately model the small scale mass structure in the cluster. The galaxies are modelled as elliptical truncated isothermal spheres. The dark matter component of the cluster is described by either non-singular isothermal ellipsoids (NSIE) or elliptical versions of the universal dark matter profile (ENFW). We use two dark matter haloes to model the smooth DM in the cluster. The total mass profile is well described by either an NSIS profile with sigma=1514+-18 km/s and core radius of r_c=71+-5kpc/h_70, or an NFW profile with C=6.0+-0.5 and r_200=2.82+-0.11 Mpc/h_70. The errors are assumed to be due to the error in assigning masses to the individual galaxies in the galaxy component. The derived total mass is in good agreement with the mass profile of Broadhurst et al. 05. Using also weak lensing we can constrain the profile further out to r~2.5 Mpc/h_70. The best fit parameters are then sigma=1499+-15 km/s and r_c=66+-5 kpc/h_70 for the NSIS profile and C=7.6+-0.5 and r_200=2.55+-0.07 Mpc/h_70 for the NFW profile. Using the same image configuration as Broadhurst et al. 2005 we obtain a strong lensing model that is superior to that of Broadhurst et al. 2005 (rms of 2.7'' compared to 3.2'').Comment: 43 pages, 22 figures, submitted to the Monthly Notices of the Royal Astronomical Society after the first referee report. Full resolution paper available from http://www.usm.uni-muenchen.de/~halkola/A1689

The sizes of galaxy halos in galaxy cluster Abell 1689

The multiple images observed in galaxy cluster Abell 1689 provide strong constraints not only on the mass distribution of the cluster but also on the ensemble properties of the cluster galaxies. Using parametric strong lensing models for the cluster, and by assuming well motivated scaling laws between the truncation radius s and the velocity dispersion sigma of a cluster galaxy we are able to derive sizes of the dark matter halos of cluster galaxies. For the scaling law expected for galaxies in the cluster environment (s propto sigma), we obtain s = 64^{+15}_{-14} (sigma / 220 km/s) kpc. For the scaling law used for galaxies in the field with s propto sigma^2 we find s = 66^{+18}_{-16} (sigma / 220 km/s)^2 kpc. Compared to halos of field galaxies, the cluster galaxy halos in Abell 1689 are strongly truncated.Comment: 12 pages, 4 figures. Accepted for publication in the Ap

The inner dark matter distribution of the Cosmic Horseshoe (J1148+1930) with gravitational lensing and dynamics

We present a detailed analysis of the inner mass structure of the Cosmic Horseshoe (J1148+1930) strong gravitational lens system observed with the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3). In addition to the spectacular Einstein ring, this systems shows a radial arc. We obtained the redshift of the radial arc counter image $z_\text{s,r} = 1.961 \pm 0.001$ from Gemini observations. To disentangle the dark and luminous matter, we consider three different profiles for the dark matter distribution: a power-law profile, the NFW, and a generalized version of the NFW profile. For the luminous matter distribution, we base it on the observed light distribution that is fitted with three components: a point mass for the central light component resembling an active galactic nucleus, and the remaining two extended light components scaled by a constant M/L. To constrain the model further, we include published velocity dispersion measurements of the lens galaxy and perform a self-consistent lensing and axisymmetric Jeans dynamical modeling. Our model fits well to the observations including the radial arc, independent of the dark matter profile. Depending on the dark matter profile, we get a dark matter fraction between 60 % and 70 %. With our composite mass model we find that the radial arc helps to constrain the inner dark matter distribution of the Cosmic Hoseshoe independently of the dark matter profile.Comment: 19 pages, 14 figures, 8 tables, submitted to A&

GLaD: Gravitational Lensing and Dynamics, combined analysis to unveil properties of high-redshift galaxies

Dynamical modelling of Integral-Field-Unit (IFU) stellar kinematics is a powerful tool to unveil the dynamical structure and mass build-up of galaxies in the local Universe, while gravitational lensing is nature's cosmic telescope to explore the properties of galaxies beyond the local Universe. We present a new approach which unifies dynamical modelling of galaxies with the magnification power of strong gravitational lensing, to reconstruct the structural and dynamical properties of high-redshift galaxies. By means of axisymmetric Jeans modelling, we create a dynamical model of the source galaxy, assuming a surface brightness and surface mass density profile. We then predict how the source's surface brightness and kinematics would look like when lensed by the foreground mass distribution and compare with the mock observed arcs of strong gravitational lensing systems. For demonstration purposes, we create and analyse mock data of the strong lensing system RX J1131-1231. By modelling both the lens and source, we recover the dynamical mass within the effective radius of strongly lensed high-redshift sources within 5% uncertainty, and we improve the constraints on the lens mass parameters by up to 50%. This machinery is particularly well suited for future observations from large segmented-mirror telescopes, such as the James Webb Space Telescope, that will yield high sensitivity and angular-resolution IFU data for studying distant and faint galaxies.Comment: 16 pages, 13 figure

The Halos of Satellite Galaxies: the Companion of the Massive Elliptical Lens SL2S J08544-0121

Strong gravitational lensing by groups or clusters of galaxies provides a powerful technique to measure the dark matter properties of individual lens galaxies. We study in detail the mass distribution of the satellite lens galaxy in the group-scale lens SL2S J08544-0121 by modelling simultaneously the spatially extended surface brightness distribution of the source galaxy and the lens mass distribution using Markov chain Monte Carlo methods. In particular, we measure the dark matter halo size of the satellite lens galaxy to be 6.0^{+2.9}_{-2.0} kpc with a fiducial velocity dispersion of 127^{+21}_{-12} km/s. This is the first time the size of an individual galaxy halo in a galaxy group has been measured using strong gravitational lensing without assumptions of mass following light. We verify the robustness of our halo size measurement using mock data resembling our lens system. Our measurement of the halo size is compatible with the estimated tidal radius of the satellite galaxy, suggesting that halos of galaxies in groups experience significant tidal stripping, a process that has been previously observed on galaxies in clusters. Our mass model of the satellite galaxy is elliptical with its major axis misaligned with that of the light by ~50 deg. The major axis of the total matter distribution is oriented more towards the centre of the host halo, exhibiting the radial alignment found in N-body simulations and observational studies of satellite galaxies. This misalignment between mass and light poses a significant challenge to modified Newtonian dynamics.Comment: 13 pages, 10 figures, minor revisions based on referee's comments, accepted for publication in A&

On the accuracy of time-delay cosmography in the Frontier Fields Cluster MACS J1149.5+2223 with supernova Refsdal

We study possible systematic effects on the values of the cosmological parameters measured through strong lensing analyses of the HFF galaxy cluster MACS J1149.5+2223. We use the observed positions of a large set of spectroscopically selected multiple images, including those of supernova "Refsdal" with their estimated time delays. Starting from our reference model in a flat $\Lambda$CDM cosmology, published in Grillo et al. (2018), we confirm the relevance of the longest measurable time delay, between SX and S1, and an approximately linear relation between its value and that of $H_{0}$. We perform true blind tests by considering a range of time delays around its original estimate of $345 \pm 10$ days, as an accurate measurement of this time delay was not known at the time of analysis and writing. We investigate separately the impact of a constant sheet of mass at the cluster redshift, of a power-law profile for the mass density of the cluster main halo and of some scatter in the cluster member scaling relations. Remarkably, we find that these systematic effects do not introduce a significant bias on the inferred values of $H_{0}$ and $\Omega_{\rm m}$ and that the statistical uncertainties dominate the total error budget: a 3% uncertainty on the time delay of image SX translates into approximately 6% and 40% (including both statistical and systematic $1\sigma$) uncertainties for $H_{0}$ and $\Omega_{\rm m}$, respectively. Furthermore, our model accurately reproduces the extended surface brightness distribution of the supernova host, covering more than $3 \times 10^{4}$ $HST$ pixels. We also present the interesting possibility of measuring the value of the equation-of-state parameter $w$ of the dark energy density, currently with a 30% uncertainty. We conclude that time-delay cluster lenses have the potential to become soon an alternative and competitive cosmological probe.Comment: 10 pages, 8 figures, 1 table; ApJ in press (all main results and figures unchanged, only minor changes during revision

The story of supernova 'Refsdal' told by MUSE

We present MUSE observations in the core of the HFF galaxy cluster MACS J1149.5+2223, where the first magnified and spatially-resolved multiple images of SN 'Refsdal' at redshift 1.489 were detected. Thanks to a DDT program with the VLT and the extraordinary efficiency of MUSE, we measure 117 secure redshifts with just 4.8 hours of total integration time on a single target pointing. We spectroscopically confirm 68 galaxy cluster members, with redshift values ranging from 0.5272 to 0.5660, and 18 multiple images belonging to 7 background, lensed sources distributed in redshifts between 1.240 and 3.703. Starting from the combination of our catalog with those obtained from extensive spectroscopic and photometric campaigns using the HST, we select a sample of 300 (164 spectroscopic and 136 photometric) cluster members, within approximately 500 kpc from the BCG, and a set of 88 reliable multiple images associated to 10 different background source galaxies and 18 distinct knots in the spiral galaxy hosting SN 'Refsdal'. We exploit this valuable information to build 6 detailed strong lensing models, the best of which reproduces the observed positions of the multiple images with a rms offset of only 0.26". We use these models to quantify the statistical and systematic errors on the predicted values of magnification and time delay of the next emerging image of SN 'Refsdal'. We find that its peak luminosity should should occur between March and June 2016, and should be approximately 20% fainter than the dimmest (S4) of the previously detected images but above the detection limit of the planned HST/WFC3 follow-up. We present our two-dimensional reconstruction of the cluster mass density distribution and of the SN 'Refsdal' host galaxy surface brightness distribution. We outline the roadmap towards even better strong lensing models with a synergetic MUSE and HST effort.Comment: 21 pages, 9 figures, 6 tables; accepted for publication in the Astrophysical Journal - extra information on data analysis added, all model predictions and results unchange

Dark Matter and Baryons in the Most X-ray Luminous and Merging Galaxy Cluster RX J1347.5-1145

The galaxy cluster RX J1347-1145 is one of the most X-ray luminous and most massive clusters known. Its extreme mass makes it a prime target for studying issues addressing cluster formation and cosmology. In this paper we present new high-resolution HST/ACS and Chandra X-ray data. The high resolution and sensitivity of ACS enabled us to detect and quantify several new multiply imaged sources, we now use a total of eight for the strong lensing analysis. Combining this information with shape measurements of weak lensing sources in the central regions of the cluster, we derive a high-resolution, absolutely-calibrated mass map. This map provides the best available quantification of the total mass of the central part of the cluster to date. We compare the reconstructed mass with that inferred from the new Chandra X-ray data, and conclude that both mass estimates agree extremely well in the observed region, namely within 400 / h_70 kpc of the cluster center. In addition we study the major baryonic components (gas and stars) and hence derive the dark matter distribution in the center of the cluster. We find that the dark matter and baryons are both centered on the BCG within the uncertainties (alignment is better than <10 kpc). We measure the corresponding 1-D profiles and find that dark matter distribution is consistent with both NFW and cored profiles, indicating that a more extended radial analysis is needed to pinpoint the concentration parameter, and hence the inner slope of the dark matter profile.Comment: 12 pages, Accepted for publication in ApJ, full-res version http://www.physics.ucsb.edu/~marusa/RXJ1347.pd

Perustulon työllisyysvaikutukset : Asiantuntijahaastatteluihin ja verrannollisiin esimerkkeihin perustuva arvio

Perustuloon kohdistuu suuria odotuksia työllisyyden, työhön kannustamisen ja työn vastaanottamisen sekä työvoiman kysynnän ja tarjonnan suhteen. Hyötyvätkö perustulosta pienituloiset, työttömät, epävakaissa työsuhteissa työskentelevät, mikroyrittäjät vai palvelualojen työnantajat ja kolmannen sektorin toimijat? Koska perustulosta ei ole konkreettisia esimerkkejä tai empiirisiä tuloksia, ei näihin kysymyksiin ole myöskään tutkimuksiin perustuvaa vastausta. Perustulon työllisyysvaikutuksia voidaan arvioida vain epäsuorasti ja ennakoiden. Tämän selvityksen tavoitteena oli kartoittaa olemassa olevaa tutkimustietoa ja arvioida sen perusteella perustulon mahdollisia työllisyysvaikutuksia. Olemme lisäksi tehneet asiantuntijahaastatteluja ja selvittäneet, miten TE-toimistojen, kuntien ja kolmannen sektorin toimijat arvioivat perustuloa ja sen vaikutusta työvoimapolitiikan toimeenpanoon ja työllisyyspalvelujen kehittämistarpeisiin. Olemme haastatelleet myös itsensä työllistäjiä (freelance toimittajia) ja pyrkineet sitä kautta saamaan selville, miten perustulo vaikuttaisi heidän toimeentuloonsa ja työssäkäyntiin. Kirjallisuuskatsauksessa selvitimme minimitulojärjestelmistä ja minimipalkoista saatuja kokemuksia eri maista. Vaikka esimerkit eivät ole suoraan verrattavissa perustuloon, ne auttavat kuitenkin hahmottamaan monia sellaisia kysymyksiä, joita liittyy perustulon työllisyysvaikutuksiin, kuten työvoiman kysyntään ja rekrytointiin sekä työvoiman tarjontaan ja mahdollisuuteen tai haluun vastaanottaa lyhytkestoisia ja pienipalkkaisia työtehtäviä. Esimerkit auttavan ymmärtämään myös sitä, miten perustulo voi vaikuttaa makrotalouden tasolla tiettyjen toimialojen kehitykseen. Tutkimuksen toisessa osassa selvitettiin perustulon mahdollisia vaikutuksia työvoimapolitiikan toimeenpanoon. Suurin osa TE-toimistojen, kuntien ja kolmannen sektorin asiantuntijoista suhtautui myönteisesti perustuloon, vaikka kriittisiäkin näkemyksiä esitettiin erityisesti perustulon vastikkeettomuuteen liittyen. Haastateltavat olivat yksimielisiä siitä, että nykyinen sosiaali- ja työttömyysturvajärjestelmä on liian monimutkainen aiheuttaen byrokratialoukkuja, ja että työn vastaanottamisen kannustavuutta tulisi lisätä. Keinoista tai perustulon mallista, joka parhaiten poistaisi näitä esteitä, oli erilaisia näkemyksiä. Kiinnostavaa oli myös se, että perustulon käyttöönoton nähtiin edellyttävän rinnalleen ennaltaehkäisevien palvelujen kehittämistä. Ennaltaehkäiseviä palveluja tulisi olla sosiaali- ja terveyspalveluissa, vapaa-ajan palveluissa sekä työllistymistä ja sosiaalista osallisuutta tukevissa palveluissa. Nuorille työnhakijoille asiantuntijat halusivat perustuloon liitettävää seurantaa ja palvelujen aktiivista tarjoamista. Tutkimuksen kolmannessa osiossa selvitettiin perustulon mahdollisia vaikutuksia itsensä työllistäjien työhön ja toimeentuloon. Haastattelujen perusteella perustulo voisi tuoda vakautta ja turvaa itsensä työllistäjille tyypilliseen epäsäännölliseen toimeentuloon luomalla perusturvan. Perustulo voisi helpottaa etenkin niiden itsensä työllistäjien taloudellista tilannetta, joilla ei tulojen pienuuden tai elämäntilanteen vuoksi ole mahdollisuutta kasvattaa säästöpuskuria taloudellisesti huonompien kuukausien varalle. Nykyisellään sosiaaliturvajärjestelmän ei koettu tuovan turvaa tulojen vaihteluun. Vaikka selvityksen tuloksia voi pitää vain alkukartoituksena, ja sen ulkopuolelle jäi monia tärkeitä asioita, niin se kuitenkin avaa ja konkretisoi kiinnostavalla monia perustulon työllisyysvaikutuksiin liitettyjä kysymyksiä

HOLISMOKES -- X. Comparison between neural network and semi-automated traditional modeling of strong lenses

Modeling of strongly gravitationally lensed galaxies is often required in order to use them as astrophysical or cosmological probes. With current and upcoming wide-field imaging surveys, the number of detected lenses is increasing significantly such that automated and fast modeling procedures for ground-based data are urgently needed. This is especially pertinent to short-lived lensed transients in order to plan follow-up observations. Therefore, we present in a companion paper (submitted) a neural network predicting the parameter values with corresponding uncertainties of a Singular Isothermal Ellipsoid (SIE) mass profile with external shear. In this work, we present a newly-developed pipeline glee_auto.py to model consistently any galaxy-scale lensing system. In contrast to previous automated modeling pipelines that require high-resolution images, glee_auto.py is optimized for ground-based images such as those from the Hyper-Suprime-Cam (HSC) or the upcoming Rubin Observatory Legacy Survey of Space and Time. We further present glee_tools.py, a flexible automation code for individual modeling that has no direct decisions and assumptions implemented. Both pipelines, in addition to our modeling network, minimize the user input time drastically and thus are important for future modeling efforts. We apply the network to 31 real galaxy-scale lenses of HSC and compare the results to the traditional models. In the direct comparison, we find a very good match for the Einstein radius especially for systems with $\theta_E \gtrsim 2$". The lens mass center and ellipticity show reasonable agreement. The main discrepancies are on the external shear as expected from our tests on mock systems. In general, our study demonstrates that neural networks are a viable and ultra fast approach for measuring the lens-galaxy masses from ground-based data in the upcoming era with $\sim10^5$ lenses expected.Comment: 17+28 pages, 7+31 figures, 2+5 tables, submitted to A&