Several recent observations using large datasets of galaxies showed non-random distribution of the spin directions of spiral galaxies, even when the galaxies are too far from each other to have gravitational interaction. Here, a dataset of $\sim8.7\cdot10^3$ spiral galaxies imaged by Hubble Space Telescope is used to test and profile a possible asymmetry between galaxy spin directions. The asymmetry between galaxies with opposite spin directions is compared to the asymmetry of galaxies from the Sloan Digital Sky Survey. The two datasets contain different galaxies at different redshift ranges, and each dataset was annotated using a different annotation method. The results show that both datasets show a similar asymmetry in the COSMOS field, which is covered by both telescopes. Fitting the asymmetry of the galaxies to cosine dependence shows a dipole axis with probabilities of $\sim2.8σ$ and $\sim7.38σ$ in HST and SDSS, respectively. The most likely dipole axis identified in the HST galaxies is at $(α=78^o,δ=47^o)$, and is well within the $1σ$ error range compared to the location of the most likely dipole axis in the SDSS galaxies with $z>0.15$, identified at $(α=71^o,δ=61^o)$.
We have carried a detailed analysis on the impact of cosmological redshift in the non-parametric approach to automated galaxy morphology classification. We artificially redshifted each galaxy from the EFIGI 4458 sample (re-centred at $z \sim 0$) simulating SDSS, DES, LSST and HST instruments set-ups over the range $0 < z < 1.5$. We then traced how the morphometry is degraded in each $z$ using MORFOMETRYKA. In the process, we re-sampled all catalogues to several resolutions and to a diverse signal-to-noise range, allowing us to understand the impact of image sampling and noise on our measuremen…
Previous observations of a large number of galaxies show differences between the photometry of spiral galaxies with clockwise spin patterns and spiral galaxies with counterclockwise spin patterns. In this study the mean magnitude of a large number of clockwise galaxies is compared to the mean magnitude of a large number of counterclockwise galaxies. The observed difference between clockwise and counterclockwise spiral galaxies imaged by the space-based COSMOS survey is compared to the differences between clockwise and counterclockwise galaxies imaged by the Earth-based SDSS and Pan-STARRS arou…
Absorption along quasar sightlines remains among the most sensitive direct measures of HeII reionization in much of the intergalactic medium (IGM). Until recently, fewer than a half-dozen unobscured quasar sightlines suitable for the HeII Gunn-Peterson test were known; although these handful demonstrated great promise, the small sample size limited confidence in cosmological inferences. We have recently added nine more such clean HeII quasars, exploiting SDSS quasar samples, broadband UV imaging from GALEX, and high-yield UV spectroscopic confirmations from HST. Here we markedly expand this ap…
Multiple observations made by several different telescopes have shown asymmetry between the number of spiral galaxies rotating in opposite directions in different parts of the sky. One of the immediate questions regarding the possible asymmetry of the spin directions is whether the distribution forms a cosmological-scale axis. This paper analyzes and compares 10 different datasets published in the past decade, collected by SDSS, Pan-STARRS, and Hubble Space Telescope. The datasets contain spiral galaxies separated by their spin direction, and the distribution can show dipole axes. The analysis…
Spin patterns of spiral galaxies can be broadly separated into galaxies with clockwise (Z-wise) patterns and galaxies with counterclockwise (S-wise) spin patterns. While the differences between these patterns are visually noticeable, they are a matter of the perspective of the observer, and therefore in a sufficiently large universe no other differences are expected between galaxies with Z-wise and S-wise patterns. Here large datasets of spiral galaxies separated by their spin patterns are used to show that spiral galaxies with Z-wise spin patterns are photometrically different from spiral gal…
Observation has not yet determined whether the distribution of spin vectors of galaxies is truly random. It is unclear whether is there any large-scale symmetry-breaking in the distribution of the vorticity field in the universe. Here, we present a formulation to evaluate the dipole component D_{max} of the observed spin distribution, whose statistical significance sigma_{D} can be calibrated by the expected amplitude for 3D random walk (random flight) simulations. We apply this formulation to evaluate the dipole component in the distribution of Sloan Digital Sky Survey (SDSS) spirals. Shamir(…
We present a combined photometric calibration of the SNLS and the SDSS supernova survey, which results from a joint effort of the SDSS and the SNLS collaborations. We deliver fluxes calibrated to the HST spectrophotometric star network for large sets of tertiary stars that cover the science fields of both surveys in all photometric bands. We also cross-calibrate directly the two surveys and demonstrate their consistency. For each survey the flat-fielding is revised based on the analysis of dithered star observations. The calibration transfer from the HST spectrophotometric standard stars to th…
The distribution of spin directions of $\sim6.4\cdot10^4$ SDSS spiral galaxies with spectra was examined, and compared to the distribution of $\sim3.3\cdot10^4$ Pan-STARRS galaxies. The analysis shows a statistically significant asymmetry between the number of SDSS galaxies with opposite spin directions, and the magnitude and direction of the asymmetry changes with the direction of observation and with the redshift. The redshift dependence shows that the distribution of the spin direction of SDSS galaxies becomes more asymmetric as the redshift gets higher. Fitting the distribution of the gala…
We present a compilation of HST images of 58 luminous SDSS type 2 AGNs at 0.3<z<0.4. 42 of them are type 2 quasars, which are a good representation of all optically selected SDSS type 2 quasars in this range. We find that the majority of the host galaxies are ellipticals (30/42 or 71%). This is consistent with studies of radio loud and radio quiet type 1 quasars which show that their host galaxies are in general ellipticals. A significant fraction of type 2 quasars (>25/42 or >59%) show clear signatures of morphological disturbance which are in most cases identified with merger/interaction pro…
We present the mass distribution at the core of SDSS J1531+3414, a strong-lensing cluster at z=0.335. We find that the mass distribution is well described by two cluster-scale halos with a contribution from cluster-member galaxies. New HST observations of SDSS J1531+3414 reveal a signature of ongoing star formation associated with the two central galaxies at the core of the cluster, in the form of a chain of star forming regions at the center of the cluster. Using the lens model presented here, we place upper limits on the contribution of a possible lensed image to the flux at the center regio…
Multiple previous studies using several different probes have shown considerable evidence for the existence of cosmological-scale anisotropy and a Hubble-scale axis. One of the probes that show such evidence is the distribution of the directions toward which galaxies spin. The advantage of the analysis of the distribution of galaxy spin directions compared to the CMB anisotropy is that the ratio of galaxy spin directions is a relative measurement, and therefore less sensitive to background contamination such as Milky Way obstruction. Another advantage is that many spiral galaxies have spectra,…
We present Hubble Space Telescope (HST) ACS and WFC3 observations of SDSS J1029+2623, a three-image quasar lens system produced by a foreground cluster at z=0.584. Our strong lensing analysis reveals 6 additional multiply imaged galaxies. We confirm the complex nature of the mass distribution of the lensing cluster, with a bimodal distribution which deviates from the Chandra X-ray SB distribution. The Einstein radius is estimated to be θ_E=15.2" \pm 0.5" for the quasar redshift of z=2.197. We derive a radial mass distribution from the combination of strong lensing, HST/ACS weak lensing, and Su…
We investigate the spatial distribution of Lyman-$α$ (Ly $α$) absorbers within cosmic voids. We create a catalogue of cosmic voids in Sloan Digital Sky Survey Data Release 7 (SDSS DR7) with the VoidFinder algorithm of the Void Analysis Software Toolkit (VAST). Using the largest catalogue of low-redshift (z $\leq$ 0.75) IGM absorbers to date, we identify 392 Ly $α$ absorbers inside voids. The fraction of Ly $α$ absorbers inside voids (65 per cent) is comparable to the volume filling fraction of voids (68 per cent), and significantly greater than the fraction of galaxies inside voids (21 per cen…
The Sloan Digital Sky Survey (SDSS) surveyed 14,555 square degrees, and delivered over a trillion pixels of imaging data. We present a study of galaxy clustering using 900,000 luminous galaxies with photometric redshifts, spanning between $z=0.45$ and $z=0.65$, constructed from the SDSS using methods described in Ross et al. (2011). This data-set spans 11,000 square degrees and probes a volume of $3h^{-3} \rm{Gpc}^3$, making it the largest volume ever used for galaxy clustering measurements. We present a novel treatment of the observational systematics and its applications to the clustering si…
Using the combined resolving power of the Hubble Space Telescope and gravitational lensing, we resolve star-forming structures in a z~2.5 galaxy on scales much smaller than the usual kiloparsec diffraction limit of HST. SGAS J111020.0+645950.8 is a clumpy, star forming galaxy lensed by the galaxy cluster SDSS J1110+6459 at z = 0.659, with a total magnification ~30x across the entire arc. We use a hybrid parametric/non-parametric strong lensing mass model to compute the deflection and magnification of this giant arc, reconstruct the light distribution of the lensed galaxy in the source plane, a…
We investigated the typical environment and physical properties of "red discs" and "blue bulges", comparing those to the "normal" objects in the blue cloud and red sequence. Our sample is composed of cluster members and field galaxies at $z \le 0.1$, so that we can assess the impact of the local and global environment. We find that disc galaxies display a strong dependence on environment, becoming redder for higher densities. This effect is more pronounced for objects within the virial radius, being also strong related to the stellar mass. We find that local and global environment affect galax…
The nature of galaxy spin is still not fully known. Iye et al (2021) applied a 3D analysis to a dataset of bright SDSS galaxies that was used in the past for photometric analysis. They showed that the distribution of spin directions of spiral galaxies is random, providing a dipole axis with low statistical significance of 0.29$σ$. However, to show random distribution, two decisions were made, each can lead to random distribution regardless of the real distribution of the spin direction of galaxies. The first decision was to limit the dataset arbitrarily to z$<$0.1, which is a redshift range in…
We study the redshift evolution of the dynamical properties of ~180,000 massive galaxies from SDSS-III/BOSS combined with a local early-type galaxy sample from SDSS-II in the redshift range 0.1<z< 0.6. The typical stellar mass of this sample is Mstar~2x10^{11} Msun. We analyze the evolution of the galaxy parameters effective radius, stellar velocity dispersion, and the dynamical to stellar mass ratio with redshift. As the effective radii of BOSS galaxies at these redshifts are not well resolved in the SDSS imaging we calibrate the SDSS size measurements with HST/COSMOS photometry for a sub-sam…
We present the first characterisation of the average dust attenuation curve at $z\sim1.3$ by combining rest-frame ultraviolet through near-IR photometry with Balmer decrement ($\mathrm{H}α$/$\mathrm{H}β$) constraints for $\sim$900 galaxies with $8\lesssim\log (M_\star /M_\odot)<10.2$ at $0.75<z<1.5$ in the HST WFC3 IR Spectroscopic Parallel (WISP) and 3D-HST grism surveys. Using galaxies in SDSS, we establish that the ($\mathrm{H}α$+[NII])/[OIII] line ratio and stellar mass are good proxies for the Balmer decrement in low-spectral resolution grism data when only upper-limits on $\mathrm{H}β$ a…
SDSS J2222+2745 is a galaxy cluster at z=0.49, strongly lensing a quasar at z=2.805 into six widely separated images. In recent HST imaging of the field, we identify additional multiply lensed galaxies, and confirm the sixth quasar image that was identified by Dahle et al. (2013). We used the Gemini North telescope to measure a spectroscopic redshift of z=4.56 of one of the secondary lensed galaxies. These data are used to refine the lens model of SDSS J2222+2745, compute the time delay and magnifications of the lensed quasar images, and reconstruct the source image of the quasar host and a se…
We present first results from the 3D-HST program, a near-IR spectroscopic survey performed with the Wide Field Camera 3 on the Hubble Space Telescope. We have used 3D-HST spectra to measure redshifts and Halpha equivalent widths for a stellar mass-limited sample of 34 galaxies at 1<z<1.5 with M(stellar)>10^11 M(sun) in the COSMOS, GOODS, and AEGIS fields. We find that a substantial fraction of massive galaxies at this epoch are forming stars at a high rate: the fraction of galaxies with Halpha equivalent widths >10 A is 59%, compared to 10% among SDSS galaxies of similar masses at z=0.1. Galax…
Recent observations using several different telescopes and sky surveys showed patterns of asymmetry in the distribution of galaxies by their spin directions as observed from Earth. These studies were done with data imaged from the Northern hemisphere, showing excellent agreement between different telescopes and different analysis methods. Here, data from the DESI Legacy Survey was used. The initial dataset contains $\sim2.2\cdot10^7$ galaxy images, reduced to $\sim8.1\cdot10^5$ galaxies annotated by their spin direction using a symmetric algorithm. That makes it not just the first analysis of …
General relativistic effects have long been predicted to subtly influence the observed large-scale structure of the universe. The current generation of galaxy redshift surveys have reached a size where detection of such effects is becoming feasible. In this paper, we report the first detection of the redshift asymmetry from the cross-correlation function of two galaxy populations which is consistent with relativistic effects. The dataset is taken from the Sloan Digital Sky Survey DR12 CMASS galaxy sample, and we detect the asymmetry at the $2.7σ$ level by applying a shell-averaged estimator to…
We report the discovery of three new cases of QSOs acting as strong gravitational lenses on background emission line galaxies: SDSS J0827+5224 (zQSO = 0.293, zs = 0.412), SDSS J0919+2720 (zQSO = 0.209, zs = 0.558), SDSS J1005+4016 (zQSO = 0.230, zs = 0.441). The selection was carried out using a sample of 22,298 SDSS spectra displaying at least four emission lines at a redshift beyond that of the foreground QSO. The lensing nature is confirmed from Keck imaging and spectroscopy, as well as from HST/WFC3 imaging in the F475W and F814W filters. Two of the QSOs have face-on spiral host galaxies a…
While galaxies at $6 \lesssim z \lesssim 10$ are believed to dominate the epoch of cosmic reionization, the escape fraction of ionizing flux $f_\mathrm{esc}$ and the photon production rate $\dot n_γ$ from these galaxies must vary with redshift to simultaneously match CMB and low-redshift observations. We constrain $f_\mathrm{esc}(z)$ and $\dot n_γ(z)$ with Planck 2015 measurements of the Thomson optical depth $τ$, recent low multipole E-mode polarization measurements from Planck 2016, SDSS BAO data, and $3 \lesssim z \lesssim 10$ galaxy observations. We compare different galaxy luminosity func…
In this letter, we investigate the nature of the dramatic `super-bubble' emission structures associated with the z=2.44 radio galaxy MRC 0406-244, using rest-frame optical spectroscopy and an archival HST NICMOS image. Based on the optical line ratios and the HST morphology, we conclude that the gas in the superbubbles is photoionized by the obscured active nucleus. We suggest that this type of structure might be related to the spatially extended HI absorbers that are detected in front of many high-z radio galaxies. We also suggest that we may be witnessing the destruction of the extended emis…
Anomalous flux ratios between quasar images are suspected to be caused by substructures in lens galaxies. We present new deep and high resolution H and Ks imaging of the strongly lensed quasar SDSS J0924+0219 obtained using the ESO VLT with adaptive optics and the Laser Guide Star system. SDSS J0924+0219 is particularly interesting as the observed flux ratio between the quasar images vastly disagree with the predictions from smooth mass models. With our adaptive optics observations we find a luminous object, Object L, located ~0.3" to the North of the lens galaxy, but we show that it can not b…
The paper shows an analysis of the large-scale distribution of galaxy spin directions of 739,286 galaxies imaged by DES. The distribution of the spin directions of the galaxies exhibits a large-scale dipole axis. Comparison of the location of the dipole axis to a similar analysis with data from SDSS, Pan-STARRS, and DESI Legacy Survey shows that all sky surveys exhibit dipole axes within 52$^o$ or less from each other, well within 1$σ$ error. While non-random distribution is unexpected, the findings are consistent across all sky surveys, regardless of the telescope or whether the data were ann…
We have derived disk scale lengths for 30374 non-interacting disk galaxies in all five SDSS bands. Virtual Observatory methods and tools were used to define, retrieve, and analyse the images for this unprecedentedly large sample classified as disk/spiral galaxies in the LEDA catalogue. Cross correlation of the SDSS sample with the LEDA catalogue allowed us to investigate the variation of the scale lengths for different types of disk/spiral galaxies. We further investigat asymmetry, concentration, and central velocity dispersion as indicators of morphological type, and are able to assess how th…
In this article I extend an earlier study of spiral galaxies in the Sloan Digital Sky Survey (SDSS) to investigate whether the universe has an overall handedness. A preference for spiral galaxies in one sector of the sky to be left-handed or right-handed spirals would indicate a parity-violating asymmetry in the overall universe and a preferred axis. The previous study used 2616 spiral galaxies with redshifts <0.04 and identified handedness. The new study uses 15158 with redshifts <0.085 and obtains very similar results to the first with a signal exceeding 5 sigma, corresponding to a probabili…
We apply the iterative MCS deconvolution method (ISMCS) to near-IR HST archives data of seven gravitationally lensed quasars currently monitored by the COSMOGRAIL collaboration: HE 0047-1756, RX J1131-1231, SDSS J1138+0314, SDSS J1155+6346, SDSS J1226-0006, WFI J2026-4536 and HS 2209+1914. In doing so, we obtain relative positions for the lensed images and shape parameters for the light distribution of the lensing galaxy in each system. The lensed image positions are derived with 1-2 mas accuracy. To predict time delays and to test the ability of simple mass models to reproduce the observed co…
Galaxies selected on the basis of their emission line strength show low metallicities, regardless of their redshifts. We conclude this from a sample of faint galaxies at redshifts between 0.6 < z < 2.4, selected by their prominent emission lines in low-resolution grism spectra in the optical with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST) and in the near-infrared using Wide-Field Camera 3 (WFC3). Using a sample of 11 emission line galaxies (ELGs) at 0.6 < z < 2.4 with luminosities of -22 < M_B < -19, which have [OII], Hβ, and [OIII] line flux measurements from th…
We identify nine galaxies with dynamical masses of M_dyn>10^10 M_sol as photometric point sources, but with redshifts between z=0.2 and z=0.6, in the Sloan Digital Sky Survey (SDSS) spectro-photometric database. All nine galaxies have archival Hubble Space Telescope (HST) images. Surface brightness profile fitting confirms that all nine galaxies are extremely compact (with circularized half-light radii between 0.4 and 6.6 kpc and the median value of 0.74 kpc) for their velocity dispersion (110<sigma<340 km/s; median sigma=178 km/s). From the SDSS spectra, three systems are dominated by very yo…
We present a lensing and photometric study of the exceptional system SDSS J1538+5817, identified by the SLACS survey. The lens is a luminous elliptical at redshift z=0.143. Using HST public images in two different filters, the presence of two background sources lensed into an Einstein ring and a double system is ascertained. Our new spectroscopic observations, performed at the NOT, reveal that the two sources are located at the same redshift z=0.531. We investigate the total mass distribution of the lens between 1 and 4 kpc from the galaxy center by means of parametric and non-parametric lensi…
We present results from strong-lens modelling of 10,000 SDSS clusters, to establish the universal distribution of Einstein radii. Detailed lensing analyses have shown that the inner mass distribution of clusters can be accurately modelled by assuming light traces mass, successfully uncovering large numbers of multiple-images. Approximate critical curves and the effective Einstein radius of each cluster can therefore be readily calculated, from the distribution of member galaxies and scaled by their luminosities. We use a subsample of 10 well-studied clusters covered by both SDSS and HST to cal…
We present Hubble Space Telescope (HST) imaging and spectroscopy of the gravitational lens SL2SJ02176-0513, a cusp arc at z=1.847. The UV continuum of the lensed galaxy is very blue, which is seemingly at odds with its redder optical colors. The 3D-HST WFC3/G141 near-infrared spectrum of the lens reveals the source of this discrepancy to be extremely strong [OIII]5007 and H-beta emission lines with rest-frame equivalent widths of 2000 +/- 100 and 520 +/- 40 Angstroms, respectively. The source has a stellar mass ~10^8 Msun, sSFR \sim 100/Gyr, and detection of [OIII]4363 yields a metallicity of …
We present the first case of strong gravitational lensing by a QSO : SDSS J0013+1523, at z = 0.120. The discovery is the result of a systematic search for emission lines redshifted behind QSOs, among 22298 spectra of the SDSS data release 7. Apart from the z = 0.120 spectral features of the foreground QSO, the spectrum of SDSS J0013+1523 also displays the OII and Hbeta emission lines and the OIII doublet, all at the same redshift, z = 0.640. Using sharp Keck adaptive optics K-band images obtained using laser guide stars, we unveil two objects within a radius of 2 arcsec from the QSO. Deep Keck…
We present the results of a search for galaxy alignments in 12 galaxy clusters at z>0.5, a statistically complete subset of the very X-ray luminous clusters from the MAssive Cluster Survey (MACS). Using high-quality images taken with the Hubble Space Telescope (HST) that render measurement errors negligible, we find no radial galaxy alignments within 500 kpc of the cluster centres for a sample of 545 spectroscopically confirmed cluster members. A mild, but statistically insignificant trend favouring radial alignments is observed within a radius of 200 kpc and traced to galaxies on the cluster …
We constrain the assembly history of galaxies in the projected central 0.5 Mpc of the Coma cluster by performing structural decomposition on 69 massive (M_star >= 10^9 M_sun) galaxies using high-resolution F814W images from the HST Treasury Survey of Coma. Each galaxy is modeled with up to three Sersic components having a free Sersic index n. After excluding the two cDs in the projected central 0.5 Mpc of Coma, 57% of the galactic stellar mass in the projected central 0.5 Mpc of Coma resides in classical bulges/ellipticals while 43% resides in cold disk-dominated structures. Most of the stella…
We use a sample of close galaxy pairs selected from the Sloan Digital Sky Survey Data Release 4 (SDSS DR4) to investigate in what environments galaxy mergers occur and how the results of these mergers depend on differences in local galaxy density. The galaxies are quantified morphologically using two-dimensional bulge-plus-disk decompositions and compared to a control sample matched in stellar mass, redshift and local projected density. Lower density environments have fractionally more galaxy pairs with small projected separations (r_p) and relative velocities (Delta v), but even high density …
We present evidence of large-scale outflows from three low-mass (log(M/M_sun)~9.75) star-forming (SFR >4 M_sun/yr) galaxies observed at z=1.24, z=1.35 and z=1.75 in the 3D-HST Survey. Each of these galaxies is located within a projected physical distance of 60 kpc around the sight line to the quasar SDSS J123622.93+621526.6, which exhibits well-separated strong (W_r>0.8A) Mg II absorption systems matching precisely to the redshifts of the three galaxies. We derive the star formation surface densities from the H-alpha emission in the WFC3 G141 grism observations for the galaxies and find that i…
We present a detailed study of the emission from a z = 2.35 galaxy that causes damped Lyman-alpha absorption in the spectrum of the background QSO, SDSS J 2222-0946. We present the results of extensive analyses of the stellar continuum covering the rest frame optical-UV regime based on broad-band HST imaging, and of spectroscopy from VLT/X-Shooter of the strong emission lines: Ly-alpha, [OII], [OIII], [NII], H-alpha and H-beta. We compare the metallicity from the absorption lines in the QSO spectrum with the oxygen abundance inferred from the strong-line methods (R23 and N2). The two emission-…
B514 is a remote M31 globular cluster which locating at a projected distance of R_p~55 kpc. Deep observations with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST) are used to provide the accurate integrated light and star counts of B514. By coupling analysis of the distribution of the integrated light with star counts, we are able to reliably follow the profile of the cluster out to ~40". Based on the combined profile, we study in detail its surface brightness distribution in F606W and F814W filters, and determine its structural parameters by fitting a single-mass iso…
We present an analysis of the Globular Cluster (GC) population of the elliptical galaxy NGC 4261 based on HST WFPC2 data in the B, V and I bands. We study the spatial distribution of the GCs in order to probe the anisotropy in the azimuthal distribution of the discrete X-ray sources in the galaxy revealed by Chandra images (Zezas et al. 2003). The luminosity function of our GC sample (complete at the 90% level for V_mag = 23.8 mag) peaks at V_mag = 25.1 (-0.6)(+1.0) mag, which corresponds to a distance consistent with previous measurements. The colour distribution can be interpreted as being t…
We present a study of the bar fraction in the Coma cluster galaxies based on a sample of ~190 galaxies selected from the SDSS-DR6 and observed with the Hubble Space Telescope (HST) Advanced Camera for Survey (ACS). The unprecedented resolution of the HST-ACS images allows us to explore the presence of bars, detected by visual classification, throughout a luminosity range of 9 mag (-23 < M_r < -14), permitting us to study the poor known region of dwarf galaxies. We find that bars are hosted by galaxies in a tight range of both luminosities (-22 < M_r < -17) and masses (10^9 < M*/Msun < 10^11). …
