Search

Context. Deep spectroscopic surveys with the Atacama Large Millimeter/submillimeter Array (ALMA) have revealed that some of the brightest infrared sources in the sky correspond to concentrations of dusty star-forming galaxies (DSFG) at high redshift. Among these, the SPT2349-56 protocluster system at z = 4.304 is amongst the most extreme examples due to its high source density and integrated star formation rate. Aims. We conducted a deep Lyman-$α$ line emission survey around SPT2349-56 using the Multi-Unit Spectroscopic Explorer (MUSE) at Very Large Telescope (VLT) in order to characterize this uniquely dense environment. Methods. Taking advantage of the deep three-dimensional nature of this survey, we performed a sensitive search for Lyman-$α$ emitters (LAEs) toward the core and northern extension of the protocluster, which correspond to the brightest infrared regions in this field. Using a smoothed narrowband image extracted from the MUSE datacube around the protocluster redshift, we searched for possible extended structures. Results. We identify only three LAEs at z = 4.3 in this field, in concordance with expectations for blank-fields, and an extended Lyman-$α$ structure spatially associated with core of the protocluster. All the previously-identified DSFGs in this field are undetected in Lyman-$α$ emission, consistent with the conspicuous dust obscuration in these systems. We find an extended Lyman-$α$ structure, about $60 \times 60$ kpc$^{2}$ in size, and located 56 kpc west of the protocluster core. Three DSFGs coincide spatially with the location of this structure. We conclude that either the three co-spatial DSFGs or the protocluster core itself are feeding ionizing photons to the Lyman-$α$ structure., 14 pages, 9 figures, 2 tables, submitted to A&A

We have observed the z=4.3 protocluster SPT2349-56 with ATCA with the aim of detecting radio-loud active galactic nuclei (AGN) amongst the ~30 submillimeter galaxies identified in the structure. We detect the central complex of SMGs at 2.2\,GHz with a luminosity of L_2.2=(4.42pm0.56)x10^{25} W/Hz. The ASKAP also detects the source at 888 MHz, constraining the radio spectral index to alpha=-1.6pm0.3, consistent with ATCA non-detections at 5.5 and 9GHz, and implying L_1.4(rest)=(2.4pm0.3)x10^{26}W/Hz. This radio luminosity is about 100 times higher than expected from star formation, assuming the usual FIR-radio correlation, which is a clear indication of an AGN driven by a forming brightest cluster galaxy (BCG). None of the SMGs in SPT2349-56 show signs of AGN in any other diagnostics available to us (notably 12CO out to J=16, OH163um, CII/IR, and optical spectra), highlighting the radio continuum as a powerful probe of obscured AGN in high-z protoclusters. No other significant radio detections are found amongst the cluster members, consistent with the FIR-radio correlation. We compare these results to field samples of radio sources and SMGs, along with the 22 SPT-SMG gravitational lenses also observed in the ATCA program, as well as powerful radio galaxies at high redshifts. Our results allow us to better understand the effects of this gas-rich, overdense environment on early supermassive black hole (SMBH) growth and cluster feedback. We estimate that (3.3pm0.7)x10^{38} W of power are injected into the growing ICM by the radio-loud AGN, whose energy over 100Myr is comparable to the binding energy of the gas mass of the central halo. The AGN power is also comparable to the instantaneous energy injection from supernova feedback from the 23 catalogued SMGs in the core region of 120kpc projected radius. The SPT2349-56 radio-loud AGN may be providing strong feedback on a nascent ICM., Comment: 31 pages, submitted to ApJ, Dec17,2022

(Abridged) To understand if the morphology-density and passive-density relations are already established at z>1.5, we study galaxies in 16 confirmed clusters at $1.3, 31 pages, 22 figures, A&A, in press

The See Change survey was designed to make z > 1 cosmological measurements by efficiently discovering high-redshift Type Ia supernovae (SNe Ia) and improving cluster mass measurements through weak lensing. This survey observed twelve galaxy clusters with the Hubble Space Telescope (HST) spanning the redshift range z = 1.13-1.75, discovering 57 likely transients and 27 likely SNe Ia at z ∼ 0.8-2.3. As in similar previous surveys, this proved to be a highly efficient use of HST for supernova observations; the See Change survey additionally tested the feasibility of maintaining, or further increasing, the efficiency at yet higher redshifts, where we have less detailed information on the expected cluster masses and star formation rates. We find that the resulting number of SNe Ia per orbit is a factor of ∼8 higher than for a field search, and 45% of our orbits contained an active SN Ia within 22 rest-frame days of peak, with one of the clusters by itself yielding 6 of the SNe Ia. We present the survey design, pipeline, and supernova discoveries. Novel features include fully blinded supernova searches, the first random forest candidate classifier for undersampled IR data (with a 50% detection threshold within 0.05 mag of human searchers), real-time forward-modeling photometry of candidates, and semi-automated photometric classifications and follow-up forecasts. We also describe the spectroscopic follow-up, instrumental in measuring host galaxy redshifts. The cosmology analysis of our sample will be presented in a companion paper.

The properties of galaxy clusters as a function of redshift can be utilized as an important cosmological tool. We present initial results from a program of follow-up observations of the Sunyaev-Zeldovich effect (SZE) in high redshift galaxy clusters detected at infrared wavelengths in the Massive and Distant Clusters of WISE Survey (MaDCoWS). Using typical on-source integration times of 3-4 hours per cluster, MUSTANG2 on the Green Bank Telescope was able to measure strong detections of SZE decrements and statistically significant masses on 14 out of 16 targets. On the remaining two, weaker (3.7 sigma) detections of the SZE signal and strong upper limits on the masses were obtained. In this paper we present masses and pressure profiles of each target and outline the data analysis used to recover these quantities. Of the clusters with strong detections, three show significantly flatter pressure profiles while, from the MUSTANG2 data, five others show signs of disruption at their cores. However, outside of the cores of the clusters, we were unable to detect significant amounts of asymmetry. Finally, there are indications that the relationship between optical richness used by MaDCoWS and SZE-inferred mass may be significantly flatter than indicated in previous studies., Accepted by ApJ ; 20 pages, 7 figures

The Gaia map of the Milky Way reveals a pair of triangular features at nearly symmetric locations on opposite sides of the Galactic Center. In this paper we explore the implications of these features assuming they are manifestations of a caustic ring in the dark matter distribution of the Milky Way halo. The existence of a series of such rings is predicted by the Caustic Ring Model. The model's phase-space distribution is that acquired by a rethermalizing Bose-Einstein condensate of axions or axion-like particles. We show that dust is gravitationally entrained by cold axion flows and propose this as an explanation for the sharpness of the triangular features. The locations of the features imply that we on Earth are much closer to the fifth caustic ring than thought on the basis of pre-Gaia observations. Most likely we are inside its tricusp cross-section. In that case the dark matter density on Earth is dominated by four cold flows, termed Big, Little, Up and Down. If we are outside the tricusp cross-section the dark matter density on Earth is dominated by two cold flows, Big and Little. We use the triangular features in the Gaia map, and a matching feature in the IRAS map, to estimate the velocity vectors and densities of the four locally dominant flows., Comment: 40 pages, 14 figures. An analysis of the statistical significance of the Gaia features has been added, and other smaller changes made. Version published in Physics of the Dark Universe

Massive galaxy-scale outflows of gas are one of the most commonly-invoked mechanisms to regulate the growth and evolution of galaxies throughout the universe. While the gas in outflows spans a large range of temperatures and densities, the cold molecular phase is of particular interest because molecular outflows may be capable of suppressing star formation in galaxies by removing the star-forming gas. We have conducted the first survey of molecular outflows at z > 4, targeting 11 strongly-lensed dusty, star-forming galaxies (DSFGs) with high-resolution Atacama Large Millimeter Array (ALMA) observations of OH 119um absorption as an outflow tracer. In this first paper, we give an overview of the survey, focusing on the detection rate and structure of molecular outflows. We find unambiguous evidence for outflows in 8/11 (73%) galaxies, more than tripling the number known at z > 4. This implies that molecular winds in z > 4 DSFGs must have both a near-unity occurrence rate and large opening angles to be detectable in absorption. Lensing reconstructions reveal that 500pc-scale clumpy structures in the outflows are common. The individual clumps are not directly resolved, but from optical depth arguments we expect that future observations will require 50-200pc spatial resolution to do so. We do not detect high-velocity [CII] wings in any of the sources with clear OH outflows, indicating that [CII] is not a reliable tracer of molecular outflows. Our results represent a first step toward characterizing molecular outflows at z > 4 at the population level, demonstrating that large-scale outflows are ubiquitous among early massive, dusty galaxies., ApJ accepted. 28 pages, 12 figures + appendix. Data and tables from Papers I and II available at https://github.com/spt-smg/publicdata

Nearly a century after the discovery that we live in an expanding Universe, and two decades after the discovery of accelerating cosmic expansion, there remains no direct detection of this acceleration via redshift drift - a change in the cosmological expansion velocity versus time. Because cosmological redshift drift directly determines the Hubble parameter H(z), it is arguably the cleanest possible measurement of the expansion history, and has the potential to constrain dark energy models (e.g. Kim et al. 2015). The challenge is that the signal is small - the best observational constraint presently has an uncertainty several orders of magnitude larger than the expected signal (Darling 2012). Nonetheless, direct detection of redshift drift is becoming feasible, with upcoming facilities such as the ESO-ELT and SKA projecting possible detection within two to three decades. This timescale is uncomfortably long given the potential of this cosmological test. With dedicated experiments it should be possible to rapidly accelerate progress and detect redshift drift with only a five-year observational baseline. Such a facility would also be ideal for precision radial velocity measurements of exoplanets, which could be obtained as a byproduct of the ongoing calibration measurements for the experiment., White paper submitted to the Astro2020 Decadal Survey. 6 pages

As astronomy moves into the era of large-scale time-domain surveys, we are seeing a flood of new transient and variable sources which will reach biblical proportions with the advent of LSST. A key strategic challenge for astronomy in this era is the lack of suitable spectroscopic followup facilities. In response to this need, we have developed the PolyOculus approach for producing large-area-equivalent telescopes by using fiber optics to link modules of multiple semi-autonomous, small, inexpensive, commercial-off-the-shelf telescopes. Crucially, this scalable design has construction costs which are $>10x$ lower than equivalent traditional large-area telescopes. In addition, PolyOculus is inherently highly automated and well-suited for remote operations. Development of this technology will enable the expansion of major research efforts in the LSST era to a host of smaller universities and colleges, including primarily-undergraduate institutions, for budgets consistent with their educational expenditures on similar facilities. We propose to develop and deploy a 1.6-m prototype demonstrator at the Mt. Laguna Observatory in California, followed by a full-scale 5-meter-class PolyOculus facility for linkage to existing and upcoming time-domain surveys., 13 pages, 5 figures; Submitted as an Astro2020 Decadal Survey Project White Paper

We propose an experiment, the Cosmic Accelerometer, designed to yield velocity precision of $\leq 1$ cm/s with measurement stability over years to decades. The first-phase Cosmic Accelerometer, which is at the scale of the Astro2020 Small programs, will be ideal for precision radial velocity measurements of terrestrial exoplanets in the Habitable Zone of Sun-like stars. At the same time, this experiment will serve as the technical pathfinder and facility core for a second-phase larger facility at the Medium scale, which can provide a significant detection of cosmological redshift drift on a 6-year timescale. This larger facility will naturally provide further detection/study of Earth twin planet systems as part of its external calibration process. This experiment is fundamentally enabled by a novel low-cost telescope technology called PolyOculus, which harnesses recent advances in commercial off the shelf equipment (telescopes, CCD cameras, and control computers) combined with a novel optical architecture to produce telescope collecting areas equivalent to standard telescopes with large mirror diameters. Combining a PolyOculus array with an actively-stabilized high-precision radial velocity spectrograph provides a unique facility with novel calibration features to achieve the performance requirements for the Cosmic Accelerometer., Comment: 13 pages, 2 figures; Submitted as an Astro 2020 Decadal Survey Project White Paper

We present the Massive and Distant Clusters of WISE Survey (MaDCoWS), a search for galaxy clusters at 0.7-30 degrees) and the remainder of the southern extragalactic sky at Dec, 26 pages, 17 figures, submitted to The Astrophysical Journal Supplement Series. Machine readable versions of tables 3-6 are included with the source files in the arXiv submission

We discuss several problems that can be solved by measuring the proper motions of galaxies in clusters of galaxies, something that should be feasible in the Next Generation Very Large Array era. First, in the Virgo Cluster, the Laser Interferometric Space-based Antenna should provide standard siren distances for a substantial number of galaxies which contain black hole-black hole binaries. Measuring the proper motions of these galaxies will give 6-dimensional phase space information about the orbits of these galaxies, providing a unique set of tracers of cluster dynamics. Additionally, in other clusters proper motion measurements should allow the determination of whether spiral galaxies are on their first infall into the cluster, and measurements of the proper motions of galaxies in merging clusters will allow direct measures of the speed of the merger, which can then be compared with estimates from shocks., Comment: 6 pages, to appear in the ngVLA Science Book

We present a detailed census of galaxies in and around PC217.96+32.3, a spectroscopically confirmed Coma analog at z=3.78. Diverse galaxy types identified in the field include Lya emitters (LAEs), massive star-forming galaxies, and ultra-massive galaxies (log (Mstar/Msun)>= 11) which may have already halted their star formation. The sky distribution of the star-forming galaxies suggests the presence of a significant overdensity (delta_g=8+/-2), which is spatially offset from the previously confirmed members by 3-4 Mpc to the west. Candidate quiescent and post-starburst galaxies are also found in large excess (a factor of ~ 8-15 higher surface density than the field) although their redshifts are less certain. We estimate that the total enclosed mass traced by star-forming galaxy candidates is roughly comparable to that of PC217.96+32.3 traced by the LAEs. We speculate that the true extent of PC217.96+32.3 may be larger than previously known, a half of which is missed by our LAE selection. Alternatively, the newly discovered overdensity may belong to another Coma progenitor not associated with PC217.96+32.3. Expectations from theory suggest that both scenarios are equally unlikely (, 21 pages, 11 figures, accepted for publication in Astrophysical Journal

Contributed talk presented at the conference Galaxy Evolution Across Time, 12-16 June 2017, Paris, France. Radio-loud AGN (RLAGN) tend to reside in the most massive dark matter halos, and have a long history of being used to efficiently identify rich high-z structures (i.e., clusters and protoclusters). Our team contributed to this effort with a targeted 400hr Spitzer program surveying 420 RLAGN (radio-loud quasars and high-z radio galaxies) at z=1.3−3.2 across the full sky: Clusters Around RLAGN (CARLA; Wylezalek+2013,2014). The CARLA Survey identified 200 cluster candidates at z=1.3−3.2 as 2−8σ overdensities of red color-selected Spitzer/IRAC galaxies around the targeted powerful RLAGN. We present results from our follow-up 40-orbit HST program on the 20 densest CARLA cluster candidates at z=1.4−2.8 (Noirot+2016,2017). We spectroscopically confirm 16/20 distant structures associated with the RLAGN, up to z=2.8. For the first time at these redshifts, we statistically investigate the star-formation content of a large sample of galaxies in dense structures. We show that >10^(10) M⊙ cluster galaxies form significantly fewer stars than their field star-forming counterparts at all redshifts within 1.4 ≤ z ≤ 2. This survey represents a unique and large homogenous sample of spectroscopically confirmed clusters at high redshifts, ideal to investigate quenching mechanisms in dense environments.

Contributed talk presented at the conference Galaxy Evolution Across Time, 12-16 June 2017, Paris, France. Radio-loud AGN (RLAGN) tend to reside in the most massive dark matter halos, and have a long history of being used to efficiently identify rich high-z structures (i.e., clusters and protoclusters). Our team contributed to this effort with a targeted 400hr Spitzer program surveying 420 RLAGN (radio-loud quasars and high-z radio galaxies) at z=1.3−3.2 across the full sky: Clusters Around RLAGN (CARLA; Wylezalek+2013,2014). The CARLA Survey identified 200 cluster candidates at z=1.3−3.2 as 2−8σ overdensities of red color-selected Spitzer/IRAC galaxies around the targeted powerful RLAGN. We present results from our follow-up 40-orbit HST program on the 20 densest CARLA cluster candidates at z=1.4−2.8 (Noirot+2016,2017). We spectroscopically confirm 16/20 distant structures associated with the RLAGN, up to z=2.8. For the first time at these redshifts, we statistically investigate the star-formation content of a large sample of galaxies in dense structures. We show that >10^(10) M⊙ cluster galaxies form significantly fewer stars than their field star-forming counterparts at all redshifts within 1.4 ≤ z ≤ 2. This survey represents a unique and large homogenous sample of spectroscopically confirmed clusters at high redshifts, ideal to investigate quenching mechanisms in dense environments.

We present the results of ALMA spectroscopic follow-up of a z =6.766 Lyα emitting galaxy behind the cluster RX J1347.1-1145. We report the detection of [C ii] 158 μm line fully consistent with the Lyα redshift and with the peak of the optical emission. Given the magnification of μ =5.0 ±0.3, the intrinsic (corrected for lensing) luminosity of the [C ii] line is L [C ii] = 1.4+0.2-0.3 × 107 L⊙, roughly ∼5 times fainter than other detections of z ∼ 7 galaxies. The result indicates that low L [C ii] in z ∼ 7 galaxies compared to the local counterparts might be caused by their low metallicities and/or feedback. The small velocity offset (δv = 20+140-40 Km s-1) between the Lyα and [C ii] line is unusual, and may be indicative of ionizing photons escaping.

We present constraints on variations in the initial mass function (IMF) of nine local early-type galaxies based on their low mass X-ray binary (LMXB) populations. Comprised of accreting black holes and neutron stars, these LMXBs can be used to constrain the important high mass end of the IMF. We consider the LMXB populations beyond the cores of the galaxies ($>0.2R_{e}$; covering $75-90\%$ of their stellar light) and find no evidence for systematic variations of the IMF with velocity dispersion ($\sigma$). We reject IMFs which become increasingly bottom heavy with $\sigma$, up to steep power-laws (exponent, $\alpha>2.8$) in massive galaxies ($\sigma>300$km/s), for galactocentric radii $>1/4\ R_{e}$. Previously proposed IMFs that become increasingly bottom heavy with $\sigma$ are consistent with these data if only the number of low mass stars $(, Comment: 13 pages, 7 figures, accepted for publication in ApJ

We present a weak-lensing study of SPT-CLJ2040-4451 and IDCSJ1426+3508 at z=1.48 and 1.75, respectively. The two clusters were observed in our "See Change" program, a HST survey of 12 massive high-redshift clusters aimed at high-z supernova measurements and weak-lensing estimation of accurate cluster masses. We detect weak but significant galaxy shape distortions using IR images from the WFC3, which has not yet been used for weak-lensing studies. Both clusters appear to possess relaxed morphology in projected mass distribution, and their mass centroids agree nicely with those defined by both the galaxy luminosity and X-ray emission. Using an NFW profile, for which we assume that the mass is tightly correlated with the concentration parameter, we determine the masses of SPT-CL J2040-4451 and IDCS J1426+3508 to be M_{200}=8.6_{-1.4}^{+1.7}x10^14 M_sun and 2.2_{-0.7}^{+1.1}x10^14 M_sun, respectively. The weak-lensing mass of SPT-CLJ2040-4451 shows that the cluster is clearly a rare object. Adopting the central value, the expected abundance of such a massive cluster at z>1.48 is only ~0.07 in the parent 2500 sq. deg. survey. However, it is yet premature to claim that the presence of this cluster creates a serious tension with the current LCDM paradigm unless that tension will remain in future studies after marginalizing over many sources of uncertainties such as the accuracy of the mass function and the mass-concentration relation at the high mass end. The mass of IDCSJ1426+3508 is in excellent agreement with our previous ACS-based weak-lensing result while the much higher source density from our WFC3 imaging data makes the current statistical uncertainty ~40% smaller., Accepted to ApJ

We present Chandra ACIS-S and ATCA radio continuum observations of the strongly lensed dusty, star-forming galaxy SPT-S J034640-5204.9 (hereafter SPT0346-52) at $z$ = 5.656. This galaxy has also been observed with ALMA, HST, Spitzer, Herschel, APEX, and the VLT. Previous observations indicate that if the infrared (IR) emission is driven by star formation, then the inferred lensing-corrected star formation rate ($\sim$ 4500 $M_{\sun}$ yr$^{-1}$) and star formation rate surface density $\Sigma_{\rm SFR}$ ($\sim$ 2000 $M_{\sun} {yr^{-1}} {kpc^{-2}}$) are both exceptionally high. It remained unclear from the previous data, however, whether a central active galactic nucleus (AGN) contributes appreciably to the IR luminosity. The {\it Chandra} upper limit shows that SPT0346-52 is consistent with being star-formation dominated in the X-ray, and any AGN contribution to the IR emission is negligible. The ATCA radio continuum upper limits are also consistent with the FIR-to-radio correlation for star-forming galaxies with no indication of an additional AGN contribution. The observed prodigious intrinsic IR luminosity of (3.6 $\pm$ 0.3) $\times$ 10$^{13}$ $L_{\sun}$ originates almost solely from vigorous star formation activity. With an intrinsic source size of 0.61 $\pm$ 0.03 kpc, SPT0346-52 is confirmed to have one of the highest $\Sigma_{SFR}$ of any known galaxy. This high $\Sigma_{SFR}$, which approaches the Eddington limit for a radiation pressure supported starburst, may be explained by a combination of very high star formation efficiency and gas fraction.

We report the detection of diffuse Ly$��$ emission, or Ly$��$ halos (LAHs), around star-forming galaxies at $z\approx3.78$ and $2.66$ in the NOAO Deep Wide-Field Survey Bo��tes field. Our samples consist of a total of $\sim$1400 galaxies, within two separate regions containing spectroscopically confirmed galaxy overdensities. They provide a unique opportunity to investigate how the LAH characteristics vary with host galaxy large-scale environment and physical properties. We stack Ly$��$ images of different samples defined by these properties and measure their median LAH sizes by decomposing the stacked Ly$��$ radial profile into a compact galaxy-like and an extended halo-like component. We find that the exponential scale-length of LAHs depends on UV continuum and Ly$��$ luminosities, but not on Ly$��$ equivalent widths or galaxy overdensity parameters. The full samples, which are dominated by low UV-continuum luminosity Ly$��$ emitters ($M_{\rm UV} \gtrsim -21$), exhibit LAH sizes of 5$\,-\,6\,$kpc. However, the most UV- or Ly$��$-luminous galaxies have more extended halos with scale-lengths of 7$\,-\,9\,$kpc. The stacked Ly$��$ radial profiles decline more steeply than recent theoretical predictions that include the contributions from gravitational cooling of infalling gas and from low-level star formation in satellites. On the other hand, the LAH extent matches what one would expect for photons produced in the galaxy and then resonantly scattered by gas in an outflowing envelope. The observed trends of LAH sizes with host galaxy properties suggest that the physical conditions of the circumgalactic medium (covering fraction, HI column density, and outflow velocity) change with halo mass and/or star-formation rates., published in ApJ, minor proof corrections applied

We study the stellar population properties of the IRAC-detected $6 \lesssim z \lesssim 10$ galaxy candidates from the Spitzer UltRa Faint SUrvey Program (SURFS UP). Using the Lyman Break selection technique, we find a total of 16 new galaxy candidates at $6 \lesssim z \lesssim 10$ with $S/N \geq 3$ in at least one of the IRAC $3.6��$m and $4.5��$m bands. According to the best mass models available for the surveyed galaxy clusters, these IRAC-detected galaxy candidates are magnified by factors of $\sim 1.2$--$5.5$. We find that the IRAC-detected $6 \lesssim z \lesssim 10$ sample is likely not a homogeneous galaxy population: some are relatively massive (stellar mass as high as $4 \times 10^9\,M_{\odot}$) and evolved (age $\lesssim 500$ Myr) galaxies, while others are less massive ($M_{\text{stellar}}\sim 10^8\,M_{\odot}$) and very young ($\sim 10$ Myr) galaxies with strong nebular emission lines that boost their rest-frame optical fluxes. We identify two Ly$��$ emitters in our sample from the Keck DEIMOS spectra, one at $z_{\text{Ly}��}=6.76$ (in RXJ1347) and one at $z_{\text{Ly}��}=6.32$ (in MACS0454). We show that IRAC $[3.6]-[4.5]$ color, when combined with photometric redshift, can be used to identify galaxies likely with strong nebular emission lines within certain redshift windows., ApJ in press

We present a deep (100 ks) Chandra observation of IDCS J1426.5+3508, a spectroscopically confirmed, infrared-selected galaxy cluster at $z = 1.75$. This cluster is the most massive galaxy cluster currently known at $z > 1.5$, based on existing Sunyaev-Zel'dovich (SZ) and gravitational lensing detections. We confirm this high mass via a variety of X-ray scaling relations, including $T_X$-M, $f_g$-M, $Y_X$-M and $L_X$-M, finding a tight distribution of masses from these different methods, spanning M$_{500}$ = 2.3-3.3 $\times 10^{14}$ M$_{\odot}$, with the low-scatter $Y_X$-based mass $M_{500,Y_X} = 2.6^{+1.5}_{-0.5} \times 10^{14}$ M$_\odot$. IDCS J1426.5+3508 is currently the only cluster at $z > 1.5$ for which X-ray, SZ and gravitational lensing mass estimates exist, and these are in remarkably good agreement. We find a relatively tight distribution of the gas-to-total mass ratio, employing total masses from all of the aforementioned indicators, with values ranging from $f_{gas,500}$ = 0.087-0.12. We do not detect metals in the intracluster medium (ICM) of this system, placing a 2$��$ upper limit of $Z(r < R_{500}) < 0.18 Z_{\odot}$. This upper limit on the metallicity suggests that this system may still be in the process of enriching its ICM. The cluster has a dense, low-entropy core, offset by $\sim$30 kpc from the X-ray centroid, which makes it one of the few "cool core" clusters discovered at $z > 1$, and the first known cool core cluster at $z > 1.2$. The offset of this core from the large-scale centroid suggests that this cluster has had a relatively recent ($\lesssim$500 Myr) merger/interaction with another massive system., Minor changes to match accepted version, results unchanged; ApJ in press

We present confirmation of the cluster MOO J1142+1527, a massive galaxy cluster discovered as part of the Massive and Distant Clusters of WISE Survey. The cluster is confirmed to lie at $z=1.19$, and using the Combined Array for Research in Millimeter-wave Astronomy we robustly detect the Sunyaev-Zel'dovich (SZ) decrement at 13.2$\sigma$. The SZ data imply a mass of $\mathrm{M}_{200m}=(1.1\pm0.2)\times10^{15}$ $\mathrm{M}_\odot$, making MOO J1142+1527 the most massive galaxy cluster known at $z>1.15$ and the second most massive cluster known at $z>1$. For a standard $\Lambda$CDM cosmology it is further expected to be one of the $\sim 5$ most massive clusters expected to exist at $z\ge1.19$ over the entire sky. Our ongoing Spitzer program targeting $\sim1750$ additional candidate clusters will identify comparably rich galaxy clusters over the full extragalactic sky., Comment: Submitted to ApJ Letters, 6 pages, 4 figures

We present 4.5 ��m luminosity functions for galaxies identified in 178 candidate galaxy clusters at 1.3 < z < 3.2. The clusters were identified as Spitzer/IRAC color-selected overdensities in the Clusters Around Radio-Loud AGN (CARLA) project, which imaged 421 powerful radio-loud AGN at z > 1.3. The luminosity functions are derived for different redshift and richness bins, and the IRAC imaging reaches depths of m*+2, allowing us to measure the faint end slopes of the luminosity functions. We find that �� = -1 describes the luminosity function very well in all redshifts bins and does not evolve significantly. This provides evidence that the rate at which the low mass galaxy population grows through star formation, gets quenched and is replenished by in-falling field galaxies does not have a major net effect on the shape of the luminosity function. Our measurements for m* are consistent with passive evolution models and high formation redshifts z_f ~ 3. We find a slight trend towards fainter m* for the richest clusters, implying that the most massive clusters in our sample could contain older stellar populations, yet another example of cosmic downsizing. Modelling shows that a contribution of a star-forming population of up to 40% cannot be ruled out. This value, found from our targeted survey, is significantly lower than the values found for slightly lower redshift, z ~ 1, clusters found in wide-field surveys. The results are consistent with cosmic downsizing, as the clusters studied here were all found in the vicinity of radio-loud AGNs -- which have proven to be preferentially located in massive dark matter halos in the richest environments at high redshift -- they may therefore be older and more evolved systems than the general protocluster population., 17 pages, accepted for publication in ApJ

ARAPAIMA is a proximity operations mission sponsored by the US Air Force Office of Scientific Research (AFOSR) and the Air Force Research Laboratory (AFRL), to perform the in-orbit demonstration of autonomous proximity operations for visible, infrared, and 3D imaging of resident space objects (RSOs) from a nanosat platform. The nanosat is of the 6U CubeSat class, with overall dimensions of 11x24x37cm, and has been selected as part of AFRL’s University NanoSat Program (UNP) Cycle 8. This paper describes the mission goals, concept of operations, science objectives and subsystem design and selection, with focus given to a detailed mission analysis and the requirements flow-down. The nanosat carries a payload consisting of a FLIR Systems MLR2K laser rangefinder (LRF), a Goodrich Aerospace GA640C IR camera, and a monochrome high resolution camera, all chosen for their small size and relatively low power consumption. ARAPAIMA is equipped with a warm gas propulsion system, enabling it to perform orbital maneuvering and reaction control of attitude. Details on these, as well as the attitude determination and control system (ADCS), communications, electric power, operational modes and power, link, and mass budgets are presented at a Preliminary Design Review (PDR) level of readiness. The complex series of events following the deployment of the nanosat from its launcher is detailed. Deployment of solar panels prior to de-tumble of the nanosat initiates the sequence. After de-tumble, the payload is pointed away from the sun, after which the second set of solar panels, which serve as payload aperture covers, are deployed. Once the system has promoted into an operational mode, it will seek to acquire its spent upper stage and begin executing mission objectives. The coupling between the top level mission requirements and the mission plan is addressed. The flow-down of these requirements to subsystem and component requirements is presented in minute detail. A detailed mission plan is developed to reduce risk and define success criteria for each phase of the mission. Mission objectives will be achieved in steps of increasing complexity. First, ARAPAIMA is commanded by ground control to maneuver to within LRF range of the RSO and acquire a relative orbit. Next, the nanosat will maneuver autonomously to reduce the size of the relative orbit to a distance of 250 meters. The third step will perform visible and IR passive and active imaging of the RSO. The final mission objective will be to close to within 100 meters and evaluate the ability of the nanosat to match attitude and remain in a constant position with respect to the RSO. By demonstrating robust, affordable, and responsive rendezvous of a nanosat with an uncooperative RSO, successful completion of the ARAPAIMA mission will validate a range of technologies for space-based space situational awareness (SSA), debris removal from Low Earth Orbit (LEO) and nanosat asteroid characterization. In addition, the mission will validate a set of key technologies at a system level, such as miniaturized commercially available sensors, a miniaturized warm gas propulsion system for CubeSat applications, as well as advanced relative navigation and proximity operations algorithms implemented on a nanosat. Integrated, in-orbit testing of these technologies will advance the technology readiness levels for future space-based SSA missions performed by inexpensive, agile nanosats.

The fraction of cluster galaxies that host luminous AGN is an important probe of AGN fueling processes, the cold ISM at the centers of galaxies, and how tightly black holes and galaxies co-evolve. We present a new measurement of the AGN fraction in a sample of 13 clusters of galaxies (M >= 10^{14} Msun) at 1= 10^{44} erg/s. This fraction is measured relative to all cluster galaxies more luminous than M*_{3.6}(z)+1, where M*_{3.6}(z) is the absolute magnitude of the break in the galaxy luminosity function at the cluster redshift in the IRAC 3.6um bandpass. The cluster AGN fraction is 30 times greater than the 3sigma upper limit on the value for AGN of similar luminosity at z~0.25, as well as more than an order of magnitude greater than the AGN fraction at z~0.75. AGN with L_{X,H} >= 10^{43} erg/s exhibit similarly pronounced evolution with redshift. In contrast with the local universe, where the luminous AGN fraction is higher in the field than in clusters, the X-ray and MIR-selected AGN fractions in the field and clusters are consistent at 1, Comment: ApJ Accepted. 16 pages, 8 figures in emulateapj format

We report on the design, on-sky performance, and status of the FLAMINGOS-2 instrument - the fully-cryogenic facility near-infrared imager and multi-object spectrograph for the Gemini 8-meter telescopes. FLAMINGOS-2 has a refractive all-spherical optical system providing 0.18-arcsecond pixels and a 6.2-arcminute circular field-of-view on a 2048x2048-pixel HAWAII-2 0.9-2.4 μm detector array. A slit/decker wheel mechanism allows the selection of up to 9 multi-object laser-machined plates or 3 long slits for spectroscopy over a 6x2-arcminute field of view, and selectable grisms provide resolutions from ∼1300 to ∼3000 over the entire spectrograph bandpass. FLAMINGOS-2 is also compatible with the Gemini Multi-Conjugate Adaptive Optics system, providing multi-object spectroscopic capabilities over a 3x1-arcminute field with high spatial resolution (0.09-arcsec/pixel). We review the designs of optical, mechanical, electronics, software, and On-Instrument WaveFront Sensor subsystems. We also present the on-sky performance measured during acceptance testing in 2009, as well as current status of the project and future plans., Ground-Based and Airborne Instrumentation for Astronomy IV, July 1-6, 2012, Amsterdam, Netherlands, Series: Proceedings of SPIE

We report the discovery of an IR-selected massive galaxy cluster in the IRAC Distant Cluster Survey (IDCS). We present new data from the Hubble Space Telescope and the W. M. Keck Observatory that spectroscopically confirm IDCS J1426+3508 at z=1.75. Moreover, the cluster is detected in archival Chandra data as an extended X-ray source, comprising 54 counts after the removal of point sources. We calculate an X-ray luminosity of L{0.5-2 keV} = (5.5 +/- 1.2) X 1e44 ergs/s within r = 60 arcsec (~1 Mpc diameter), which implies M_{200,L_x} = (5.6 +/- 1.6) X 1e14 Msun. IDCS J1426+3508 appears to be an exceptionally massive cluster for its redshift., Comment: Accepted for publication in The Astrophysical Journal

This document summarizes the results of a community-based discussion of the potential science impact of the Mayall+BigBOSS highly multiplexed multi-object spectroscopic capability. The KPNO Mayall 4m telescope equipped with the DOE- and internationally-funded BigBOSS spectrograph offers one of the most cost-efficient ways of accomplishing many of the pressing scientific goals identified for this decade by the "New Worlds, New Horizons" report. The BigBOSS Key Project will place unprecedented constraints on cosmological parameters related to the expansion history of the universe. With the addition of an open (publicly funded) community access component, the scientific impact of BigBOSS can be extended to many important astrophysical questions related to the origin and evolution of galaxies, stars, and the IGM. Massive spectroscopy is the critical missing ingredient in numerous ongoing and planned ground- and space-based surveys, and BigBOSS is unique in its ability to provide this to the US community. BigBOSS data from community-led projects will play a vital role in the education and training of students and in maintaining US leadership in these fields of astrophysics. We urge the NSF-AST division to support community science with the BigBOSS multi-object spectrograph through the period of the BigBOSS survey in order to ensure public access to the extraordinary spectroscopic capability., Comment: 5 pages; this white paper was produced as input to the NSF-AST portfolio review

Unresolved near-infrared background anisotropies are expected to have contributions from the earliest galaxies during reionization and faint, dwarf galaxies at intermediate redshifts. Previous measurements were unable to conclusively pinpoint the dominant origin because they did not sample spatial scales that were sufficiently large to distinguish between these two possibilities. Here we report a measurement of the anisotropy power spectrum from sub-arcminute to one degree angular scales and find the clustering amplitude to be larger than the model predictions involving the two existing explanations. As the shot-noise level of the power spectrum is consistent with that expected from faint galaxies, a new source population on the sky is not necessary to explain the observations. A physical mechanism that increases the clustering amplitude, however, is needed. Motivated by recent results related to the extended stellar light profile in dark matter halos, we consider the possibility that the fluctuations originate from diffuse intrahalo stars of all galaxies. We find that the measured power spectrum can be explained by an intrahalo light fraction of 0.07 to 0.2 % relative to the total luminosity in dark matter halos of masses log(M/M_Sun) ~ 9 to 12 at redshifts of ~ 1 to 4., Comment: To appear in this week's issue of Nature (25 October) ; Under press embargo till 24 Oct 2012 1 PM EST. This preprint is the submitted version to Nature. Please see Nature for the final version, which includes editorial corrections and the revised title. This preprint will be updated with the final version in six months after publication. Data and details available from http://herschel.uci.edu

The X-ray source CXOXBJ142607.6+353351 (CXOJ1426+35), which was identified in a 172 ks Chandra image in the Bootes field, shows double-peaked rest-frame optical/UV emission lines, separated by 0.69" (5.5 kpc) in the spatial dimension and by 690 km s^-1 in the velocity dimension. The high excitation lines and emission line ratios indicate both systems are ionized by an AGN continuum, and the double-peaked profile resembles that of candidate dual AGN. At a redshift of z=1.175, this source is the highest redshift candidate dual AGN yet identified. However, many sources have similar emission line profiles for which other interpretations are favored. We have analyzed the substantial archival data available in this field, as well as acquired near-infrared (NIR) adaptive optics (AO) imaging and NIR slit spectroscopy. The X-ray spectrum is hard, implying a column density of several 10^23 cm^-2. Though heavily obscured, the source is also one of the brightest in the field, with an absorption-corrected 2-10 keV luminosity of ~10^45 erg s^-1. Outflows driven by an accretion disk may produce the double-peaked lines if the central engine accretes near the Eddington limit. However, we may be seeing the narrow line regions of two AGN following a galactic merger. While the AO image reveals only a single source, a second AGN would easily be obscured by the significant extinction inferred from the X-ray data. Understanding the physical processes producing the complex emission line profiles seen in CXOJ1426+35 and related sources is important for interpreting the growing population of dual AGN candidates., Comment: 18 pages and 9 figures. Accepted for publication in The Astrophysical Journal

(Brief Summary) What is the total radiative content of the Universe since the epoch of recombination? The extragalactic background light (EBL) spectrum captures the redshifted energy released from the first stellar objects, protogalaxies, and galaxies throughout cosmic history. Yet, we have not determined the brightness of the extragalactic sky from UV/optical to far-infrared wavelengths with sufficient accuracy to establish the radiative content of the Universe to better than an order of magnitude. Among many science topics, an accurate measurement of the EBL spectrum from optical to far-IR wavelengths, will address: What is the total energy released by stellar nucleosynthesis over cosmic history? Was significant energy released by non-stellar processes? Is there a diffuse component to the EBL anywhere from optical to sub-millimeter? When did first stars appear and how luminous was the reionization epoch? Absolute optical to mid-IR EBL spectrum to an astrophysically interesting accuracy can be established by wide field imagingat a distance of 5 AU or above the ecliptic plane where the zodiacal foreground is reduced by more than two orders of magnitude., Comment: 7 pages; Science White Paper for the US Astro 2010-2020 Decadal Survey. If interested in further community-wide efforts on this topic please contact the first author

Using the Infrared Spectrograph on board the Spitzer Space Telescope, we present low-resolution (64 < lambda / dlambda < 124), mid-infrared (20-38 micron) spectra of 23 high-redshift ULIRGs detected in the Bootes field of the NOAO Deep Wide-Field Survey. All of the sources were selected to have 1) fnu(24 micron) > 0.5 mJy; 2) R-[24] > 14 Vega mag; and 3) a prominent rest-frame 1.6 micron stellar photospheric feature redshifted into Spitzer's 3-8 micron IRAC bands. Of these, 20 show emission from polycyclic aromatic hydrocarbons (PAHs), usually interpreted as signatures of star formation. The PAH features indicate redshifts in the range 1.5 < z < 3.0, with a mean of =1.96 and a dispersion of 0.30. Based on local templates, these sources have extremely large infrared luminosities, comparable to that of submillimeter galaxies. Our results confirm previous indications that the rest-frame 1.6 micron stellar bump can be efficiently used to select highly obscured starforming galaxies at z~2, and that the fraction of starburst-dominated ULIRGs increases to faint 24 micron flux densities. Using local templates, we find that the observed narrow redshift distribution is due to the fact that the 24 micron detectability of PAH-rich sources peaks sharply at z = 1.9. We can analogously explain the broader redshift distribution of Spitzer-detected AGN-dominated ULIRGs based on the shapes of their SEDs. Finally, we conclude that z~2 sources with a detectable 1.6 micron stellar opacity feature lack sufficient AGN emission to veil the 7.7 micron PAH band., accepted for publication in ApJ; references corrected in Section 3.2 and Figure 8

We have identified 335 galaxy cluster and group candidates spanning 01, and over 60 at z < 0.5 have been spectroscopically confirmed. The mean I-[3.6] color for cluster galaxies up to z~1 is well matched by a z_f=3 passively evolving model. At z>1, a wider range of formation histories is needed, but higher formation redshifts (i.e. z_f \ge 4-5) are favored for most clusters. The cluster autocorrelation function, measured for the first time out to z=1.5, is found not to have evolved over the last 10 Gyr, in agreement with the prediction from LCDM. The average mass of the IRAC Shallow Cluster Survey sample, inferred from its clustering, is ~ 10^14 Msun., Comment: 5 pages, 3 figures, proceedings of the first Subaru International Conference: "Panoramic Views of Galaxy Formation and Evolution", in Hayama, Japan, December 2007

We present the discovery of three z>5 quasars in the AGN and Galaxy Evolution Survey (AGES) spectroscopic observations of the NOAO Deep Wide-Field Survey (NDWFS) Bootes Field. These quasars were selected as part of a larger Spitzer mid-infrared quasar sample with no selection based on optical colors. The highest redshift object, NDWFS J142516.3+325409, z=5.85, is the lowest-luminosity z>5.8 quasar currently known. We compare mid-infrared techniques for identifying z>5 quasars to more traditional optical techniques and show that mid-infrared colors allow for selection of high-redshift quasars even at redshifts where quasars lie near the optical stellar locus and at z>7 where optical selection is impossible. Using the superb multi-wavelength coverage available in the NDWFS Bootes field, we construct the spectral energy distributions (SEDs) of high-redshift quasars from observed Bw-band to 24 microns (rest-frame 600 Angstroms - 3.7 microns). We show that the three high-redshift quasars have quite similar SEDs, and the rest-frame composite SED of low-redshift quasars from the literature shows little evolution compared to our high-redshift objects. We compare the number of z>5 quasars we have discovered to the expected number from published quasar luminosity functions. While analyses of the quasar luminosity function are tenuous based on only three objects, we find that a relatively steep luminosity function with Psi L^(-3.2) provides the best agreement with the number of high-redshift quasars discovered in our survey., 9 page, 7 figures. Accepted for publication in AJ

The galaxy cluster 1E0657-56 (z = 0.296) is remarkably well-suited for addressing outstanding issues in both galaxy evolution and fundamental physics. We present a reconstruction of the mass distribution from both strong and weak gravitational lensing data. Multi-color, high-resolution HST ACS images allow detection of many more arc candidates than were previously known, especially around the subcluster. Using the known redshift of one of the multiply imaged systems, we determine the remaining source redshifts using the predictive power of the strong lens model. Combining this information with shape measurements of "weakly" lensed sources, we derive a high-resolution, absolutely-calibrated mass map, using no assumptions regarding the physical properties of the underlying cluster potential. This map provides the best available quantification of the total mass of the central part of the cluster. We also confirm the result from Clowe et al. (2004,2006a)., Comment: Accepted for publication in ApJ; Version with full-resolution figures available at http://www.slac.stanford.edu/~marusa/Work/bradac_strong_weak_III.pdf

We present the Las Campanas Distant Cluster Survey, which has produced over a thousand galaxy cluster candidates at 0.35 < z < 1.1 (see Gonzalez et al. 2001 for the full catalog). We discuss the technique that enabled us to use short (~ 3 min) exposures and a small (1m) telescope to efficiently survey ~ 130 sq. deg. of sky. Follow-up imaging and spectroscopy using a wide array of telescopes including the Keck and VLT suggest that the bona-fide cluster fraction is ~70%. We construct methods to estimate both the redshift and cluster mass from the survey data themselves and discuss our first result on large-scale structure, the dependence of the cluster correlation length with mean cluster separation at z ~ 0.5 (Gonzalez, Zaritsky, & Wechsler 2001)., 10 pages. to appear in the proceedings of AMiBA 2001: High-z Clusters, Missing Baryons, and CMB Polarization

(Abridged) We analyze photometry and spectroscopy of a sample of 63 clusters at 0.3~ 5) and in which many of these galaxies, if not all, accrete mass either in the form of evolved stellar populations or gas that causes only a short term episode of star formation at lower redshifts (1.5 < z < 2). Our data are too crude to reach conclusions regarding the evolutionary state of any particular cluster or to investigate whether the morphological evolution of galaxies matches the simple scenario we discuss, but the statistical nature of this study suggests that the observed evolutionary trends are universal in massive clusters., 35 pages, accepted for publication in ApJ

[NIRSS is one of three concepts that contributed to the Wide-Field Infrared Survey Telescope (WFIRST) mission advocated by the Decadal Survey.] Operating beyond the reaches of the Earth's atmosphere, free of its limiting absorption and thermal background, the Near-Infrared Sky Surveyor (NIRSS) will deeply map the entire sky at near-infrared wavelengths, thereby enabling new and fundamental discoveries ranging from the identification of extrasolar planets to probing the reionization epoch by identifying thousands of quasars at z>10. NIRSS will directly address the NASA scientific objective of studying cosmic origins by using a 1.5-meter telescope to reach full-sky 0.2 uJy (25.6 mag AB) sensitivities in four passbands from 1 to 4 microns in a 4-yr mission. At the three shorter passbands (1 - 2.5 microns), the proposed depth is comparable to the deepest pencil-beam surveys done to date and is 3000 times more sensitive than the only previous all-sky near-infrared survey, 2MASS. At the longest passband (3.5 micron), which is not feasible from the ground, NIRSS will be 500 times more sensitive than WISE. NIRSS fills a pivotal gap in our knowledge of the celestial sphere, is a natural complement to WISE, and is well matched to the next generation of deep (0.1 uJy), wide-area (>2 pi ster), ground-based optical surveys (LSST and Pan-Starrs). With the high thermal backgrounds of ground-based infrared observations, a near-infrared full sky survey at sub-uJy sensitivity is only feasible from space., A Response to the Astro2010 Request for Information by the Electromagnetic Observations from Space (EOS) Panel

The Las Campanas Distant Cluster Survey (LCDCS), which contains over 1000 cluster candidates at z>0.3, is a unique sample with which to probe the evolution of both cluster galaxies and the properties of the cluster population. Programs are now underway to utilize the LCDCS for both purposes. We provide a brief overview of these programs, and also present new results for the LCDCS cluster correlation function. Utilizing well-defined, approximately dispersion-limited subsamples, we measure the angular correlation function for clusters at z~0.5. Spatial correlation lengths are then derived via Limber inversion. We find that the correlation length depends upon mass, as parameterized by the mean cluster separation, in a manner that is consistent with both local observations and CDM predictions for the clustering strength at z=0.5., 2 page blurb, to appear in the ASP Conference Series, "Tracing Cosmic Evolution with Galaxy Clusters", Sesto, Italy, 3-6 July 2001, eds. S. Borgani, M. Mezzetti, R. Valdarnini

We report spectroscopic results from our 40-orbit $Hubble~Space~Telescope$ slitless grism spectroscopy program observing the 20 densest CARLA candidate galaxy clusters at $1.4 < z < 2.8$. These candidate rich structures, among the richest and most distant known, were identified on the basis of $[3.6]-[4.5]$ color from a $408~$hr multi-cycle $Spitzer$ program targeting $420$ distant radio-loud AGN. We report the spectroscopic confirmation of $16$ distant structures at $1.4 < z < 2.8$ associated with the targeted powerful high-redshift radio-loud AGN. We also report the serendipitous discovery and spectroscopic confirmation of seven additional structures at $0.87 < z < 2.12$ not associated with the targeted radio-loud AGN. We find that $10^{10} - 10^{11}\,M_{\odot}$ member galaxies of our confirmed CARLA structures form significantly fewer stars than their field counterparts at all redshifts within $1.4\leq z\leq 2$. We also observe higher star-forming activity in the structure cores up to $z = 2$, finding similar trends as cluster surveys at slightly lower redshifts ($1.0 < z < 1.5$). By design, our efficient strategy of obtaining just two grism orbits per field only obtains spectroscopic confirmation of emission-line galaxies. Deeper spectroscopy will be required to study the population of evolved, massive galaxies in these (forming) clusters. Lacking multi-band coverage of the fields, we adopt a very conservative approach of calling all confirmations "structures", although we note that a number of features are consistent with some of them being bona fide galaxy clusters. Together, this survey represents a unique and large homogenous sample of spectroscopically confirmed structures at high redshifts, potentially more than doubling the census of confirmed, massive clusters at $z > 1.4$., Accepted for publication in the Astrophysical Journal