• ALMA Observations of the Sub-kpc Structure of the Host Galaxy of a z = 6.5 Lensed Quasar: A Rotationally Supported Hyper-Starburst System at the Epoch of Reionization

      Yue, M.; Yang, J.; Fan, X.; Wang, F.; Spilker, J.; Georgiev, I.Y.; Keeton, C.R.; Litke, K.C.; Marrone, D.P.; Walter, F.; et al. (IOP Publishing Ltd, 2021)
      Pls check pdf. We report Atacama Large Millimeter/Submillimeter Array (ALMA) observations of the dust continuum and [C ii] emission of the host galaxy of J0439+1634, a gravitationally lensed quasar at z = 6.5. Gravitational lensing boosts the source-plane resolution to ∼0.″15 (∼0.8 kpc). The lensing model derived from the ALMA data is consistent with the fiducial model in Fan et al. based on HST imaging. The host galaxy of J0439+1634 can be well-fitted by a Sérsic profile consistent with an exponential disk, both in the far-infrared (FIR) continuum and the [C ii] emission. The overall magnification is 4.53 0.05 for the continuum and 3.44 0.05 for the [C ii] line. The host galaxy of J0439+1634 is a compact ultraluminous infrared galaxy, with a total star formation rate (SFR) of 1.56 103 M o˙ yr-1 after correcting for lensing and an effective radius of 0.74 kpc. The resolved regions in J0439+1634 follow the "[C ii] deficit,"where the [C ii]-to-FIR ratio decreases with FIR surface brightness. The reconstructed velocity field of J0439+1634 appears to be rotation-like. The maximum line-of-sight rotation velocity is 130 km s-1 at a radius of 2 kpc. However, our data cannot be fit by an axisymmetric thin rotating disk, and the inclination of the rotation axis, i, remains unconstrained. We estimate the dynamical mass of the host galaxy to be 7.9{\sin } {-2}(i) {10} {9}{M}_{\odot }. J0439+1634 is likely to have a high gas-mass fraction and an oversized SMBH compared to local relations. The SFR of J0439+1634 reaches the maximum possible values, and the SFR surface density is close to the highest value seen in any star-forming galaxy currently known in the universe. © 2021. The American Astronomical Society. All rights reserved.
    • Deep XMM-Newton Observations of an X-ray Weak Broad Absorption Line Quasar at z = 6.5

      Yang, J.; Fan, X.; Wang, F.; Lanzuisi, G.; Nanni, R.; Cappi, M.; Chartas, G.; Dadina, M.; Decarli, R.; Jin, X.; et al. (American Astronomical Society, 2022)
      We report X-ray observations of the most distant known gravitationally lensed quasar, J0439+1634 at z = 6.52, which is also a broad absorption line (BAL) quasar, using the XMM-Newton Observatory. With a 130 ks exposure, the quasar is significantly detected as a point source at the optical position with a total of net counts using the EPIC instrument. By fitting a power law plus Galactic absorption model to the observed spectra, we obtain a spectral slope of . The derived optical-to-X-ray spectral slope a ox is , suggesting that the X-ray emission of J0439+1634 is weaker by a factor of 18 than the expectation based on its 2500 Å luminosity and the average a ox versus luminosity relationship. This is the first time that an X-ray weak BAL quasar at z > 6 has been observed spectroscopically. Its X-ray weakness is consistent with the properties of BAL quasars at lower redshift. By fitting a model including an intrinsic absorption component, we obtain intrinsic column densities of and , assuming a fixed G of 1.9 and a free G, respectively. The intrinsic rest-frame 2-10 keV luminosity is derived as (9.4-15.1) 1043 erg s-1, after correcting for lensing magnification (µ = 51.3). The absorbed power-law model fitting indicates that J0439+1634 is the highest redshift obscured quasar with a direct measurement of the absorbing column density. The intrinsic high column density absorption can reduce the X-ray luminosity by a factor of 3-7, which also indicates that this quasar could be a candidate intrinsically X-ray weak quasar. © 2022. The Author(s). Published by the American Astronomical Society..
    • Fresh Insights on the Kinematics of M49's Globular Cluster System with MMT/Hectospec Spectroscopy

      Taylor, M.A.; Ko, Y.; Côté, P.; Ferrarese, L.; Peng, E.W.; Zabludoff, A.; Roediger, J.; Sánchez-Janssen, R.; Hendel, D.; Chilingarian, I.; et al. (IOP Publishing Ltd, 2021)
      We present the first results of an MMT/Hectospec campaign to measure the kinematics of globular clusters (GCs) around M49 - the brightest galaxy in the Virgo galaxy cluster, which dominates the Virgo B subcluster. The data include kinematic tracers beyond 95 kpc (∼5.2 effective radii) for M49 for the first time, enabling us to achieve three key insights reported here. First, beyond ∼20′-30′ (∼100-150 kpc), the GC kinematics sampled along the minor photometric axis of M49 become increasingly hotter, indicating a transition from GCs related to M49 to those representing the Virgo B intra-cluster medium. Second, there is an anomaly in the line-of-sight radial velocity dispersion (σ r,los) profile in an annulus ∼10-15′ (∼50-90 kpc) from M49 in which the kinematics cool by Δσ r,los ≈ 150 km s-1 relative to those in- or outward. The kinematic fingerprint of a previous accretion event is hinted at in projected phase-space, and we isolate GCs that both give rise to this feature, and are spatially co-located with two prominent stellar shells in the halo of M49. Third, we find a subsample of GCs with velocities representative of the dwarf galaxy VCC 1249 that is currently interacting with M49. The spatial distribution of these GCs closely resembles the morphology of VCC 1249's isophotes, indicating that several of these GCs are likely in the act of being stripped from the dwarf during its passage through M49's halo. Taken together, these results point toward the opportunity of witnessing ongoing giant halo assembly in the depths of a cluster environment. © 2021. The American Astronomical Society. All rights reserved.
    • Linking Extragalactic Transients and Their Host Galaxy Properties: Transient Sample, Multiwavelength Host Identification, and Database Construction

      Qin, Y.-J.; Zabludoff, A.; Kisley, M.; Liu, Y.; Arcavi, I.; Barnard, K.; Behroozi, P.; French, K.D.; McCully, C.; Merchant, N.; et al. (American Astronomical Society, 2022)
      Understanding the preferences of transient types for host galaxies with certain characteristics is key to studies of transient physics and galaxy evolution, as well as to transient identification and classification in the LSST era. Here we describe a value-added database of extragalactic transients - supernovae, tidal disruption events, gamma-ray bursts, and other rare events - and their host galaxy properties. Based on reported coordinates, redshifts, and host galaxies (if known) of events, we cross-identify their host galaxies or most likely host candidates in various value-added or survey catalogs, and compile the existing photometric, spectroscopic, and derived physical properties of the host galaxies in these catalogs. This new database covers photometric measurements from the far-ultraviolet to mid-infrared. Spectroscopic measurements and derived physical properties are also available for a smaller subset of hosts. For our 36,333 unique events, we have cross-identified 13,753 host galaxies using host names, plus 4480 using host coordinates. Besides those with known hosts, there are 18,100 transients with newly identified host candidates. This large database will allow explorations of the connections of transients to their hosts, including a path toward transient alert filtering and probabilistic classification based on host properties. © 2022. The Author(s). Published by the American Astronomical Society.
    • Searches after Gravitational Waves Using ARizona Observatories (SAGUARO): Observations and Analysis from Advanced LIGO/Virgo's Third Observing Run

      Paterson, K.; Lundquist, M.J.; Rastinejad, J.C.; Fong, W.; Sand, D.J.; Andrews, J.E.; Amaro, R.C.; Eskandari, O.; Wyatt, S.; Daly, P.N.; et al. (IOP Publishing Ltd, 2021)
      With the conclusion of the third observing run for Advanced LIGO/Virgo (O3), we present a detailed analysis of both triggered and serendipitous observations of 17 gravitational-wave (GW) events (7 triggered and 10 purely serendipitous) from the Searches After Gravitational-waves Using ARizona Observatories (SAGUARO) program. We searched a total of 4935 deg2 down to a median 5σ transient detection depth of 21.1 AB mag using the Mt. Lemmon 1.5 m telescope, the discovery engine for SAGUARO. In addition to triggered events within 24 hr, our transient search encompassed a time interval following GW events of <120 hr, providing observations on ∼1/2 of the events accessible to the Mt. Lemmon 1.5 m telescope. We covered 2.1%-86% of the LVC total probability (P total) for individual events, with a median P total ≈ 8% within <120 hr. Following improvements to our pipeline and the addition of serendipitous observations, we find a total of seven new optical candidates across five GW events, which we are unable to rule out after searching for additional information and comparing to kilonova models. Using both publicly available and our own late-time data, we investigated a total of 252 optical candidates for these 17 events, finding that only 65% were followed up in some capacity by the community. Of the total 252 candidates, we are able to rule out an additional 12 previously reported counterpart candidates. In light of these results, we discuss lessons learned from the SAGUARO GW counterpart search. We discuss how community coordination of observations and candidate follow-up, as well as the role of archival data, are crucial to improving the efficiency of follow-up efforts and preventing unnecessary duplication of effort with limited electromagnetic resources. © 2021. The American Astronomical Society. All rights reserved..
    • Searches after Gravitational Waves Using ARizona Observatories (SAGUARO): System Overview and First Results from Advanced LIGO/Virgo’s Third Observing Run

      Lundquist, M. J.; Sand, D. J.; Andrews, J. E.; Shivaei, I.; Daly, P. N.; Christensen, E.; Gibbs, A. R.; Shelly, F.; Wyatt, S.; Amaro, R. C.; et al. (IOP PUBLISHING LTD, 2019-08-15)
      We present Searches After Gravitational-waves Using ARizona Observatories (SAGUARO), a comprehensive effort dedicated to the discovery and characterization of optical counterparts to gravitational-wave (GW) events. SAGUARO utilizes ground-based facilities ranging from 1.5 to 10 m in diameter, located primarily in the Northern Hemisphere. We provide an overview of SAGUARO's telescopic resources, its pipeline for transient detection, and its database for candidate visualization. We describe SAGUARO' s discovery component, which utilizes the 5 deg 2 field of view optical imager on the Mt. Lemmon 1.5 m telescope, reaching limits of approximate to 21.3 AB mag while rapidly tiling large areas. We also describe the follow-up component of SAGUARO, used for rapid vetting and monitoring of optical candidates. With the onset of Advanced LIGO/Virgo's third observing run, we present results from the first three SAGUARO searches following the GW events S190408an, S190425z and S190426c, which serve as a valuable proof-of-concept of SAGUARO. We triggered and searched 15, 60, and 60 deg(2) respectively, 17.6, 1.4, and 41.8 hr after the initial GW alerts. We covered 7.8%, 3.0%, and 5.1% of the total probability within the GW event localizations, reaching 3 sigma limits of 19.8, 21.3, and 20.8 AB mag, respectively. Although no viable counterparts associated with these events were found, we recovered six known transients and ruled out five potential candidates. We also present Large Binocular Telescope spectroscopy of PS19eq/SN2019ebq, a promising kilonova candidate that was later determined to be a supernova. With the ability to tile large areas and conduct detailed follow-up, SAGUARO represents a significant addition to GW counterpart searches.