Abstract
We report the detection of 23 OH
+
1 → 0 absorption, emission, or P-Cygni-shaped lines and CO(
J
= 9→8) emission lines in 18 Herschel-selected
z
= 2–6 starburst galaxies with the Atacama ...Large Millimeter/submillimeter Array and the NOrthern Extended Millimeter Array, taken as part of the Gas And Dust Over cosmic Time Galaxy Survey. We find that the CO(
J
= 9→8) luminosity is higher than expected based on the far-infrared luminosity when compared to nearby star-forming galaxies. Together with the strength of the OH
+
emission components, this may suggest that shock excitation of warm, dense molecular gas is more prevalent in distant massive dusty starbursts than in nearby star-forming galaxies on average, perhaps due to an impact of galactic winds on the gas. OH
+
absorption is found to be ubiquitous in massive high-redshift starbursts, and is detected toward 89% of the sample. The majority of the sample shows evidence for outflows or inflows based on the velocity shifts of the OH
+
absorption/emission, with a comparable occurrence rate of both at the resolution of our observations. A small subsample appears to show outflow velocities in excess of their escape velocities. Thus, starburst-driven feedback appears to be important in the evolution of massive galaxies in their most active phases. We find a correlation between the OH
+
absorption optical depth and the dust temperature, which may suggest that warmer starbursts are more compact and have higher cosmic-ray energy densities, leading to more efficient OH
+
ion production. This is in agreement with a picture in which these high-redshift galaxies are “scaled-up” versions of the most intense nearby starbursts.
Abstract
We present a morphological study of the 17 lensed Ly
α
emitter (LAE) galaxies of the Baryon Oscillation Spectroscopic Survey Emission-Line Lens Survey (BELLS) for the GALaxy-Ly
α
EmitteR ...sYstems (BELLS GALLERY) sample. This analysis combines the magnification effect of strong galaxy–galaxy lensing with the high resolution of the
Hubble Space Telescope
to achieve a physical resolution of ∼80 pc for this 2 <
z
< 3 LAE sample, allowing a detailed characterization of the LAE rest-frame ultraviolet continuum surface brightness profiles and substructure. We use lens-model reconstructions of the LAEs to identify and model individual clumps, which we subsequently use to constrain the parameters of a generative statistical model of the LAE population. Since the BELLS GALLERY sample is selected primarily on the basis of Ly
α
emission, the LAEs that we study here are likely to be directly comparable to those selected in wide-field, narrowband LAE surveys, in contrast with the lensed LAEs identified in cluster-lensing fields. We find an LAE clumpiness fraction of approximately 88%, which is significantly higher than that found in previous (non-lensing) studies. We find a well-resolved characteristic clump half-light radii of ∼350 pc, a scale comparable to the largest H
ii
regions seen in the local universe. This statistical characterization of LAE surface-brightness profiles will be incorporated into future lensing analyses using the BELLS GALLERY sample to constrain the incidence of dark-matter substructure in the foreground lensing galaxies.
ABSTRACT
We present
Hubble Space Telescope
F606W-band imaging observations of 21 galaxy-Ly
α
emitter lens candidates in the Baryon Oscillation Spectroscopic Survey Emission-Line Lens Survey (BELLS) ...for the GALaxy-Ly
α
EmitteR sYstems (BELLS GALLERY) survey. Seventeen systems are confirmed to be definite lenses with unambiguous evidence of multiple imaging. The lenses are primarily massive early-type galaxies (ETGs) at redshifts of approximately 0.55, while the lensed sources are Ly
α
emitters (LAEs) at redshifts from two to three. Although most of the lens systems are well fit by smooth lens models consisting of singular isothermal ellipsoids in an external shear field, a thorough exploration of dark substructures in the lens galaxies is required. The Einstein radii of the BELLS GALLERY lenses are, on average, 60% larger than those of the BELLS lenses because of the much higher source redshifts. This will allow for a detailed investigation of the radius evolution of the mass profile in ETGs. With the aid of the average ∼13× lensing magnification, the LAEs are frequently resolved into individual star-forming knots with a wide range of properties. They have characteristic sizes from less than 100 pc to several kiloparsecs, rest-frame far-UV apparent AB magnitudes from 29.6 to 24.2, and typical projected separations of 500 pc to 2 kpc.
ABSTRACT
We introduce the Baryon Oscillation Spectroscopic Survey (BOSS) Emission-Line Lens Survey GALaxy-Ly
α
EmitteR sYstems (BELLS GALLERY) Survey, which is a
Hubble Space Telescope
program to ...image a sample of galaxy-scale strong gravitational lens candidate systems with high-redshift Ly
α
emitters (LAEs) as the background sources. The goal of the BELLS GALLERY Survey is to illuminate dark substructures in galaxy-scale halos by exploiting the small-scale clumpiness of rest-frame far-UV emission in lensed LAEs, and to thereby constrain the slope and normalization of the substructure-mass function. In this paper, we describe in detail the spectroscopic strong-lens selection technique, which is based on methods adopted in the previous Sloan Lens ACS (SLACS) Survey, BELLS, and SLACS for the Masses Survey. We present the BELLS GALLERY sample of the 21 highest-quality galaxy–LAE candidates selected from
galaxy spectra in the BOSS of the Sloan Digital Sky Survey III. These systems consist of massive galaxies at redshifts of approximately 0.5 strongly lensing LAEs at redshifts from 2–3. The compact nature of LAEs makes them an ideal probe of dark substructures, with a substructure-mass sensitivity that is unprecedented in other optical strong-lens samples. The magnification effect from lensing will also reveal the structure of LAEs below 100 pc scales, providing a detailed look at the sites of the most concentrated unobscured star formation in the universe. The source code used for candidate selection is available for download as a part of this release.
We investigate the relation between star formation rates (
$\dot{{M}}_s$
) and AGN properties in optically selected type 1 quasars at 2 < z < 3 using data from Herschel and the SDSS. We find that
...$\dot{{M}}_s$
remains approximately constant with redshift, at 300 ± 100 M⊙ yr−1. Conversely,
$\dot{{M}}_s$
increases with AGN luminosity, up to a maximum of ∼ 600 M⊙ yr−1, and with C iv FWHM. In context with previous results, this is consistent with a relation between
$\dot{{M}}_s$
and black hole accretion rate (
$\dot{{M}}_{{\rm bh}}$
) existing in only parts of the
$z-\dot{{M}}_{s}-\dot{{M}}_{{\rm bh}}$
plane, dependent on the free gas fraction, the trigger for activity, and the processes that may quench star formation. The relations between
$\dot{{M}}_s$
and both AGN luminosity and C iv FWHM are consistent with star formation rates in quasars scaling with black hole mass, though we cannot rule out a separate relation with black hole accretion rate. Star formation rates are observed to decline with increasing C iv equivalent width. This decline can be partially explained via the Baldwin effect, but may have an additional contribution from one or more of three factors; M
i
is not a linear tracer of L
2500, the Baldwin effect changes form at high AGN luminosities, and high C iv EW values signpost a change in the relation between
$\dot{{M}}_s$
and
$\dot{{M}}_{{\rm bh}}$
. Finally, there is no strong relation between
$\dot{{M}}_s$
and Eddington ratio, or the asymmetry of the C iv line. The former suggests that star formation rates do not scale with how efficiently the black hole is accreting, while the latter is consistent with C iv asymmetries arising from orientation effects.
ABSTRACT We report the discovery of SDSS J0909+4449, an exceptional system consisting of a quasar at z = 2.788 strongly lensed by a group of galaxies at z ∼ 0.9 into three images separated by up to ...14 arcsec based on archival data collected by the Sloan Digital Sky Survey, extended Baryon Oscillation Spectroscopic Survey, Beijing–Arizona Sky Survey, the Mayall z-band Legacy Survey, and the Gemini Telescope. We discuss two hypotheses on the nature of SDSS J0909+4449, i.e. a rare triply imaged quasar in the naked cusp configuration and a typical quadruply imaged quasar with the fourth image undetected in this data. We find that simple lens models can provide excellent fits to the observed image positions and the non-detection under either hypothesis. Deeper imaging data, spectroscopic observations, and follow-up light-curve measurements will be helpful in determining which hypothesis is correct and provide better constraints on the lens mass distribution. Nevertheless, given its unusually large image separations, SDSS J0909+4449 will be a unique probe for the mass structure and the underlying cooling and stellar feedback processes on group or cluster scales.
We present CO (J = 1 → 0; 3 → 2; 5 → 4; 10 → 9) and 1.2 kpc resolution C ii line observations of the dusty star-forming galaxy (SFG) HXMM05-carried out with the Karl G. Jansky Very Large Array, the ...Combined Array for Research in Millimeter-wave Astronomy, the Plateau de Bure Interferometer, and the Atacama Large Millimeter/submillimeter Array, measuring an unambiguous redshift of z = 2.9850 0.0009. We find that HXMM05 is a hyperluminous infrared galaxy ( = (4 1) × 1013 L ) with a total molecular gas mass of (2.1 0.7) × 1011( /0.8) M . The CO (J = 1 → 0) and C ii emission are extended over ∼9 kpc in diameter, and the CO line FWHM exceeds 1100 km s−1. The C ii emission shows a monotonic velocity gradient consistent with a disk, with a maximum rotation velocity of = 616 100 km s−1 and a dynamical mass of (7.7 3.1) × 1011 M . We find a star formation rate of 2900 M yr−1. HXMM05 is thus among the most intensely SFGs known at high redshift. Photodissociation region modeling suggests physical conditions similar to nearby SFGs, showing extended star formation, which is consistent with our finding that the gas emission and dust emission are cospatial. Its molecular gas excitation resembles the local major merger Arp 220. The broad CO and C ii lines and a pair of compact dust nuclei suggest the presence of a late-stage major merger at the center of the extended disk, again reminiscent of Arp 220. The observed gas kinematics and conditions, together with the presence of a companion and the pair of nuclei, suggest that HXMM05 is experiencing multiple mergers as a part of the evolution.
Abstract
The LIGO/Virgo detected a gravitational wave (GW) event, named GW200224_222234 (also known as S200224ca) and classified as a binary-black hole coalescence, on 2020 February 24. Given its ...relatively small localization skymap (71 deg
2
for a 90% credible region; revised to 50 deg
2
in GWTC-3), we performed target-of-opportunity observations using the Subaru/Hyper Suprime-Cam (HSC) in the
r
2 and
z
bands. Observations were conducted on 2020 February 25 and 28 and March 23, with the first epoch beginning 12.3 hr after the GW detection. The survey covered the highest-probability sky area of 56.6 deg
2
, corresponding to a 91% probability. This was the first deep follow-up (
m
r
≳ 24,
m
z
≳ 23) for a binary-black hole merger covering >90% of the localization. By performing image subtraction and candidate screening including light-curve fitting with transient templates and examples, we found 22 off-nucleus transients that were not ruled out as the counterparts of GW200224_222234 with our Subaru/HSC data alone. We also performed GTC/OSIRIS spectroscopy of the probable host galaxies for five candidates; two are likely to be located within the 3D skymap, whereas the others are not. In conclusion, 19 transients remain as possible optical counterparts of GW200224_222234; but we could not identify a unique promising counterpart. If there are no counterparts in the remaining candidates, the upper limits of the optical luminosity are
ν
L
ν
<
5.2
−
1.9
+
2.4
×
10
41
erg s
−1
and
ν
L
ν
<
1.8
−
0.6
+
0.8
×
10
42
erg s
−1
in the
r
2 and
z
bands, respectively, at ∼12 hr after GW detection. We also discuss improvements in the strategies of optical follow-ups for future GW events.
We present the new Very Large Array 22 GHz and extended Multi-Element Remote-Linked Interferometer Network 5 GHz observations of CLASS B1030+074, a two-image strong gravitational lens system whose ...background source is a compact flat-spectrum radio quasar. In such systems we expect a third image of the background source to form close to the centre of the lensing galaxy. The existence and brightness of such images is important for investigation of the central mass distributions of lensing galaxies, but only one secure detection has been made so far in a galaxy-scale lens system. The noise levels achieved in our new B1030+074 images reach 3 μJy beam−1 and represent an improvement in central image constraints of nearly an order of magnitude over previous work, with correspondingly better resulting limits on the shape of the central mass profile of the lensing galaxy. Simple models with an isothermal outer power-law slope now require either the influence of a central supermassive black hole (SMBH), or an inner power-law slope very close to isothermal, in order to suppress the central image below our detection limit. Using the central mass profiles inferred from light distributions in Virgo galaxies, moved to z = 0.5, and matching to the observed Einstein radius, we now find that 45 per cent of such mass profiles should give observable central images, 10 per cent should give central images with a flux density still below our limit, and the remaining systems have extreme demagnification produced by the central SMBH. Further observations of similar objects will therefore allow proper statistical constraints to be placed on the central properties of elliptical galaxies at high redshift.
PDF
