Abstract
We present a detailed study of the Planck-selected binary galaxy cluster PLCK G165.7+67.0 (G165;
z
= 0.348). A multiband photometric catalog is generated incorporating new imaging from the ...Large Binocular Telescope/Large Binocular Camera and Spitzer/IRAC to existing imaging. To cope with the different image characteristics, robust methods are applied in the extraction of the matched-aperture photometry. Photometric redshifts are estimated for 143 galaxies in the 4 arcmin
2
field of overlap covered by these data. We confirm that strong-lensing effects yield 30 images of 11 background galaxies, of which we contribute new photometric redshift estimates for three image multiplicities. These constraints enable the construction of a revised lens model with a total mass of
M
600 kpc
= (2.36 ± 0.23) × 10
14
M
⊙
. In parallel, new spectroscopy using MMT/Binospec and archival data contributes thirteen galaxies that meet our velocity and transverse radius criteria for cluster membership. The two cluster components have a pair-wise velocity of ≲100 km s
−1
, favoring an orientation in the plane of the sky with a transverse velocity of 100–1700 km s
−1
. At the same time, the brightest cluster galaxy (BCG) is offset in velocity from the systemic mean value, suggesting dynamical disturbance. New LOFAR and Very Large Array data uncover head-tail radio galaxies in the BCG and a large red galaxy in the northeast component. From the orientation and alignment of the four radio trails, we infer that the two cluster components have already traversed each other, and are now exiting the cluster.
Abstract
The massive galaxy cluster El Gordo (
z
= 0.87) imprints multitudes of gravitationally lensed arcs onto James Webb Space Telescope Near-Infrared Camera (NIRCam) images. Eight bands of NIRCam ...imaging were obtained in the “Prime Extragalactic Areas for Reionization and Lensing Science” (“PEARLS”) program. Point-spread function–matched photometry across Hubble Space Telescope and NIRCam filters supplies new photometric redshifts. A new light-traces-mass lens model based on 56 image multiplicities identifies the two mass peaks and yields a mass estimate within 500 kpc of (7.0 ± 0.30) × 10
14
M
⊙
. A search for substructure in the 140 cluster members with spectroscopic redshifts confirms the two main mass components. The southeastern mass peak that contains the brightest cluster galaxy is more tightly bound than the northwestern one. The virial mass within 1.7 Mpc is (5.1 ± 0.60)×10
14
M
⊙
, lower than the lensing mass. A significant transverse velocity component could mean the virial mass is underestimated. We contribute one new member to the previously known
z
= 4.32 galaxy group. Intrinsic (delensed) positions of the five secure group members span a physical extent of ∼60 kpc. 13 additional candidates selected by spectroscopic/photometric constraints are small and faint, with a mean intrinsic luminosity ∼2.2 mag fainter than
L
*
. NIRCam imaging admits a fairly wide range of brightnesses and morphologies for the group members, suggesting a more diverse galaxy population in this galaxy overdensity.
Abstract
A Type Ia supernova (SN) at
z
= 1.78 was discovered in James Webb Space Telescope Near Infrared Camera imaging of the galaxy cluster PLCK G165.7+67.0 (G165;
z
= 0.35). The SN is situated ...1.5–2 kpc from the host-galaxy nucleus and appears in three different locations as a result of gravitational lensing by G165. These data can yield a value for Hubble’s constant using time delays from this multiply imaged SN Ia that we call “SN H0pe.” Over the cluster, we identified 21 image multiplicities, confirmed five of them using the Near-Infrared Spectrograph, and constructed a new lens model that gives a total mass within 600 kpc of (2.6 ± 0.3) × 10
14
M
⊙
. The photometry uncovered a galaxy overdensity coincident with the SN host galaxy. NIRSpec confirmed six member galaxies, four of which surround the SN host galaxy with relative velocity ≲900 km s
−1
and projected physical extent ≲33 kpc. This compact galaxy group is dominated by the SN host galaxy, which has a stellar mass of (5.0 ± 0.1) × 10
11
M
⊙
. The group members have specific star formation rates of 2–260 Gyr
−1
derived from the H
α
-line fluxes corrected for stellar absorption, dust extinction, and slit losses. Another group centered on a strongly lensed dusty star-forming galaxy is at
z
= 2.24. The total (unobscured and obscured) SFR of this second galaxy group is estimated to be (≳ 100
M
⊙
yr
−1
), which translates to a supernova rate of ∼1 SNe yr
−1
, suggesting that regular monitoring of this cluster may yield additional SNe.
The first James Webb Space Telescope ({\it JWST}) Near InfraRed Camera
(NIRCam) imaging in the field of the galaxy cluster PLCK G165.7+67.0 ($z=0.35$)
uncovered a Type Ia supernova (SN~Ia) at ...$z=1.78$, called ``SN H0pe." Three
different images of this one SN were detected as a result of strong
gravitational lensing, each one traversing a different path in spacetime,
thereby inducing a relative delay in the arrival of each image. Follow-up {\it
JWST} observations of all three SN images enabled photometric and rare
spectroscopic measurements of the two relative time delays. Following strict
blinding protocols which oversaw a live unblinding and regulated
post-unblinding changes, these two measured time delays were compared to the
predictions of seven independently constructed cluster lens models to measure a
value for the Hubble constant, $H_0=71.8^{+9.8}_{-7.6}$~km~s$^{-1}$~Mpc$^{-1}$.
The range of admissible $H_0$ values predicted across the lens models limits
further precision, reflecting the well-known degeneracies between lens model
constraints and time delays. It has long been theorized that a way forward is
to leverage a standard candle, however this has not been realized until now.
For the first time, the lens models are evaluated by their agreement with the
SN absolute magnification, breaking these degeneracies and producing our best
estimate, $H_0=75.4^{+8.1}_{-5.5}$~km~s$^{-1}$~Mpc$^{-1}$. This is the first
precision measurement of $H_0$ from a multiply-imaged SN~Ia, and provides a
measurement in a rarely utilized redshift regime. This result agrees with other
local universe measurements, yet exceeds the value of $H_0$ derived from the
early Universe with $\gtrsim90\%$ confidence, increasing evidence of the Hubble
tension. With the precision provided by only four more events, this approach
could solidify this disagreement to $>3\sigma$.
We present a new parametric lens model for the G165.7+67.0 galaxy cluster,
which was discovered with $Planck$ through its bright submillimeter flux,
originating from a pair of extraordinary dusty ...star-forming galaxies (DSFGs) at
$z\approx 2.2$. Using JWST and interferometric mm/radio observations, we
characterize the intrinsic physical properties of the DSFGs, which are
separated by only $\sim 1^{\prime\prime}$ (8 kpc) and a velocity difference
$\Delta V \lesssim 600~{\rm km}~{\rm s}^{-1}$ in the source plane, and thus
likely undergoing a major merger. Boasting intrinsic star formation rates ${\rm
SFR}_{\rm IR} = 320 \pm 70$ and $400 \pm 80~ M_\odot~{\rm yr}^{-1}$, stellar
masses ${\rm log}M_\star/M_\odot = 10.2 \pm 0.1$ and $10.3 \pm 0.1$, and dust
attenuations $A_V = 1.5 \pm 0.3$ and $1.2 \pm 0.3$, they are remarkably similar
objects. We perform spatially-resolved pixel-by-pixel SED fitting using
rest-frame near-UV to near-IR imaging from JWST/NIRCam for both galaxies,
resolving some stellar structures down to 100 pc scales. Based on their
resolved specific SFRs and $UVJ$ colors, both DSFGs are experiencing
significant galaxy-scale star formation events. If they are indeed interacting
gravitationally, this strong starburst could be the hallmark of gas that has
been disrupted by an initial close passage. In contrast, the host galaxy of the
recently discovered triply-imaged SN H0pe has a much lower SFR than the DSFGs,
and we present evidence for the onset of inside-out quenching and large column
densities of dust even in regions of low specific SFR. Based on the intrinsic
SFRs of the DSFGs inferred from UV through FIR SED modeling, this pair of
objects alone is predicted to yield an observable $1.1 \pm 0.2~{\rm
CCSNe~yr}^{-1}$, making this cluster field ripe for continued monitoring.
A Type Ia supernova (SN) at \(z=1.78\) was discovered in James Webb Space Telescope Near Infrared Camera imaging of the galaxy cluster PLCK G165.7+67.0 (G165; \(z = 0.35\)). The SN is situated 1.5-2 ...kpc from the host-galaxy nucleus and appears in three different locations as a result of gravitational lensing by G165. These data can yield a value for Hubble's constant using time delays from this multiply-imaged SN Ia that we call "SN H0pe." Over the cluster, we identified 21 image multiplicities, confirmed five of them using the Near-Infrared Spectrograph, and constructed a new lens model that gives a total mass within 600 kpc of (\(2.6 \pm 0.3) \times 10^{14}\) \(M_{\odot}\). The photometry uncovered a galaxy overdensity coincident with the SN host galaxy. NIRSpec confirmed six member galaxies, four of which surround the SN host galaxy with relative velocity \(\lesssim\)900 km s\(^{-1}\) and projected physical extent \(\lesssim\)33 kpc. This compact galaxy group is dominated by the SN host galaxy, which has a stellar mass of \((5.0 \pm 0.1) \times 10^{11}\) \(M_{\odot}\). The group members have specific star-formation rates of 2-260 Gyr\(^{-1}\) derived from the H\(\alpha\)-line fluxes corrected for stellar absorption, dust extinction, and slit losses. Another group centered on a strongly-lensed dusty star forming galaxy is at \(z=2.24\). The total (unobscured and obscured) SFR of this second galaxy group is estimated to be (\(\gtrsim\)100 \(M_{\odot}\) yr\(^{-1}\)), which translates to a supernova rate of \(\sim\)1 SNe yr\(^{-1}\), suggesting that regular monitoring of this cluster may yield additional SNe.
We present a detailed study of the Planck-selected binary galaxy cluster PLCK G165.7+67.0 (G165; \(z\)=0.348). A multiband photometric catalog is generated that incorporates new imaging from the ...Large Binocular Telescope/Large Binocular Camera and Spitzer/IRAC to existing imaging. To cope with the different image characteristics, robust methods are applied in the extraction of the matched-aperture photometry. Photometric redshifts are estimated for 143 galaxies in the 4 arcmin\(^{2}\) field of overlap covered by all these data. We confirm that strong lensing effects yield 30 images of 11 background galaxies, of which we contribute photometric redshift estimates for three image multiplicities. These constraints enable the construction of a revised lens model that confirms the bimodal structure, and from which we measure a mass of M\(_{600 kpc}\)=(2.36\(\pm\)0.23)\(\times\)10\(^{14}\)M\(_{\odot}\). In parallel, new spectroscopy using MMT/Binospec and archival data contributes thirteen galaxies which meet our velocity and transverse radius criteria for cluster membership. The two cluster components have a pair-wise velocity of \(\lessapprox\)100 kms\(^{-1}\), favoring an orientation in the plane of the sky with a transverse velocity of 100-1700 kms\(^{-1}\). At the same time, the brightest cluster galaxy is offset in velocity from the systemic mean value. New LOFAR and VLA radio maps uncover the BCG and a large red galaxy in the northeastern side to be head-tail galaxies, suggesting that this component has already traversed southwestern side and is now exiting the cluster to the northeast.
The massive galaxy cluster El Gordo (z=0.87) imprints multitudes of gravitationally lensed arcs onto James Webb Space Telescope (JWST) Near-Infrared Camera (NIRCam) images. Eight bands of NIRCam ...imaging were obtained in the ``Prime Extragalactic Areas for Reionization and Lensing Science'' (``PEARLS'') program. PSF-matched photometry across Hubble Space Telescope (HST) and NIRCam filters supplies new photometric redshifts. A new light-traces-mass lens model based on 56 image multiplicities identifies the two mass peaks and yields a mass estimate within 500 kpc of ~(7.0 +/- 0.30) x 10^14 Msun. A search for substructure in the 140 cluster members with spectroscopic redshifts confirms the two main mass components. The southeastern mass peak that contains the BCG is more tightly bound than the northwestern one. The virial mass within 1.7 Mpc is (5.1 +/- 0.60) x 10^14 Msun, lower than the lensing mass. A significant transverse velocity component could mean the virial mass is underestimated. We contribute one new member to the previously known z=4.32 galaxy group. Intrinsic (delensed) positions of the five secure group members span a physical extent of ~60 kpc. Thirteen additional candidates selected by spectroscopic/photometric constraints are small and faint with a mean intrinsic luminosity ~2.2 mag fainter than L*. NIRCam imaging admits a fairly wide range of brightnesses and morphologies for the group members, suggesting a more diverse galaxy population in this galaxy overdensity.
The first James Webb Space Telescope ({\it JWST}) Near InfraRed Camera (NIRCam) imaging in the field of the galaxy cluster PLCK G165.7+67.0 (\(z=0.35\)) uncovered a Type Ia supernova (SN~Ia) at ...\(z=1.78\), called ``SN H0pe." Three different images of this one SN were detected as a result of strong gravitational lensing, each one traversing a different path in spacetime, thereby inducing a relative delay in the arrival of each image. Follow-up {\it JWST} observations of all three SN images enabled photometric and rare spectroscopic measurements of the two relative time delays. Following strict blinding protocols which oversaw a live unblinding and regulated post-unblinding changes, these two measured time delays were compared to the predictions of seven independently constructed cluster lens models to measure a value for the Hubble constant, \(H_0=71.8^{+9.8}_{-7.6}\)~km~s\(^{-1}\)~Mpc\(^{-1}\). The range of admissible \(H_0\) values predicted across the lens models limits further precision, reflecting the well-known degeneracies between lens model constraints and time delays. It has long been theorized that a way forward is to leverage a standard candle, however this has not been realized until now. For the first time, the lens models are evaluated by their agreement with the SN absolute magnification, breaking these degeneracies and producing our best estimate, \(H_0=75.4^{+8.1}_{-5.5}\)~km~s\(^{-1}\)~Mpc\(^{-1}\). This is the first precision measurement of \(H_0\) from a multiply-imaged SN~Ia, and provides a measurement in a rarely utilized redshift regime. This result agrees with other local universe measurements, yet exceeds the value of \(H_0\) derived from the early Universe with \(\gtrsim90\%\) confidence, increasing evidence of the Hubble tension. With the precision provided by only four more events, this approach could solidify this disagreement to \(>3\sigma\).
We present a new parametric lens model for the G165.7+67.0 galaxy cluster, which was discovered with \(Planck\) through its bright submillimeter flux, originating from a pair of extraordinary dusty ...star-forming galaxies (DSFGs) at \(z\approx 2.2\). Using JWST and interferometric mm/radio observations, we characterize the intrinsic physical properties of the DSFGs, which are separated by only \(\sim 1^{\prime\prime}\) (8 kpc) and a velocity difference \(\Delta V \lesssim 600~{\rm km}~{\rm s}^{-1}\) in the source plane, and thus likely undergoing a major merger. Boasting intrinsic star formation rates \({\rm SFR}_{\rm IR} = 320 \pm 70\) and \(400 \pm 80~ M_\odot~{\rm yr}^{-1}\), stellar masses \({\rm log}M_\star/M_\odot = 10.2 \pm 0.1\) and \(10.3 \pm 0.1\), and dust attenuations \(A_V = 1.5 \pm 0.3\) and \(1.2 \pm 0.3\), they are remarkably similar objects. We perform spatially-resolved pixel-by-pixel SED fitting using rest-frame near-UV to near-IR imaging from JWST/NIRCam for both galaxies, resolving some stellar structures down to 100 pc scales. Based on their resolved specific SFRs and \(UVJ\) colors, both DSFGs are experiencing significant galaxy-scale star formation events. If they are indeed interacting gravitationally, this strong starburst could be the hallmark of gas that has been disrupted by an initial close passage. In contrast, the host galaxy of the recently discovered triply-imaged SN H0pe has a much lower SFR than the DSFGs, and we present evidence for the onset of inside-out quenching and large column densities of dust even in regions of low specific SFR. Based on the intrinsic SFRs of the DSFGs inferred from UV through FIR SED modeling, this pair of objects alone is predicted to yield an observable \(1.1 \pm 0.2~{\rm CCSNe~yr}^{-1}\), making this cluster field ripe for continued monitoring.
