Extremely light bosonic wave dark matter ($ψ$DM) is an emerging dark matter candidate contesting the conventional cold dark matter paradigm and a model subject to intense scrutiny of late. This work for the first time reports testable salient features pertinent to gravitational lenses of $ψ$DM halos. $ψ$DM halos are distinctly filled with large-amplitude, small-scale density fluctuations with $δρ/ρ_{\rm halo}\sim 1$ in form of density granules. This halo yields ubiquitous flux ratio anomalies of a few tens of percent, as is typically found for lensed quasars, and may also produce rare hexad and octad images, for sources located in well-defined caustic zones. We have found new critical features appearing in the highly de-magnified lens center when the halo has sufficiently high surface density near a very compact massive core.
We present the discovery of a gravitationally lensed dust-reddened QSO at z = 2.517, identified in a survey for QSOs by infrared selection. Hubble Space Telescope imaging reveals a quadruply lensed system in a cusp configuration, with a maximum image separation of ~1.8\arcsec. We find that compared to the central image of the cusp, the neighboring brightest image is anomalous by a factor of ~ 7 - 10, which is the largest flux anomaly measured to date in a lensed QSO. Incorporating high-resolution Jansky Very Large Array radio imaging and sub-mm imaging with the Atacama Large (sub-)Millimetre A…
We present an analysis of archival observations with the Atacama Large (sub-)Millimetre Array (ALMA) of the gravitationally lensed quasar MG J0414+0534, which show four compact images of the quasar and an Einstein ring from the dust associated with the quasar host galaxy. We confirm that the flux-ratio anomalies observed in the mid-infrared and radio persists into the sub-mm for the continuum images of the quasar. We report the detection of CO (11-10) spectral line emission, which traces a region of compact gas around the quasar nucleus. This line emission also shows evidence of a flux-ratio a…
We present the discovery of a gravitationally lensed dust-reddened QSO at $z=2.517$ discovered in a survey for red QSOs by infrared selection. $Hubble~Space~Telescope$ imaging in the WFC3/IR F160W and F125W filters reveals a quadruply lensed system in a cusp configuration. We find that compared to the central image of the cusp, the nearby, brightest image is anomalous by a factor of $\sim7-11$. Although the source is extremely bright in the mid-infrared, a magnification by a factor of $\sim50-120$ places an upper limit of 1.35 mJy on the intrinsic mid-infrared brightness, well below the $WISE~…
Gravitational lens flux-ratio anomalies provide a powerful technique for measuring dark matter substructure in distant galaxies. However, before using these flux-ratio anomalies to test galaxy formation models, it is imperative to ascertain that the given anomalies are indeed due to the presence of dark matter substructure and not due to some other component of the lensing galaxy halo or to propagation effects. Here we present the case of CLASS~B1555+375, which has a strong radio-wavelength flux-ratio anomaly. Our high-resolution near-infrared Keck~II adaptive optics imaging and archival Hubbl…
We explore the weak lensing effects by ministructures in the line-of-sight in a quadruply lensed quasar MG0414+0534 that shows an anomaly in the flux-ratios. We find that the observed flux-ratio anomaly can be explained by a presence of either a minifilament or a minivoid in the line-of-sight with a surface mass density of the order of 10^(8-9) h^(-1) solar mass /arcsec^2 without taking into account any subhalos in the lensing galaxy. The astrometric perturbation by a possible minifilament/minivoid is <~ 0.001 arcsec and the amplitudes of convergence perturbations due to these perturbers are ~…
We report the result of our search for the 380 GHz H2O line emissions from the quadruply lensed QSO MG J0104+0534 at z = 2.639 with the Atacama Large Millimeter/submillimeter Array (ALMA). Our observation shows a tentative detection of the 380 GHz line from the lensed QSO, and line spectrum shows a broad spectral distribution that has a velocity width of ~290 km/s and a peak flux of ~0.8 mJy. The integrated-intensity map of the H2O line show lensed emissions at the A1 and A2 component of the QSO, with the A2 component slightly resolved. The integrated line flux ratio between the A1 and A2 comp…
The flux ratios in the multiple images of gravitationally lensed quasars can provide evidence for dark matter substructure in the halo of the lensing galaxy if the flux ratios differ from those predicted by a smooth model of the lensing galaxy mass distribution. However, it is also possible that baryonic structures in the lensing galaxy, such as edge-on discs, can produce flux-ratio anomalies. In this work, we present the first statistical analysis of flux-ratio anomalies due to baryons from a numerical simulation perspective. We select galaxies with various morphological types in the Illustri…
We examine the flux density ratio anomaly in the quadruply-imaged strong gravitational lens, B1422+231, and consider the contribution of $10-10^3M_{\odot}$ primordial black holes (PBHs) as a potential dark matter constituent. We describe the first flux density ratio measurement of B1422+231 in the millimeter-wave band using the Atacama Large Millimeter Array (ALMA). This fills an important multi-wavelength gap in our knowledge of this key lensed system. The flux density of the quasar at 233 GHz is dominated by synchrotron emission and the source size is estimated to be 66.9 pc. The observed fl…
We present the first resolved mid-IR (11 micron) observations of the four-image quasar lens H1413+117 using the Michelle camera on Gemini North. All previous observations (optical, near-IR, and radio) of this lens show a "flux anomaly," where the image flux ratios cannot be explained by a simple, central lens galaxy. We attempt to reproduce the mid-IR flux ratios, which are insensitive to extinction and microlensing, by modeling the main lens as a singular isothermal ellipsoid. This model fails to reproduce the flux ratios. However, we can explain the flux ratios simply by adding to the model …
We report the $4 \, σ$ detection of a faint object with a flux of ~ 0.3 mJy, in the vicinity of the quadruply lensed QSO MG0414+0534 using the Atacama Large Millimeter/submillimeter array (ALMA) Band 7. The object is most probably a dusty dark dwarf galaxy, which has not been detected in either the optical, near-infrared (NIR) or radio (cm) bands. An anomaly in the flux ratio of the lensed images observed in Band 7 and the mid-infrared (MIR) band and the reddening of the QSO light color can be simultaneously explained if we consider the object as a lensing substructure with an ellipticity ~ 0.…
Flux ratio anomalies in quasar lenses can be attributed to dark matter substructure surrounding the lensing galaxy and, thus, used to constrain the substructure mass fraction. Previous applications of this approach infer a substructure abundance that potentially in tension with the predictions of a $Λ$CDM cosmology. However, the assumption that all flux ratio anomalies are due to substructure is a strong one, and alternative explanations have not been fully investigated. Here, we use new high-resolution near-IR Keck~II adaptive optics imaging for the lens system CLASS B0712+472 to perform pixe…
We explore the origin of flux ratio anomaly in quadruple lens systems. Using a semi-analytic method based on $N$-body simulations, we estimate the effect of possible magnification perturbation caused by subhaloes with a mass scale of <$\sim 10^9\,h^{-1} \textrm{M}_\odot$ in lensing galaxy haloes. Taking into account astrometric shifts, assuming that the primary lens is described by a singular isothermal ellipsoid, the expected change to the flux ratios per a multiply lensed image is just a few percent and the mean of the expected convergence perturbation at the effective Einstein radius of the…
We present an analysis of the ALMA long baseline science verification data of the gravitational lens system SDP.81. We fit the positions of the brightest clumps at redshift z=3.042 and a possible AGN component of the lensing galaxy at redshift z=0.2999 in the band 7 continuum image using a canonical lens model, a singular isothermal ellipsoid plus an external shear. Then, we measure the ratio of fluxes in some apertures at the source plane where the lensed images are inversely mapped. We find that the aperture flux ratios of band 7 continuum image are perturbed by 10-20 percent with a signific…
We show that the measured abundance of ultra-faint lensed galaxies at $z\approx 6$ in the Hubble Frontier Fields (HFF) provides stringent constraints on the parameter space of i) Dark Matter models based on keV sterile neutrinos; ii) the "fuzzy" wavelike Dark Matter models, based on Bose-Einstein condensate of ultra-light particles. For the case of the sterile neutrinos, we consider two production mechanisms: resonant production through the mixing with active neutrinos and the decay of scalar particles. For the former model, we derive constraints for the combination of sterile neutrino mass $m…
Probing Dark Matter Substructure with Image Number Anomaly in Strong Lensing Systems
School of Physics and Technology, Wuhan University（武汉大学物理科学与技术学院）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；School of Astronomy and Space Sciences, University of Chinese Academy of Sciences（中国科学院大学天文与空间科学学院）
For nearly 40 years, dark matter has been widely assumed to be cold and collisionless. Cold dark matter models make fundamental predictions for the behavior of dark matter on small (<10 kpc) scales. These predictions include cuspy density profiles at the centers of dark matter halos and a halo mass function that increases as dN/dM ~ M^-1.9 down to very small masses. We suggest two observational programs relying on extremely large telescopes to critically test these predictions, and thus shed new light on the nature of dark matter. (1) Combining adaptive optics-enabled imaging with deep spectro…
Discrepancies between the observed and model-predicted radio flux ratios are seen in a number of quadruply-lensed quasars. The most favored interpretation of these anomalies is that CDM substructures present in lensing galaxies perturb the lens potentials and alter image magnifications and thus flux ratios. So far no consensus has emerged regarding whether or not the predicted CDM substructure abundance fully accounts for the lensing flux anomaly observations. Accurate modeling relies on a realistic lens sample in terms of both the lens environment and internal structures and substructures. In…
In a galactic halo like the Milky Way, bosonic dark matter particles lighter than about $30$ eV have a de Broglie wavelength larger than the average inter-particle separation and are therefore well described as a set of classical waves. This applies to, for instance, the QCD axion as well as to lighter axion-like particles such as fuzzy dark matter. We show that the interference of waves inside a halo inevitably leads to vortices, locations where chance destructive interference takes the density to zero. The phase of the wavefunction has non-trivial winding around these points. This can be int…
