GRAVITATIONAL LENS MODELS BASED ON SUBMILLIMETER ARRAY IMAGING OFHERSCHEL-SELECTED STRONGLY LENSED SUB-MILLIMETER GALAXIES ATz> 1.5

Abstract

Strong gravitational lenses are now being routinely discovered in wide-field surveys at (sub-)millimeter wavelengths. We present Submillimeter Array (SMA) high-spatial resolution imaging and Gemini-South and Multiple Mirror Telescope optical spectroscopy of strong lens candidates discovered in the two widest extragalactic surveys conducted by the Herschel Space Observatory: the Herschel-Astrophysical Terahertz Large Area Survey (H-ATLAS) and the Herschel Multi-tiered Extragalactic Survey (HerMES). From a sample of 30 Herschel sources with S 500 > 100 mJy, 21 are strongly lensed (i.e., multiply imaged), 4 are moderately lensed (i.e., singly imaged), and the remainder require additional data to determine their lensing status. We apply a visibility-plane lens modeling technique to the SMA data to recover information about the masses of the lenses as well as the intrinsic (i.e., unlensed) sizes (r half ) and far-infrared luminosities (L FIR ) of the lensed submillimeter galaxies (SMGs). The sample of lenses comprises primarily isolated massive galaxies, but includes some groups and clusters as well. Several of the lenses are located at z lens > 0.7, a redshift regime that is inaccessible to lens searches based on Sloan Digital Sky Survey spectroscopy. The lensed SMGs are amplified by factors that are significantly below statistical model predictions given the 500 µm flux densities of our sample. We speculate that this may reflect a deficiency in our understanding of the intrinsic sizes and luminosities of the brightest SMGs. The lensed SMGs span nearly one decade in L FIR (median L FIR = 7.9 × 10 12 L ) and two decades in FIR luminosity surface density (median Σ FIR = 6.0 × 10 11 L kpc −2 ). The strong lenses in this sample and others identified via (sub-)mm surveys will provide a wealth of information regarding the astrophysics of galaxy formation and evolution over a wide range in redshift.

The Strong Gravitationally Lensed Herschel Galaxy HLock01: Optical Spectroscopy Reveals a Close Galaxy Merger with Evidence of Inflowing Gas

“…The new images show the same spatial offsets of the bright lensed images seen between the short and long wavelengths (see Figure 1), noticed by Conley et al (2011) and Gavazzi et al (2011). A new lens model was determined by Bussmann et al (2013) using the SMA 880 μm data, showing a large dust distribution, magnified by 9.2±0.4 with an effective radius of 4 kpc in the source plane. Its centroid matches the position of the gas distribution traced by the molecular gas, which we attribute to the source of the luminous far-IR emission, but both are offset with respect to the stars that are seen in the visible/near-IR (UV/optical in the rest-frame).…”

“…HLock01 was identified with Herschel/ SPIRE in the Herschel Multi-tiered Extragalactic Survey (HerMES; Oliver et al 2012), and investigated in a series of papers after significant follow-up effort Gavazzi et al 2011;Riechers et al 2011;Scott et al 2011;Bussmann et al 2013;Wardlow et al 2013). Here we give a summary of the main results from those papers.…”

“…Later on, Bussmann et al (2013) and Wardlow et al (2013) presented new imaging data for this system, using Hubble Space Telescope (HST) WFC3 F110W, new 880 μm SMA with higher spatial resolution than the data presented in Conley et al F110W image with labeled multiply lensed images at z;2.95 (blue) and foreground galaxies at z;0.65 (green). G4 is massive enough to split the lensed image B into two pieces on both sides (B1 and B2, see more details in Gavazzi et al 2011).…”

The Herschel Bright Sources (HerBS): sample definition and SCUBA-2 observations

“…The SCUBA-2 observations do not resolve lensing directly, as the beam size (13") is much larger than the typical Einstein rings caused by galaxy-galaxy lensing (∼ 1") (Bussmann et al 2013;ALMA Partnership 2015). However, we can estimate the lensing fraction of our sample when we compare the distribution of flux densities of our sources to the predictions of galaxy evolution models that include gravitational lensing.…”

Primordial star clusters at extreme magnification

“…Gonzalez et al 2010;Bussmann et al 2013;Bradley et al 2014), whereas magnifications of µ ≫ 100 are hampered both by the extremely low probabilities for such sightlines (often assumed to obey P (µ) ∝ µ −3 at the highmagnification end; e.g. Pei 1993, or equivalently P (> µ) ∝ µ −2 ) and the fact that the region in the source plane subject to such magnifications tends to be smaller than kpc-scale galaxies (e.g.…”