A new strong-lensing galaxy at z= 0.066: another elliptical galaxy with a lightweight IMF

Collier, William P.; Smith, Russell J.; Lucey, J. R.

doi:10.1093/mnras/sty1188

Cited by 32 publications

(35 citation statements)

References 46 publications

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“…The FORS2 spectrum does not exhibit the strong Hγ and Hδ absorption expected from a < 3 Gyr stellar population, nor the strong high-order Balmer absorption characteristic of composite populations with < 1 Gyr components. Despite the evidence for a recent interaction or accretion event in J0403-5055, the FORS2 spectrum supports the assumption in Collier et al (2018b) of an old stellar population inside the R Ein . A more rigorous analysis will be presented elsewhere.…”

Section: Double-image Lens J0403-0239contrasting

confidence: 67%

“…From the total sample, we have discovered one new galaxy-scale strong lens, J0403-0239, which is consistent with a MW-like IMF, α = 1.15 ± 0.17 (see Collier, Smith & Lucey 2018b), for an assumed old stellar population. The newly acquired, high S/N, FORS2 spectrum of J0403-0239 will be used to precisely constrain the age of the stellar population and hence α.…”

Section: Resultsmentioning

confidence: 64%

“…The pair of background emitters lie at z = 0.195, and the system has an R Ein of 1.47 arcsec. This R Ein probes the stellar dominated galaxy core, and in Collier et al (2018b) we reported the implications of this system on the IMF within massive ETGs. We found this galaxy to have a lightweight IMF, under the assumption of a typical old stellar population.…”

Section: Double-image Lens J0403-0239mentioning

confidence: 73%

“…The intrinsic distribution of the IMF within ETGs can be inferred from the four confirmed low-z lenses (taking values for SNL-0, SNL-1, SNL-2, J0403-0239 from Newman et al 2017;Collier et al 2018a,b). We have shown in Collier et al (2018b) that for a normal distribution with a flat prior on the mean and marginalising over the intrinsic scatter, α = 1.09 ± 0.08. Alternatively, by marginalising over the mean, the 90 per cent upper limit on the standard deviation of α is 0.32 (29 per cent).…”

Section: The Lens Populationmentioning

confidence: 95%

“…Analysis can then constrain α, using the same technique as the other low-z systems (i.e. J0403-0239 in Collier et al 2018b). In addition, the second faint source, separated by 3.4 arcsec, offers a potential double source-plane if the lens IMF is even modestly heavier than Kroupa (including DM).…”

Section: J0202-5055mentioning

confidence: 99%

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MNELLS: the MUSE nearby early-type galaxy lens locator survey

Collier

Smith

Lucey

2020

Monthly Notices of the Royal Astronomical Society

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Low-redshift strong-lensing galaxies can provide robust measurements of the stellar mass-to-light ratios in early-type galaxies (ETG), and hence constrain variations in the stellar initial mass function (IMF). At present, only a few such systems are known. Here, we report the first results from a blind search for gravitationally-lensed emission line sources behind 52 massive z < 0.07 ETGs with MUSE integral field spectroscopy. For 16 galaxies, new observations were acquired, whilst the other 36 were analysed from archival data. This project has previously yielded one confirmed galaxy-scale strong lens (J0403-0239) which we report in an earlier paper. J0403-0239 has since received follow-up observations, presented here, which indicate support for our earlier IMF results. Three cluster-scale, and hence dark-matter-dominated, lensing systems were also discovered (central galaxies of A4059, A2052 and AS555). For nine further galaxies, we detect a singly-imaged but closely-projected source within 6 arcsec (including one candidate with sources at three different redshifts); such cases can be exploited to derive upper limits on the IMF mass-excess factor, α. Combining the new lens and new upper limits, with the previously-discovered systems, we infer an average α = 1.06 ± 0.08 (marginalised over the intrinsic scatter), which is inconsistent with a Salpeter-like IMF (α = 1.55) at the 6σ level. We test the detection threshold in these short-exposure MUSE observations with the injection and recovery of simulated sources, and predict that one in twenty-five observations is expected to yield a new strong-lens system. Our observational results are consistent with this expected yield.

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Section: Double-image Lens J0403-0239contrasting

confidence: 67%

Section: Resultsmentioning

confidence: 64%

Section: Double-image Lens J0403-0239mentioning

confidence: 73%

Section: The Lens Populationmentioning

confidence: 95%

Section: J0202-5055mentioning

confidence: 99%

See 3 more Smart Citations

MNELLS: the MUSE nearby early-type galaxy lens locator survey

Collier

Smith

Lucey

2020

Monthly Notices of the Royal Astronomical Society

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Searching for Strong Gravitational Lenses

Lemon,

Courbin,

et al. 2024

Space Sci Rev

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Strong gravitational lenses provide unique laboratories for cosmological and astrophysical investigations, but they must first be discovered – a task that can be met with significant contamination by other astrophysical objects and asterisms. Here we review strong lens searches, covering various sources (quasars, galaxies, supernovae, FRBs, GRBs, and GWs), lenses (early- and late-type galaxies, groups, and clusters), datasets (imaging, spectra, and lightcurves), and wavelengths. We first present the physical characteristics of the lens and source populations, highlighting relevant details for constructing targeted searches. Search techniques are described based on the main lensing feature that is required for the technique to work, namely one of: (i) an associated magnification, (ii) multiple spatially-resolved images, (iii) multiple redshifts, or (iv) a non-zero time delay between images. To use the current lens samples for science, and for the design of future searches, we list several selection biases that exist due to these discovery techniques. We conclude by discussing the future of lens searches in upcoming surveys and the new population of lenses that will be discovered.

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Survey of gravitationally-lensed objects in HSC imaging (SuGOHI)

Sonnenfeld

Jaelani

Chan

et al. 2019

A&A

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Context. The determination of the stellar initial mass function (IMF) of massive galaxies is one of the open problems in cosmology. Strong gravitational lensing is one of the few methods that allow us to constrain the IMF outside of the Local Group. Aims. The goal of this study is to statistically constrain the distribution in the IMF mismatch parameter, defined as the ratio between the true stellar mass of a galaxy and that inferred assuming a reference IMF, of massive galaxies from the Baryon Oscillation Spectroscopic Survey (BOSS) constant mass (CMASS) sample. Methods. We took 23 strong lenses drawn from the CMASS sample, measured their Einstein radii and stellar masses using multi-band photometry from the Hyper Suprime-Cam survey, then fitted a model distribution for the IMF mismatch parameter and dark matter halo mass to the whole sample. We used a prior on halo mass from weak lensing measurements and accounted for strong lensing selection effects in our model. Results. Assuming a Navarro Frenk and White density profile for the dark matter distribution, we infer a value μIMF = −0.04 ± 0.11 for the average base-10 logarithm of the IMF mismatch parameter, defined with respect to a Chabrier IMF. A Salpeter IMF is in tension with our measurements. Conclusions. Our results are consistent with a scenario in which the region of massive galaxies where the IMF normalisation is significantly heavier than that of the Milky Way is much smaller than the scales 5 − 10 kpc probed by the Einstein radius of the lenses in our sample, as recent spatially-resolved studies of the IMF in massive galaxies suggest.

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A new strong-lensing galaxy at z= 0.066: another elliptical galaxy with a lightweight IMF

Cited by 32 publications

References 46 publications

MNELLS: the MUSE nearby early-type galaxy lens locator survey

MNELLS: the MUSE nearby early-type galaxy lens locator survey

Searching for Strong Gravitational Lenses

Survey of gravitationally-lensed objects in HSC imaging (SuGOHI)

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