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The Most Powerful Lenses in the Universe: Quasar Micro-Lensing

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The Most Powerful Lenses in the Universe: Quasar Micro-Lensing The Most Powerful Lenses in the Universe: Quasar Micro-lensing Dave Pooley (Trinity University) Paul Schechter (MIT), Joachim Wambsganss (Heidelberg), Saul Rappaport (MIT), Jeffrey Blackburne (Arete), Jordan Koeller, Brian Guerrero (Trinity), Naim Barnett (Trinity), Jackson Braley (Trinity) Subject: Chandra data Date: December 7, 1999 at 7:56:02 PM EST This Saturday will be my To: [email protected], [email protected], [email protected] th From [email protected] Tue Dec 7 17:58:28 1999 20 anniversary of Message-Id: <[email protected]> X-Mailer: exmh version 2.0.2 2/24/98 To: LEWIN (Walter Lewin) analyzing Chandra data. cc: [email protected] (Pepi Fabbiano), [email protected], [email protected] (Arcops Account), [email protected] (Joy S. Nichols), [email protected] (Roger J. Brissenden) Subject: Your Chandra Observation 500059 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Tue, 07 Dec 1999 17:57:27 -0500 SN 1999em, ObsID 763 From: "Tomas P. Girnius" <[email protected]> Status: RO Dear Dr. Lewin, This message is to let you know that your observation SeqNum 500059, ObsId 763 is available for downloading by you through anonymous ftp: ftp asc.harvard.edu anonymous <your name and address as password> bin cd /pub/arcftp/.go/763/763_3399/tar_1805 dir -rw-r--r-- 1 arcops 2465 Dec 7 17:47 500059.contents -rw-r--r-- 1 arcops 144389120 Dec 7 17:47 500059.tar -rw-r--r-- 1 arcops 2216 Dec 7 17:42 README -rw-r--r-- 1 arcops 1090 Dec 7 17:47 caveat.txt -rw-r--r-- 1 arcops 4096 Dec 7 17:42 vv.763 mget * bye 0 5 10 15 20 25 30 35 40 45 50 Untarring the data will create a directory 500059 in the current directory, containing a small directory tree with the data. The .contents file contains a listing of the .tar file. The vv file contains the V&V report. Fundamental astronomy has a fundamental problem. Nobody ever measures the stellar mass. That is not a measurable thing; it’s an inferred quantity. You measure light, OK? You can measure light in many bands, but you infer stellar mass. Everybody seems to agree on certain assumptions that are completely unproven. — Carlos Frenk, 2017 May 15 The Astrophysical Journal, 845:157 (18pp), 2017 August 20 https://doi.org/10.3847/1538-4357/aa816d © 2017. The American Astronomical Society. All rights reserved. The Initial Mass Function in the Nearest Strong Lenses from SNELLS: Assessing the Consistency of Lensing, Dynamical, and Spectroscopic Constraints Andrew B. Newman1 , Russell J. Smith2 , Charlie Conroy3 , Alexa Villaume4 , and Pieter van Dokkum5 1 The Observatories of the Carnegie Institution for Science, Pasadena, CA, USA; [email protected] 2 Centre for Extragalactic Astronomy, University of Durham, South Road, Durham, UK 3 Department of Astronomy, Harvard University, Cambridge, MA, USA 4 Department ofMain Astronomy and sources Astrophysics, University of ofuncertainty California, Santa Cruz, CA, USA 5 Department of Astrophysical Sciences, Yale University, New Haven, CT, USA Received 2016 December 16;lensing: revised 2017 July 5;contribution accepted 2017 July 19; published of 2017 dark August 22 matter stellar dynamics:Abstractcontribution of dark matter We present new observations of the three nearest early-type galaxy (ETG) strong lenses discovered in the SINFONI Nearby Elliptical Lens Locator Survey (SNELLS). Based on their lensing masses, these ETGs were inferredstellar to have a stellar pop. initial masssynthesis: function (IMF) consistentlow-mass with that of the cutoff Milky Way, of not theIMF bottom-heavy IMF that has been reported as typical for high-σ ETGs based on lensing, dynamical, and stellar population synthesis techniques. We use these unique systems to test the consistency of IMF estimates derived from different The Astrophysical Journal, 837:166 (8pp), 2017 Marchfi 10 https://doi.org/10.3847/1538-4357/aa6190fi methods. We rst estimate the stellar M*/L using lensing and stellar dynamics. We then t high-quality“To illustrate optical the sensitivity of © 2017. The American Astronomical Society. All rightsspectra reserved. of the lenses using an updated version of the stellar population synthesis models developed by Conroy & van Dokkum. When examined individually, we find good agreement among these methods for onethe galaxy. total The mass to the cutoff, for a The Stellar Initialother Mass two Functiongalaxies show in 2– Early-type3σ tension with Galaxies lensing estimates, from dependingAbsorption on the Line dark matter contribution,single whenpower law with α=2.7, considering IMFs that extend to 0.08 Me. Allowing a variable low-mass cutoff or a nonparametric form of the IMF Spectroscopy.reduces IV. the A tension Super-Salpeter among the IMF IMF estimates in the to < Center2σ. There of is moderate NGC 1407 evidence for a reduced numberthe mass-to-light of low- ratio is 70% mass stars infrom the SNELLS Non-parametric spectra, but no Modelssuch evidence in a composite spectrum of matched-σ ETGs drawn from the SDSS. Such variation in the form of the IMF at low stellar masses (m 0.3 M ), if present, couldhigher reconcile if the cutoff is 0.05M 1 2 3 e ⊙ lensingCharlie/dynamical Conroy , Pieter and spectroscopic G. van Dokkum IMF, and estimates Alexa Villaume for the SNELLS lenses and account for their lighter M /L 1 Department of Astronomy, Harvard University, Cambridge, MA, 02138, USA compared* to 0.08M .” relative2 Department to the of mean Astronomy, matched- Yale University,σ ETG. New We Haven, provide CT, 06511, the spectra USA used in this study to facilitate future comparisons. ⊙ 3 DepartmentKey of words: Astronomygalaxies: and Astrophysics, elliptical University and lenticular, of California, cD Santa– galaxies: Cruz, CA 95064, stellar USA content – gravitational lensing: strong Received 2016 November 30; revised 2017 February 8; accepted 2017 February 16; published 2017 March 15 Supporting material: machine-readable table Abstract It is now well-established that the stellar initial mass function (IMF) can be determined from the absorption line spectra of old stellar systems, and this1. has Introduction been used to measure the IMF and its variationanomalies, across which the early-type Schechter et al. (2014) have demonstrated using ten multiply imaged quasars. galaxy population.The Previous stellar initial work mass focused function on measuring(IMF) is the both slope fundamental of the IMF over one or more stellar mass The second method is based on a detailed analysis of absorption intervals, implicitlyas a basic assuming outcome that this of the is a star good formation description process of the IMF and anda critical that the IMF has a universal low-mass cutoff. In this work we consider more flexible IMFs, including two-component powerline laws spectra. with a variable Recent low- stellar population synthesis (SPS) models ingredient for interpreting numerous extragalactic observations. mass cutoff and a general non-parametric model. We demonstrate with mock spectra thathave the detailedopened upshape studies of the of the chemical abundance patterns and Although the IMF is consistent with being independent of the−1 IMF can be accurately recovered as long as the data quality is high (S/N 300 Å ) andthe cover IMF a wide in unresolved wavelength old populations at a remarkable level of range (0.4–1.0environmentμm). We apply within these theflexible Milky IMF Way models(e.g., Bastian to a high et S al./N2010 spectrum), ofdetail the center(Conroy of the & massive van Dokkum 2012a, 2012b;vanDokkum& elliptical galaxythere NGC is little 1407. theoretical Fitting the reason spectrum for with this non-parametric to hold across IMFs, all star- we find thatConroy the IMF2012;LaBarberaetal. in the center 2013;Spinielloetal.2014).While shows a continuousforming rise regions extending where toward the physical the hydrogen-burning conditions can limit, vary with widely a behaviorvarying that is well-approximated the age and metallicity imparts large and well-known by a power law(e.g., with Hennebelle an index of − &2.7. Chabrier These results2008; provide Krumholz strong et evidence al. 2011 for; the existencechanges of to extreme integrated(super- galaxy spectra, variations in the IMF also Salpeter) IMFs in the cores of massive galaxies. Hopkins 2012, 2013; Chabrier et al. 2014). Since only the affect surface gravity-sensitive absorption lines at levels that are Key words: galaxies:brightest evolution stars beyond– galaxies: the local stellar volume content – canstars: be luminosity individually function,subtle mass function but detectable (;1%) with high-quality data. detected, constraints on the IMF in external systems are When these two methods are applied to ETGs, both are challenging and must rely on integrated light observations. consistent with a trend of “heavier” IMFs in higher-σ (Cappellari 1.Two Introduction such approaches have been applied tofor early-type radial variation galaxies in the IMF (McConnell et al. 2016; Zieleniewski et al. 2017), thoughet al. 2013a it is not; La clear Barbera if the different et al. 2015), more metal-rich (Martín- The initial mass function(ETGs).The(IMFfi) rstconnects is to model a variety the total of mass distribution using conclusions are due to smallNavarro sample et al.sizes2015c or the), or analysis more α-enhanced (Conroy & van astrophysical phenomenagravitational including lensing, star formation, stellar kinematics, stellar or both in combination techniques. The existence ofDokkum strong IMF2012b gradients) galaxies. implies(Since that these quantities are mutually feedback, the relative number of stellar remnants, and heavy (Auger et al. 2010b;Treuetal.2010;Spinielloetal.direct comparison2011 between; differentcorrelated, techniques the primary requires driver careful of the correlation is more difficult element production, andThomas is a critical et al. ingredient2011;Barnabèetal. in modeling2013 the ;Cappellarietal.consideration2013a of aperture; effects.to establish.) The “heaviness” of the IMF can be expressed via integrated light from distantConroy galaxies.
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