3,050 research outputs found
SNOWMASS WHITE PAPER - SLHC Endcap 1.4<y<4 Hadron Optical Calorimetry Upgrades in CMS with Applications to NLC/T-LEP, Intensity Frontier, and Beyond
Radiation damage in the plastic scintillator and/or readout WLS fibers in the
HE endcap calorimeter 1.4<y<4 in the CMS experiment at LHC and SLHC will
require remediation after 2018. We describe one alternative using the existing
brass absorber in the Endcap calorimeter, to replace the plastic scintillator
tiles with BaF2 tiles, or quartz tiles coated with thin(1-5 micron) films of
radiation-hard pTerphenyl(pTP) or the fast phosphor ZnO:Ga. These tiles would
be read-out by easily replaceable arrays of straight, parallel WLS fibers
coupled to clear plastic-cladded quartz fibers of proven radiation resistance.
We describe a second alternative with a new absorber matrix extending to
1.4<y<4 in a novel Analog Particle Flow Cerenkov Compensated Calorimeter, using
a dual readout of quartz tiles and scintillating (plastic, BaF2, or pTP/ ZnO:Ga
thin film coated quartz, or liquid scintillator) tiles, also using easily
replaceable arrays of parallel WLS fibers coupled to clear quartz transmitting
fibers for readout. An Analog Particle Flow Scintillator-Cerenkov Compensated
Calorimeter has application in NLC/T-LEP detectors and Intensity Frontier
detectors
Snowmass White Paper CMS Upgrade: Forward Lepton-Photon System
This White Paper outlines a proposal for an upgraded forward region to extend
CMS lepton (e, mu) and photon physics reach out to 2.2<eta<5 for LHC and SLHC,
which also provides better performance for the existing or new forward hadron
calorimetry for jet energy and (eta, phi) measurements, especially under
pileup/overlaps at high lumi, as LHC luminosity, energy and radiation damage
increases
G-2 and CMS Fast Optical Calorimetry
Final report on CMS funding for the construction, tests and installation of the Forward Hadron Calorimeter
Measuring Supermassive Black Holes in Distant Galaxies with Central Lensed Images
The supermassive black hole at the center of a distant galaxy can be weighed,
in rare but realistic cases, when the galaxy acts as a strong gravitational
lens. The central image that should be produced by the lens is either destroyed
or accompanied by a second central image, depending on the mass of the black
hole. We demonstrate that when a central image pair is detected, the mass of
the black hole can be determined with an accuracy of < 0.1 dex, if the form of
the smooth mass distribution near the galaxy core is known. Uncertainty in the
central mass distribution introduces a systematic error in the black hole mass
measurement. However, even with nearly complete ignorance of the inner mass
distribution, the black hole mass can still be determined to within a factor of
10. Central image pairs should be readily observable with future radio
interferometers, allowing this technique to be used for a census of
supermassive black holes in inactive galaxies at significant redshift (0.2 < z
< 1.0).Comment: 12 pages including 4 figures, ApJL in press (edited to match
published version, one typo corrected
The central image of a gravitationally lensed quasar
A galaxy can act as a gravitational lens, producing multiple images of a
background object. Theory predicts there should be an odd number of images but,
paradoxically, almost all observed lenses have 2 or 4 images. The missing image
should be faint and appear near the galaxy's center. These ``central images''
have long been sought as probes of galactic cores too distant to resolve with
ordinary observations. There are five candidates, but in one case the third
image is not necessarily a central image, and in the others, the central
component might be a foreground source rather than a lensed image. Here we
report the most secure identification of a central image, based on radio
observations of PMN J1632-0033, one of the latter candidates. Lens models
incorporating the central image show that the mass of the lens galaxy's central
black hole is less than 2 x 10^8 M_sun, and the galaxy's surface density at the
location of the central image is more than 20,000 M_sun per square parsec, in
agreement with expectations based on observations of galaxies hundreds of times
closer to the Earth.Comment: Nature, in press [7 pp, 2 figs]. Standard media embargo applies
before publicatio
TERMS Photometry of Known Transiting Exoplanets
The Transit Ephemeris Refinement and Monitoring Survey (TERMS) conducts
radial velocity and photometric monitoring of known exoplanets in order to
refine planetary orbits and predictions of possible transit times. This effort
is primarily directed towards planets not known to transit, but a small sample
of our targets consist of known transiting systems. Here we present precision
photometry for 6 WASP planets acquired during their transit windows. We perform
a Markov Chain Monte Carlo (MCMC) analysis for each planet and combine these
data with previous measurements to redetermine the period and ephemerides for
these planets. These observations provide recent mid-transit times which are
useful for scheduling future observations. Our results improve the ephemerides
of WASP-4b, WASP-5b and WASP-6b and reduce the uncertainties on the mid-transit
time for WASP-29b. We also confirm the orbital, stellar and planetary
parameters of all 6 systems.Comment: 12 pages; 6 figures; 9 tables; accepted for publication in AJ; two
references updated and minor improvements made to match the version to be
publishe
Securing the legacy of TESS through the care and maintenance of TESS planet ephemerides
Much of the science from the exoplanets detected by the TESS mission relies
on precisely predicted transit times that are needed for many follow-up
characterization studies. We investigate ephemeris deterioration for simulated
TESS planets and find that the ephemerides of 81% of those will have expired
(i.e. 1 mid-transit time uncertainties greater than 30 minutes) one
year after their TESS observations. We verify these results using a sample of
TESS planet candidates as well. In particular, of the simulated planets that
would be recommended as JWST targets by Kempton et al. (2018), 80% will
have mid-transit time uncertainties 30 minutes by the earliest time JWST
would observe them. This rapid deterioration is driven primarily by the
relatively short time baseline of TESS observations. We describe strategies for
maintaining TESS ephemerides fresh through follow-up transit observations. We
find that the longer the baseline between the TESS and the follow-up
observations, the longer the ephemerides stay fresh, and that 51% of simulated
primary mission TESS planets will require space-based observations. The
recently-approved extension to the TESS mission will rescue the ephemerides of
most (though not all) primary mission planets, but the benefits of these new
observations can only be reaped two years after the primary mission
observations. Moreover, the ephemerides of most primary mission TESS planets
(as well as those newly discovered during the extended mission) will again have
expired by the time future facilities such as the ELTs, Ariel and the possible
LUVOIR/OST missions come online, unless maintenance follow-up observations are
obtained.Comment: 16 pages, 10 figures, accepted to AJ; main changes are cross-checking
results against the sample of real TOIs, and addressing the impact of the
TESS extended missio
The Reddest Quasars
In a survey of quasar candidates selected by matching the FIRST and 2MASS
catalogs, we have found two extraordinarily red quasars. FIRST J013435.7-093102
is a 1 Jy source at z=2.216 and has B-K > 10, while FIRST J073820.1+275045 is a
2.5 mJy source at z=1.985 with B-K = 8.4. FIRST J073820.1+275045 has strong
absorption lines of MgII and CIV in the rest frame of the quasar and is highly
polarized in the rest frame ultraviolet, strongly favoring the interpretation
that its red spectral energy distribution is caused by dust reddening local to
the quasar. FIRST J073820.1+275045 is thus one of the few low radio-luminosity,
highly dust-reddened quasars known. The available observational evidence for
FIRST J013435.7-093102 leads us to conclude that it too is reddened by dust. We
show that FIRST J013435.7-093102 is gravitationally lensed, increasing the
number of known lensed, extremely dust-reddened quasars to at least three,
including MG0414-0534 and PKS1830-211. We discuss the implications of whether
these objects are reddened by dust in the host or lensing galaxies. If reddened
by their local environment, then we estimate that between 10 and 20% of the
radio-loud quasar population is reddened by dust in the host galaxy. The
discovery of FIRST J073820.1+275045 and objects now emerging from X-ray surveys
suggests the existence of an analogous radio-quiet red quasar population. Such
objects will be entirely missed by standard radio or optical quasar surveys. If
dust in the lensing galaxies is primarily responsible for the extreme redness
of the lensed quasars, then an untold number of gravitationally lensed quasars
are being overlooked.Comment: AASTEX 24 pp., 7 figs; accepted by ApJ. See also the preprint
astro-ph/0107435 by Winn et al., who independently discovered that
J013435.7-093102 is gravitationally lense
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