arXiv subjects

A. Peck

Publications and source records attributed to A. Peck.

14 recordsLinked to original sources

arXiv2026

High Multiplicity Trigger for Long-Lived Particles in CMS detector

Searches for long-lived particles (LLPs) at the CMS experiment often involve unconventional event topologies that are difficult to efficiently select using standard trigger strategies. To improve sensitivity to such signatures during LHC Run~3 operation, a dedicated High Multiplicity Trigger (HMT) has been developed and deployed in the CMS trigger system. The trigger targets events containing unusually large numbers of hits in the CMS cathode strip chamber (CSC) muon detectors, a characteristic signature of several LLP scenarios involving displaced decays in the muon system. The HMT implementation, trigger logic, rate dependence with pileup, and operational stability are described. Optimized hit multiplicity thresholds are used to maintain acceptable trigger rates under high-luminosity and high-pileup conditions while preserving high efficiency across a broad range of LLP lifetimes and kinematic regimes. The trigger performance is evaluated using both simulated event samples and proton-proton collision data collected during Run~3 of the LHC. The HMT substantially extends the CMS sensitivity to non-standard signatures associated with LLP decays and provides a flexible platform for future searches for physics beyond the Standard Model.

hep-ex↗

arXiv2022

Alignment of the CLAS12 central hybrid tracker with a Kalman Filter

Several factors can contribute to the difficulty of aligning the sensors of tracking detectors, including a large number of modules, multiple types of detector technologies, and non-linear strip patterns on the sensors. All three of these factors apply to the CLAS12 CVT, which is a hybrid detector consisting of planar silicon sensors with non-parallel strips, and cylindrical micromegas sensors with longitudinal and arc-shaped strips located within a 5~T superconducting solenoid. To align this detector, we used the Kalman Alignment Algorithm, which accounts for correlations between the alignment parameters without requiring the time-consuming inversion of large matrices. This is the first time that this algorithm has been adapted for use with hybrid technologies, non-parallel strips, and curved sensors. We present the results for the first alignment of the CLAS12 CVT using straight tracks from cosmic rays and from a target with the magnetic field turned off. After running this procedure, we achieved alignment at the level of 10~$\mu$m, and the widths of the residual spectra were greatly reduced. These results attest to the flexibility of this algorithm and its applicability to future use in the CLAS12 CVT and other hybrid or curved trackers, such as those proposed for the future Electron-Ion Collider.

physics.ins-det↗

arXiv2022

The Apollo ATCA Design for the CMS Track Finder and the Pixel Readout at the HL-LHC

The challenging conditions of the High-Luminosity LHC require tailored hardware designs for the trigger and data acquisition systems. The Apollo platform features a "Service Module" with a powerful system-on-module computer that provides standard ATCA communications and application-specific "Command Module"s with large FPGAs and high-speed optical fiber links. The CMS version of Apollo will be used for the track finder and the pixel readout. It features up to two large FPGAs and more than 100 optical links with speeds up to 25\,Gb/s. We study carefully the design and performance of the board by using customized firmware to test power consumption, heat dissipation, and optical link integrity. This paper presents the results of these performance tests, design updates, and future plans.

physics.ins-det↗

arXiv2021

On-sky commissioning of MAROON-X: A new precision radial velocity spectrograph for Gemini North

MAROON-X is a fiber-fed, red-optical, high precision radial velocity spectrograph recently commissioned at the Gemini North telescope on Mauna Kea, Hawai'i. With a resolving power of 85,000 and a wavelength coverage of 500-920 nm, it delivers radial velocity measurements for late K and M dwarfs with sub-50 cm s$^{-1}$ precision. MAROON-X is currently the only optical EPRV spectrograph on a 8m-class telescope in the northern hemisphere and the only EPRV instrument on a large telescope with full access by the entire US community. We report here on the results of the commissioning campaign in December 2019 and early science results.

astro-ph.IM↗

arXiv2019

Strategic Scientific Plan for Gemini Observatory

We present the Strategic Scientific Plan (SSP) for the direction and activities of the Gemini Observatory in the 2020s. The overarching goal is to ensure that Gemini best uses the available resources to serve the needs of its international user community throughout the coming decade. The actionable items fall into three general categories: (1) preserving Gemini's current facilities and strengths; (2) developing instrumentation and software systems, including data pipelines, to enable new scientific capabilities that build on those strengths; (3) strategizing how visiting instruments can deliver additional valuable capabilities. We provide a high-level timeline (schematically illustrated in one figure) for the main developments discussed in this SSP. The schedule is ambitious, but in light of the recent Gemini in the Era of Multi-Messenger Astronomy (GEMMA) award from the NSF, the plan becomes achievable. Lists of milestones are given for gauging progress. As these milestones are reached and new instruments become available, some current instruments will need to be retired; we make recommendations in this regard. The final section concludes by reemphasizing the importance of a strong partnership committed to the needs of all members.

astro-ph.IM↗

arXiv2015

Construction of a medium-sized Schwarzschild-Couder telescope as a candidate for the Cherenkov Telescope Array: development of the optical alignment system

The Cherenkov Telescope Array (CTA) is an international project for a next-generation ground-based gamma-ray observatory. CTA, conceived as an array of tens of imaging atmospheric Cherenkov telescopes, comprising small, medium and large-size telescopes, is aiming to improve on the sensitivity of current-generation experiments by an order of magnitude and provide energy coverage from 20 GeV to more than 300 TeV. The Schwarzschild-Couder (SC) medium-size candidate telescope model features a novel aplanatic two-mirror optical design capable of a wide field-of-view with significantly improved imaging resolution as compared to the traditional Davis-Cotton optics design. Achieving this imaging resolution imposes strict alignment requirements to be accomplished by a dedicated alignment system. In this contribution we present the status of the development of the SC optical alignment system, soon to be materialized in a full-scale prototype SC medium-size telescope at the Fred Lawrence Whipple Observatory in southern Arizona.

astro-ph.IM↗

arXiv2012

[CII] line emission in massive star-forming galaxies at z=4.7

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of the [CII] 157.7micron fine structure line and thermal dust continuum emission from a pair of gas-rich galaxies at z=4.7, BR1202-0725. This system consists of a luminous quasar host galaxy and a bright submm galaxy (SMG), while a fainter star-forming galaxy is also spatially coincident within a 4" (25 kpc) region. All three galaxies are detected in the submm continuum, indicating FIR luminosities in excess of 10^13 Lsun for the two most luminous objects. The SMG and the quasar host galaxy are both detected in [CII] line emission with luminosities, L([CII]) = (10.0 +/- 1.5)x10^9 Lsun and L([CII]) = (6.5+/-1.0)x10^9 Lsun, respectively. We estimate a luminosity ratio, L([CII])/L(FIR) = (8.3+/-1.2)x10^-4 for the starburst SMG to the North, and L([CII])/L(FIR) = (2.5+/-0.4)x10^-4 for the quasar host galaxy, in agreement with previous high-redshift studies that suggest lower [CII]-to-FIR luminosity ratios in quasars than in starburst galaxies. The third fainter object with a flux density, S(340GHz) = 1.9+/-0.3 mJy, is coincident with a Ly-Alpha emitter and is detected in HST ACS F775W and F814W images but has no clear counterpart in the H-band. Even if this third companion does not lie at a similar redshift to BR1202-0725, the quasar and the SMG represent an overdensity of massive, infrared luminous star-forming galaxies within 1.3 Gyr of the Big Bang.

astro-ph.CO↗

arXiv2011

Pre-ALMA observations of GRBs in the mm/submm range

GRBs generate an afterglow emission that can be detected from radio to X-rays during days, or even weeks after the initial explosion. The peak of this emission crosses the mm/submm range during the first hours to days, making their study in this range crucial for constraining the models. Observations have been limited until now due to the low sensitivity of the observatories in this range. We present observations of 10 GRB afterglows obtained from APEX and SMA, as well as the first detection of a GRB with ALMA, and put them into context with all the observations that have been published until now in the spectral range that will be covered by ALMA. The catalogue of mm/submm observations collected here is the largest to date and is composed of 102 GRBs, of which 88 had afterglow observations, whereas the rest are host galaxy searches. With our programmes, we contributed with data of 11 GRBs and the discovery of 2 submm counterparts. In total, the full sample, including data from the literature, has 22 afterglow detections with redshift ranging from 0.168 to 8.2. GRBs have been detected in mm/submm wavelengths with peak luminosities spanning 2.5 orders of magnitude, the most luminous reaching 10^33erg s^-1 Hz^-1. We observe a correlation between the X-ray brightness at 0.5 days and the mm/submm peak brightness. Finally we give a rough estimate of the distribution of peak flux densities of GRB afterglows, based on the current mm/submm sample. Observations in the mm/submm bands have been shown to be crucial for our understanding of the physics of GRBs, but have until now been limited by the sensitivity of the observatories. With the start of the operations at ALMA, the sensitivity will be increased by more than an order of magnitude. Our estimates predict that, once completed, ALMA will detect up to 98% of the afterglows if observed during the passage of the peak synchrotron emission.

astro-ph.CO↗

arXiv2011

SMA/PdBI multiple line observations of the nearby Seyfert2 galaxy NGC 1068: Shock related gas kinematics and heating in the central 100pc?

We present high angular resolution (0.5-2.0") observations of the mm continuum and the 12CO(J=3-2), 13CO(J=3-2), 13CO(J=2-1), C18O(J=2-1), HCN(J=3-2), HCO+(J=4-3) and HCO+(J=3-2) line emission in the circumnuclear disk (r=100pc) of the proto-typical Seyfert type-2 galaxy NGC1068, carried out with the Submillimeter Array. We further include in our analysis new 13CO(J=1-0) and improved 12CO(J=2-1) observations of NGC1068 at high angular resolution (1.0-2.0") and sensitivity, conducted with the IRAM Plateau de Bure Interferometer. Based on the complex dynamics of the molecular gas emission indicating non-circular motions in the central ~100pc, we propose a scenario in which part of the molecular gas in the circumnuclear disk of NGC1068 is radially blown outwards as a result of shocks. This shock scenario is further supported by quite warm (Tkin>=200K) and dense (nH2=10^4cm^-3) gas constrained from the observed molecular line ratios. The HCN abundance in the circumnuclear disk is found to be [HCN]/[12CO]=10^-3.5. This is slightly higher than the abundances derived for galactic and extragalactic starforming/starbursting regions. This results lends further support to X-ray enhanced HCN formation in the circumnuclear disk of NGC1068, as suggested by earlier studies. The HCO+ abundance ([HCO+]/[12CO]=10^-5) appears to be somewhat lower than that of galactic and extragalactic starforming/starbursting regions. When trying to fit the cm to mm continuum emission by different thermal and non-thermal processes, it appears that electron-scattered synchrotron emission yields the best results while thermal free-free emission seems to over-predict the mm continuum emission.

astro-ph.CO↗

arXiv2009

Disentangling the circumnuclear environs of Centaurus A: I. High resolution molecular gas imaging

We present high resolution images of the 12CO(2-1) emission in the central 1' (1 kpc) of NGC 5128 (Centaurus A), observed using the SMA. We elucidate for the first time the distribution and kinematics of the molecular gas in this region with a resolution of 6'.0 x 2'.4 (100 pc x 40 pc). We spatially resolve the circumnuclear molecular gas in the inner 24'' x 12'' (400 pc x 200 pc), which is elongated along a position angle P.A. = 155 deg and perpendicular to the radio/X-ray jet. The SE and NW components of the circumnuclear gas are connected to molecular gas found at larger radii. This gas appears as two parallel filaments at P.A. = 120 deg, which are coextensive with the long sides of the 3 kiloparsec parallelogram shape of the previously observed dust continuum, as well as ionized and pure rotational H2 lines. Spatial and kinematical asymmetries are apparent in both the circumnuclear and outer gas, suggesting non-coplanar and/or non-circular motions. We extend to inner radii (r < 200 pc) previously studied warped disk models built to reproduce the central parallelogram-shaped structure. Adopting the warped disk model we would confirm a gap in emission between the radii r = 200 - 800 pc (12'' - 50''), as has been suggested previously. Although this model explains this prominent feature, however, our 12CO(2-1) observations show relevant deviations from this model. Namely, the physical connection between the circumnuclear gas and that at larger radii, brighter SE and NW sides on the parallelogram-shaped feature, and an outer curvature of its long sides. Overall it resembles more closely an S-shaped morphology, a trend that is also found in other molecular species. Hence, we explore qualitatively the possible contribution of a weak bi-symmetric potential which would naturally explain these peculiarities.

astro-ph.GA↗

arXiv2008

Results from an extensive simultaneous broadband campaign on the underluminous active nucleus M81*: further evidence for mass-scaling accretion in black holes

We present the results of a broadband simultaneous campaign on the nearby low-luminosity active galactic nucleus M81*. From February through August 2005, we observed M81* five times using the Chandra X-ray Observatory with the High-Energy Transmission Grating Spectrometer, complemented by ground-based observations with the Giant Meterwave Radio Telescope, the Very Large Array and Very Large Baseline Array, the Plateau de Bure Interferometer at IRAM, the Submillimeter Array and Lick Observatory. We discuss how the resulting spectra vary over short and longer timescales compared to previous results, especially in the X-rays where this is the first ever longer-term campaign at spatial resolution high enough to nearly isolate the nucleus (17pc). We compare the spectrum to our Galactic center weakly active nucleus Sgr A*, which has undergone similar campaigns, as well as to weakly accreting X-ray binaries in the context of outflow-dominated models. In agreement with recent results suggesting that the physics of weakly-accreting black holes scales predictably with mass, we find that the exact same model which successfully describes hard state X-ray binaries applies to M81*, with very similar physical parameters.

astro-ph↗

arXiv2007

High Resolution Imaging of Warm and Dense Molecular Gas in the Nuclear Region of the Luminous Infrared Galaxy NGC6240

We present ~2'' resolution CO(3-2), HCO+(4-3) and 880micron continuum images of the luminous infrared galaxy NGC6240 obtained at the Submillimeter Array. We find that the spatially resolved CO(3-2), HCO+(4-3) and the 880micron emission peaks between the two nuclear components that are both known to harbor AGNs. Our Large Velocity Gradient (LVG) analysis performed on each velocity channel suggests that the peak of the molecular gas emission traced in our observations is warm (T = 20 - 100K), dense (nH2 = 10^(5.0 - 5.4) cm^-3) and moderately optically thin (tau = 0.2 - 2) in the central 1 kpc. We also find large column densities of ~10^(23) cm^(-2). Such extreme conditions are observed over ~300 km s^(-1) centered around the CO derived systemic velocity. The derived molecular gas mass from the CO(3-2) emission and a CO-to-H2 conversion factor commonly used for ULIRGs is (6.9 +/- 1.7) x 10^9 Msun, and this is consistent with the mass derived from previous CO(2-1) observations. The gas is highly turbulent in the central kpc (Delta v_(FWZI) ~ 1175 km s^(-1)). Furthermore, possible inflow or outflow activity is suggested from the CO(3-2) velocity distribution. We tentatively state that 3.5 x 10^8 Msun of isolated CO(3-2) emission seen west of the northern disk may be associated with outflows from starburst superwinds, but the gas outflow scenario from one of the central AGN is not completely ruled out. Piecing all of the information together, the central region of NGC 6240 harbors 2 AGNs, ~10^(10) Msun of molecular gas mass, 5 x 10^7 Msun of dust mass, and has possible evidence of inflow and outflow activity.

astro-ph↗

arXiv2006

A Detection of [CII] line emission in the z=4.7 QSO BR1202-0725

We present ~3'' resolution imaging of the z=4.7 QSO BR1202-0725 at 900 micron from the Submillimeter Array. The two submillimeter continuum components are clearly resolved from each other, and the positions are consistent with previous lower frequency images. In addition, we detect [CII] line emission from the northern component. The ratio of [CII] to far-infrared luminosity is 0.04% for the northern component, and an upper limit of < 0.03% is obtained for the southern component. These ratios are similar to the low values found in local ultraluminous galaxies, indicating that the excitation conditions are different from those found in local field galaxies. X-ray emission is detected by Chandra from the southern component at L$_{0.5-2keV}=3\times10^{45}$~erg~s$^{-1}$, and detected at 99.6% confidence from the northern component at L$_{0.5-2keV}\sim3\times10^{44}$erg~s$^{-1}$, supporting the idea that BR1202-0725 is a pair of interacting galaxies at z=4.7 that each harbor an active nucleus.

astro-ph↗

arXiv2000

A Jet Model for the Afterglow Emission from GRB000301C

We present broad-band radio observations of the afterglow of GRB000301C, spanning from 1.4 to 350 GHz for the period of 3 to 83 days after the burst. This radio data, in addition to measurements at the optical bands, suggest that the afterglow arises from a collimated outflow, i.e. a jet. To test this hypothesis in a self-consistent manner, we employ a global fit and find that a model of a jet, expanding into a constant density medium (ISM+jet), provides the best fit to the data. A model of the burst occurring in a wind-shaped circumburst medium (wind-only model) can be ruled out, and a wind+jet model provides a much poorer fit of the optical/IR data than the ISM+jet model. In addition, we present the first clear indication that the reported fluctuations in the optical/IR are achromatic with similar amplitudes in all bands, and possibly extend into the radio regime. Using the parameters derived from the global fit, in particular a jet break time, t_{jet}=7.5 days, we infer a jet opening angle of θ=0.2, and consequently the estimate of the emitted energy in the GRB itself is reduced by a factor of 50 relative to the isotropic value, giving E=1.1 \times 10^{51} ergs.

astro-ph↗