N. R. Erickson

University of Massachusetts Amherst, Amherst Center, Massachusetts, United States

Are you N. R. Erickson?

Claim your profile

Publications (150)327.92 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Measuring redshifted CO line emission is an unambiguous method for obtaining an accurate redshift and total cold gas content of optically faint, dusty starburst systems. Here, we report the first successful spectroscopic redshift determination of AzTEC J095942.9+022938 ("COSMOS AzTEC-1"), the brightest 1.1mm continuum source found in the AzTEC/JCMT survey (Scott et al. 2008), through a clear detection of the redshifted CO (4-3) and CO (5-4) lines using the Redshift Search Receiver on the Large Millimeter Telescope. The CO redshift of $z=4.3420\pm0.0004$ is confirmed by the detection of the redshifted 158 micron [C II] line using the Submillimeter Array. The new redshift and Herschel photometry yield $L_{FIR}=(1.1\pm0.1)\times 10^{13} L_\odot$ and $SFR = 1300\, M_\odot$ yr$^{-1}$. Its molecular gas mass derived using the ULIRG conversion factor is $1.4\pm0.2 \times 10^{11} M_\odot$ while the total ISM mass derived from the 1.1mm dust continuum is $3.7\pm0.7 \times 10^{11} M_\odot$ assuming dust temperature of 35 K. Our dynamical mass analysis suggests that the compact gas disk ($r\approx 1.1$ kpc, inferred from dust continuum and SED analysis) has to be nearly face-on, providing a natural explanation for the uncommonly bright, compact stellar light seen by the HST. The [C II] line luminosity $L_{[C~II]} = 7.8\pm1.1 \times 10^9 L_\odot$ is remarkably high, but it is only 0.04 per cent of the total IR luminosity. AzTEC COSMOS-1 and other high redshift sources with a spatially resolved size extend the tight trend seen between [C II]/FIR ratio and $\Sigma_{FIR}$ among IR-bright galaxies reported by Diaz-Santos et al. (2013) by more than an order of magnitude, supporting the explanation that the higher intensity of the IR radiation field is responsible for the "[C II] deficiency" seen among luminous starburst galaxies.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The design, packaging, and characterization of a 70-95 GHz downconverter with 25 GHz of instantaneous bandwidth is presented. The circuit features a novel LO pass-through feature, making it suitable for integration in two-dimensional focal plane arrays with large-N. The chip has been packaged in a waveguide module and, in the packaged configuration, has a noise temperature below 2000 K (9 dB NF) and greater than 23 dB conversion gain, 8 dB input return loss, and 13 dB output return loss over the entire frequency range. The circuit operates with an LO power of just -5 dBm and has a DC power consumption of 170 mW.
    2014 IEEE/MTT-S International Microwave Symposium - MTT 2014; 06/2014
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We present 12CO (J=1-0) observations of a sample of local galaxies (0.04<z<0.08) with a large neutral hydrogen reservoir, or "HI monsters". The data were obtained using the Redshift Search Receiver on the FCRAO 14 m telescope. The sample consists of 20 HI-massive galaxies with M(HI)>3e10Msun from the ALFALFA survey and 8 LSBs with a comparable M(HI) (>1.5e10Msun). Our sample selection is purely based on the amount of neutral hydrogen, thereby providing a chance to study how atomic and molecular gas relate to each other in these HI-massive systems. We have detected CO in 15 out of 20 ALFALFA selected galaxies and 4 out of 8 LSBs with molecular gas mass M(H2) of (1-11)e9Msun. Their total cold gas masses of (2-7e10Msun make them some of the most gas-massive galaxies identified to date in the Local Universe. Observed trends associated with HI, H2, and stellar properties of the HI massive galaxies and the field comparison sample are analyzed in the context of theoretical models of galaxy cold gas content and evolution, and the importance of total gas content and improved recipes for handling spatially differentiated behaviors of disk and halo gas are identified as potential areas of improvement for the modeling.
    Monthly Notices of the Royal Astronomical Society 04/2014; 441(2). DOI:10.1093/mnras/stu670 · 5.23 Impact Factor
  • Source
    Aeree Chung · Min S. Yun · Gopal Naraynan · Mark Heyer · Neal R. Erickson
    [Show abstract] [Hide abstract]
    ABSTRACT: The feedback from galactic outflows is thought to play an important role in shaping the gas content, star formation history, and ultimately the stellar mass function of galaxies. Here we present evidence for massive molecular outflows associated with ultra-luminous infrared galaxies (ULIRGs) in the coadded Redshift Search Receiver 12CO(1-0) spectrum. Our stacked spectrum of 27 ULIRGs at z = 0.043-0.11 (freq_rest = 110-120 GHz) shows broad wings around the CO line with delta_V(FWZI)~2000 km/s. Its integrated line flux accounts for up to 25+/-5% of the total CO line luminosity. When interpreted as a massive molecular outflow wind, the associated mechanical energy can be explained by a concentrated starburst with SFR \geq 100 M_sun/yr, which agrees well with their SFR derived from the FIR luminosity. Using the high signal-to-noise stacked composite spectrum, we also probe 13CO and 12CN emission in the sample and discuss how the chemical abundance of molecular gas may vary depending on the physical conditions of the nuclear region.
    The Astrophysical Journal Letters 03/2011; 732(1). DOI:10.1088/2041-8205/732/1/L15 · 5.60 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The 3 mm wavelength spectra of 10 galaxies have been obtained at the Five College Radio Astronomy Observatory using a new, very broadband receiver and spectrometer, called the Redshift Search Receiver (RSR). The RSR has an instantaneous bandwidth of 37 GHz covering frequencies from 74 to 111 GHz and has a spectral resolution of 31 MHz (~100 km s–1). During tests of the RSR on the FCRAO 14 m telescope the complete 3 mm spectra of the central regions of NGC 253, Maffei 2, NGC1068, IC 342, M82, NGC 3079, NGC 3690, NGC 4258, Arp 220, and NGC 6240 were obtained. Within the wavelength band covered by the RSR, 20 spectral lines from 14 different atomic and molecular species were detected. Based on simultaneous fits to the spectrum of each galaxy, a number of key molecular line ratios are derived. A simple model which assumes the emission arises from an ensemble of Milky Way like Giant Molecular Cloud cores can adequately fit the observed line ratios using molecular abundances based on Galactic molecular cloud cores. Variations seen in some line ratios, such as 13CO/HCN and HCO+/HCN, can be explained if the mean density of the molecular gas varies from galaxy to galaxy. However, NGC 3690, NGC 4258, and NGC 6240 show very large HCO+/HCN ratios and require significant abundance enhancement of HCO+ over HCN, possible due to the proximity to active galactic nucleus activity. Finally, the mass of dense molecular gas is estimated and we infer that 25%-85% of the total molecular gas in the central regions of these galaxies must have densities greater than 104 cm–3.
    The Astronomical Journal 01/2011; 141(2):38. DOI:10.1088/0004-6256/141/2/38 · 4.05 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The reactive molecular ions, OH+, H2O+, and H3O+, key probes of the oxygen chemistry of the interstellar gas, have been observed toward Orion KL with the Heterodyne Instrument for Far Infrared on board the Herschel Space Observatory. All three N = 1 - 0 fine-structure transitions of OH+ at 909, 971, and 1033 GHz and both fine-structure components of the doublet ortho-H2O+ 111 - 000 transition at 1115 and 1139 GHz were detected, and an upper limit was obtained for H3O+. OH+ and H2O+ are observed purely in absorption, showing a narrow component at the source velocity of 9 km s-1, and a broad blue shifted absorption similar to that reported recently for HF and para-H218O, and attributed to the low velocity outflow of Orion KL. We estimate column densities of OH+ and H2O+ for the 9 km s-1 component of 9 ± 3 x 1012 cm-2 and 7 ± 2 x 1012 cm-2, and those in the outflow of 1.9 ± 0.7 x 1013 cm-2 and 1.0 ± 0.3 x 1013 cm-2. Upper limits of 2.4 x 1012 cm-2 and 8.7 ± 1012 cm-2 were derived for the column densities of ortho and para-H3O+ from transitions near 985 and 1657 GHz. The column densities of the three ions are up to an order of magnitude lower than those obtained from recent observations of W31C and W49N. A higher gas density, despite the assumption of a large ionization rate, may explain the comparatively low column densities of the ions. A part of this work was performed at the Jet Propulsion Laboratory, California Institute of Technology under contract with the National Aeronautics and Space Administration. Copyright 2010© California Institute of Technology. All rights reserved.
    Astronomy and Astrophysics 01/2011; 521. DOI:10.1051/0004-6361/201015117 · 4.48 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We report observations of the reactive molecular ions OH$^+$, H$_2$O$^+$, and H$_3$O$^+$ towards Orion KL with Herschel/HIFI. All three $N=1-0$ fine-structure transitions of OH$^+$ at 909, 971, and 1033GHz and both fine-structure components of the doublet {\it ortho}-H$_2$O$^+$ $1_{11}-0_{00}$ transition at 1115 and 1139GHz were detected; an upper limit was obtained for H$_3$O$^+$. OH$^+$ and H$_2$O$^+$ are observed purely in absorption, showing a narrow component at the source velocity of 9 kms$^{-1}$, and a broad blueshifted absorption similar to that reported recently for HF and {\it para}-H$_{2}^{18}$O, and attributed to the low velocity outflow of Orion KL. We estimate column densities of OH$^+$ and H$_2$O$^+$ for the 9 km s$^{-1}$ component of $9 \pm 3 \times 10^{12}$cm$^{-2}$ and $7 \pm 2 \times 10^{12}$cm$^{-2}$, and those in the outflow of $1.9 \pm 0.7 \times 10^{13}$cm$^{-2}$ and $1.0 \pm 0.3 \times 10^{13}$cm$^{-2}$. Upper limits of $2.4\times 10^{12}$cm$^{-2}$ and $8.7\times 10^{12}$cm$^{-2}$ were derived for the column densities of {\it ortho} and {\it para}-H$_3$O$^+$ from transitions near 985 and 1657GHz. The column densities of the three ions are up to an order of magnitude lower than those obtained from recent observations of W31C and W49N. The comparatively low column densities may be explained by a higher gas density despite the assumption of a very high ionization rate. Comment: 5 pages, 1 figure. Accepted to and to be published in the Herschel HIFI special issue of A\&A Letters
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We present the first results of a high-spectral-resolution survey of the carbon-rich evolved star IRC+10216 that was carried out with the HIFI spectrometer onboard Herschel. This survey covers all HIFI bands, with a spectral range from 488 to 1901GHz. In this letter we focus on the band-1b spectrum, in a spectral range 554.5-636.5GHz, where we identified 130 spectral features with intensities above 0.03 K and a signal-to-noise ratio >5. Detected lines arise from HCN, SiO, SiS, CS, CO, metal-bearing species and, surprisingly, silicon dicarbide (SiC2). We identified 55 SiC2 transitions involving energy levels between 300 and 900 K. By analysing these rotational lines, we conclude that SiC2 is produced in the inner dust formation zone, with an abundance of ~2x10^-7 relative to molecular hydrogen. These SiC2 lines have been observed for the first time in space and have been used to derive an SiC2 rotational temperature of ~204 K and a source-averaged column density of ~6.4x10^15 cm^-2. Furthermore, the high quality of the HIFI data set was used to improve the spectroscopic rotational constants of SiC2. Comment: A&A HIFI Special Issue, 2010
    Astronomy and Astrophysics 08/2010; 521. DOI:10.1051/0004-6361/201015150 · 4.48 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper describes the current status of the Large Millimeter Telescope (LMT), the near-term plans for the telescope and the initial suite of instrumentation. The LMT is a bi-national collaboration between Mexico and the USA, led by the Instituto Nacional de Astrofísica, Óptica y Electrónica (INAOE) and the University of Massachusetts at Amherst, to construct, commission and operate a 50m-diameter millimeter-wave radio telescope. Construction activities are nearly complete at the 4600m LMT site on the summit of Volcán Sierra Negra, an extinct volcano in the Mexican state of Puebla. Full movement of the telescope, under computer control in both azimuth and elevation, has been achieved. The commissioning and scientific operation of the LMT is divided into two major phases. As part of phase 1, the installation of precision surface segments for millimeter-wave operation within the inner 32m-diameter of the LMT surface is now complete. The alignment of these surface segments is underway. The telescope (in its 32-m diameter format) will be commissioned later this year with first-light scientific observations at 1mm and 3mm expected in early 2011. In phase 2, we will continue the installation and alignment of the remainder of the reflector surface, following which the final commissioning of the full 50-m LMT will take place. The LMT antenna, outfitted with its initial complement of scientific instruments, will be a world-leading scientific research facility for millimeter-wave astronomy.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We present Herschel/HIFI observations of the fundamental rotational transitions of ortho- and para-H$_2^{16}$O and H$_2^{18}$O in absorption towards Sagittarius~B2(M) and W31C. The ortho/para ratio in water in the foreground clouds on the line of sight towards these bright continuum sources is generally consistent with the statistical high-temperature ratio of 3, within the observational uncertainties. However, somewhat unexpectedly, we derive a low ortho/para ratio of $2.35 \pm 0.35$, corresponding to a spin temperature of $\sim$27~K, towards Sagittarius~B2(M) at velocities of the expanding molecular ring. Water molecules in this region appear to have formed with, or relaxed to, an ortho/para ratio close to the value corresponding to the local temperature of the gas and dust.
    Astronomy and Astrophysics 07/2010; 521. DOI:10.1051/0004-6361/201015072 · 4.48 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: H2O+ has been observed in its ortho- and para- states toward the massive star forming core Sgr B2(M), located close to the Galactic center. The observations show absorption in all spiral arm clouds between the Sun and Sgr B2. The average o/p ratio of H2O+ in most velocity intervals is 4.8, which corresponds to a nuclear spin temperature of 21 K. The relationship of this spin temperature to the formation temperature and current physical temperature of the gas hosting H2O+ is discussed, but no firm conclusion is reached. In the velocity interval 0 to 60 km/s, an ortho/para ratio of below unity is found, but if this is due to an artifact of contamination by other species or real is not clear. Comment: A&A, HIFI special issue, accepted
    Astronomy and Astrophysics 07/2010; 521. DOI:10.1051/0004-6361/201015087 · 4.48 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper describes the current status of the Large Millimeter Telescope (LMT), the near-term plans for the telescope and the initial suite of instrumentation. The LMT is a bi-national collaboration between Mexico and the USA, led by the Instituto Nacional de Astrofísica, Óptica y Electrónica (INAOE) and the University of Massachusetts at Amherst, to construct, commission and operate a 50m-diameter millimeter-wave radio telescope. Construction activities are nearly complete at the 4600m LMT site on the summit of Volcán Sierra Negra, an extinct volcano in the Mexican state of Puebla. Full movement of the telescope, under computer control in both azimuth and elevation, has been achieved. The commissioning and scientific operation of the LMT is divided into two major phases. As part of phase 1, the installation of precision surface segments for millimeter-wave operation within the inner 32m-diameter of the LMT surface is now complete. The alignment of these surface segments is underway. The telescope (in its 32-m diameter format) will be commissioned later this year with first-light scientific observations at 1mm and 3mm expected in early 2011. In phase 2, we will continue the installation and alignment of the remainder of the reflector surface, following which the final commissioning of the full 50-m LMT will take place. The LMT antenna, outfitted with its initial complement of scientific instruments, will be a world-leading scientific research facility for millimeter-wave astronomy.
    Proceedings of SPIE - The International Society for Optical Engineering 07/2010; 35:31-. DOI:10.1117/12.857974 · 0.20 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We report the first detection of the ground-state rotational transition of the methylidyne cation CH+ towards the massive star-forming region DR21 with the HIFI instrument onboard the Herschel satellite. The line profile exhibits a broad emission line, in addition to two deep and broad absorption features associated with the DR21 molecular ridge and foreground gas. These observations allow us to determine a CH+ J=1-0 line frequency of 835137 +/- 3 MHz, in good agreement with a recent experimental determination. We estimate the CH+ column density to be a few 1e13 cm^-2 in the gas seen in emission, and > 1e14 cm^-2 in the components responsible for the absorption, which is indicative of a high line of sight average abundance [CH+]/[H] > 1.2x10^-8. We show that the CH+ column densities agree well with the predictions of state-of-the-art C-shock models in dense UV-illuminated gas for the emission line, and with those of turbulent dissipation models in diffuse gas for the absorption lines. Comment: Accepted for publication in A&A
    Astronomy and Astrophysics 07/2010; 518:L118. DOI:10.1051/0004-6361/201014671 · 4.48 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Aims. This paper describes the Heterodyne Instrument for the Far-Infrared ( HIFI) that was launched onboard ESA's Herschel Space Observatory in May 2009. Methods. The instrument is a set of 7 heterodyne receivers that are electronically tuneable, covering 480-1250 GHz with SIS mixers and the 1410-1910 GHz range with hot electron bolometer (HEB) mixers. The local oscillator (LO) subsystem comprises a Ka-band synthesizer followed by 14 chains of frequency multipliers and 2 chains for each frequency band. A pair of auto-correlators and a pair of acousto-optical spectrometers process the two IF signals from the dual-polarization, single-pixel front-ends to provide instantaneous frequency coverage of 2 x 4 GHz, with a set of resolutions (125 kHz to 1 MHz) that are better than 0.1 kms(-1). Result. After a successful qualification and a pre-launch TB/TV test program, the flight instrument is now in-orbit and completed successfully the commissioning and performance verification phase. The in-orbit performance of the receivers matches the pre-launch sensitivities. We also report on the in-orbit performance of the receivers and some first results of HIFI's operations.
    Astronomy and Astrophysics 07/2010; 518. DOI:10.1051/0004-6361/201014698 · 4.48 Impact Factor
  • Source
    Neal R. Erickson · Thomas M. Goyette
    [Show abstract] [Hide abstract]
    ABSTRACT: We report on the first THz balanced mixer/upconverter using a Schottky diode MMIC chip. Using an optically pumped laser at 1562 GHz as an LO source with a coupled power of about 1 mW, and 1 mW input at an IF frequency of 10 GHz, we obtained a sideband output power of 23 uW (sum of two sidebands). As a mixer, at an LO of 1621 GHz, we obtain a conversion loss of 12.4 dB DSB and a noise temperature of 5600 K DSB. Response is believed to be similar over a band 1250-1650 GHz. New diodes have been designed for easier application as mixers up through 3 THz, and a new wafer run is in process.
    Proceedings of SPIE - The International Society for Optical Engineering 03/2010; DOI:10.1117/12.807505 · 0.20 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We report observations of the reactive molecular ions OH + , H 2 O + , and H 3 O + towards Orion KL with Herschel/HIFI. All three N = 1−0 fine-structure transitions of OH + at 909, 971, and 1033 GHz and both fine-structure components of the doublet ortho-H 2 O + 1 11 −0 00 transition at 1115 and 1139 GHz were detected; an upper limit was obtained for H 3 O + . OH + and H 2 O + are observed purely in absorption, showing a narrow component at the source velocity of 9 km s −1 , and a broad blueshifted absorption similar to that reported recently for HF and para-H 18 2 O, and attributed to the low velocity outflow of Orion KL. We estimate column densities of OH + and H 2 O + for the 9 km s −1 component of 9±3×10 12 cm −2 and 7± 2× 10 12 cm −2 , and those in the outflow of 1.9± 0.7× 10 13 cm −2 and 1.0± 0.3× 10 13 cm −2 . Upper limits of 2.4× 10 12 cm −2 and 8.7× 10 12 cm −2 were derived for the column densities of ortho and para-H 3 O + from transitions near 985 and 1657 GHz. The column densities of the three ions are up to an order of magnitude lower than those obtained from recent observations of W31C and W49N. The comparatively low column densities may be explained by a higher gas density despite the assumption of a very high ionization rate.
    Astronomy and Astrophysics 01/2010; 2526(14). · 4.48 Impact Factor
  • Source
    Aeree Chung · Gopal Narayanan · Min S. Yun · Mark Heyer · Neal R. Erickson
    [Show abstract] [Hide abstract]
    ABSTRACT: We present 12CO J=1-->0 observations of ultraluminous infrared galaxies (ULIRGs) obtained using the Redshift Search Receiver (RSR) on the 14-m telescope of the Five College Radio Astronomy Observatory. The RSR is a novel, dual-beam, dual-polarization receiver equipped with an ultra-wideband spectrometer backend that is being built as a facility receiver for the Large Millimeter Telescope. Our sample consists of 29 ULIRGs in the redshift range of 0.04-0.11, including 10 objects with no prior 12CO measurements. We have detected 27 systems (a detection rate of 93%), including 9 ULIRGs that are detected in CO for the first time. Our study has increased the number of local ULIRGs with CO measurements by ~15%. The CO line luminosity L'_CO, correlates well with far-infrared luminosity L_FIR, following the general trend of other local ULIRGs. However, compared to previous surveys we probe deeper into the low CO luminosity end of ULIRG population as a single study by including a number of CO faint objects in the sample. As a result, we find 1) a smoother transition between the ULIRG population and local QSOs in L_FIR-L'_CO ("star formation efficiency") space, and 2) a broader range of L_FIR/L'_CO flux ratio (~60--1000 L_sun/[K km/s/pc^2]) than previously reported. In our new survey, we also have found a small number of ULIRGs with extreme L_FIR/L'_CO which had been known to be rare. The mid-IR color and radio-excess of 56 local ULIRGs as a function of FIR-to-CO flux ratio is examined and compared with those of spirals/starburst galaxies and low-z QSOs. In this paper, using a large sample of local ULIRGs we explore the origin of their current power source and potential evolution to QSOs. Comment: 16 pages, 12 figures; accepted for publication in the Astronomical Journal
    The Astronomical Journal 06/2009; DOI:10.1088/0004-6256/138/3/858 · 4.05 Impact Factor
  • Aeree Chung · G. Narayanan · M. Yun · M. Heyer · N. Erickson
    [Show abstract] [Hide abstract]
    ABSTRACT: We present 12CO (J=1-0) observations of ultraluminous infrared galaxies (ULIRGs) obtained using the redshift search receiver (RSR) on the Five Colleges Radio Astronomy Observatory 14-m telescope. The RSR is a novel, dual-beam, dual-polarization receiver equipped with an ultra-wideband spectrometer backend that is being built as a facility receiver for the Large Millimeter Telescope. Our sample consists of 29 ULIRGs in the redshift range of 0.04-0.11, including 18 objects that were never observed at this wavelength before. We have detected 25 systems (a detection rate of 86%), including sixteen ULIRGs that are detected in CO for the first time. Our study has doubled the number of local ULIRGs with CO measurement and probed deeper into the CO faint objects compared to previous similar surveys. As a result, we find 1) a smoother transition between ULIRG population and local QSOs in LFIR-LCO' ("star formation efficiency") space, and 2) a broader range of LFIR/L CO' flux ratio (a few tens to 103 Lsun [K km/s pc2]) than previously reported. In our new survey, we also have found a small number of ULIRGs with extreme LFIR/LCO' which had been known to be rare. In this paper, we have investigated the mid-IR color and radio-excess of 58 local ULIRGs as a function of FIR-to-CO flux ratio, and compared it with those of spirals/starburst galaxies and low-z QSOs. Using a large sample of local ULIRGs, we explore the origin of their current power source and potential evolution to QSOs.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The three-millimeter-wavelength spectra of ten nearby galaxies have been obtained at the Five College Radio Astronomy Observatory (FCRAO) using a new, very broadband receiver and spectrometer. This instrument, which we call the Redshift Search Receiver (RSR), has an instantaneous bandwidth of 36 GHz covering wavelengths from 75 to 111 GHz, and has a spectral resolution of 31 MHz ( 100 km/s). The RSR is being build as one of the facility instruments for the Large Millimeter Telescope and designed primarily to determine the redshift of distant, dust-obscured galaxies. Tests of the RSR on the FCRAO 14-m telescope provided an opportunity to obtain complete three-millimeter spectra of the central regions of 10 nearby galaxies, Within the wavelength band covered by the RSR we detected 20 spectral lines from 14 different atomic and molecular species. We present the results of this spectral survey, examine some key molecular line ratios and discuss how differences in the chemistry and physical properties might give rise to the observed variation in these line ratios.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Three-millimeter-wavelength spectra of a number of nearby galaxies have been obtained at the Five College Radio Astronomy Observatory (FCRAO) using a new, very broadband receiver. This instrument, which we call the Redshift Search Receiver, has an instantaneous bandwidth of 36 GHz and operates from 74 to 110.5 GHz. The receiver has been built at UMass/FCRAO to be part of the initial instrumentation for the Large Millimeter Telescope (LMT) and is intended primarily for determination of the redshift of distant, dust-obscured galaxies. It is being tested on the FCRAO 14m by measuring the 3mm spectra of a number of nearby galaxies. There are interesting differences in the chemistry of these galaxies.
    Proceedings of the International Astronomical Union 12/2008; 4(S251). DOI:10.1017/S1743921308021698

Publication Stats

2k Citations
327.92 Total Impact Points

Institutions

  • 1980–2014
    • University of Massachusetts Amherst
      • Department of Astronomy
      Amherst Center, Massachusetts, United States
  • 1999
    • Johns Hopkins University
      • Department of Physics and Astronomy
      Baltimore, Maryland, United States
    • University of Virginia
      • Department of Electrical and Computer Engineering (ECE)
      Charlottesville, VA, United States
  • 1998
    • California Institute of Technology
      • Jet Propulsion Laboratory
      Pasadena, CA, United States
  • 1982–1984
    • National Radio Astronomy Observatory
      Charlottesville, Virginia, United States
  • 1980–1983
    • University of Texas at Austin
      • Department of Astronomy
      Austin, Texas, United States
  • 1977–1982
    • University of California, Berkeley
      • Department of Physics
      Berkeley, California, United States
  • 1978
    • Massachusetts Institute of Technology
      • Department of Electrical Engineering and Computer Science
      Cambridge, Massachusetts, United States