Millimetre/submillimetre-wave emission line searches for high-redshift galaxies

The redshifted spectral line radiation emitted from both atomic fine-structure and molecular rotational transitions in the interstellar medium (ISM) of high-redshift galaxies can be detected in the centimetre, millimetre and submillimetre wavebands. Here we predict the counts of galaxies detectable in an array of molecular and atomic lines. This calculation requires a reasonable knowledge of both the surface density of these galaxies on the sky, and the physical conditions in their ISM. The surface density is constrained using the results of submillimetre-wave continuum surveys. Follow-up OVRO Millimeter Array observations of two of the galaxies detected in the dust continuum have provided direct measurements of CO rotational line emission at redshifts of 2.56 and 2.81. Based on these direct high-redshift observations and on models of the ISM that are constrained by observations of low-redshift ultraluminous infrared galaxies, we predict the surface density of line-emitting galaxies as a function of line flux density and observing frequency. We incorporate the sensitivities and mapping speeds of existing and future millimetre/submillimetre-wave telescopes and spectrographs, and so assess the prospects for blank-field surveys to detect this line emission from gas-rich high-redshift galaxies.Comment: 13 pages, 12 figures, to appear in MNRAS. Final proof versio

New evaluation of the Castel di Guido \u27hyoid\u27

Castel di Guido is located west of Rome and part of the Aurelian formation (Mariani-Constantini et al., 2001) along with other sites such as Torre in Petra and La Polledrara (Mussi, 2001). These localities are a mixture of surface collections and excavated sites, all associated with Acheulean tools and dated to MIS 9. At Castel di Guido material was collected from the surface and excavations in an erosional channel (Mariani-Constantini et al., 2001; Mussi, 2001). The Middle Pleistocene dates suggest an age of around 400 ka. Direct associations between the human bones and tools do not exist, but based on the size and degree of fossilization the human material is thought to be late Acheulean. The deposits overlie tuffs from the Sabatini volcanic eruptions, dated at 431 ka+/-40 ka - 438 ka +/- 40 ka. so cannot be older than this. Originally six fragmentary bones were recovered from the site (Alciati et al., 2005) but Capasso, Michetti & D\u27Anastasio (2008) found additional material based on their survey of the material for post-mortem modifications

Interferometric Observations of Powerful CO Emission from the three Submillimeter Galaxies at z=2.30, 2.51 and 3.35

We report IRAM Plateau de Bure, millimeter interferometry of three z=~2.4 to 3.4, SCUBA deep field galaxies. Our CO line observations confirm the rest-frame UV/optical redshifts, thus more than doubling the number of confirmed, published redshifts of the faint submillimeter population and proving their high-z nature. In all three sources our measurements of the intrinsic gas and dynamical mass are large (1e10 to 1e11 Msun). In at least two cases the data show that the submillimeter sources are part of an interacting system. Together with recent information gathered in the X-ray, optical and radio bands our observations support the interpretation that the submm-population consists of gas rich (gas to dynamical mass ratio ~0.5) and massive, composite starburst/AGN systems, which are undergoing a major burst of star formation and are evolving into m*-galaxies.Comment: only minor modifications to comply with the ApJL edition rule

Reduction algorithms for the multiband imaging photometer for Spitzer: 6 months of flight data

The first six months of flight data from the Multiband Imaging Photometer for Spitzer (MIPS) were used to test MIPS reduction algorithms based on extensive preflight laboratory data and modeling. The underlying approach for the preflight algorithms has been found to be sound, but some modifications have improved the performance. The main changes are scan mirror dependent flat fields at 24 μm, hand processing to remove the time dependent stim flash latents and fast/slow response variations at 70 μm, and the use of asteroids and other sources instead of stars for flux calibration at 160 μm due to a blue "leak." The photometric accuracy of flux measurements is currently 5%, 10%, and 20% at 24, 70, and 160 μm, respectively. These numbers are expected to improve as more flight data are analyzed and data reduction algorithms refined

A Study of CO Emission in High Redshift QSOs Using the Owens Valley Millimeter Array

Searches for CO emission in high-redshift objects have traditionally suffered from the accuracy of optically-derived redshifts due to lack of bandwidth in correlators at radio observatories. This problem has motivated the creation of the new COBRA continuum correlator, with 4 GHz available bandwidth, at the Owens Valley Radio Observatory Millimeter Array. Presented here are the first scientific results from COBRA. We report detections of redshifted CO(J=3-2) emission in the QSOs SMM J04135+10277 and VCV J140955.5+562827, as well as a probable detection in RX J0911.4+0551. At redshifts of z=2.846, z=2.585, and z=2.796, we find integrated CO flux densities of 5.4 Jy km/s, 2.4 Jy km/s, and 2.9 Jy km/s for SMM J04135+10277, VCV J140955.5+562827, and RX J0911.4+0551, respectively, over linewidths of Delta(V_{FWHM}) ~ 350 km/s. These measurements, when corrected for gravitational lensing, correspond to molecular gas masses of order M(H_2) ~ 10^{9.6-11.1} solar masses, and are consistent with previous CO observations of high-redshift QSOs. We also report 3-sigma upper limits on CO(3-2) emission in the QSO LBQS 0018-0220 of 1.3 Jy km/s. We do not detect significant 3mm continuum emission from any of the QSOs, with the exception of a tentative (3-sigma) detection in RX J0911.4+0551 of S_{3mm}=0.92 mJy/beam.Comment: 18 pages, 5 figures, 2 tables, accepted to ApJ. Changes made for version 2: citations added, 2 objects added to Table 2 and Figure

OH Satellite Line Masers and an AGN Candidate in M82

We report the detection of OH satellite line masers at 1720 MHz and 1612 MHz from the nuclear region of the starburst galaxy M82. The observations were aimed at detecting 1720 MHz maser emission from the known radio emitting SNR in the nuclear region. At 1720 MHz we detect six features above the 5-sigma limit set by noise, four in emission and two in absorption. Three of the emission features appear closely associated with known discrete continuum radio sources, and one of the absorption features is precisely coincident with the discrete continuum source 44.01+59.6. The latter source also exhibits strong 1612 MHz emission at the same velocity. No other 1612 MHz features were detected. All of the 1720 MHz emission features are consistent with masers pumped by collisions with molecular hydrogen at densities between 10^3 cm^{-3} and 10^5 cm^{-3}, and T_k between 50 K and 250 K. The absorption and emission associated with the two satellite lines in 44.01+59.6, together with other evidence, points to the possibility that this source is the AGN in M82.Comment: accepted ApJ

Molecular Gas and Nuclear Activity in Radio Galaxies Detected by IRAS

This paper reports the latest results from a millimeter-wave (CO) spectroscopic survey of IRAS-detected radio galaxies with L_1.4GHz ~ 10^23-28 W/Hz in the redshift range z ~ 0.02-0.15. The IRAS flux-limited sample contains 33 radio galaxies with different radio morphologies and a broad range of infrared luminosities L_IR = 10^9-12 L_sun), allowing for an investigation of (a) whether low-z radio-selected AGN reside in molecular gas-rich host galaxes, and (b) whether the CO properties are correlated with the properties of the host galaxy or the AGN. All of the radio galaxies in Mazzarella et al. (1993) and Mirabel et al. (1989) have been reobserved. Three new CO detections have been made, raising the total number of CO detections to nine and setting the survey detection rate at ~ 25%. Many of the CO lines have double-peaked profiles, and the CO line widths are broad (average Delta v_FWHM ~ 500+/-130 km/s), exceeding the average CO widths of both ultraluminous infrared galaxies (300+/-90 km/s) and Palomar-Green QSOs (260+/-160 km/s), and thus being indicative of massive host galaxies. The CO luminosities translate into molecular gas masses of ~ 0.4-7x10^9 M_sun, however, the 3-sigma CO upper limits for nondetections do not rule out a molecular gas mass as high as that of the Milky Way (~ 3x10^9 M_sun). Optical images of eight out of nine molecular gas-rich radio galaxies show evidence of close companions and/or tidal features. Finally, there is no obvious correlation between radio power and molecular gas mass. However, it is notable that only one F-R II galaxy out of 12 is detected in this CO survey; the remaining detections are of galaxies hosting F-R I and compact radio jets.Comment: LaTex, 33 pages, including 1 jpg figure and 14 postscript figures, ApJS, in press (August 2005

MIPS J142824.0+352619: A Hyperluminous Starburst Galaxy at z=1.325

Using the SHARC-II camera at the Caltech Submillimeter Observatory to obtain 350 micron images of sources detected with the MIPS instrument on Spitzer, we have discovered a remarkable object at z=1.325+/-0.002 with an apparent Far-Infrared luminosity of 3.2(+/-0.7) x 10^13 Lsun. Unlike other z>1 sources of comparable luminosity selected from mid-IR surveys, MIPS J142824.0+352619 lacks any trace of AGN activity, and is likely a luminous analog of galaxies selected locally by IRAS, or at high redshift in the submillimeter. This source appears to be lensed by a foreground elliptical galaxy at z=1.034, although the amplification is likely modest (~10). We argue that the contribution to the observed optical/Near-IR emission from the foreground galaxy is small, and hence are able to present the rest-frame UV through radio Spectral Energy Distribution of this galaxy. Due to its unusually high luminosity, MIPS J142824.0+352619 presents a unique chance to study a high redshift dusty starburst galaxy in great detail.Comment: 6 pages, 3 figures, accepted for publication in Ap

Molecular Gas in Infrared-Excess, Optically-Selected QSOs and the Connection with Infrared Luminous Galaxies

The initial results of a millimeter (CO) survey of infrared-excess, optically-selected quasars from the Palomar-Green (PG) Bright Quasar Survey (BQS) with redshifts in the range 0.04 < z < 0.17 are presented. These observations represent the first step towards establishing with a complete sample whether or not quasi-stellar objects (QSOs) reside in molecular gas-rich galaxies, as well as towards determining how the infrared and molecular gas properties of QSOs compare with those of ultraluminous infrared galaxies (ULIGs), which are a possible evolutionary precursor of QSOs. The sample consists of QSOs having absolute blue magnitudes, M_B <~ -22.0, and infrared excesses, L_IR (8-1000 um) /L_bbb (0.1-1.0 um) >0.36, where the contribution to the bolometric luminosity of infrared thermal dust emission for all PG QSOs is typically 20--40%. Six out of 10 of the QSOs observed are detected in the CO(1-0) emission line; two detections confirm previous, less sensitive detections of CO(1-0) in PG 1613+658 and PG 0838+770, and four additional QSOs are detected for the first time (PG 1119+120, PG 1351+640, PG 1415+451, and PG 1440+356). These six detections, plus two previous detections of CO in IZw1 and Mrk 1014, bring the total number of 0.04 < z < 0.17 infrared-excess PG QSOs detected in CO to date to eight, and provide possible evidence that, in addition to fueling star formation, molecular gas may also serve as a primary source of fuel for QSO activity...Comment: LaTex, 16 pages, including 7 postscript figures, AJ, in press (April, 2001