A Sensitive Search For [NII] Emission in a z=6.4 Quasar Host Galaxy

Abstract

We present a sensitive search for the ^3P_1->^3P_0 ground state fine structure line at 205 microns of ionized nitrogen ([NII]) in one of the highest redshift quasars (J1148+5251 at z=6.42) using the IRAM 30m telescope. The line is not detected at a (3 sigma) depth of 0.47 Jy km s^-1, corresponding to a [NII] luminosity limit of L_[NII] < 4.0x10^8 L_sun and a L_[NII]/L$_FIR ratio of <2x10^-5. In parallel, we have observed the CO(J=6-5) line in J1148+5251, which is detected at a flux level consistent with earlier interferometric observations. Using our earlier measurements of the [CII] 158 micron line strength, we derive an upper limit for the [NII]/[CII] line luminosity ratio of ~1/10 in J1148+5251. Our upper limit for the [CII]/[NII] ratio is similar to the value found for our Galaxy and M82 (the only extragalactic system where the [NII] line has been detected to date). Given the non-detection of the [NII] line we can only speculate whether or not high-z detections are within reach of currently operating observatories. However, [NII] and other fine strucure lines will play a critical role in characterizing the interstellar medium at the highest redshifts (z>7) using the Atacama Large Millimeter/submillimeter Array (ALMA), for which the highly excited rotational transitions of CO will be shifted outside the accessible (sub-)millimeter bands.

Accepted for publication in the ApJ Letters

References in corpus (11)

• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• 350 Micron Dust Emission from High Redshift Quasars
• Highly-excited CO emission in APM08279+5255 at z=3.9
• Vigorous star formation with low efficiency in massive disk galaxies at z=1.5
• CO(1-0) in z >/~ 4 Quasar Host Galaxies: No Evidence for Extended Molecular Gas Reservoirs
• Detection of the 205 um [NII] Line from the Carina Nebula
• Imaging the Molecular Gas in a z=3.9 Quasar Host Galaxy at 0.3" Resolution: A Central, Sub-Kiloparsec Scale Star Formation Reservoir in APM 08279+5255
• A Detection of [CII] line emission in the z=4.7 QSO BR1202-0725
• Detection of Two Massive CO Systems in 4C 41.17 at z = 3.8
• SMA High Angular Resolution Imaging of the Lensed Quasar APM08279+5255
• Detecting the Most Distant (z>7) Objects with ALMA

Cited by in corpus (11)

• Physical conditions of the interstellar medium of high-redshift, strongly lensed submillimetre galaxies from the Herschel-ATLAS
• Bright [CII] 158$\mu$m emission in a quasar host galaxy at $z=6.54$
• Physical constraints on the extended interstellar medium of the z=6.42 quasar J1148+5251: [CII] 158um, [NII] 205um and [OI] 146um observations
• Measuring Star-formation Rate and Far-Infrared Color in High-redshift Galaxies Using the CO (7-6) and [NII] 205 micron Lines
• Optical and mid-infrared line emission in nearby Seyfert galaxies
• The Survey of Lines in M31 (SLIM): Investigating the Origins of [CII] Emission
• The "Red Radio Ring": Ionised and Molecular Gas in a Starburst/Active Galactic Nucleus at $z\sim 2.55$
• The Survey of Lines in M31 (SLIM): The Drivers of the [CII]/TIR Variation
• Infrared fine-structure lines at high redshift
• The Unusual AGN Host NGC 1266: Evidence for Shocks in a Molecular Gas Rich S0 Galaxy with a Low Luminosity Nucleus
• The [NII] 205 $\mu$m line emission from high-z SMGs and QSOs