K band SINFONI spectra of two $z\sim 5$ SMGs: upper limits to the un-obscured star formation from [O II] optical emission line searches

Abstract

We present deep SINFONI K band integral field spectra of two submillimeter (SMG) galaxy systems: BR 1202-0725 and J1000+0234, at $z=4.69$ and $4.55$ respectively. Spectra extracted for each object in the two systems do not show any signature of the [O II]$\lambda \lambda$3726,29Å emission-lines, placing upper flux limits of $3.9$ and $2.5\times 10^{-18}$$\mathrm{erg}{\mathrm{s}}^{-1}\mathrm{c}{\mathrm{m}}^{-2}$ for BR 1202-0725 and J1000+0234, respectively. Using the relation between the star formation rate (SFR) and the luminosity of the [O II] doublet from Kennicutt (1998), we estimate unobscured SFR upper limits of $\sim$ $10-15{\mathrm{M}}_{\odot }\mathrm{y}{\mathrm{r}}^{-1}$ and $\sim$ $30-40{\mathrm{M}}_{\odot }\mathrm{y}{\mathrm{r}}^{-1}$ for the objects of the two systems, respectively. For the SMGs, these values are at least two orders of magnitude lower than those derived from SED and IR luminosities. The differences on the SFR values would correspond to internal extinction of, at least, $3.4-4.9$ and $2.1-3.6$ mag in the visual for BR 1202-0725 and J1000+0234 SMGs, respectively. The upper limit for the [O II]-derived SFR in one of the LAEs (Ly$\alpha 2$) in the BR1202-0725 system is at least one order of magnitude lower than the previous SFR derived from infrared tracers, while both estimates are in good agreement for Ly$\alpha$1. The lower limits to the internal extinction in these two Lyman-alpha emitters (LAEs) are $0.6$ mag and $1.3$ mag, respectively. No evidence for the previously claimed (Ohta et al. 2000) [O II] emission associated with Ly$\alpha$1 is identified in our data, implying that residuals of the K-band sky emission lines after subtraction in medium-band imaging data could provide the adequate flux.

arXiv comment7 pages, 4 figures, 2 tables, accepted for publication by A&A

References in corpus (27)

• On the variation of the Initial Mass Function
• Star Formation in Galaxies Along the Hubble Sequence
• The Dust Content and Opacity of Actively Star-Forming Galaxies
• Cosmic Star Formation History
• A Cosmological Framework for the Co-Evolution of Quasars, Supermassive Black Holes, and Elliptical Galaxies: I. Galaxy Mergers & Quasar Activity
• A Quantitative Comparison of SMC, LMC, and Milky Way UV to NIR Extinction Curves
• Formation of z ~ 6 quasars from hierarchical galaxy mergers
• Molecular gas and dust around a radio-quiet quasar at redshift 4.7
• On Sizes, Kinematics, M/L Gradients, and Light Profiles of Massive Compact Galaxies at z~2
• Spectroscopic Confirmation Of An Extreme Starburst At Redshift 4.547
• High resolution imaging of molecular line emission from high redshift QSOs
• Molecular Gas in a Submillimeter Galaxy at z=4.5: Evidence for a Major Merger at 1 Billion Years after the Big Bang
• [CII] line emission in massive star-forming galaxies at z=4.7
• A Spatially Resolved Map of the Kinematics, Star-Formation and Stellar Mass Assembly in a Star-Forming Galaxy at z=4.9
• A Detection of [CII] line emission in the z=4.7 QSO BR1202-0725
• Strongly star-forming rotating disks in a complex merging system at z = 4,7 as revealed by ALMA
• The anatomy of an extreme starburst within 1.3Gyr of the Big Bang revealed by ALMA
• Intense Star-formation and Feedback at High Redshift: Spatially-resolved Properties of the z=2.6 Submillimeter Galaxy SMMJ14011+0252
• Mapping the Clumpy Structures within Submillimeter Galaxies using Laser-Guide Star Adaptive Optics Spectroscopy
• VLT-SINFONI integral field spectroscopy of low-z luminous and ultraluminous infrared galaxies II. 2D extinction structure and distance effects
• BR1202-0725: An Extreme Multiple Merger at z = 4.7
• Star formation and black hole growth at z=4.8
• Extreme star formation in the host galaxies of the fastest growing super-massive black holes at z=4.8
• Constraining the Nature of Two Ly-alpha Emitters detected by ALMA at z = 4.7
• Subaru Deep Spectroscopy of a Star-forming Companion Galaxy of BR 1202-0725 at $z=4.7$
• [OII]3727 Emission from the Companion to the Quasar BR 1202-0725 at z=4.7
• Star-formation at z=4.7 in the environment of the QSO BR1202-07

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