Deep 2 micron imaging of the sky - Evidence for a new extragalactic population

We measure the sizes of redshift ∼ 2 star-forming galaxies by stacking data from the Atacama Large Millimeter/submillimeter Array (ALMA). We use a uv-stacking algorithm in combination with model fitting in the uv-domain and show that this allows for robust measures of the sizes of marginally resolved sources. The analysis is primarily based on the 344 GHz ALMA continuum observations centred on 88 sub-millimeter galaxies in the LABOCA ECDFS Submillimeter Survey (ALESS). We study several samples of galaxies at z ≈ 2 with M * ≈ 5 × 10 10 M , selected using near-infrared photometry (distant red galaxies, extremely red objects, sBzK-galaxies, and galaxies selected on photometric redshift). We find that the typical sizes of these galaxies are ∼ 0. 6 which corresponds to ∼ 5 kpc at z = 2, this agrees well with the median sizes measured in the near-infrared z-band (∼ 0. 6).We find errors on our size estimates of ∼ 0. 1 − 0. 2, which agree well with the expected errors for model fitting at the given signal-to-noise ratio. With the uv-coverage of our observations (18-160 m), the size and flux density measurements are sensitive to scales out to 2 . We compare this to a simulated ALMA Cycle 3 dataset with intermediate length baseline coverage, and we find that, using only these baselines, the measured stacked flux density would be an order of magnitude fainter. This highlights the importance of short baselines to recover the full flux density of high-redshift galaxies.

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“…(iv) Extremely red objects (EROs) selected using (R − K) > 3.35 and (J − K) > 0.1 (Elston, Rieke & Rieke 1988).…”

Section: P H Oto M E T R I C G a L A X Y S E L E C T I O Nmentioning

confidence: 99%

Estimating sizes of faint, distant galaxies in the submillimetre regime

Lindroos

Knudsen

Fan

et al. 2016

Mon. Not. R. Astron. Soc.

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“…In particular, PID352 is associated with an extremely red object (ERO, Elston et al 1988), because it has an R−K color (AB mag) of ∼3.8 (5.4 in Vega mag). This class of sources represents one of the major components of the stellar mass build-up at redshifts z ≈ 1−2 (e.g., Daddi et al 2000).…”

Section: Spectral Energy Distribution Of Pid352mentioning

confidence: 99%

The XMM deep survey in the CDF-S

Vignali

Iwasawa

Comastri

et al. 2015

A&A

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In active galactic nuclei (AGN)-galaxy co-evolution models, AGN winds and outflows are often invoked to explain why super-massive black holes and galaxies stop growing efficiently at a certain phase of their lives. They are commonly referred to as the leading actors of feedback processes. Evidence of ultra-fast (v > ∼ 0.05c) outflows in the innermost regions of AGN has been collected in the past decade by sensitive X-ray observations for sizable samples of AGN, mostly at low redshift. Here we present ultra-deep XMM-Newton and Chandra spectral data of an obscured (N H ≈ 2 × 10 23 cm −2 ), intrinsically luminous (L 2−10 keV ≈ 4 × 10 44 erg s −1 ) quasar (named PID352) at z ≈ 1.6 (derived from the X-ray spectral analysis) in the Chandra Deep Field-South. The source is characterized by an iron emission and absorption line complex at observed energies of E ≈ 2−3 keV. While the emission line is interpreted as being due to neutral iron (consistent with the presence of cold absorption), the absorption feature is due to highly ionized iron transitions (FeXXV, FeXXVI) with an outflowing velocity of 0.14 +0.02 −0.06 c, as derived from photoionization models. The mass outflow rate -∼2 M yr −1 -is similar to the source accretion rate, and the derived mechanical energy rate is ∼9.5 × 10 44 erg s −1 , corresponding to 9% of the source bolometric luminosity. PID352 represents one of the few cases where indications of X-ray outflowing gas have been observed at high redshift thus far. This wind is powerful enough to provide feedback on the host galaxy.

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“…Special notes about the photometry: see Table 3. galaxies. These galaxies are usually called extremely red objects (EROs) and were first addressed in the context of deep NIR surveys (Elston et al 1988). Number counts for these galaxies are now available (Gonzalez-Perez et al 2009;Hempel et al 2011;Kim et al 2011) and will be used in the following.…”

Section: Selecting Host Galaxy Candidatesmentioning

confidence: 99%

A deep search for the host galaxies of gamma-ray bursts with no detected optical afterglow

Rossi

Klose

Ferrero

et al. 2012

A&A

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Context. Gamma-ray bursts (GRBs) can provide information about star formation at high redshifts. Even in the absence of a bright optical/nearinfrared/radio afterglow, the high detection rate of X-ray afterglows by Swift/XRT and its localization precision of 2-3 arcsec facilitates the identification and the study of GRB host galaxies. Aims. We focus on the search for the host galaxies of 17 bursts with arcsec-sized XRT error circles but no detected long-wavelength afterglow, in spite of their deep and rapid follow-up observations. Three of these events can also be classified as truly dark bursts, i.e., the observed upper limit on the optical flux of the afterglow was less than expected based on the measured X-ray flux. Our goals are to identify the GRB host galaxy candidates and characterize their phenomenological parameters. Methods. Our study is based on deep R C and K s -band observations performed with FORS1, FORS2, VIMOS, ISAAC, and HAWK-I at the ESO/VLT, partly supported by observations with the seven-channel imager GROND at the 2.2-m telescope on La Silla, and supplemented by observations with NEWFIRM at the 4-m telescope on Kitt Peak. To be conservative, we searched for host galaxy candidates within an area of twice the radius of each associated 90% c.l. Swift/XRT error circle. Results. For 15 of the 17 bursts, we find at least one galaxy within the searching area, and in the remaining two cases only a deep upper limit to R C and K s can be provided. In seven cases, we discover extremely red objects in the error circles, at least four of which might be dust-enshrouded galaxies. The most remarkable case is the host of GRB 080207, which has a color of (R C − K s ) AB ∼ 4.7 mag, and is one of the reddest galaxies ever associated with a GRB. As a by-product of our study we identify the optical afterglow of GRB 070517. Conclusions. Only a minority of optically dim afterglows are due to Lyman dropout ( 1/3). Extinction by dust in the host galaxies might explain all other events. Thereby, a seemingly non-negligible fraction of these hosts are globally dust-enshrouded, extremely red galaxies. This suggests that at least a fraction of GRB afterglows trace a subpopulation of massive starburst galaxies, which are markedly different from the main body of the GRB host galaxy population, namely the blue, subluminous, compact galaxies.

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Deep 2 micron imaging of the sky - Evidence for a new extragalactic population

Cited by 168 publications

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Estimating sizes of faint, distant galaxies in the submillimetre regime

Estimating sizes of faint, distant galaxies in the submillimetre regime

The XMM deep survey in the CDF-S

A deep search for the host galaxies of gamma-ray bursts with no detected optical afterglow

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