scholarly journals A Joint Discussion on the Topic of Cold Gas and Dust at High Redshift

2002 ◽  
Vol 12 ◽  
pp. 453-455
Author(s):  
D.J. Wilner
Keyword(s):  
High Redshift ◽  
Galactic Nuclei ◽  
Far Infrared ◽  
Continuum Emission ◽  
Color Selection ◽  
Technical Developments ◽  
Infrared Background ◽  
Large Telescopes ◽  
New Generation ◽  
Cold Gas

The number of spectroscopically confirmed galaxies at high redshift is increasing rapidly, with many being found efficiently by deep optical imaging and color selection. In parallel, a confluence of technical developments is bringing rapid progress to the domain of observations of cold gas and dust at high redshift. Large telescopes operating at high, dry sites, with a new generation of sensitive detectors, together with recent satellite missions, are opening up new areas of study through observations of dust continuum emission and associated atomic and molecular emission and absorption lines. These data bear directly on fundamental questions of cosmic evolution by probing the ordinary cool material that forms stars and fuels active galactic nuclei. Analysis of data from theCOBEsatellite confirms the presence of a diffuse far-infrared background from a widespread population of distant dusty objects. The global energetics of the optical and far-infrared backgrounds suggest that perhaps half of distant activity may be enshrouded by dust. Understanding the nature and redshifts of the sources responsible for these emissions is profoundly important. The intent of Joint Discussion 9, between Division X (Radio Astronomy) and Division XIII (Galaxies and the Universe), was to provide a forum to present observations from this newly accessible realm and to consider the astrophysical implications.

scholarly journals Astronomy from Antarctica

2005 ◽  
Vol 17 (4) ◽  
pp. 555-560 ◽  
Author(s):  
J.W.V. STOREY
Keyword(s):  
Absolute Humidity ◽  
Far Infrared ◽  
Antarctic Plateau ◽  
Earth Like Planets ◽  
Remote Sites ◽  
Large Telescopes ◽  
New Generation ◽  
The Antarctic ◽  
City Centres ◽  
Optical Telescopes

Astronomers have always sought the very best locations for their telescopes. From observatories in city centres, astronomers moved first to nearby mountain tops, then to remote sites in distant countries, to aircraft, and into space. In the past decade we have come to realize that the best astronomical observing conditions on the surface of the earth are to be found on the Antarctic plateau. The combination of high altitude, low temperature, low absolute humidity, low wind and extremely stable atmosphere offers astronomers gains in sensitivity and measurement precision that can exceed two orders of magnitude over even the best temperate sites. In addition, spectral windows are opened up – particularly in the far-infrared and terahertz regions – that are otherwise only accessible from high-flying aircraft or from space. Established and highly successful telescopes at the South Pole are soon to be joined by a new generation of facilities at Concordia Station, including large telescopes and interferometers. It has even been suggested that the largest optical telescopes currently proposed, with diameters of up to 100 m, might achieve their science goals at a lower overall cost if they are built on the Antarctic plateau rather than at a temperate site. Such telescopes offer the possibility of not only detecting earth-like planets in other star systems, but also of analysing their atmospheres spectroscopically.

scholarly journals X-ray emission of z > 2.5 active galactic nuclei can be obscured by their host galaxies

2019 ◽  
Vol 623 ◽  
pp. A172 ◽  
Author(s):  
C. Circosta ◽  
C. Vignali ◽  
R. Gilli ◽  
A. Feltre ◽  
F. Vito ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
High Redshift ◽  
Galactic Nuclei ◽  
Far Infrared ◽  
Host Galaxy ◽  
Spectral Energy ◽  
X Rays ◽  
Host Galaxies ◽  
X Ray ◽  
Stellar Masses

We present a multiwavelength study of seven active galactic nuclei (AGN) at spectroscopic redshift >2.5 in the 7 Ms Chandra Deep Field South that were selected for their good far-infrared (FIR) and submillimeter (submm) detections. Our aim is to investigate the possibility that the obscuration observed in the X-rays can be produced by the interstellar medium (ISM) of the host galaxy. Based on the 7 Ms Chandra spectra, we measured obscuring column densities NH,  X in excess of 7 × 1022 cm−2 and intrinsic X-ray luminosities LX >  1044 erg s−1 for our targets, as well as equivalent widths for the Fe Kα emission line EWrest ≳ 0.5−1 keV. We built the UV-to-FIR spectral energy distributions (SEDs) by using broadband photometry from the CANDELS and Herschel catalogs. By means of an SED decomposition technique, we derived stellar masses (M* ∼ 1011 M⊙), IR luminosities (LIR >  1012 L⊙), star formation rates (SFR ∼ 190−1680 M⊙ yr−1) and AGN bolometric luminosities (Lbol ∼ 1046 erg s−1) for our sample. We used an empirically calibrated relation between gas masses and FIR/submm luminosities and derived Mgas ∼ 0.8−5.4 × 1010 M⊙. High-resolution (0.3−0.7″) ALMA data (when available, CANDELS data otherwise) were used to estimate the galaxy size and hence the volume enclosing most of the ISM under simple geometrical assumptions. These measurements were then combined to derive the column density associated with the ISM of the host, which is on the order of NH,  ISM ∼ 1023−24 cm−2. The comparison between the ISM column densities and those measured from the X-ray spectral analysis shows that they are similar. This suggests that at least at high redshift, significant absorption on kiloparsec scales by the dense ISM in the host likely adds to or substitutes that produced by circumnuclear gas on parsec scales (i.e., the torus of unified models). The lack of unobscured AGN among our ISM-rich targets supports this scenario.

scholarly journals The Impact of Extremely Large Telescopes on the Study of the Most Luminous Stellar Objects

2007 ◽  
Vol 3 (S250) ◽  
pp. 495-502
Author(s):  
Sandro D'Odorico
Keyword(s):  
Adaptive Optics ◽  
Angular Resolution ◽  
High Redshift ◽  
Chemical Abundances ◽  
Stellar Objects ◽  
Nearby Galaxies ◽  
Infrared Wavelengths ◽  
Large Telescopes ◽  
New Generation ◽  
The Impact

AbstractThe potential advantages of the new generation of Extremely Large Telescopes are briefly summarized. When used in combination with advanced adaptive optics modules which can substantially remove the effect of atmospheric turbulence at infrared wavelengths, these telescopes will provide unique capabilities both in terms of photon collecting power (→2-4 magnitude advantage) and angular resolution (4-5 times higher than with current 8-10m telescopes). The instruments under study for the TMT and E-ELT projects are presented and compared. I discuss the impact of the ELTs on three major science topics: stellar populations in galaxies to the Virgo distance, chemical abundances of the brighter stars in nearby galaxies and high redshift SN and GRBs.

scholarly journals First detection of the 448 GHz ortho-H2O line at high redshift: probing the structure of a starburst nucleus at z = 3.63

2020 ◽  
Vol 634 ◽  
pp. L3 ◽  
Author(s):  
C. Yang ◽  
E. González-Alfonso ◽  
A. Omont ◽  
M. Pereira-Santaella ◽  
J. Fischer ◽  
...  
Keyword(s):  
High Redshift ◽  
Galactic Nuclei ◽  
Far Infrared ◽  
Dust Temperature ◽  
Unique Constraint ◽  
Order Of Magnitude ◽  
Ism Structure ◽  
Excitation Conditions ◽  
Disk Component ◽  
Luminous Infrared Galaxy

Submillimeter rotational lines of H2O are a powerful probe in warm gas regions of the interstellar medium (ISM), tracing scales and structures ranging from kiloparsec disks to the most compact and dust-obscured regions of galactic nuclei. The ortho-H2O(423 − 330 line at 448 GHz, which has recently been detected in a local luminous infrared galaxy, offers a unique constraint on the excitation conditions and ISM properties in deeply buried galaxy nuclei because the line requires high far-infrared optical depths to be excited. In this letter, we report the first high-redshift detection of the 448 GHz H2O(423–330) line using ALMA in a strongly lensed submillimeter galaxy (SMG) at z = 3.63. After correcting for magnification, the luminosity of the 448 GHz H2O line is ∼106 L⊙. In combination with three other previously detected H2O lines, we build a model that resolves the dusty ISM structure of the SMG, and find that it is composed of a ∼1 kpc optically thin (optical depth at 100 μm τ100 ∼ 0.3) disk component with a dust temperature Tdust ≈ 50 K that emits a total infrared power of 5 × 1012 L⊙ with a surface density ΣIR = 4 × 1011 L⊙ kpc−2, and a very compact (0.1 kpc) heavily dust-obscured (τ100 ≳ 1) nuclear core with very warm dust (100 K) and ΣIR = 8 × 1012 L⊙ kpc−2. The H2O abundance in the core component, XH2O ∼ (0.3–5) × 10−5, is at least one order of magnitude higher than in the disk component. The optically thick core has the characteristic properties of an Eddington-limited starburst, providing evidence that radiation pressure on dust is capable of supporting the ISM in buried nuclei at high redshifts. The multicomponent ISM structure revealed by our models illustrates that dust and molecules such as H2O are present in regions that are characterized by highly differing conditions and scales, extending from the nucleus to more extended regions of SMGs.

scholarly journals Infrared Emission from AGN

1999 ◽  
Vol 194 ◽  
pp. 25-38
Author(s):  
D. B. Sanders
Keyword(s):  
Near Infrared ◽  
High Redshift ◽  
Dust Emission ◽  
Far Infrared ◽  
Infrared Emission ◽  
Substantial Fraction ◽  
Bolometric Luminosity ◽  
Submillimeter Wavelengths ◽  
Infrared Background ◽  
X Ray Background

Infrared observations of complete samples of active galactic nuclei (AGN) have shown that a substantial fraction of their bolometric luminosity is emitted at wavelengths ˜8–1000μm. In radio-loud and Blazar-like objects much of this emission appears to be direct non-thermal synchrotron radiation. However, in the much larger numbers of radio-quiet AGN it is now clear that thermal dust emission is responsible for the bulk of radiation from the near-infrared through submillimeter wavelengths. Luminous infrared-selected AGN are often surrounded by powerful nuclear starbursts, both of which appear to be fueled by enormous supplies of molecular gas and dust funneled into the nuclear region during the strong interaction/merger of gas rich disks. All-sky surveys in the infrared show that luminous infrared AGN are at least as numerous as optically-selected AGN of comparable bolometric luminosity, suggesting that AGN may spend a substantial fraction of their lifetime in a dust-enshrouded phase. The space density of luminous infrared AGN at high redshift may be sufficient to account for much of the X-Ray background, and for a substantial fraction of the far-infrared background as well. These objects plausibly represent a major epoch in the formation of spheroids and massive black holes (MBH).

scholarly journals Prospects for Future Far-Infrared/Submillimeter Studies of the High-Redshift Universe

2002 ◽  
Vol 12 ◽  
pp. 493-496
Author(s):  
Andrew W. Blain
Keyword(s):  
Background Radiation ◽  
High Redshift ◽  
Wide Band ◽  
Far Infrared ◽  
High Mass ◽  
Background Intensity ◽  
Spectral Structure ◽  
Dusty Galaxies ◽  
Infrared Background ◽  
Balloon Experiments

AbstractObservations made usingCOBE, SCUBA,ISOand MAMBO have provided a reasonable working knowledge of both the intensity of the submm and far-infrared background radiation and the source counts of luminous high-redshift dusty galaxies. However, because there are uncertainties in the background intensity determinations, the samples of detected galaxies are small, and most importantly, their redshift distributions are very incomplete, details of the evolution of dusty galaxies remain unresolved. The next steps forward in the field will be the launches ofSIRTFandASTRO-F, the commissioning of SOFIA and new, more capable ground-based mm/submm-wave cameras - BOLOCAM, SHARC-II and SCUBA-II - the use of ultra-long duration balloon experiments, such as BLAST, the construction of ALMA and the arrival ofFIRST, and ultimately the advent of space-borne far-infrared interferometers, such asSPECS. There are also exciting prospects for direct mm/submm-wave CO-line redshift surveys using wide-band spectrographs. Using these new facilities, the number of high-redshift dusty galaxies known will be increased dramatically. Spectroscopy usingSIRTF, SOFIA andFIRSTwill probe the astrophysical processes within these sources in detail, hopefully addressing the open question of the fraction of the counts and background radiation that is generated by the formation of high-mass stars and by active galactic nuclei (AGNs). The spatial and spectral structure of distant dusty galaxies will finally be resolved in detail using ALMA andSPECS.

The First Galaxies in the Universe

2013 ◽  
Author(s):  
Abraham Loeb ◽  
Steven R. Furlanetto
Keyword(s):  
Galaxy Evolution ◽  
Big Bang ◽  
First Stars ◽  
Distant Galaxies ◽  
Formation And Evolution ◽  
Early Galaxies ◽  
First Galaxies ◽  
Large Telescopes ◽  
New Generation ◽  
The Big Bang

This book provides a comprehensive, self-contained introduction to one of the most exciting frontiers in astrophysics today: the quest to understand how the oldest and most distant galaxies in our universe first formed. Until now, most research on this question has been theoretical, but the next few years will bring about a new generation of large telescopes that promise to supply a flood of data about the infant universe during its first billion years after the big bang. This book bridges the gap between theory and observation. It is an invaluable reference for students and researchers on early galaxies. The book starts from basic physical principles before moving on to more advanced material. Topics include the gravitational growth of structure, the intergalactic medium, the formation and evolution of the first stars and black holes, feedback and galaxy evolution, reionization, 21-cm cosmology, and more.

scholarly journals Testing the evolution of correlations between supermassive black holes and their host galaxies using eight strongly lensed quasars

2020 ◽  
Vol 501 (1) ◽  
pp. 269-280
Author(s):  
Xuheng Ding ◽  
Tommaso Treu ◽  
Simon Birrer ◽  
Adriano Agnello ◽  
Dominique Sluse ◽  
...  
Keyword(s):  
Black Holes ◽  
Hubble Space Telescope ◽  
High Redshift ◽  
Galactic Nuclei ◽  
Host Galaxy ◽  
Wide Field ◽  
Host Galaxies ◽  
Field Surveys ◽  
Instrumental Resolution ◽  
The Moment

ABSTRACT One of the main challenges in using high-redshift active galactic nuclei (AGNs) to study the correlations between the mass of a supermassive black hole ($\mathcal {M}_{\rm BH}$) and the properties of its active host galaxy is instrumental resolution. Strong lensing magnification effectively increases instrumental resolution and thus helps to address this challenge. In this work, we study eight strongly lensed AGNs with deep Hubble Space Telescope imaging, using the lens modelling code lenstronomy to reconstruct the image of the source. Using the reconstructed brightness of the host galaxy, we infer the host galaxy stellar mass based on stellar population models. $\mathcal {M}_{\rm BH}$ are estimated from broad emission lines using standard methods. Our results are in good agreement with recent work based on non-lensed AGNs, demonstrating the potential of using strongly lensed AGNs to extend the study of the correlations to higher redshifts. At the moment, the sample size of lensed AGNs is small and thus they provide mostly a consistency check on systematic errors related to resolution for non-lensed AGNs. However, the number of known lensed AGNs is expected to increase dramatically in the next few years, through dedicated searches in ground- and space-based wide-field surveys, and they may become a key diagnostic of black holes and galaxy co-evolution.

scholarly journals Mapping large-scale-structure evolution over cosmic times

2021 ◽  
Author(s):  
Marta B. Silva ◽  
Ely D. Kovetz ◽  
Garrett K. Keating ◽  
Azadeh Moradinezhad Dizgah ◽  
Matthieu Bethermin ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Large Scale ◽  
High Redshift ◽  
Formation Rate ◽  
Far Infrared ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Structure Evolution ◽  
Intensity Mapping ◽  
Wide Range

AbstractThis paper outlines the science case for line-intensity mapping with a space-borne instrument targeting the sub-millimeter (microwaves) to the far-infrared (FIR) wavelength range. Our goal is to observe and characterize the large-scale structure in the Universe from present times to the high redshift Epoch of Reionization. This is essential to constrain the cosmology of our Universe and form a better understanding of various mechanisms that drive galaxy formation and evolution. The proposed frequency range would make it possible to probe important metal cooling lines such as [CII] up to very high redshift as well as a large number of rotational lines of the CO molecule. These can be used to trace molecular gas and dust evolution and constrain the buildup in both the cosmic star formation rate density and the cosmic infrared background (CIB). Moreover, surveys at the highest frequencies will detect FIR lines which are used as diagnostics of galaxies and AGN. Tomography of these lines over a wide redshift range will enable invaluable measurements of the cosmic expansion history at epochs inaccessible to other methods, competitive constraints on the parameters of the standard model of cosmology, and numerous tests of dark matter, dark energy, modified gravity and inflation. To reach these goals, large-scale structure must be mapped over a wide range in frequency to trace its time evolution and the surveyed area needs to be very large to beat cosmic variance. Only a space-borne mission can properly meet these requirements.

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