Thomas Boller

The 4MOST instrument concept overview

The 4MOST[1] instrument is a concept for a wide-field, fibre-fed high multiplex spectroscopic instrument facility on the ESO VISTA telescope designed to perform a massive (initially >25x106 spectra in 5 years) combined all-sky public survey. The main science drivers are: Gaia follow up of chemo-dynamical structure of the Milky Way, stellar radial velocities, parameters and abundances, chemical tagging; eROSITA follow up of cosmology with x-ray clusters of galaxies, X-ray AGN/galaxy evolution to z~5, Galactic X-ray sources and resolving the Galactic edge; Euclid/LSST/SKA and other survey follow up of Dark Energy, Galaxy evolution and transients. The surveys will be undertaken simultaneously requiring: highly advanced targeting and scheduling software, also comprehensive data reduction and analysis tools to produce high-level data products. The instrument will allow simultaneous observations of ~1600 targets at R~5,000 from 390-900nm and ~800 targets at R<18,000 in three channels between ~395-675nm (channel bandwidth: 45nm blue, 57nm green and 69nm red) over a hexagonal field of view of ~ 4.1 degrees. The initial 5-year 4MOST survey is currently expect to start in 2020. We provide and overview of the 4MOST systems: optomechanical, control, data management and operations concepts; and initial performance estimates.

4MOST-4-metre Multi-Object Spectroscopic Telescope

4MOST is a wide-field, high-multiplex spectroscopic survey facility under development for the VISTA telescope of the European Southern Observatory (ESO). Its main science drivers are in the fields of galactic archeology, high-energy physics, galaxy evolution and cosmology. 4MOST will in particular provide the spectroscopic complements to the large area surveys coming from space missions like Gaia, eROSITA, Euclid, and PLATO and from ground-based facilities like VISTA, VST, DES, LSST and SKA. The 4MOST baseline concept features a 2.5 degree diameter field-of-view with ~2400 fibres in the focal surface that are configured by a fibre positioner based on the tilting spine principle. The fibres feed two types of spectrographs; ~1600 fibres go to two spectrographs with resolution R<5000 (λ~390-930 nm) and ~800 fibres to a spectrograph with R>18,000 (λ~392-437 nm and 515-572 nm and 605-675 nm). Both types of spectrographs are fixed-configuration, three-channel spectrographs. 4MOST will have an unique operations concept in which 5 year public surveys from both the consortium and the ESO community will be combined and observed in parallel during each exposure, resulting in more than 25 million spectra of targets spread over a large fraction of the southern sky. The 4MOST Facility Simulator (4FS) was developed to demonstrate the feasibility of this observing concept. 4MOST has been accepted for implementation by ESO with operations expected to start by the end of 2020. This paper provides a top-level overview of the 4MOST facility, while other papers in these proceedings provide more detailed descriptions of the instrument concept[1], the instrument requirements development[2], the systems engineering implementation[3], the instrument model[4], the fibre positioner concepts[5], the fibre feed[6], and the spectrographs[7].

eROSITA on SRG

eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the core instrument on the Russian/German Spektrum-Roentgen-Gamma (SRG) mission which is now officially scheduled for launch on March 26, 2016. eROSITA will perform a deep survey of the entire X-ray sky. In the soft band (0.5-2 keV), it will be about 30 times more sensitive than ROSAT, while in the hard band (2-8 keV) it will provide the first ever true imaging survey of the sky. The design driving science is the detection of large samples of galaxy clusters to redshifts z < 1 in order to study the large scale structure in the universe and test cosmological models including Dark Energy. In addition, eROSITA is expected to yield a sample of a few million AGN, including obscured objects, revolutionizing our view of the evolution of supermassive black holes. The survey will also provide new insights into a wide range of astrophysical phenomena, including X-ray binaries, active stars and diffuse emission within the Galaxy. eROSITA is currently (June 2014) in its flight model and calibration phase. All seven flight mirror modules (+ 1 spare) have been delivered and measured in X-rays. The first camera including the complete electronics has been extensively tested (vacuum + X-rays). A pre-test of the final end-toend test has been performed already. So far, all subsystems and components are well within their expected performances.

A Large, Uniform Sample of X-Ray-emitting AGNs: Selection Approach and an Initial Catalog from the ROSAT All-Sky and Sloan Digital Sky Surveys

Many open questions in X-ray astronomy are limited by the relatively small number of objects in uniform optically identified and observed samples, especially when rare subclasses are considered or when subsets are isolated to search for evolution or correlations between wavebands. We describe the initial results of a new program aimed to ultimately yield ~104 fully characterized X-ray source identifications?a sample about an order of magnitude larger than earlier efforts. The technique is detailed and employs X-ray data from the ROSAT All-Sky Survey (RASS) and optical imaging and spectroscopic follow-up from the Sloan Digital Sky Survey (SDSS); these two surveys prove to be serendipitously very well matched in sensitivity. As part of the SDSS software pipelines, optical objects in the SDSS photometric catalogs are automatically positionally cross-correlated with RASS X-ray sources. Then priorities for follow-on SDSS optical spectra of candidate counterparts are automatically assigned using an algorithm based on the known ratios of fx/fopt for various classes of X-ray emitters at typical RASS fluxes of ~10-13 ergs cm-2 s-1. SDSS photometric parameters for optical morphology, magnitude, and colors, plus FIRST radio information, serve as proxies for object class. Initial application of this approach to RASS/SDSS data from 1400 deg2 of sky provides a catalog of more than 1200 spectroscopically confirmed quasars and other AGNs that are probable RASS identifications. Most of these are new identifications, and only a few percent of the AGN counterparts are likely to be random superpositions. The magnitude and redshift ranges of the counterparts are very broad, extending over 15 < m < 21 and 0.03 < z < 3.6, respectively. Although most identifications are quasars and Seyfert 1 galaxies, a variety of other AGN subclasses are also sampled. Substantial numbers of rare AGN types are found, including more than 130 narrow-line Seyfert 1 galaxies and 45 BL Lac candidates. These early results already provide a very sizable set of source identifications, demonstrate the utility of the sample in multiwaveband investigations, and show the capability of the joint RASS/SDSS approach to efficiently proceed toward the largest homogeneously selected/observed sample of X-ray?emitting quasars and other kinds of AGNs.

Experimental Tests of Pseudo-Complex General Relativity

Based on a recently proposed extension to General Relativity (GR), called pseudo-complex General Relativity (pc-GR), we present a selection of several tests of GR near compact massive objects. The investigated phenomena are the redshift, the orbital frequency of a test particle and the innermost stable circular orbit (ISCO) around a massive object. We observe that the redshift and orbital frequency are in general lower in pc-GR compared to Einstein’s GR. Also the orbital frequency for prograde motion now exhibits a maximum, which is not present in GR. In addition the concept of an innermost stable circular orbit does not hold in pc-GR as it arises in GR. All modifications due to pc-GR correction terms appear only at small distances (mostly below three Schwarzschild radii) and thus can only be observed by measurements in regions of strong gravity. Those and more results have been published already in [1].

XMM-Newton spectroscopy of the highly polarized and luminous broad absorption line quasar CSO 755

We present the results from XMM-Newton observations of the highly optically polarized broad absorption line quasar (BALQSO) CSO 755. By analyzing its X-ray spectrum with a total of ~3000 photons, we find that this source has the X-ray continuum of a typical radio-quiet quasar, with a photon index of Γ = 1.83 and a rather flat (X-ray bright) intrinsic optical–X-ray spectral slope of αox = -1.51. The source shows evidence for intrinsic absorption, and fitting the spectrum with a neutral-absorption model gives a column density of NH ~ 1.2 × 1022 cm-2; this is among the lowest X-ray columns measured for BALQSOs. We do not detect, with high significance, any other absorption features in the X-ray spectrum. We place upper limits on the rest-frame equivalent width of a neutral (ionized) Fe Kα line, ≤180 eV (≤120 eV), and on the Compton-reflection component parameter, R ≤ 0.2, suggesting that most of the X-rays from the source are directly observed rather than being scattered or reflected; this is also supported by the relatively flat intrinsic αox we measure. The possibility that most of the X-ray flux is scattered due to the high level of UV-optical polarization is ruled out. Considering data for 46 BALQSOs from the literature, including CSO 755, we have found that the UV-optical continuum polarization level of BALQSOs is not correlated with any of their X-ray properties. A lack of significant short- and long-term X-ray flux variations in the source may be attributed to a large black hole mass in CSO 755. We note that another luminous BALQSO, PG 2112+059, has both similar shallow C IV BALs and moderate X-ray absorption.

Partial Covering Interpretation of the X-Ray Spectrum of the NLS1 1H 0707-495

The X-ray spectrum of 1H 0707−495 obtained with XMM-Newton showing a deep flux drop at∼ 7keV (Boller et al. 2002) is studied based on the partial covering concept. The previously inferred extreme iron overabundance can be reduced down to ∼ 3× solar if the hard component gradually steepens at high energies. The spectral shape supports that 1H 0707−495 is an AGN analogue of the galactic black-hole binaries in the soft state. Interpreting the soft excess as the emission from an optically-thick disk, the minimum black hole mass M is estimated to be 2 · 106M from the intrinsic luminosity corrected for partial covering. Based on the slim disk model, the observed disk temperature implies that the luminosity is close to the Eddington limit. The rapid and large flux variations with little change in the spectral shape can also be explained, if not all, as due to changes in the partial covering fraction. Partial covering may account for the large variability characteristics of NLS1.

Narrow-line Seyfert 1 galaxies: observational and theoretical progress until 2003

Narrow-Line Seyfert 1 galaxies are an important class of Seyfert 1 galaxies. X-ray observations with ROSAT. XMM-Newton and Chandra have revealed many interesting and unexpected properties, e.g. steep soft (0.1-2.4) keV and hard (2-10) keV X-ray continua, a strong soft X-ray excess in many of these objects and unusually rapid and extreme X-ray variability. These X-ray properties are related to many optical and UV properties, such as the strength of the Fe II multiplet emission or the strength of the [OIII] emission. The unique combination of extreme observational properties in Narrow-Line Seyfert 1 galaxies allows for a more general understanding of the Seyfert phenomenon. This paper reviews the observational and theoretical progress made until October 2003.

ISO observations of four active galaxies

We present ISO PHOT-S spectra of four galaxies known or suspected to host a central AGN. Two of them are selected, among several others, from the initial Iras/Rosat sample of Boller et al. (1992) because of their substantial X-ray emission, while no obvious Seyfert features was present in their optical spectra: IRAS 14201+2956 and IRAS 21582+1018. The latter, also known as Mrk 520, was bright enough to also allow SWS observations around selected neon lines, to establish its excitation. While both PHOT-S spectra are characteristic of starburst-dominated galaxies, the neon line ratios in IRAS 21582+1018 indicate the presence of a hard excitation source. Complementary optical spectra, both at low and high spectral resolution, show only a weak, broad component around Ha, establishing the presence of a central AGN which may not be detected in standard, classification spectra. Both objects are now classified as Sey 1.9 galaxies. These results show therefore that, although IR observations were expected to be able to pierce through the dusty central regions to reveal the presence of an active nucleus, the result may be ambiguous: the broad band IR energy distribution can still be dominated by starburts located in a wider circumnuclear region, and the AGN appear only in specific observations (high-excitation lines in the IR, or high-resolution optical spectra). As a complement, two other galaxies from the same initial sample were also observed with PHOT-S: the Narrow Line Seyfert galaxies (NLS1) Mrk 359 and Mrk 1388. NLS1s appear in high proportion in the Rosat/Iras sample, and in soft X-ray samples in general, and their Balmer line-widths are sometimes comparable to those of interacting, star-forming galaxies. Their ISO spectra however do not reveal the typical, strong PAH features found in the starburst galaxies and are more like those of standard Seyferts. All these observations therefore indicate that the key element is the presence or absence of a circumnuclear starburst region which, if strong enough, may completely hide the presence of a central AGN in the IR spectral energy distribution. The dust obscuration however needs to be patchy rather than complete to explain the detection of the high-excitation lines and Balmer wings in some cases. Only high-energy observations can then establish the strength of the central AGN and the amount of extinction with certainty.

Observational Tests of the Pseudo-complex Theory of GR Using Black Hole Candidates

We have worked out astronomical tests of the pseudo-complex gravitational field theory (pc-GR) proposed by Hess and Greiner [1] going beyond our first paper on pc-GR tests [2]. Observational tests of the standard GR theory (standard-GR) and the pc-GR theory include (i) Galactic binaries, (ii) the Galactic Center, and (iii) supermassive black holes. For Galactic binaries with both relativistic Fe K line emission and QPO frequencies we have calculated the distances of both observational quantities to the central black hole. While the relativistic Fe K emission arises only within a few gravitational radii (\(R_G = GM/c^2\)) from the black hole with mass M, the QPO frequencies when related to Keplerian motions place their origin to much larger distances. This discrepancy is not understood so far. As very little has been done going beyond the phenomenological description of that problem, we applied the pseudo-complex theory to these Galactic black hole binaries and find that the Fe K and QPO emission is arising at quite similar radii from the black hole. While this is not any proof for the pc-GR, it is worth pointing out that both theories give different results. For the Galactic Center we show that the orbital frequencies of test particles are different in pc-GR and standard GR. In addition, we show that VLBI interferometry will result into the first direct image of the black hole in the GC and that ray-tracing images in both theories are different for the GC and can be used to probe standard GR and pc-GR. Finally, we argue that in supermassive black holes the QPO frequencies and the relativistic Fe K emission occur from the same physical origin. This further allows performing tests on pc-GR and standard GR from both observational quantities.