Massive Black Hole Mass Research Articles

Are the black hole masses in narrow-line Seyfert 1 galaxies actually small?

Abstract Narrow-line Seyfert 1 galaxies (NLS1s) are generally considered peculiar objects among the broad class of type 1 active galactic nuclei, due to the relatively small width of the broad lines, strong X-ray variability, soft X-ray continua, weak [O iii], and strong Fe ii line intensities. The mass MBH of the central massive black hole (MBH) is claimed to be lighter than expected from known MBH–host galaxy scaling relations, while the accretion rate on to the MBH larger than the average value appropriate to Seyfert 1 galaxies. In this Letter, we show that NLS1 peculiar MBH and L/LEdd turn out to be fairly standard, provided that the broad-line region is allowed to have a disc-like, rather than isotropic, geometry. Assuming that NLS1s are rather ‘normal’ Seyfert 1 objects seen along the disc axis, we could estimate the typical inclination angles from the fraction of Seyfert 1 classified as NLS1s, and compute the geometrical factor relating the observed full width at half-maximum of broad lines to the virial mass of the MBH. We show that the geometrical factor can fully account for the ‘black hole mass deficit’ observed in NLS1s, and that L/LEdd is (on average) comparable to the value of the more common broad-line Seyfert 1 galaxies.

The Unified Model of Active Galactic Nuclei. II. Evolutionary Connection

(Abbreviated) We assemble a sample composed of 243 nearby Seyfert galaxies with redshifts $z\le 0.05$ to test the unification scheme. The sample contains 94 BLS1s, 44 NLS1s, 36 X-ray absorbed HBLR S2s, 42 X-ray absorbed non-HBLR S2s and 27 X-ray unabsorbed Seyfert 2s (unabsorbed non-HBLR S2s and HBLR S2s). We find that: 1) NLS1s have less massive black hole masses than BLS1s; 2) HBLRS2s have the same mass distribution of the black holes with BLS1s; 3) the absorbed non-HBLR S2s have less massive black holes than HBLR S2s; 4) unabsorbed non-HBLR S2s have the most massive black holes. We thus have a queue of black hole masses from small to large: narrow to broad line Seyfert galaxies, providing new evidence for the evolutionary sequence of Seyfert galaxies. We find that the opening angles of the torus in NLS1s and absorbed non-HBLR S2s are significantly smaller than that in BLS1s and HBLR S2s. The growth of the black holes and increases of the opening angles of the tori determine the various appearances of Seyfert galaxies. We also find that the unabsorbed Seyfert 2 galaxies could be caused by low gas-to-dust ratios in the present sample. This indicates that the star formation histories could be different in the unabsorbed from in absorbed Seyfert 2 galaxies, showing evidence for suppressed star formation by black hole activities. We outline a new unification scheme based on the orientation hypothesis: Seyfert galaxies can be unified by including growth of black holes, Eddington ratios, changing opening angles of tori and gas-to-dust ratios in the tori. Seyfert galaxies are tending to finally evolve to unabsorbed non-HBLR Seyfert 2 galaxies, in which the black holes are accreting with low accretion rates and both the broad line region and dusty torus disappear.

Growth of Massive Black Holes during Radiatively Inefficient Accretion Phases

We derive the black hole mass density as a function of redshift from the hard X-ray active galactic nucleus (AGN) luminosity function, assuming that massive black holes grow via accreting circumnuclear gases. The derived black hole mass density matches the measured local black hole mass density at z = 0, which requires the average radiative efficiency of AGNs to be ~0.1-0.17. The massive black holes in most faint AGNs and even normal galaxies are still accreting gases, although their accretion rates are very low. Radiatively inefficient accretion flows (RIAFs) are supposed in these faint sources, which should radiate mostly in the hard X-ray band. We calculate the contribution to the X-ray background (XRB) from both the bright AGNs and the RIAFs in faint AGNs and normal galaxies. Our calculations show that both the observed intensity and spectral shape of the XRB with an energy peak at ~30 keV can be well reproduced without including the emission of Compton-thick AGNs, if the massive black holes in faint AGNs and normal galaxies are spinning rapidly, with a ~ 0.9, and are accreting at rates of ~ (1.0-3.0) × 10-4. It indicates that less than ~5% of the local massive black hole mass density was accreted during radiatively inefficient accretion phases, which is obviously only an upper limit, because Compton-thick AGNs have not been considered. If the same number of Compton-thick AGNs with log NH = 24-25 as those with log NH = 23-24 is considered, the fraction of the local black hole mass density accumulated during inefficient accretion phases should be lower than ~2%. The constraints of the XRB can provide upper limits on the average accretion rate for inactive galaxies.

Models of mass segregation at the Galactic Centre

We study the process of mass segregation through 2-body relaxation in galactic nuclei with a central massive black hole (MBH). This study has bearing on a variety of astrophysical questions, from the distribution of X-ray binaries at the Galactic centre, to tidal disruptions of main- sequence and giant stars, to inspirals of compact objects into the MBH, an important category of events for the future space borne gravitational wave interferometer LISA. In relatively small galactic nuclei, typical hosts of MBHs with masses in the range 104 − 107 M⊙, the relaxation induces the formation of a steep density cusp around the MBH and strong mass segregation. Using a spherical stellar dynamical Monte-Carlo code, we simulate the long-term relaxational evolution of galactic nucleus models with a spectrum of stellar masses. Our focus is the concentration of stellar black holes to the immediate vicinity of the MBH. Special attention is given to models developed to match the conditions in the Milky Way nucleus.

Stellar Remnants in Galactic Nuclei: Mass Segregation

The study of how stars distribute themselves around a massive black hole (MBH) in the center of a galaxy is an important prerequisite for the understanding of many galactic-center processes. These include the observed overabundance of point X-ray sources at the Galactic center, the prediction of rates and characteristics of tidal disruptions of extended stars by the MBH and of inspirals of compact stars into the MBH, the latter being events of high importance for the future space borne gravitational wave interferometer LISA. In relatively small galactic nuclei, hosting MBHs with masses in the range 10^5-10^7 Msun, the single most important dynamical process is 2-body relaxation. It induces the formation of a steep density cusp around the MBH and strong mass segregation, as more massive stars lose energy to lighter ones and drift to the central regions. Using a spherical stellar dynamical Monte-Carlo code, we simulate the long-term relaxational evolution of galactic nucleus models with a spectrum of stellar masses. Our focus is the concentration of stellar black holes to the immediate vicinity of the MBH. We quantify this mass segregation for a variety of galactic nucleus models and discuss its astrophysical implications. Special attention is given to models developed to match the conditions in the Milky Way nucleus; we examine the presence of compact objects in connection to recent high-resolution X-ray observations.

Probing Post-Newtonian Physics near the Galactic Black Hole with Stellar Redshift Measurements

Stars very close to the massive black hole (MBH) in the center of the Galaxy allow us to probe post-Newtonian (PN) physics in a yet unexplored regime of celestial mechanics. Recent advances in infrared spectroscopy enable us to take precise measurements of stellar redshift curves and thereby detect (?2) PN effects (gravitational redshift in the MBH's potential and the transverse Doppler shift). We use simulations to show that these effects can be decisively detected with existing instruments after ~10 years of observations. We find that neglecting these effects leads to statistically significant systematic errors in the derived MBH mass and distance.

Metal Enrichment of the Intergalactic Medium and Production of Massive Black Holes

A model for the chemical evolution of the intergalactic medium (IGM) is presented using theoretical yields of very massive stars (VMSs; M_(VMS) > 100 M_☉) and Type II supernovae (SNe II). It is shown that if [Si/C] is indeed as high as ~0.7 in the IGM, then VMSs (M_(VMS) ≈ 140-260 M_☉) associated with pair-instability supernovae (PI-SNe) in low-mass (~10^5 M_☉) halos at high redshift must produce at least 50% of the Si. The remainder is from later galactic outflows of SN II debris, which also provide most of the C and O. Both sources are required to account for the metal inventory in the IGM. The early VMS production must continue until redshift z ~ 15 so that the efficiency of VMS formation per low-mass halo is significantly below unity. Contributions from the later galactic outflows mainly occur at z ~ 4-6. Using a Salpeter initial mass function, we infer that the number of VMSs (M_(VMS) ≈ 260-2000 M_☉) producing massive black holes (MBHs) with an average mass 〈M_(MBH)〉 ~ 270-550 M_☉ is ≈0.72 times the number of VMSs associated with PI-SNe. The amount of metals (particularly Si) in the IGM that is attributable to PI-SNe is thus closely coupled with the total mass of MBHs produced in epochs prior to galaxy formation. Production of ~50% of the Si in the IGM by PI-SNe corresponds to an early inventory of MBHs that constitutes a fraction ~(4-8) × 10^(-5) of the total baryonic mass in the universe. This is comparable to the global mass budget of the central supermassive black holes (SMBHs) in present-day galaxies. The corresponding occurrence rates in each halo of ~10^5 M_☉ during the epoch of VMS formation at z ≳ 15 are ~0.9 Gyr^(-1) for VMSs associated with PI-SNe and ~0.6 Gyr^(-1) for the concomitant more massive stars producing MBHs. These rates may be of use to studies of H_2 dissociation and reionization and to models of SMBH formation.

A log-quadratic relation between the nuclear black hole masses and velocity dispersions of galaxies

We demonstrate, we have coloured green the names that we have assumed are surnames. If any of these are wrong, please let us know so we can amend the tagging. that a log-linear relation does not provide an adequate description of the correlation between the masses of super massive black holes (SMBHs, M bh ) and the velocity dispersions of their host spheroid (a). An unknown relation between log M bh and log σ may be expanded to second order to obtain a log-quadratic relation of the form log (M bh ) = a + β log (σ/200km s -1 ) + β 2 [log (σ /200km s -1 )]2. We perform a Bayesian analysis using the local sample described in Tremaine et al., and solve for β, β 2 and a, in addition to the intrinsic scatter (δ). We find unbiased parameter estimates of β = 4.2 ± 0.37, β 2 = 1.6 ± 1.3 and δ = 0.275 ± 0.05. At the 90 per cent level the M bh -σ relation does not follow a uniform power law. Indeed, over the velocity range 70? σ? 380 km s -1 the logarithmic slope d log M bh / d log a of the best-fitting relation varies between 2.7 and 5.1, which should be compared with a power-law estimate of 4.02 ± 0.33. The addition of the 14 galaxies with reverberation SMBH masses and measured velocity dispersions to the local SMBH sample leads to a log-quadratic relation with the same best fit as the local sample. However, the addition of the reverberation masses increases the significance of the log-quadratic contribution, yielding a value of β 2 that is non-zero at the 5σ level. Furthermore, assuming no systematic offset, single epoch virial SMBH masses estimated for active galactic nuclei (AGNs) follow the same log-quadratic M bh -a relation as the local sample, but extend it downward in mass by an order of magnitude. The log-quadratic term in the M bh -σ relation has a significant effect on estimates of the local SMBH mass function at M bh ? 10 9 M ⊙ , leading to densities of SMBHs with M bh ? 10 10 M ⊙ that are several orders of magnitude larger than inferred from a log-linear M bh -σ relation. We also estimate unbiased parameters for the SMBH-bulge mass relation using the sample assembled by Haring and Rix. With a parametrization log(M bh ) = α bulge + β bulge log(M bulge /10 11 M ⊙ ) + β 2,bulge [log(M bulge /10 11 M ⊙ )] 2 , we find β bulge = 1.15 ± 0.18 and β 2,bulge = 0.12 ± 0.14. We determined an intrinsic scatter δ bulge = 0.41 ± 0.07 which is ∼50 per cent larger than the scatter in the M bh-σ relation.

The Orbital Statistics of Stellar Inspiral and Relaxation near a Massive Black Hole: Characterizing Gravitational Wave Sources

We study the orbital parameter distribution of stars that are scattered into nearly radial orbits and then spiral into a massive black hole (MBH) due to dissipation, in particular by emission of gravitational waves (GWs). This is important for GW detection, e.g., by the Laser Interferometer Space Antenna (LISA). Signal identification requires knowledge of the waveforms, which depend on the orbital parameters. We use analytical and Monte Carlo methods to analyze the interplay between GW dissipation and scattering in the presence of a mass sink during the transition from the initial scattering-dominated phase to the final dissipation-dominated phase of the inspiral. Our main results are as follows. (1) Stars typically enter the GW-emitting phase with high eccentricities. (2) The GW event rate per galaxy is a few × 10-9 yr-1 for typical central stellar cusps, almost independently of the relaxation time or the MBH mass. (3) For intermediate-mass black holes of ~103 M☉ such as may exist in dense stellar clusters, the orbits are very eccentric and the inspiral is rapid, so the sources are very short-lived.

Nuclear Properties of Nearby Spiral Galaxies fromHubble Space TelescopeNICMOS Imaging and STIS Spectroscopy

We investigate the central regions of 23 spiral galaxies using archival NICMOS imaging and STIS spectroscopy. The sample is taken from our program to determine the masses of central massive black holes (MBH) in 54 nearby spiral galaxies. Stars are likely to contribute significantly to any dynamical central mass concentration that we find in our MBH program and this paper is part of a series to investigate the nuclear properties of these galaxies. We use the Nuker law to fit surface brightness profiles, derived from the NICMOS images, to look for nuclear star clusters and find possible extended sources in 3 of the 23 galaxies studied (13 per cent). The fact that this fraction is lower than that inferred from optical Hubble Space Telescope studies is probably due to the greater spatial resolution of those studies. Using R-H and J-H colors and equivalent widths of H-alpha emission (from the STIS spectra) we investigate the nature of the stellar population with evolutionary models. Under the assumption of hot stars ionizing the gas, as opposed to a weak AGN, we find that there are young stellar populations (~10-20 Myr) however these data do not allow us to determine what percentage of the total nuclear stellar population they form. Also, in an attempt to find any unknown AGN we use [N II] and [S II] line flux ratios (relative to H-alpha) and find tentative evidence for weak AGN in NGC 1300 and NGC 4536.

The Distribution and Cosmic Evolution of Massive Black Hole Spins

We study the expected distribution of massive black hole (MBH) spins and its evolution with cosmic time in the context of hierarchical galaxy formation theories. Our model uses Monte Carlo realizations of the merger hierarchy in a LCDM cosmology, coupled to semi-analytical recipes, to follow the merger history of dark matter halos, the dynamics of the MBHs they host, and their growth via gas accretion and binary coalescences. The coalescence of comparable mass holes increases the spin of MBHs, while the capture of smaller companions in randomly-oriented orbits acts to spin holes down. We find that, given the distribution of MBH binary mass ratios in hierarchical models, binary coalescences alone do not lead to a systematic spin-up or spin-down of MBHs with time: the spin distribution retains memory of its initial conditions. By contrast, because of the Bardeen-Petterson effect, gas accretion via a thin disk tends to spin holes up even if the direction of the spin axis changes randomly in time. In our models, accretion dominates over black hole captures and efficiently spins holes up. The spin distribution is heavily skewed towards fast-rotating Kerr holes, is already in place at early epochs, and does not change much below redshift 5. If accretion is via a thin disk, about 70% of all MBHs are maximally rotating and have radiative efficiencies approaching 30% (assuming a "standard'' spin-efficiency conversion). Even in the conservative case where accretion is via a geometrically thick disk, about 80% of all MBHs have spin parameters a/m > 0.8 and accretion efficiencies > 12%. Rapidly spinning holes with high radiative efficiencies may satisfy constraints based on comparing the local MBH mass density with the mass density inferred from luminous quasars (Soltan's argument).

Weighing the cusp at the Galactic Centre

AbstractAs stars close to the galactic centre have short orbital periods it has been possible to trace large fractions of their orbits in the recent years. Previously the data of the orbit of the star S2 have been fitted with Keplerian orbits corresponding to a massive black hole (MBH) with a mass of MBH = 3–4 × 106M⊙ implying an insignificant cusp mass. However, it has also been shown that the central black hole resides in a ∼1″ diameter stellar cluster of a priori unknown mass. In a spherical potential which is neither Keplerian nor harmonic, orbits will precess resulting in inclined rosetta shaped trajectories on the sky. In this case, the assumption of non‐Keplerian orbits is a more physical approach. It is also the only approach through which cusp mass information can be obtained via stellar dynamics of the cusp members. This paper presents the first exemplary modelling efforts in this direction. Using positional and radial data of star S2, we find that there could exist an unobserved extended mass component of several 105M⊙ forming a so‐called ‘cusp’ centered on the black hole position. Considering only the fraction of the cusp mass M within the apo‐center of the S2 orbit we find as an upper limit that M/(MBH + M) ≤ 0.05. A large extended cusp mass, if present, is unlikely to be composed of sub‐solar mass constituents, but could be explained rather well by a cluster of high M/L stellar remnants, which we find to form a stable configuration. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Detection of Gravitational Waves from the Coalescence of Population III Remnants with Advanced LIGO

The comoving mass density of massive black hole (MBH) remnants from pre-galactic star formation could have been similar in magnitude to the mass-density of supermassive black holes (SMBHs) in the present-day universe. We show that the fraction of MBHs that coalesce during the assembly of SMBHs can be extracted from the rate of ring-down gravitational waves that are detectable by Advanced LIGO. Based on the SMBH formation history inferred from the evolution of the quasar luminosity function, we show that an observed event rate of 1 per year will constrain the SMBH mass fraction that was contributed by MBHs coalescence down to a level of ~10^-6 for 20 solar mass MBH remnants (or ~10^-4 for 260 solar mass remnants).

Massive black hole remnants of the first stars - III. Observational signatures from the past

The first stars forming in minihaloes at redshifts greater than 20 may have been very massive and could have left behind massive black hole (MBH) remnants. In previous papers we investigated the hierarchical merging of these `seed' MBHs and their associated haloes, using a semi-analytical approach consisting of a hierarchical merger tree algorithm and explicit prescriptions for the dynamics of merged substructure inside a larger host halo following a merger. We also estimated accretion luminosities for these MBHs and found them to be consistent with observations of ultra-luminous X-ray point sources. Here we compute the strength of gravitational wave events as MBHs merge to grow from seed mass MBH at high redshifts to those that we predict to reside in galaxy haloes today. If MBHs merge efficiently we predict that some 10^4 - 10^5 events per year could be observed, that fall just within the sensitivity limits of the proposed LISA gravitational wave observatory. The collapse of the first massive stars to form MBHs may be accompanied by gamma ray bursts (GRBs). If this is the case and GRBs are in principle observable out to the redshifts of first star formation, we find that about 10^5 - 10^6 GRBs per year could be detected. As merging MBH binaries reach their last stable orbits before final coalescence a fraction of the gravitational wave energy may be released as a pulse of gamma rays (for instance, through interaction with material enveloping a merging MBH binary). This fraction has to be in the range between 10^{-14} - 10^{-10} for MBH mergers to be less luminous than GBRs, yet detectable out to cosmological distances with upcoming GRB detector missions.

Massive black hole remnants of the first stars - I. Abundance in present-day galactic haloes

We investigate the possibility that present-day galaxies and their dark matter haloes contain a population of massive black holes (MBHs) that form by hierarchical merging of the black hole remnants of the first stars in the Universe. Some of the MBHs may be large enough or close enough to the centre of the galactic host that they merge within a Hubble time. We estimate to what extent this process could contribute to the mass of the super-massive black holes (SMBHs) observed in galactic centres today. The relation between SMBH and galactic bulge mass in our model displays the same slope as that found in observations. Many MBHs will not reach the centre of the host halo, however, but continue to orbit within it. In doing so MBHs may remain associated with remnants of the satellite halo systems of which they were previously a part. Using a semi-analytical approach that explicitly accounts for dynamical friction, tidal disruption and encounters with galactic disks, we follow the hierarchical merging of MBH systems and their subsequent dynamical evolution inside the respective host haloes. We predict the mass and abundance of MBHs in present-day galactic haloes, and also estimate the MBH mass accretion rates as well as bolometric luminosities for two different accretion scenarios. MBHs that have not undergone recent merging will retain associated dark matter cusps that were enhanced by black hole accretion growth, and may be possible sources of gamma rays via neutralino annihilations.

Evidence for Anisotropic Motion of the Clouds in Broad‐Line Regions of BL Lacertae Objects

The masses of central massive black holes in BL Lac objects are estimated from their host galaxy absolute magnitude R at R-band by using the empirical relation between R and black hole mass Mbh. Only a small fraction of BL Lac objects exhibit weak broad-line emission, and we derive the sizes of the broad-line regions (BLRs) in these BL Lac objects from the widths of their broad emission lines on the assumption of the clouds being virilized in BLRs. It is found that the sizes of the BLRs in these sources are usually 2-3 orders of magnitude larger than those expected by the empirical correlation RBLR-λLλ(3000 A) defined by a sample of Seyfert galaxies and quasars. We discuss a variety of possibilities and suggest that this difference can probably be attributed to anisotropic motion of the BLR clouds in these BL Lac objects. If the BLR geometry of these sources is disklike, the viewing angles between the axis and the line of sight are in the range ~2°-12°, which is consistent with the unification schemes.

Jet Formation in BL Lacertae Objects with Different Accretion Modes

We estimate the masses of massive black holes in BL Lac objects from their host galaxy luminosity. The power of jets and central optical ionizing luminosity for a sample of BL Lac objects are derived from their extended radio emission and the narrow-line emission, respectively. The maximal jet power that can be extracted from a standard thin accretion disk/spinning black hole is calculated as a function of dimensionless accretion rate (m) over dot ((m) over dot = (M) over dot/(M) over dot (Edd)). Comparing with the derived jet power, we find that the accretion disks in most BL Lac objects should not be standard accretion disks. For a pure advection-dominated accretion flow (ADAF), there is an upper limit on its optical continuum luminosity because of the existence of an upper limit (m) over dot(crit) on the accretion rate. It is found that a pure ADAF is too faint to produce the optical ionizing luminosity of BL Lac objects derived from their narrow-line luminosity. We propose that an ADAF is present in the inner region of the disk, and it becomes a standard thin disk in the outer region in most BL Lac objects, i.e., ADAF+SD (standard disk) scenario. This ADAF+SD scenario can explain both the jet power and optical ionizing continuum emission of these BL Lac objects. The inferred transition radii between the inner ADAF and outer SD are in the range of 40-150 GM(bh)/c(2), if the disks are accreting at the rate (m) over dot = 0.01.

Black Hole-Bulge Relation for Narrow-Line Objects

Abstract It has been thought that narrow-line Seyfert 1 galaxies are likely to be in the early stages of the evolution of active galaxies. To test this suggestion, the ratios of the central massive black hole (MBH) mass to the bulge mass ($M_{\mathrm{bh}} / M_{\mathrm{bulge}}$) were estimated for 22 Narrow Line AGNs (NL AGNs). It is found that NL AGNs appear to have genuinely lower MBH/Bulge mass ratio ($M_{\mathrm{bh}} / M_{\mathrm{bulge}}$). The mean $\log (M_{\mathrm{bh}}/M_{\mathrm{bulge}})$ for 22 NL AGNs is $-3.9 \pm 0.07$, which is an order of magnitude lower than that for Broad Line AGNs and quiescent galaxies. We suggest a nonlinear MBH/Bulge relation and find there exists a relation between the $M_{\mathrm{bh}} / M_{\mathrm{bulge}}$ and the velocity dispersion, $\sigma$, derived from the [O iii] width. A scenario of MBH growth for NL AGNs is one of our interpretations of the nonlinear MBH/Bulge relation. The MBH growth timescales for 22 NL AGNs were calculated, with a mean value $(1.29 \pm 0.24) \times 10^8 \,\mathrm{yr}$. Another plausible interpretation is also possible: that NL AGNs occur in low-$M_{\mathrm{bulge}}$ galaxies and that in such galaxies $M_{\mathrm{bh}} / M_{\mathrm{bulge}}$ is lower than that in galaxies with a higher $M_{\mathrm{bulge}}$, if we consider that NL AGNs already have their “final” $M_{\mathrm{bh}} / M_{\mathrm{bulge}}$. More information of the bulge in NL AGNs is needed to clarify the black hole-bulge relation.

Accretion efficiency at the Eddington luminous stage in quasars

Abstract Non-steady and eruptive phenomena in quasars are thought to be associated with the Eddington or super-Eddington luminous stage. Although there is no lack of hypotheses about the total duration of such a stage, the latter remains essentially unknown. We calculate the duration of the quasar luminous stage as a function of the initial mass of a newborn massive black hole (MBH) by comparing the observed luminosity- and redshift distributions of quasars with the mass distribution of MBHs in normal galactic nuclei. It is assumed that, at the quasar stage, each MBH goes through a single (or recurrent) phase(s) of accretion with, or close to, the Eddington luminosity. The mass distributions of quasars is found to be connected with that of MBHs residing in normal galaxies by a single-valued relationship through the mass range 107−1011 M[odot] of the inferred MBHs.

The Constellation X-ray mission

Constellation-X combines both the large collecting area and sensitive spectrometers required to obtain high spectral resolution, broad bandpass (0.25—40 keV) spectroscopy for all classes of X-ray sources, over a wide range of luminosity and redshift. It represents a major advance in sensitivity, providing up to a factor of 100 increase in throughput over currently planned high resolution (R > 300) X-ray spectroscopy missions. Constellation-X is the X-ray equivalent of the Keck Telescope. When observations begin towards the end of the next decade, they will mark the start of a new era with high resolution X-ray spectra obtained for all classes of X-ray sources over a wide range of luminosity and distance. With its increased capabilities, Constellation-X will address many fundamental astrophysics questions such as observing the formation and evolution of clusters of galaxies; constraining the Baryon content of the Universe; determining the spin and mass of super massive black holes in AGN; and probing strong gravity in the vicinity of black holes.