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Considering first DM model A, which is a combination of the [MATH] (84.4%) and [MATH] (15.2%) final states, we find that the gamma-ray spectrum is well fit by either a single DMFIT model with a [MATH] final state or to a combination of two DMFIT models, one for each final state, keeping the relative normalizations free... |
. For a combination of final states, however, we recover the mass and the branching ratios quite well with [MATH] GeV and [MATH] . The degeneracy between final state branching ratio and dark matter particle mass can be seen in the left panel of Fig. , showing the confidence level contours on these two parameters. In th... |
To further understand how the unknown final state combination affects the reconstructed particle properties, we consider DM model B, whose dominant final state is [MATH] (90.4%) with a small contribution from a [MATH] final state (7.2%). Fitting the spectrum to a purely [MATH] or a purely [MATH] final state, a good fit... |
, they give similar constraints on the particle mass ( [MATH] GeV for [MATH] and [MATH] GeV for [MATH] ) within [MATH] 3 GeV and [MATH] of the true mass. However, these two final states give significantly different normalizations (respectively, [MATH] =236 for a purely [MATH] model and 167 for [MATH] ), implying, for a... |
The DMFIT tool, as implemented in XSPEC, outputs the photon yield in given energy bins for a given annihilation final state, per pair-annihilation event (i.e., the quantity [MATH] of Eq. ( ) integrated over given energy bins). The XSPEC output, therefore, is in units of [MATH] . To convert this to physically relevant q... |
[EQUATION] Calling [MATH] the XSPEC output normalization, the conversion to the physically relevant quantity [MATH] for a WIMP mass [MATH] is then simply |
[EQUATION] Assuming knowledge of [MATH] , one can then extract the pair annihilation cross section [EQUATION] The right panel of Fig. shows the confidence level contours of the particle mass and pair annihilation cross section from DMFIT for DM model B assuming either a [MATH] or [MATH] final state. While both models r... |
In the reconstruction of the cross section from the XSPEC normalization as well as the derivation of source flux and luminosity, another very important systematic effect needs to be emphasized. In the extraction of instrumental response files appropriate for use with XSPEC, the GLAST tools ( gtrspgen ) assume that the ... |
The Galactic Center Region This section is devoted to the analysis of the anticipated gamma-ray sky in the direction of the center of the Galaxy. The full results of our simulations are shown in Fig. , for [MATH] GeV (upper panel) and [MATH] GeV (lower panel), and assuming background Scenario 1 and DM model B. The figu... |
5.1 The Optimal Energy and Angular Regions Prior to embarking on the analysis of the full simulated gamma-ray sky in the Galactic center region and to addressing the question of the potential of GLAST to pinpoint particle dark matter properties (sec. 5.2 ), in the present section we investigate the optimal energy and a... |
Fig. shows the simulation results for the integrated number of photons as recorded by LAT above 1 GeV (upper panels, (a) and (b)) and above 5 GeV (lower panels (c) and (d)), within a given angular region. To produce this figure, we took the simulated event-by-event photon tables and simply summed the number of photons ... |
As expected, at large angles the background is in all cases dominated by the diffuse emission. The estimated number of photons at large angles is very close for all background models. The inclusion of the source associated to 3EG J1744-3011 [HESS J1745-303] manifests itself in the bump visible in the [MATH] GeV panels ... |
Since we assume the same dark matter profile, modulo statistical fluctuations, the dark matter annihilation signals from models A, B and C are obviously proportional to each other. The signal is dominated by the innermost region, and the increase at large angular scales (due to both the instrumental PSF and to the actu... |
Comparing the simulated photon counts above 1 and 5 GeV, it is clear that the ratio of the signal to the square root of the background event counts ( [MATH] ) is more favorable for the [MATH] 1 GeV case than for the [MATH] 5 GeV case for DM model C and background Scenario 3. Quantitatively, we find that [MATH] is large... |
The optimal energy range and angular region, however, does not only depend on [MATH] : considering a lower energy cut significantly increases the statistics in the number of signal events and carries additional important spectral information. For the case of a NFW profile, the 5 GeV cut simply limits the statistics of ... |
In view of these considerations, we decided to adopt a 1 GeV cut. Fig. illustrates the number of photon counts inside shells of [MATH] , between 0 and [MATH] , for background Scenario 1 (dashed black line) and for DM model B with our reference dark matter profile (upper solid green line) and with a NFW profile (lower g... |
. Notice that the number of background photons within spherical shells appears to be at a minimum between 2 and 3 degrees (3 and 4 for the background setups of ref. |
), and it keeps increasing for shells at larger angles. With our standard dark matter profile, we find that considering circular annular shells around the Galactic center region does not help in increasing the signal-to-noise; for a NFW profile, we find that an annulus between 2 and 3 degrees can actually have a larger... |
We also tried alternative angular cuts, such as for instance a cut in Galactic latitude, that would allow us to remove part of the Galactic diffuse background. We find that with this cut topology the signal-to-noise does not improve neither for a NFW nor for a steeper dark matter profile. |
Having assessed that leaving out the innermost angular regions is not an optimal strategy, we show in Fig. 10 the total [MATH] within given angular regions, for a few choices of background and DM models and with an energy cut at 1 GeV. In particular, the left panel shows [MATH] for DM model C with background Scenario 3... |
. Even if at small angular region [MATH] decreases, it still peaks in an angular region of around [MATH] In the case where instead 3EG J1746-2851 is part of the background, the total signal-to-noise increases up to [MATH] , and then flattens out. At even larger angular regions, [MATH] starts to decrease, particularly s... |
In summary, we find that the optimal energy cut is likely around 1 GeV, and that the optimal angular region includes the innermost part of the Galactic center and depends on the assumed dark matter profile. For a steeply rising profile, the optimal angular range is between [MATH] and [MATH] degrees, while for a NFW pro... |
In view of the above considerations, in the following analysis we will use an angular region of 0.5 degrees for DM model C and background Scenario 3, and of 1 degree for DM models A and B and background Scenarios 1 or 2. For background Scenarios 1 and 2 we will use only photons above 1 GeV, while for background Scenari... |
5.2 Dark Matter Particle Properties from the Galactic Center We now investigate whether we can significantly detect the spectral signature of dark matter annihilation and constrain dark matter particle properties in one year of GLAST data from the Galactic center in the three background Scenarios detailed in sec. 3.1.4... |
Scenarios 1 and 2 . For background Scenario 1, where the EGRET and HESS sources near the Galactic center are different, the EGRET source dominates and the background spectrum can be fairly well modeled by a simple broken power law as shown in Fig. 11 (left) and Tab. . The reduced [MATH] of this fit is 1.22 due to a sma... |
We then add a dark matter source with either model A or B and investigate the necessity of a dark matter component in the spectral fit and our ability to constrain its parameters. We first make minimal assumptions about the background spectrum, assuming only the rough spectral shape (a broken power law for background S... |
For both background Scenarios and DM model B, a background only spectrum with no dark matter component is ruled out at better than 99% confidence level even without assuming the background spectral parameters. The addition of a DMFIT model with the dominant [MATH] final state significantly improves the fit, showing tha... |
For a dark matter source with DM model A the flux is lower, and a dark matter component is not clearly necessary in the spectral fits. Adding a dark matter component with the dominant [MATH] final state does, however, improve the fits, and in the case background Scenario 2 the low energy slope of the broken power law i... |
Scenario 3 . Here we reconsider the analysis in sec. 4.1 for the case where the EGRET source 3EG J1746-2851 is due to dark matter annihilation with DM model C, but now we include the backgrounds. As we take a relatively small spectral extraction region (radius 0.5 degrees), the only significant background sources are t... |
As shown in Fig. 13 (left), the background only spectrum is well fit by a simple broken power law with a spectral index of 2.7 ( [MATH] ). Considering the full background plus DM model C spectrum, we again ask the question whether we can distinguish between a source with a dark matter-like spectrum modeled with DMFIT v... |
Fig. 14 shows a comparison of the confidence level contours for the dark matter particle mass and annihilation cross section for the case where we fix the background power law at the best fit for the background only versus the case where we fit for the power-law parameters. We have again corrected the spectral normaliz... |
The constraints on the final state branching ratios versus mass when including a [MATH] final state are shown in Fig. 15 for both a fixed and fit background model. In both cases, the true particle mass and branching ratio is reproduced within the errors. If the background model is known independently, as could easily b... |
In summary, for a bright dark matter source like DM model C, one year of GLAST data will make it possible to constrain the dark matter particle mass to [MATH] 10% accuracy (systematic and statistical) even if the background model and final state branching ratios are unknown. For fainter dark matter sources like models ... |
As a final test, we looked for correlations between the parameters of the background spectral model and the DMFIT particle mass. We limit this study to DM models B and C. For example, Fig. 16 shows the confidence level contours on the particle mass versus high energy slope and break energy for background Scenario 1 and... |
. For instance, the optimized model gives approximately an 80% higher diffuse flux above 1 GeV within 1 degree of the Galactic center. We find that our results are quite insensitive to the diffuse model. With the optimized diffuse model, we find for DM model C and background Scenario 3 very similar uncertainties in the... |
Summary and Conclusions With the detailed analysis of a specific example, the Galactic center region, this study reaffirms and reinforces the point that GLAST has the potential to play a pioneering role in the race towards the discovery of the fundamental nature of dark matter. While eagerly awaiting real data to go be... |
the nature of the EGRET source in the Galactic center, and its possible association to dark matter annihilation, will be conclusively probed by GLAST with less than one year of data; |
the determination of the dark matter particle properties such as the mass and the dominant and sub-dominant annihilation modes is possible to a varying degree of accuracy, depending on the brightness of the source and on the knowledge of the background spectrum; |
for realistic particle dark matter models, GLAST has the potential to (i) firmly establish the presence of a dark matter source in the Galactic center, even when it is not the brightest source in the region, (ii) estimate the dark matter particle mass to better than 10%, and (iii) to disentangle the occurrence of more ... |
if the EGRET source at the Galactic center is associated to dark matter annihilation, we showed that the optimal energy range includes all photons above 0.1 GeV within an angular region of [MATH] ; otherwise, the optimal energy range for dark matter searches is above 1 GeV, and the optimal angular region goes from [MAT... |
the finite spatial extent of the dark matter source at the Galactic center amounts to a systematic effect in the estimate of the normalization of the dark matter signal by a factor [MATH] compared to the point source approximation, even for very steep profiles; |
the estimate of the dark matter particle properties is affected by two sources of bias: (i) the background model and (ii) assumptions on the dark matter annihilation mode; specifically, we showed that different backgrounds can lead to both under- and over-estimates of the dark matter mass, and that the inclusion of ann... |
We introduced and showed applications of DMFIT, a numerical package that, interfaced with any spectral fitting routine, allows one to fit gamma-ray spectra to the emission of generic WIMP models. DMFIT includes the [MATH] annihilation mode, relevant e.g. for Kaluza-Klein dark matter, and is able to fit for low neutrali... |
Acknowledgments We greatly thank Johann Cohen-Tanugi and Eric Nuss for several comments and suggestions on this manuscript. We also acknowledge useful discussions and inputs from other members of the GLAST collaboration, in particular Jan Conrad, Robert Johnson, Aldo Morselli, Troy Porter and others involved in the Dar... |
# Source: arxiv 0808.2643 # Title: Ubiquitous Water Masers in Nearby Star-Forming Galaxies # Sections: all # Downloaded: 2026-03-02T07:58:16.480770+00:00 |
Ubiquitous Water Masers in Nearby Star-Forming Galaxies Abstract We report the detection of water maser emission from four nearby galaxies hosting ultradense H ii (UDHII) regions, He 2-10, the Antennae galaxies (NGC 4038/4039), NGC 4214, and NGC 5253, with the Green Bank Telescope. Our detection rate is 100%, and all o... |
“kilomasers” ( [MATH] ) are located toward regions of known star formation as traced by UDHII regions and bright 24 [MATH] m emission. Some of the newly discovered masers have luminosities 1–2 orders of magnitude less than previous extragalactic studies and the same order of magnitude as those typical of Galactic massi... |
Subject headings: galaxies: interactions — galaxies: ISM — galaxies: star clusters — galaxies: starburst — masers — radio lines: galaxies |
1. Introduction Extreme star-forming environments known as “ultradense H ii regions” (UDHIIs) have been discovered in a number of starburst galaxies (e.g., Kobulnicky & Johnson, 1999 ; Turner et al., 2000 ; Tarchi et al., 2000 ; Johnson et al., 2004 ; Reines et al., 2008 UDHIIs are identified through their thermal mid-... |
Given the tremendous number and density of young massive stars in UDHIIs, it is logical to ask whether typical signposts of Galactic massive star formation are associated with these objects. |
Churchwell et al. ( 1990 found that [MATH] % of Galactic UCHIIs are associated with H O (22.235 GHz) masers. Subsequent interferometric follow-up showed that while some H O masers are coincident with the UCHII regions themselves, many are instead associated with younger members of the forming massive protocluster of wh... |
cm -3 and [MATH] K) are fairly persistent during the early stages of massive star cluster evolution. If extragalactic UDHIIs are composed of thousands of UCHIIs, then it is reasonable to expect O masers to be associated with a large fraction of the embedded massive stars in these giant clusters. |
The term “kilomasers” has been coined to describe extragalactic 22 GHz H O masers with luminosities comparable to the brightest Galactic star formation-associated H O masers (e.g., W49N; |
[MATH] ). The luminosities of H O kilomasers [MATH] ) are much lower than the more widely studied “megamasers,” which are associated with the nuclear regions of AGN (i.e., NGC 4258) and have been observed with luminosities up to 10 |
(Barvainis & Antonucci, 2005 kilomasers have been associated with both AGN and star formation activity; this luminosity regime includes the tails (high and low) of both maser populations. Although kilomasers can be used to help pinpoint sites of active star formation, there have been few searches with the sensitivity n... |
(Hofner et al., 2006 and not current star formation. We have carried out a Green Bank Telescope (GBT) search for kilomasers toward four nearby starburst galaxies ( [MATH] Mpc), known to host UDHIIs, down to a sensitivity level consistent with strong Galactic UCHII region masers. Positive detections were found for all f... |
2. Observations and Data Reduction We observed the [MATH] 22.23508 GHz ortho-water maser line in He 2-10, the Antennae (NGC 4038/4039), NGC 4214, and NGC 5253 with the GBT on 2004 May 3–6 (Table ). Two 25 MHz offset IFs were observed simultaneously with 200 MHz bandpasses in two polarizations and 12.2 or 24.4 kHz wide ... |
For all observations, records were individually calibrated and bandpasses flattened using the calibration diode and the corresponding off-source records, respectively. Scans and polarizations were subsequently averaged, and a fifth-order polynomial baseline was fitted and subtracted. The bandpasses were rarely contamin... |
3. Results We have detected water maser emission in all four galaxies observed. Measured line properties are listed in Table , and further information for each galaxy is presented below. In all cases, given the complex velocity structure of the galaxies in this sample (likely due to the combined effect of large and sma... |
He 2-10: Kobulnicky & Johnson ( 1999 identified five distinct UDHII regions within the blue compact dwarf (BCD) galaxy He 2-10, which is located at a distance of 10.5 Mpc. He 2-10 has roughly solar metallicity |
(12+log(O/H)=8.93; Vacca & Conti, 1992 implying that molecules may be relatively abundant. The He 2-10 UDHII regions are associated with bright 24 [MATH] m emission, and the main body of the BCD fits completely within the [MATH] GBT beam as shown in Figure , so at the current resolution it is not possible to pinpoint w... |
(Kobulnicky et al., 1995 Mohan et al. ( 2001 find a H92 [MATH] line velocity peak of [MATH] km s -1 , with a broad blue wing, and Henry et al. ( 2007 find narrow Brackett line features in the range [MATH] –900 km s -1 . The maser velocity presented here of 887 km s -1 is roughly consistent with all of these studies. |
The Antennae: At an adopted distance of 20 Mpc, the interacting galaxy pair known as the Antennae (NGC 4038/NGC 4039) is the most distant source in our survey. As shown in Figure , the single GBT pointing ( [MATH] beam) was centered on a 24 [MATH] m-bright region of copious star formation within the “interaction region... |
Gilbert & Graham ( 2007 , as well as that of CO toward the IAR (1350–1700 km s -1 ; see, e.g., Wilson et al., 2000 ; Schulz et al., 2007 . However, the second maser component at 1670 km s -1 is on the high end of the CO gas velocities observed within the IAR, and may instead be associated with a “bridge” of CO at 1650–... |
Schulz et al. ( 2007 . Emission from the NGC 4039 nuclear region itself is unlikely because it lies near the first null of the GBT’s beam; thus, Antennae feature 2 is unlikely to be associated with nuclear activity. |
NGC 4214: NGC 4214 is a BCD at a distance of 2.9 Mpc with a subsolar metallicity (12+log(O/H)=8.28; Kobulnicky & Skillman, 1996 . As shown in Figure maser emission is detected toward a region of bright 24 [MATH] m emission near the center of the galaxy. The 24 [MATH] m and emission are also coincident with several unre... |
Walter et al. ( 2001 found that the CO(1–0) emission in this galaxy is concentrated into three main regions, the centralmost of which is coincident with the GBT pointing and the bright 24 [MATH] emission. This CO emission has a peak hel (CO)= 291.4 km s -1 and a velocity extent of 287–308 km s -1 , in good agreement wi... |
hel ) = 301.6 km s -1 NGC 5253: NGC 5253 is a dwarf starburst galaxy at a distance of 3.3 Mpc with subsolar metallicity (12+log(O/H)=8.23; Martin, 1997 . Using OVRO, Meier et al. ( 2002 |
found that the CO(2–1) emission is concentrated toward the optically dark dust lane with a velocity range of 350–450 km s -1 . The GBT beam was centered on the UDHII region discovered by Turner et al. ( 2000 and a region of bright 24 [MATH] m emission (see Fig. ). This region is also coincident with the weak CO(2–1) mo... |
[MATH] =15 km s -1 (Meier et al., 2002 . However, the GBT beam also encompasses parts of CO cloud ”C” ( hel =418 km s -1 ) to the southeast and cloud ”A” ( hel =363 km s -1 ) to the east. Thus, the maser emission at 366 and 375 km s -1 is significantly blueward of the CO gas toward the UDHII region and most closely agr... |
Mohan et al. ( 2001 and Rodríguez-Rico et al. ( 2007 measure peak velocities of [MATH] km s -1 , both with broad wings. These velocities are somewhat higher than, but consistent with, the maser velocities. Given that the ionized gas in NGC 5253 is known to have a sinusoidal velocity structure (López-Sánchez et al., 200... |
4. Discussion Could the strong Galactic maser source W49N be detected in our sample galaxies? Using a fiducial distance of 11.4 kpc and a 10 kJy peak flux density (see e.g., Liljestrom et al., 1989 , W49N is marginally detectable in the Antennae (3 mJy) but easily detectable in the other sample galaxies (12–150 mJy). B... |
[MATH] ), W49N should be detectable in NGC 4214 and NGC 5253 and possibly in He 2-10, but not in the Antennae. It is remarkable that we can now detect sub-W49N H O masers in external galaxies, which means that extragalactic kilomaser observations may now be interpretable in a Galactic star formation context. |
Two of our new H O maser detections are extremely low luminosity; there is only one other system known with a total [MATH] [MATH] , and this was a brief flaring episode in IC 342 (Tarchi et al., 2002a ; Henkel et al., 2005 . The detection of deci-W49N emission in a larger sample of galaxies similar to NGC 4214 and NGC ... |
(Henkel et al., 2005 and will genuinely explore the link between masers and star formation in galaxies as a function of environment, metallicity, and age. |
Our minisurvey sample has a 100% detection rate, and expands by 2/3 the sample of known kilomaser galaxies associated with star formation. The GBT beam excludes the nuclei in the Antennae, so the association of maser emission with star formation is likely in this galaxy merger. Moreover, the three dwarf galaxies in our... |
Ulvestad et al. ( 2007 , and neither has pointlike radio sources down to a detection level of [MATH] Jy, consistent with no AGN activity. The mid-infrared spectrum of NGC 4214 was studied by |
Satyapal et al. ( 2008 , and they find no evidence of high-ionization lines that would be suggestive of an AGN. Indeed, given the association between the presence of AGN and host galaxy bulge mass |
(e.g., Kauffman et al., 2003 , it would be surprising if any of these three dwarf galaxies harbored an AGN. Without spectral line maps, however, the connection between and UDHII regions has not yet been demonstrated. |
All four detected masers lie [MATH] dex below the [MATH] relationship obtained for Galactic masers by Felli et al. ( 1992 . That is, these masers are “subluminous” in the |
line given their host galaxies’ far-IR luminosities. They are, however, in good agreement with the [MATH] relationship for kilomasers obtained by Castangia et al. ( 2008 The origin of this difference between kilomasers and Galactic masers is unknown, but is likely due to spatially unresolved far-IR ( IRAS ) observation... |
5. Conclusions We have identified H O masers in four galaxies hosting ultradense ii regions. The high detection rate and the low luminosity of the O lines in our minisurvey indicate that previous water maser surveys of nearby IR-bright galaxies lacked the sensitivity to detect most H O kilomasers associated with bursts... |
This research has made use of the NASA/IPAC Extragalactic Database (NED) and uses observations made with the Spitzer Space Telescope both of which are operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. K. E. J. acknowledges support from NSF through CAREER award 05... |
# Source: arxiv 0808.2644 # Title: A discontinuity in the low-mass IMF - the case of high multiplicity # Sections: all # Downloaded: 2026-03-02T07:58:17.789075+00:00 |
A discontinuity in the low-mass IMF – the case of high multiplicity Abstract The empirical binary properties of brown dwarfs (BDs) differ from those of normal stars suggesting BDs form a separate population. Recent work by Thies and Kroupa revealed a discontinuity of the initial mass function (IMF) in the very-low-mass... |
keywords: binaries: general — open clusters and associations: general — stars: low-mass, brown dwarfs — stars: luminosity function, mass function |
Introduction The origin of brown dwarfs (BDs) remains the subject of intense discussions. There are two broad ideas on their origin: 1. the classical star-like formation scenario of BDs (e.g. Adams & Fatuzzo 1996 ; Padoan & Nordlund 2004 ), and 2. BDs and some very-low-mass stars (VLMSs) form as a separate population (... |
The star-like formation scenario fails to reproduce the observed different binary properties of BDs and stars. Especially the truncation of the semi-major axis distribution between 10 and 20 AU for BDs and the different mass-ratio distribution of BDs and stars |
(Bouy et al. 2003 ; Burgasser et al. 2003 ; Martín et al. 2003 ; Kroupa et al. 2003 ; Close et al. 2003 , as well as the BD desert (McCarthy et al. 2003 ; Grether & Lineweaver 2006 are difficult to account for if BDs form indistinguishably to stars. This implies the need of treating BDs as a separate population to star... |
(Lodieu et al. 2007 , a discontinuity in the IMF may be present but be masked by ‘hidden’ (unresolved) binaries only emerging if the observed MF is corrected for unresolved multiplicity. This issue has been discussed in greater detail in Thies & Kroupa (2007, hereafter TK07) for the case of a low multiplicity of 15 % o... |
In Section we review the evidence for a separate BD-like population. Section briefly introduces the mathematical method of calculating the IMF including unresolved binaries. In Section the new results are presented and compared to those of TK07. The Summary follows in Section |
Brown dwarfs as a separate population 2.1 Motivation It may be argued that by treating the BDs as a separate population this forces an IMF discontinuity near the stellar/sub-stellar mass limit by construction. Indeed, the semi-major axis data and binary fraction (here used as a simplification for the multiplicity, negl... |
(Burgasser et al. 2007 Given this argumentation, it is essential to describe the methodology applied in our analysis: We seek one mathematical formulation which is a unification of the binary population for G-, K-, M-dwarfs and VLM-stars and BDs. This is found to be possible for G-, K- and M-dwarfs: thus, for example, ... |
(Kroupa et al. 2003 ; Goodwin et al. 2007 One single mathematical model can therewith be written down which treats G-, K- and M-dwarfs on exactly the same footing – one can say that G-, K- and M-dwarf stars mix according to one rule (random pairing from the IMF at birth). |
If BDs are to be introduced into a similar mathematical formulation which does not differentiate between BDs and stars, then the model fails, because it leads to (1) a too wide BD period-distribution function, (2) too many BD binaries, (3) far too many stellar–BD binaries, and (4) far too few star–star binaries (Kroupa... |
Lafrenière et al. ( 2008 show that the mass-ratio of binaries depends on the primary-star mass in a way that results in an almost constant lower mass limit of the companions near 0.075 [MATH] for the Chamaeleon I star-forming region (see the figures 7 and 12 in their paper). This distribution can be reproduced by rando... |
TK07 show that this necessarily implies a discontinuity in the IMF, given the observational data. We emphasise that the observational mass distributions lead to this conclusion, once the correct mathematical description is incorporated consistently. However, TK07 assume a rather low binary fraction of the BD-like popul... |
2.2 A short review of binarity analysis This contribution is, like TK07, part of a series on the theoretical interpretation of observational stellar cluster data. |
Kroupa et al. ( 1991 1993 ); Kroupa ( 2001 showed for the first time that the true individual-body stellar IMF is changed significantly by correcting for the bias due to unresolved binary stars. A detailed study in |
Kroupa ( 1995a , in Kroupa, Petr & McCaughrean ( 1999 , and in Kroupa, Aarseth & Hurley ( 2001 of the observed binary properties of field stars, stars in the Orion Nebula Cluster (ONC), the Pleiades and the Taurus-Auriga association (TA) led to a thorough understanding of the energy distribution of binary systems. This... |
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