Exploring Tidal Disruption Events: X-ray Insights and Discoveries

1. Peter Maksym University of Alabama wpmaksym@ua.edu, @StellarBones Chandra and the X-ray Viewof Tidal Disruption Events Left: A1795 X-ray/optical CXO/Maksym et al./Donato et al press release, 2014; Right: Maksym et al. 2013 15 Years of Chandra: Chandra and the X-ray View of TDEs, Peter Maksym

2. 15 Years of Chandra: Chandra and the X-ray View of TDEs, Peter Maksym

3. 15 Years of Chandra: Chandra and the X-ray View of TDEs, Peter Maksym X-ray Selection and Follow-up

4. 15 Years of Chandra: Chandra and the X-ray View of TDEs, Peter Maksym Chandra and ROSAT flares • First TDEs seen in ROSAT • NGC 5905 (Bade et al., 1996) • RX J1242-11A (Komossa & Greiner, 1999) • RX J1624+75 (Grupe et al., 1999) • RX J1420+53 (Greiner et al, 2000) • Chandra follow-up with Halpern et al. (2004, left) critical to: • Demonstrate nuclear location • Eliminate confusion • Sensitivity: 10-yr extreme (x6000) variability • Spectral hardening? Still relatively soft

5. 15 Years of Chandra: Chandra and the X-ray View of TDEs, Peter Maksym Follow-up of UV/Optical Flares • UV/X-ray – extremely important for distinguishing optical TDEs from nuclear SNe • X-ray Detections: • Gezari et al. (2006, 2008, upper-right) – Chandra • D3-13 • ruled out pre-existing AGN with deep AEGIS observations • LX~1043 erg/s, Γ~7, ~day-scale variability ~1 year post-disruption • D1-9 • LX~3.5 x 1041 erg/s, 2 years post-disruption • X-rays require hotter temperatures than UV blackbody • trace different radii, physical regimes: inner disk, debris near Rd • Arcavi et al. (2014) – Swift • PTF 09axc, ~7 x 1042 erg/s ~5 years post-disruption • Non-detections • Gezari et al. (2009) – Chandra • D23H-1 • LX<1041 erg/s, 3 days & 116 days post-disruption • Gezari et al. (2012 – lower right) – Chandra • PS-10jh – disrupted helium core or (Guillochon 2014) ordinary? • Lx<5.8 x 1041 erg/s, >200 days post-peak • Arcavi et al. (2014) – Swift • PTF 09ge (<2 x 1042 erg/s), 09djl (<2 x 1043 erg/s), ~5 years post-disruption

6. 15 Years of Chandra: Chandra and the X-ray View of TDEs, Peter Maksym Finding (and following) TDEs with Chandra • Variability search in CDF: Luo et al. (2008) – upper limits, no detections • ..but see Luo et al. (2014) Atel 6625 – possible TDE at z~1.5 ?!? • CXO J033831.8-352604 – Gradually decaying ULX in GC of NGC 1399 (Fornax) • [O III] and [N II] but no Balmer... evidence for a TDE? (Irwin et al, 2010, left) • Consistent with TDE of red clump HB star by 50-100 Msun BH (Clausen et al., 2012) • See also poster by Dacheng Lin – late-term Chandra follow-up of 2XMMi J184725.1-631724 (identified in Lin et al., 2011 – right)

7. 15 Years of Chandra: Chandra and the X-ray View of TDEs, Peter Maksym Relativistic Flares! • Swift J1644+57: multiple Swift-BAT triggers, regular monitoring for 3+ years • Breaks the mold: Hard Spectrum, attributed to beamed line-of-sight jet (blazar analogue) (Levan et al., 2011; Burrows et al., 2011; Bloom et al., 2011; many subsequent papers) • Extremely bright; ~1048 erg/s inferred • Fits t-5/3 decay for >1 yr, but highly variable – large epoch-to-epoch variations • First ~500 days emission probably due to internal dissipation of jet (Burrows et al., 2011; Bloom et al., 2011, Zauderer et al, 2011, Metzger et al, 2012, Liu et al, 2012, Zou et al, 2013) • Dramatic transition! Jet shuts off • Chandra observation at ~610 days: Too hard disk accretion. Consistent with a forward shock? Zauderer et al (2013, UR) • Inverse compton cooling in an external shock? (Kumar et al., 2013) • Swift J2058+05: Another relativistic flare (Cenko et al., 2012; top, LR) • Both flares localized with Chandra HRC

8. 15 Years of Chandra: Chandra and the X-ray View of TDEs, Peter Maksym Tidal Disruptions in Galaxy Clusters UL: CXO/Maksym et al./Donato et al. press release UR: Maksym et al. (2013) –A1795 LR: Maksym et al. (2010) -A1689

9. 15 Years of Chandra: Chandra and the X-ray View of TDEs, Peter Maksym Tidal Disruptions in Galaxy Clusters UL: Cappeluti: ROSAT & optical, w/X-ray error circles UR: WINGS J1348 in A1795, XMM(<500 eV) blue, Gemini red, XMM (2 arcsec) and Chandra (<0.5 arcsec) error circles (See Maksym et al. 2013; 2014; Donato et al., 2014)

10. 15 Years of Chandra: Chandra and the X-ray View of TDEs, Peter Maksym What Don't We know? • How common is X-ray emission from TDEs? • Is there a dichotomy between X-ray selected flares (e.g. via ROSAT, XMM-Newton [Esquej et al., 2007; 2008; Lin et al., 2011]) and optically selected flares with upper limits? • How well do existing multi-band models describe X-ray evolution beyond t-5/3 (e.g. Lodato & Rossi 2009; 2011; Strubbe & Quataert 2009; 2011; Guillochon et al, 2014) • Can super-Eddington accretion smother the X-ray emission (e.g. “Dougie” from ROTSE; Vinko et al., 2014) • Does X-ray emission require a preferred viewing angle? • Could X-ray emission occupy a preferred “phase” of TDE evolution? • Modulated accretion rate (Lodato & Rossi, 2011) • Evolving debris covering fraction (Strubbe & Quataert, 2009) • Changing opacity • Changing temperature (Lodato & Rossi 2011) • How common are jets, and how do they form? • What about X-ray emission/absorption lines/edges? (e.g. Strubbe & Quataert 2011) • What can we learn from PDS analysis (e.g. Lin et al., 2011; Reis et al., 2012)

11. 15 Years of Chandra: Chandra and the X-ray View of TDEs, Peter Maksym Where Should We Go? • Solid physical basis for optical selection • Important groundwork before LSST can be used for statistical purposes • More X-ray selected events with prompt multi-wavelength follow-up • Chandra/XMM cluster monitoring? It would take an XVP • TDEs are rare, so TDE “surveys” need to be parasitic by nature • Sociological paradigm shift • If you're not interested in your point sources, share them... • ...or don't share – but do check! • eROSITA • Aggressive X-ray follow-up of low-z optical flares • Abundance of data – easier to rule out AGN • Good astrometry – easier to rule out SNe • Swift can select, follow-up with Chandra/XMM • Long-term monitoring – Early & Late • Easiest for bright, nearby flares • Check e.g. for corona formation • Cooling out-of-band (e.g. Lodato & Rossi, 2011) • Frequent enough to ignore stochastic variability (see, e.g. Liu et al., 2014) Maksym et al., 2014, based on Lodato & Rossi 2011; See also Khabibullin & Sazonov, 2014